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 // Copyright 2007, Google Inc.
 // All rights reserved.
 //
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
 // in the documentation and/or other materials provided with the
 // distribution.
 //     * Neither the name of Google Inc. nor the names of its
 // contributors may be used to endorse or promote products derived from
 // this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 //
 // Author: wan@google.com (Zhanyong Wan)
 
 // Google Mock - a framework for writing C++ mock classes.
 //
 // This file implements some commonly used argument matchers.  More
 // matchers can be defined by the user implementing the
 // MatcherInterface<T> interface if necessary.
 
 #ifndef GMOCK_INCLUDE_GMOCK_GMOCK_MATCHERS_H_
 #define GMOCK_INCLUDE_GMOCK_GMOCK_MATCHERS_H_
 
 #include <math.h>
 #include <algorithm>
 #include <iterator>
 #include <limits>
 #include <ostream>  // NOLINT
 #include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "gmock/internal/gmock-internal-utils.h"
 #include "gmock/internal/gmock-port.h"
 #include "gtest/gtest.h"
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 # include <initializer_list>  // NOLINT -- must be after gtest.h
 #endif
 
 namespace testing {
 
 // To implement a matcher Foo for type T, define:
 //   1. a class FooMatcherImpl that implements the
 //      MatcherInterface<T> interface, and
 //   2. a factory function that creates a Matcher<T> object from a
 //      FooMatcherImpl*.
 //
 // The two-level delegation design makes it possible to allow a user
 // to write "v" instead of "Eq(v)" where a Matcher is expected, which
 // is impossible if we pass matchers by pointers.  It also eases
 // ownership management as Matcher objects can now be copied like
 // plain values.
 
 // MatchResultListener is an abstract class.  Its << operator can be
 // used by a matcher to explain why a value matches or doesn't match.
 //
 // TODO(wan@google.com): add method
 //   bool InterestedInWhy(bool result) const;
 // to indicate whether the listener is interested in why the match
 // result is 'result'.
 class MatchResultListener {
  public:
   // Creates a listener object with the given underlying ostream.  The
   // listener does not own the ostream, and does not dereference it
   // in the constructor or destructor.
   explicit MatchResultListener(::std::ostream* os) : stream_(os) {}
   virtual ~MatchResultListener() = 0;  // Makes this class abstract.
 
   // Streams x to the underlying ostream; does nothing if the ostream
   // is NULL.
   template <typename T>
   MatchResultListener& operator<<(const T& x) {
     if (stream_ != NULL)
       *stream_ << x;
     return *this;
   }
 
   // Returns the underlying ostream.
   ::std::ostream* stream() { return stream_; }
 
   // Returns true iff the listener is interested in an explanation of
   // the match result.  A matcher's MatchAndExplain() method can use
   // this information to avoid generating the explanation when no one
   // intends to hear it.
   bool IsInterested() const { return stream_ != NULL; }
 
  private:
   ::std::ostream* const stream_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(MatchResultListener);
 };
 
 inline MatchResultListener::~MatchResultListener() {
 }
 
 // An instance of a subclass of this knows how to describe itself as a
 // matcher.
 class MatcherDescriberInterface {
  public:
   virtual ~MatcherDescriberInterface() {}
 
   // Describes this matcher to an ostream.  The function should print
   // a verb phrase that describes the property a value matching this
   // matcher should have.  The subject of the verb phrase is the value
   // being matched.  For example, the DescribeTo() method of the Gt(7)
   // matcher prints "is greater than 7".
   virtual void DescribeTo(::std::ostream* os) const = 0;
 
   // Describes the negation of this matcher to an ostream.  For
   // example, if the description of this matcher is "is greater than
   // 7", the negated description could be "is not greater than 7".
   // You are not required to override this when implementing
   // MatcherInterface, but it is highly advised so that your matcher
   // can produce good error messages.
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "not (";
     DescribeTo(os);
     *os << ")";
   }
 };
 
 // The implementation of a matcher.
 template <typename T>
 class MatcherInterface : public MatcherDescriberInterface {
  public:
   // Returns true iff the matcher matches x; also explains the match
   // result to 'listener' if necessary (see the next paragraph), in
   // the form of a non-restrictive relative clause ("which ...",
   // "whose ...", etc) that describes x.  For example, the
   // MatchAndExplain() method of the Pointee(...) matcher should
   // generate an explanation like "which points to ...".
   //
   // Implementations of MatchAndExplain() should add an explanation of
   // the match result *if and only if* they can provide additional
   // information that's not already present (or not obvious) in the
   // print-out of x and the matcher's description.  Whether the match
   // succeeds is not a factor in deciding whether an explanation is
   // needed, as sometimes the caller needs to print a failure message
   // when the match succeeds (e.g. when the matcher is used inside
   // Not()).
   //
   // For example, a "has at least 10 elements" matcher should explain
   // what the actual element count is, regardless of the match result,
   // as it is useful information to the reader; on the other hand, an
   // "is empty" matcher probably only needs to explain what the actual
   // size is when the match fails, as it's redundant to say that the
   // size is 0 when the value is already known to be empty.
   //
   // You should override this method when defining a new matcher.
   //
   // It's the responsibility of the caller (Google Mock) to guarantee
   // that 'listener' is not NULL.  This helps to simplify a matcher's
   // implementation when it doesn't care about the performance, as it
   // can talk to 'listener' without checking its validity first.
   // However, in order to implement dummy listeners efficiently,
   // listener->stream() may be NULL.
   virtual bool MatchAndExplain(T x, MatchResultListener* listener) const = 0;
 
   // Inherits these methods from MatcherDescriberInterface:
   //   virtual void DescribeTo(::std::ostream* os) const = 0;
   //   virtual void DescribeNegationTo(::std::ostream* os) const;
 };
 
 // A match result listener that stores the explanation in a string.
 class StringMatchResultListener : public MatchResultListener {
  public:
   StringMatchResultListener() : MatchResultListener(&ss_) {}
 
   // Returns the explanation accumulated so far.
   internal::string str() const { return ss_.str(); }
 
   // Clears the explanation accumulated so far.
   void Clear() { ss_.str(""); }
 
  private:
   ::std::stringstream ss_;
 
   GTEST_DISALLOW_COPY_AND_ASSIGN_(StringMatchResultListener);
 };
 
 namespace internal {
 
 struct AnyEq {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a == b; }
 };
 struct AnyNe {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a != b; }
 };
 struct AnyLt {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a < b; }
 };
 struct AnyGt {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a > b; }
 };
 struct AnyLe {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a <= b; }
 };
 struct AnyGe {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a >= b; }
 };
 
 // A match result listener that ignores the explanation.
 class DummyMatchResultListener : public MatchResultListener {
  public:
   DummyMatchResultListener() : MatchResultListener(NULL) {}
 
  private:
   GTEST_DISALLOW_COPY_AND_ASSIGN_(DummyMatchResultListener);
 };
 
 // A match result listener that forwards the explanation to a given
 // ostream.  The difference between this and MatchResultListener is
 // that the former is concrete.
 class StreamMatchResultListener : public MatchResultListener {
  public:
   explicit StreamMatchResultListener(::std::ostream* os)
       : MatchResultListener(os) {}
 
  private:
   GTEST_DISALLOW_COPY_AND_ASSIGN_(StreamMatchResultListener);
 };
 
 // An internal class for implementing Matcher<T>, which will derive
 // from it.  We put functionalities common to all Matcher<T>
 // specializations here to avoid code duplication.
 template <typename T>
 class MatcherBase {
  public:
   // Returns true iff the matcher matches x; also explains the match
   // result to 'listener'.
   bool MatchAndExplain(T x, MatchResultListener* listener) const {
     return impl_->MatchAndExplain(x, listener);
   }
 
   // Returns true iff this matcher matches x.
   bool Matches(T x) const {
     DummyMatchResultListener dummy;
     return MatchAndExplain(x, &dummy);
   }
 
   // Describes this matcher to an ostream.
   void DescribeTo(::std::ostream* os) const { impl_->DescribeTo(os); }
 
   // Describes the negation of this matcher to an ostream.
   void DescribeNegationTo(::std::ostream* os) const {
     impl_->DescribeNegationTo(os);
   }
 
   // Explains why x matches, or doesn't match, the matcher.
   void ExplainMatchResultTo(T x, ::std::ostream* os) const {
     StreamMatchResultListener listener(os);
     MatchAndExplain(x, &listener);
   }
 
   // Returns the describer for this matcher object; retains ownership
   // of the describer, which is only guaranteed to be alive when
   // this matcher object is alive.
   const MatcherDescriberInterface* GetDescriber() const {
     return impl_.get();
   }
 
  protected:
   MatcherBase() {}
 
   // Constructs a matcher from its implementation.
   explicit MatcherBase(const MatcherInterface<T>* impl)
       : impl_(impl) {}
 
   virtual ~MatcherBase() {}
 
  private:
   // shared_ptr (util/gtl/shared_ptr.h) and linked_ptr have similar
   // interfaces.  The former dynamically allocates a chunk of memory
   // to hold the reference count, while the latter tracks all
   // references using a circular linked list without allocating
   // memory.  It has been observed that linked_ptr performs better in
   // typical scenarios.  However, shared_ptr can out-perform
   // linked_ptr when there are many more uses of the copy constructor
   // than the default constructor.
   //
   // If performance becomes a problem, we should see if using
   // shared_ptr helps.
   ::testing::internal::linked_ptr<const MatcherInterface<T> > impl_;
 };
 
 }  // namespace internal
 
 // A Matcher<T> is a copyable and IMMUTABLE (except by assignment)
 // object that can check whether a value of type T matches.  The
 // implementation of Matcher<T> is just a linked_ptr to const
 // MatcherInterface<T>, so copying is fairly cheap.  Don't inherit
 // from Matcher!
 template <typename T>
 class Matcher : public internal::MatcherBase<T> {
  public:
   // Constructs a null matcher.  Needed for storing Matcher objects in STL
   // containers.  A default-constructed matcher is not yet initialized.  You
   // cannot use it until a valid value has been assigned to it.
   explicit Matcher() {}  // NOLINT
 
   // Constructs a matcher from its implementation.
   explicit Matcher(const MatcherInterface<T>* impl)
       : internal::MatcherBase<T>(impl) {}
 
   // Implicit constructor here allows people to write
   // EXPECT_CALL(foo, Bar(5)) instead of EXPECT_CALL(foo, Bar(Eq(5))) sometimes
   Matcher(T value);  // NOLINT
 };
 
 // The following two specializations allow the user to write str
 // instead of Eq(str) and "foo" instead of Eq("foo") when a string
 // matcher is expected.
 template <>
 class GTEST_API_ Matcher<const internal::string&>
     : public internal::MatcherBase<const internal::string&> {
  public:
   Matcher() {}
 
   explicit Matcher(const MatcherInterface<const internal::string&>* impl)
       : internal::MatcherBase<const internal::string&>(impl) {}
 
   // Allows the user to write str instead of Eq(str) sometimes, where
   // str is a string object.
   Matcher(const internal::string& s);  // NOLINT
 
   // Allows the user to write "foo" instead of Eq("foo") sometimes.
   Matcher(const char* s);  // NOLINT
 };
 
 template <>
 class GTEST_API_ Matcher<internal::string>
     : public internal::MatcherBase<internal::string> {
  public:
   Matcher() {}
 
   explicit Matcher(const MatcherInterface<internal::string>* impl)
       : internal::MatcherBase<internal::string>(impl) {}
 
   // Allows the user to write str instead of Eq(str) sometimes, where
   // str is a string object.
   Matcher(const internal::string& s);  // NOLINT
 
   // Allows the user to write "foo" instead of Eq("foo") sometimes.
   Matcher(const char* s);  // NOLINT
 };
 
 #if GTEST_HAS_STRING_PIECE_
 // The following two specializations allow the user to write str
 // instead of Eq(str) and "foo" instead of Eq("foo") when a StringPiece
 // matcher is expected.
 template <>
 class GTEST_API_ Matcher<const StringPiece&>
     : public internal::MatcherBase<const StringPiece&> {
  public:
   Matcher() {}
 
   explicit Matcher(const MatcherInterface<const StringPiece&>* impl)
       : internal::MatcherBase<const StringPiece&>(impl) {}
 
   // Allows the user to write str instead of Eq(str) sometimes, where
   // str is a string object.
   Matcher(const internal::string& s);  // NOLINT
 
   // Allows the user to write "foo" instead of Eq("foo") sometimes.
   Matcher(const char* s);  // NOLINT
 
   // Allows the user to pass StringPieces directly.
   Matcher(StringPiece s);  // NOLINT
 };
 
 template <>
 class GTEST_API_ Matcher<StringPiece>
     : public internal::MatcherBase<StringPiece> {
  public:
   Matcher() {}
 
   explicit Matcher(const MatcherInterface<StringPiece>* impl)
       : internal::MatcherBase<StringPiece>(impl) {}
 
   // Allows the user to write str instead of Eq(str) sometimes, where
   // str is a string object.
   Matcher(const internal::string& s);  // NOLINT
 
   // Allows the user to write "foo" instead of Eq("foo") sometimes.
   Matcher(const char* s);  // NOLINT
 
   // Allows the user to pass StringPieces directly.
   Matcher(StringPiece s);  // NOLINT
 };
 #endif  // GTEST_HAS_STRING_PIECE_
 
 // The PolymorphicMatcher class template makes it easy to implement a
 // polymorphic matcher (i.e. a matcher that can match values of more
 // than one type, e.g. Eq(n) and NotNull()).
 //
 // To define a polymorphic matcher, a user should provide an Impl
 // class that has a DescribeTo() method and a DescribeNegationTo()
 // method, and define a member function (or member function template)
 //
 //   bool MatchAndExplain(const Value& value,
 //                        MatchResultListener* listener) const;
 //
 // See the definition of NotNull() for a complete example.
 template <class Impl>
 class PolymorphicMatcher {
  public:
   explicit PolymorphicMatcher(const Impl& an_impl) : impl_(an_impl) {}
 
   // Returns a mutable reference to the underlying matcher
   // implementation object.
   Impl& mutable_impl() { return impl_; }
 
   // Returns an immutable reference to the underlying matcher
   // implementation object.
   const Impl& impl() const { return impl_; }
 
   template <typename T>
   operator Matcher<T>() const {
     return Matcher<T>(new MonomorphicImpl<T>(impl_));
   }
 
  private:
   template <typename T>
   class MonomorphicImpl : public MatcherInterface<T> {
    public:
     explicit MonomorphicImpl(const Impl& impl) : impl_(impl) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       impl_.DescribeTo(os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       impl_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
       return impl_.MatchAndExplain(x, listener);
     }
 
    private:
     const Impl impl_;
 
     GTEST_DISALLOW_ASSIGN_(MonomorphicImpl);
   };
 
   Impl impl_;
 
   GTEST_DISALLOW_ASSIGN_(PolymorphicMatcher);
 };
 
 // Creates a matcher from its implementation.  This is easier to use
 // than the Matcher<T> constructor as it doesn't require you to
 // explicitly write the template argument, e.g.
 //
 //   MakeMatcher(foo);
 // vs
 //   Matcher<const string&>(foo);
 template <typename T>
 inline Matcher<T> MakeMatcher(const MatcherInterface<T>* impl) {
   return Matcher<T>(impl);
 }
 
 // Creates a polymorphic matcher from its implementation.  This is
 // easier to use than the PolymorphicMatcher<Impl> constructor as it
 // doesn't require you to explicitly write the template argument, e.g.
 //
 //   MakePolymorphicMatcher(foo);
 // vs
 //   PolymorphicMatcher<TypeOfFoo>(foo);
 template <class Impl>
 inline PolymorphicMatcher<Impl> MakePolymorphicMatcher(const Impl& impl) {
   return PolymorphicMatcher<Impl>(impl);
 }
 
 // Anything inside the 'internal' namespace IS INTERNAL IMPLEMENTATION
 // and MUST NOT BE USED IN USER CODE!!!
 namespace internal {
 
 // The MatcherCastImpl class template is a helper for implementing
 // MatcherCast().  We need this helper in order to partially
 // specialize the implementation of MatcherCast() (C++ allows
 // class/struct templates to be partially specialized, but not
 // function templates.).
 
 // This general version is used when MatcherCast()'s argument is a
 // polymorphic matcher (i.e. something that can be converted to a
 // Matcher but is not one yet; for example, Eq(value)) or a value (for
 // example, "hello").
 template <typename T, typename M>
 class MatcherCastImpl {
  public:
   static Matcher<T> Cast(const M& polymorphic_matcher_or_value) {
     // M can be a polymorhic matcher, in which case we want to use
     // its conversion operator to create Matcher<T>.  Or it can be a value
     // that should be passed to the Matcher<T>'s constructor.
     //
     // We can't call Matcher<T>(polymorphic_matcher_or_value) when M is a
     // polymorphic matcher because it'll be ambiguous if T has an implicit
     // constructor from M (this usually happens when T has an implicit
     // constructor from any type).
     //
     // It won't work to unconditionally implict_cast
     // polymorphic_matcher_or_value to Matcher<T> because it won't trigger
     // a user-defined conversion from M to T if one exists (assuming M is
     // a value).
     return CastImpl(
         polymorphic_matcher_or_value,
         BooleanConstant<
             internal::ImplicitlyConvertible<M, Matcher<T> >::value>());
   }
 
  private:
   static Matcher<T> CastImpl(const M& value, BooleanConstant<false>) {
     // M can't be implicitly converted to Matcher<T>, so M isn't a polymorphic
     // matcher.  It must be a value then.  Use direct initialization to create
     // a matcher.
     return Matcher<T>(ImplicitCast_<T>(value));
   }
 
   static Matcher<T> CastImpl(const M& polymorphic_matcher_or_value,
                              BooleanConstant<true>) {
     // M is implicitly convertible to Matcher<T>, which means that either
     // M is a polymorhpic matcher or Matcher<T> has an implicit constructor
     // from M.  In both cases using the implicit conversion will produce a
     // matcher.
     //
     // Even if T has an implicit constructor from M, it won't be called because
     // creating Matcher<T> would require a chain of two user-defined conversions
     // (first to create T from M and then to create Matcher<T> from T).
     return polymorphic_matcher_or_value;
   }
 };
 
 // This more specialized version is used when MatcherCast()'s argument
 // is already a Matcher.  This only compiles when type T can be
 // statically converted to type U.
 template <typename T, typename U>
 class MatcherCastImpl<T, Matcher<U> > {
  public:
   static Matcher<T> Cast(const Matcher<U>& source_matcher) {
     return Matcher<T>(new Impl(source_matcher));
   }
 
  private:
   class Impl : public MatcherInterface<T> {
    public:
     explicit Impl(const Matcher<U>& source_matcher)
         : source_matcher_(source_matcher) {}
 
     // We delegate the matching logic to the source matcher.
     virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
       return source_matcher_.MatchAndExplain(static_cast<U>(x), listener);
     }
 
     virtual void DescribeTo(::std::ostream* os) const {
       source_matcher_.DescribeTo(os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       source_matcher_.DescribeNegationTo(os);
     }
 
    private:
     const Matcher<U> source_matcher_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 };
 
 // This even more specialized version is used for efficiently casting
 // a matcher to its own type.
 template <typename T>
 class MatcherCastImpl<T, Matcher<T> > {
  public:
   static Matcher<T> Cast(const Matcher<T>& matcher) { return matcher; }
 };
 
 }  // namespace internal
 
 // In order to be safe and clear, casting between different matcher
 // types is done explicitly via MatcherCast<T>(m), which takes a
 // matcher m and returns a Matcher<T>.  It compiles only when T can be
 // statically converted to the argument type of m.
 template <typename T, typename M>
 inline Matcher<T> MatcherCast(const M& matcher) {
   return internal::MatcherCastImpl<T, M>::Cast(matcher);
 }
 
 // Implements SafeMatcherCast().
 //
 // We use an intermediate class to do the actual safe casting as Nokia's
 // Symbian compiler cannot decide between
 // template <T, M> ... (M) and
 // template <T, U> ... (const Matcher<U>&)
 // for function templates but can for member function templates.
 template <typename T>
 class SafeMatcherCastImpl {
  public:
   // This overload handles polymorphic matchers and values only since
   // monomorphic matchers are handled by the next one.
   template <typename M>
   static inline Matcher<T> Cast(const M& polymorphic_matcher_or_value) {
     return internal::MatcherCastImpl<T, M>::Cast(polymorphic_matcher_or_value);
   }
 
   // This overload handles monomorphic matchers.
   //
   // In general, if type T can be implicitly converted to type U, we can
   // safely convert a Matcher<U> to a Matcher<T> (i.e. Matcher is
   // contravariant): just keep a copy of the original Matcher<U>, convert the
   // argument from type T to U, and then pass it to the underlying Matcher<U>.
   // The only exception is when U is a reference and T is not, as the
   // underlying Matcher<U> may be interested in the argument's address, which
   // is not preserved in the conversion from T to U.
   template <typename U>
   static inline Matcher<T> Cast(const Matcher<U>& matcher) {
     // Enforce that T can be implicitly converted to U.
     GTEST_COMPILE_ASSERT_((internal::ImplicitlyConvertible<T, U>::value),
                           T_must_be_implicitly_convertible_to_U);
     // Enforce that we are not converting a non-reference type T to a reference
     // type U.
     GTEST_COMPILE_ASSERT_(
         internal::is_reference<T>::value || !internal::is_reference<U>::value,
         cannot_convert_non_referentce_arg_to_reference);
     // In case both T and U are arithmetic types, enforce that the
     // conversion is not lossy.
     typedef GTEST_REMOVE_REFERENCE_AND_CONST_(T) RawT;
     typedef GTEST_REMOVE_REFERENCE_AND_CONST_(U) RawU;
     const bool kTIsOther = GMOCK_KIND_OF_(RawT) == internal::kOther;
     const bool kUIsOther = GMOCK_KIND_OF_(RawU) == internal::kOther;
     GTEST_COMPILE_ASSERT_(
         kTIsOther || kUIsOther ||
         (internal::LosslessArithmeticConvertible<RawT, RawU>::value),
         conversion_of_arithmetic_types_must_be_lossless);
     return MatcherCast<T>(matcher);
   }
 };
 
 template <typename T, typename M>
 inline Matcher<T> SafeMatcherCast(const M& polymorphic_matcher) {
   return SafeMatcherCastImpl<T>::Cast(polymorphic_matcher);
 }
 
 // A<T>() returns a matcher that matches any value of type T.
 template <typename T>
 Matcher<T> A();
 
 // Anything inside the 'internal' namespace IS INTERNAL IMPLEMENTATION
 // and MUST NOT BE USED IN USER CODE!!!
 namespace internal {
 
 // If the explanation is not empty, prints it to the ostream.
 inline void PrintIfNotEmpty(const internal::string& explanation,
                             ::std::ostream* os) {
   if (explanation != "" && os != NULL) {
     *os << ", " << explanation;
   }
 }
 
 // Returns true if the given type name is easy to read by a human.
 // This is used to decide whether printing the type of a value might
 // be helpful.
 inline bool IsReadableTypeName(const string& type_name) {
   // We consider a type name readable if it's short or doesn't contain
   // a template or function type.
   return (type_name.length() <= 20 ||
           type_name.find_first_of("<(") == string::npos);
 }
 
 // Matches the value against the given matcher, prints the value and explains
 // the match result to the listener. Returns the match result.
 // 'listener' must not be NULL.
 // Value cannot be passed by const reference, because some matchers take a
 // non-const argument.
 template <typename Value, typename T>
 bool MatchPrintAndExplain(Value& value, const Matcher<T>& matcher,
                           MatchResultListener* listener) {
   if (!listener->IsInterested()) {
     // If the listener is not interested, we do not need to construct the
     // inner explanation.
     return matcher.Matches(value);
   }
 
   StringMatchResultListener inner_listener;
   const bool match = matcher.MatchAndExplain(value, &inner_listener);
 
   UniversalPrint(value, listener->stream());
 #if GTEST_HAS_RTTI
   const string& type_name = GetTypeName<Value>();
   if (IsReadableTypeName(type_name))
     *listener->stream() << " (of type " << type_name << ")";
 #endif
   PrintIfNotEmpty(inner_listener.str(), listener->stream());
 
   return match;
 }
 
 // An internal helper class for doing compile-time loop on a tuple's
 // fields.
 template <size_t N>
 class TuplePrefix {
  public:
   // TuplePrefix<N>::Matches(matcher_tuple, value_tuple) returns true
   // iff the first N fields of matcher_tuple matches the first N
   // fields of value_tuple, respectively.
   template <typename MatcherTuple, typename ValueTuple>
   static bool Matches(const MatcherTuple& matcher_tuple,
                       const ValueTuple& value_tuple) {
     return TuplePrefix<N - 1>::Matches(matcher_tuple, value_tuple)
         && get<N - 1>(matcher_tuple).Matches(get<N - 1>(value_tuple));
   }
 
   // TuplePrefix<N>::ExplainMatchFailuresTo(matchers, values, os)
   // describes failures in matching the first N fields of matchers
   // against the first N fields of values.  If there is no failure,
   // nothing will be streamed to os.
   template <typename MatcherTuple, typename ValueTuple>
   static void ExplainMatchFailuresTo(const MatcherTuple& matchers,
                                      const ValueTuple& values,
                                      ::std::ostream* os) {
     // First, describes failures in the first N - 1 fields.
     TuplePrefix<N - 1>::ExplainMatchFailuresTo(matchers, values, os);
 
     // Then describes the failure (if any) in the (N - 1)-th (0-based)
     // field.
     typename tuple_element<N - 1, MatcherTuple>::type matcher =
         get<N - 1>(matchers);
     typedef typename tuple_element<N - 1, ValueTuple>::type Value;
     Value value = get<N - 1>(values);
     StringMatchResultListener listener;
     if (!matcher.MatchAndExplain(value, &listener)) {
       // TODO(wan): include in the message the name of the parameter
       // as used in MOCK_METHOD*() when possible.
       *os << "  Expected arg #" << N - 1 << ": ";
       get<N - 1>(matchers).DescribeTo(os);
       *os << "\n           Actual: ";
       // We remove the reference in type Value to prevent the
       // universal printer from printing the address of value, which
       // isn't interesting to the user most of the time.  The
       // matcher's MatchAndExplain() method handles the case when
       // the address is interesting.
       internal::UniversalPrint(value, os);
       PrintIfNotEmpty(listener.str(), os);
       *os << "\n";
     }
   }
 };
 
 // The base case.
 template <>
 class TuplePrefix<0> {
  public:
   template <typename MatcherTuple, typename ValueTuple>
   static bool Matches(const MatcherTuple& /* matcher_tuple */,
                       const ValueTuple& /* value_tuple */) {
     return true;
   }
 
   template <typename MatcherTuple, typename ValueTuple>
   static void ExplainMatchFailuresTo(const MatcherTuple& /* matchers */,
                                      const ValueTuple& /* values */,
                                      ::std::ostream* /* os */) {}
 };
 
 // TupleMatches(matcher_tuple, value_tuple) returns true iff all
 // matchers in matcher_tuple match the corresponding fields in
 // value_tuple.  It is a compiler error if matcher_tuple and
 // value_tuple have different number of fields or incompatible field
 // types.
 template <typename MatcherTuple, typename ValueTuple>
 bool TupleMatches(const MatcherTuple& matcher_tuple,
                   const ValueTuple& value_tuple) {
   // Makes sure that matcher_tuple and value_tuple have the same
   // number of fields.
   GTEST_COMPILE_ASSERT_(tuple_size<MatcherTuple>::value ==
                         tuple_size<ValueTuple>::value,
                         matcher_and_value_have_different_numbers_of_fields);
   return TuplePrefix<tuple_size<ValueTuple>::value>::
       Matches(matcher_tuple, value_tuple);
 }
 
 // Describes failures in matching matchers against values.  If there
 // is no failure, nothing will be streamed to os.
 template <typename MatcherTuple, typename ValueTuple>
 void ExplainMatchFailureTupleTo(const MatcherTuple& matchers,
                                 const ValueTuple& values,
                                 ::std::ostream* os) {
   TuplePrefix<tuple_size<MatcherTuple>::value>::ExplainMatchFailuresTo(
       matchers, values, os);
 }
 
 // TransformTupleValues and its helper.
 //
 // TransformTupleValuesHelper hides the internal machinery that
 // TransformTupleValues uses to implement a tuple traversal.
 template <typename Tuple, typename Func, typename OutIter>
 class TransformTupleValuesHelper {
  private:
   typedef ::testing::tuple_size<Tuple> TupleSize;
 
  public:
   // For each member of tuple 't', taken in order, evaluates '*out++ = f(t)'.
   // Returns the final value of 'out' in case the caller needs it.
   static OutIter Run(Func f, const Tuple& t, OutIter out) {
     return IterateOverTuple<Tuple, TupleSize::value>()(f, t, out);
   }
 
  private:
   template <typename Tup, size_t kRemainingSize>
   struct IterateOverTuple {
     OutIter operator() (Func f, const Tup& t, OutIter out) const {
       *out++ = f(::testing::get<TupleSize::value - kRemainingSize>(t));
       return IterateOverTuple<Tup, kRemainingSize - 1>()(f, t, out);
     }
   };
   template <typename Tup>
   struct IterateOverTuple<Tup, 0> {
     OutIter operator() (Func /* f */, const Tup& /* t */, OutIter out) const {
       return out;
     }
   };
 };
 
 // Successively invokes 'f(element)' on each element of the tuple 't',
 // appending each result to the 'out' iterator. Returns the final value
 // of 'out'.
 template <typename Tuple, typename Func, typename OutIter>
 OutIter TransformTupleValues(Func f, const Tuple& t, OutIter out) {
   return TransformTupleValuesHelper<Tuple, Func, OutIter>::Run(f, t, out);
 }
 
 // Implements A<T>().
 template <typename T>
 class AnyMatcherImpl : public MatcherInterface<T> {
  public:
   virtual bool MatchAndExplain(
       T /* x */, MatchResultListener* /* listener */) const { return true; }
   virtual void DescribeTo(::std::ostream* os) const { *os << "is anything"; }
   virtual void DescribeNegationTo(::std::ostream* os) const {
     // This is mostly for completeness' safe, as it's not very useful
     // to write Not(A<bool>()).  However we cannot completely rule out
     // such a possibility, and it doesn't hurt to be prepared.
     *os << "never matches";
   }
 };
 
 // Implements _, a matcher that matches any value of any
 // type.  This is a polymorphic matcher, so we need a template type
 // conversion operator to make it appearing as a Matcher<T> for any
 // type T.
 class AnythingMatcher {
  public:
   template <typename T>
   operator Matcher<T>() const { return A<T>(); }
 };
 
 // Implements a matcher that compares a given value with a
 // pre-supplied value using one of the ==, <=, <, etc, operators.  The
 // two values being compared don't have to have the same type.
 //
 // The matcher defined here is polymorphic (for example, Eq(5) can be
 // used to match an int, a short, a double, etc).  Therefore we use
 // a template type conversion operator in the implementation.
 //
 // The following template definition assumes that the Rhs parameter is
 // a "bare" type (i.e. neither 'const T' nor 'T&').
 template <typename D, typename Rhs, typename Op>
 class ComparisonBase {
  public:
   explicit ComparisonBase(const Rhs& rhs) : rhs_(rhs) {}
   template <typename Lhs>
   operator Matcher<Lhs>() const {
     return MakeMatcher(new Impl<Lhs>(rhs_));
   }
 
  private:
   template <typename Lhs>
   class Impl : public MatcherInterface<Lhs> {
    public:
     explicit Impl(const Rhs& rhs) : rhs_(rhs) {}
     virtual bool MatchAndExplain(
         Lhs lhs, MatchResultListener* /* listener */) const {
       return Op()(lhs, rhs_);
     }
     virtual void DescribeTo(::std::ostream* os) const {
       *os << D::Desc() << " ";
       UniversalPrint(rhs_, os);
     }
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << D::NegatedDesc() <<  " ";
       UniversalPrint(rhs_, os);
     }
    private:
     Rhs rhs_;
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
   Rhs rhs_;
   GTEST_DISALLOW_ASSIGN_(ComparisonBase);
 };
 
 template <typename Rhs>
 class EqMatcher : public ComparisonBase<EqMatcher<Rhs>, Rhs, AnyEq> {
  public:
   explicit EqMatcher(const Rhs& rhs)
       : ComparisonBase<EqMatcher<Rhs>, Rhs, AnyEq>(rhs) { }
   static const char* Desc() { return "is equal to"; }
   static const char* NegatedDesc() { return "isn't equal to"; }
 };
 template <typename Rhs>
 class NeMatcher : public ComparisonBase<NeMatcher<Rhs>, Rhs, AnyNe> {
  public:
   explicit NeMatcher(const Rhs& rhs)
       : ComparisonBase<NeMatcher<Rhs>, Rhs, AnyNe>(rhs) { }
   static const char* Desc() { return "isn't equal to"; }
   static const char* NegatedDesc() { return "is equal to"; }
 };
 template <typename Rhs>
 class LtMatcher : public ComparisonBase<LtMatcher<Rhs>, Rhs, AnyLt> {
  public:
   explicit LtMatcher(const Rhs& rhs)
       : ComparisonBase<LtMatcher<Rhs>, Rhs, AnyLt>(rhs) { }
   static const char* Desc() { return "is <"; }
   static const char* NegatedDesc() { return "isn't <"; }
 };
 template <typename Rhs>
 class GtMatcher : public ComparisonBase<GtMatcher<Rhs>, Rhs, AnyGt> {
  public:
   explicit GtMatcher(const Rhs& rhs)
       : ComparisonBase<GtMatcher<Rhs>, Rhs, AnyGt>(rhs) { }
   static const char* Desc() { return "is >"; }
   static const char* NegatedDesc() { return "isn't >"; }
 };
 template <typename Rhs>
 class LeMatcher : public ComparisonBase<LeMatcher<Rhs>, Rhs, AnyLe> {
  public:
   explicit LeMatcher(const Rhs& rhs)
       : ComparisonBase<LeMatcher<Rhs>, Rhs, AnyLe>(rhs) { }
   static const char* Desc() { return "is <="; }
   static const char* NegatedDesc() { return "isn't <="; }
 };
 template <typename Rhs>
 class GeMatcher : public ComparisonBase<GeMatcher<Rhs>, Rhs, AnyGe> {
  public:
   explicit GeMatcher(const Rhs& rhs)
       : ComparisonBase<GeMatcher<Rhs>, Rhs, AnyGe>(rhs) { }
   static const char* Desc() { return "is >="; }
   static const char* NegatedDesc() { return "isn't >="; }
 };
 
 // Implements the polymorphic IsNull() matcher, which matches any raw or smart
 // pointer that is NULL.
 class IsNullMatcher {
  public:
   template <typename Pointer>
   bool MatchAndExplain(const Pointer& p,
                        MatchResultListener* /* listener */) const {
 #if GTEST_LANG_CXX11
     return p == nullptr;
 #else  // GTEST_LANG_CXX11
     return GetRawPointer(p) == NULL;
 #endif  // GTEST_LANG_CXX11
   }
 
   void DescribeTo(::std::ostream* os) const { *os << "is NULL"; }
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "isn't NULL";
   }
 };
 
 // Implements the polymorphic NotNull() matcher, which matches any raw or smart
 // pointer that is not NULL.
 class NotNullMatcher {
  public:
   template <typename Pointer>
   bool MatchAndExplain(const Pointer& p,
                        MatchResultListener* /* listener */) const {
 #if GTEST_LANG_CXX11
     return p != nullptr;
 #else  // GTEST_LANG_CXX11
     return GetRawPointer(p) != NULL;
 #endif  // GTEST_LANG_CXX11
   }
 
   void DescribeTo(::std::ostream* os) const { *os << "isn't NULL"; }
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "is NULL";
   }
 };
 
 // Ref(variable) matches any argument that is a reference to
 // 'variable'.  This matcher is polymorphic as it can match any
 // super type of the type of 'variable'.
 //
 // The RefMatcher template class implements Ref(variable).  It can
 // only be instantiated with a reference type.  This prevents a user
 // from mistakenly using Ref(x) to match a non-reference function
 // argument.  For example, the following will righteously cause a
 // compiler error:
 //
 //   int n;
 //   Matcher<int> m1 = Ref(n);   // This won't compile.
 //   Matcher<int&> m2 = Ref(n);  // This will compile.
 template <typename T>
 class RefMatcher;
 
 template <typename T>
 class RefMatcher<T&> {
   // Google Mock is a generic framework and thus needs to support
   // mocking any function types, including those that take non-const
   // reference arguments.  Therefore the template parameter T (and
   // Super below) can be instantiated to either a const type or a
   // non-const type.
  public:
   // RefMatcher() takes a T& instead of const T&, as we want the
   // compiler to catch using Ref(const_value) as a matcher for a
   // non-const reference.
   explicit RefMatcher(T& x) : object_(x) {}  // NOLINT
 
   template <typename Super>
   operator Matcher<Super&>() const {
     // By passing object_ (type T&) to Impl(), which expects a Super&,
     // we make sure that Super is a super type of T.  In particular,
     // this catches using Ref(const_value) as a matcher for a
     // non-const reference, as you cannot implicitly convert a const
     // reference to a non-const reference.
     return MakeMatcher(new Impl<Super>(object_));
   }
 
  private:
   template <typename Super>
   class Impl : public MatcherInterface<Super&> {
    public:
     explicit Impl(Super& x) : object_(x) {}  // NOLINT
 
     // MatchAndExplain() takes a Super& (as opposed to const Super&)
     // in order to match the interface MatcherInterface<Super&>.
     virtual bool MatchAndExplain(
         Super& x, MatchResultListener* listener) const {
       *listener << "which is located @" << static_cast<const void*>(&x);
       return &x == &object_;
     }
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "references the variable ";
       UniversalPrinter<Super&>::Print(object_, os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "does not reference the variable ";
       UniversalPrinter<Super&>::Print(object_, os);
     }
 
    private:
     const Super& object_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
   T& object_;
 
   GTEST_DISALLOW_ASSIGN_(RefMatcher);
 };
 
 // Polymorphic helper functions for narrow and wide string matchers.
 inline bool CaseInsensitiveCStringEquals(const char* lhs, const char* rhs) {
   return String::CaseInsensitiveCStringEquals(lhs, rhs);
 }
 
 inline bool CaseInsensitiveCStringEquals(const wchar_t* lhs,
                                          const wchar_t* rhs) {
   return String::CaseInsensitiveWideCStringEquals(lhs, rhs);
 }
 
 // String comparison for narrow or wide strings that can have embedded NUL
 // characters.
 template <typename StringType>
 bool CaseInsensitiveStringEquals(const StringType& s1,
                                  const StringType& s2) {
   // Are the heads equal?
   if (!CaseInsensitiveCStringEquals(s1.c_str(), s2.c_str())) {
     return false;
   }
 
   // Skip the equal heads.
   const typename StringType::value_type nul = 0;
   const size_t i1 = s1.find(nul), i2 = s2.find(nul);
 
   // Are we at the end of either s1 or s2?
   if (i1 == StringType::npos || i2 == StringType::npos) {
     return i1 == i2;
   }
 
   // Are the tails equal?
   return CaseInsensitiveStringEquals(s1.substr(i1 + 1), s2.substr(i2 + 1));
 }
 
 // String matchers.
 
 // Implements equality-based string matchers like StrEq, StrCaseNe, and etc.
 template <typename StringType>
 class StrEqualityMatcher {
  public:
   StrEqualityMatcher(const StringType& str, bool expect_eq,
                      bool case_sensitive)
       : string_(str), expect_eq_(expect_eq), case_sensitive_(case_sensitive) {}
 
   // Accepts pointer types, particularly:
   //   const char*
   //   char*
   //   const wchar_t*
   //   wchar_t*
   template <typename CharType>
   bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
     if (s == NULL) {
       return !expect_eq_;
     }
     return MatchAndExplain(StringType(s), listener);
   }
 
   // Matches anything that can convert to StringType.
   //
   // This is a template, not just a plain function with const StringType&,
   // because StringPiece has some interfering non-explicit constructors.
   template <typename MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
     const StringType& s2(s);
     const bool eq = case_sensitive_ ? s2 == string_ :
         CaseInsensitiveStringEquals(s2, string_);
     return expect_eq_ == eq;
   }
 
   void DescribeTo(::std::ostream* os) const {
     DescribeToHelper(expect_eq_, os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     DescribeToHelper(!expect_eq_, os);
   }
 
  private:
   void DescribeToHelper(bool expect_eq, ::std::ostream* os) const {
     *os << (expect_eq ? "is " : "isn't ");
     *os << "equal to ";
     if (!case_sensitive_) {
       *os << "(ignoring case) ";
     }
     UniversalPrint(string_, os);
   }
 
   const StringType string_;
   const bool expect_eq_;
   const bool case_sensitive_;
 
   GTEST_DISALLOW_ASSIGN_(StrEqualityMatcher);
 };
 
 // Implements the polymorphic HasSubstr(substring) matcher, which
 // can be used as a Matcher<T> as long as T can be converted to a
 // string.
 template <typename StringType>
 class HasSubstrMatcher {
  public:
   explicit HasSubstrMatcher(const StringType& substring)
       : substring_(substring) {}
 
   // Accepts pointer types, particularly:
   //   const char*
   //   char*
   //   const wchar_t*
   //   wchar_t*
   template <typename CharType>
   bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
     return s != NULL && MatchAndExplain(StringType(s), listener);
   }
 
   // Matches anything that can convert to StringType.
   //
   // This is a template, not just a plain function with const StringType&,
   // because StringPiece has some interfering non-explicit constructors.
   template <typename MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
     const StringType& s2(s);
     return s2.find(substring_) != StringType::npos;
   }
 
   // Describes what this matcher matches.
   void DescribeTo(::std::ostream* os) const {
     *os << "has substring ";
     UniversalPrint(substring_, os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "has no substring ";
     UniversalPrint(substring_, os);
   }
 
  private:
   const StringType substring_;
 
   GTEST_DISALLOW_ASSIGN_(HasSubstrMatcher);
 };
 
 // Implements the polymorphic StartsWith(substring) matcher, which
 // can be used as a Matcher<T> as long as T can be converted to a
 // string.
 template <typename StringType>
 class StartsWithMatcher {
  public:
   explicit StartsWithMatcher(const StringType& prefix) : prefix_(prefix) {
   }
 
   // Accepts pointer types, particularly:
   //   const char*
   //   char*
   //   const wchar_t*
   //   wchar_t*
   template <typename CharType>
   bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
     return s != NULL && MatchAndExplain(StringType(s), listener);
   }
 
   // Matches anything that can convert to StringType.
   //
   // This is a template, not just a plain function with const StringType&,
   // because StringPiece has some interfering non-explicit constructors.
   template <typename MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
     const StringType& s2(s);
     return s2.length() >= prefix_.length() &&
         s2.substr(0, prefix_.length()) == prefix_;
   }
 
   void DescribeTo(::std::ostream* os) const {
     *os << "starts with ";
     UniversalPrint(prefix_, os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't start with ";
     UniversalPrint(prefix_, os);
   }
 
  private:
   const StringType prefix_;
 
   GTEST_DISALLOW_ASSIGN_(StartsWithMatcher);
 };
 
 // Implements the polymorphic EndsWith(substring) matcher, which
 // can be used as a Matcher<T> as long as T can be converted to a
 // string.
 template <typename StringType>
 class EndsWithMatcher {
  public:
   explicit EndsWithMatcher(const StringType& suffix) : suffix_(suffix) {}
 
   // Accepts pointer types, particularly:
   //   const char*
   //   char*
   //   const wchar_t*
   //   wchar_t*
   template <typename CharType>
   bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
     return s != NULL && MatchAndExplain(StringType(s), listener);
   }
 
   // Matches anything that can convert to StringType.
   //
   // This is a template, not just a plain function with const StringType&,
   // because StringPiece has some interfering non-explicit constructors.
   template <typename MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
     const StringType& s2(s);
     return s2.length() >= suffix_.length() &&
         s2.substr(s2.length() - suffix_.length()) == suffix_;
   }
 
   void DescribeTo(::std::ostream* os) const {
     *os << "ends with ";
     UniversalPrint(suffix_, os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't end with ";
     UniversalPrint(suffix_, os);
   }
 
  private:
   const StringType suffix_;
 
   GTEST_DISALLOW_ASSIGN_(EndsWithMatcher);
 };
 
 // Implements polymorphic matchers MatchesRegex(regex) and
 // ContainsRegex(regex), which can be used as a Matcher<T> as long as
 // T can be converted to a string.
 class MatchesRegexMatcher {
  public:
   MatchesRegexMatcher(const RE* regex, bool full_match)
       : regex_(regex), full_match_(full_match) {}
 
   // Accepts pointer types, particularly:
   //   const char*
   //   char*
   //   const wchar_t*
   //   wchar_t*
   template <typename CharType>
   bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
     return s != NULL && MatchAndExplain(internal::string(s), listener);
   }
 
   // Matches anything that can convert to internal::string.
   //
   // This is a template, not just a plain function with const internal::string&,
   // because StringPiece has some interfering non-explicit constructors.
   template <class MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
     const internal::string& s2(s);
     return full_match_ ? RE::FullMatch(s2, *regex_) :
         RE::PartialMatch(s2, *regex_);
   }
 
   void DescribeTo(::std::ostream* os) const {
     *os << (full_match_ ? "matches" : "contains")
         << " regular expression ";
     UniversalPrinter<internal::string>::Print(regex_->pattern(), os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't " << (full_match_ ? "match" : "contain")
         << " regular expression ";
     UniversalPrinter<internal::string>::Print(regex_->pattern(), os);
   }
 
  private:
   const internal::linked_ptr<const RE> regex_;
   const bool full_match_;
 
   GTEST_DISALLOW_ASSIGN_(MatchesRegexMatcher);
 };
 
 // Implements a matcher that compares the two fields of a 2-tuple
 // using one of the ==, <=, <, etc, operators.  The two fields being
 // compared don't have to have the same type.
 //
 // The matcher defined here is polymorphic (for example, Eq() can be
 // used to match a tuple<int, short>, a tuple<const long&, double>,
 // etc).  Therefore we use a template type conversion operator in the
 // implementation.
 template <typename D, typename Op>
 class PairMatchBase {
  public:
   template <typename T1, typename T2>
   operator Matcher< ::testing::tuple<T1, T2> >() const {
     return MakeMatcher(new Impl< ::testing::tuple<T1, T2> >);
   }
   template <typename T1, typename T2>
   operator Matcher<const ::testing::tuple<T1, T2>&>() const {
     return MakeMatcher(new Impl<const ::testing::tuple<T1, T2>&>);
   }
 
  private:
   static ::std::ostream& GetDesc(::std::ostream& os) {  // NOLINT
     return os << D::Desc();
   }
 
   template <typename Tuple>
   class Impl : public MatcherInterface<Tuple> {
    public:
     virtual bool MatchAndExplain(
         Tuple args,
         MatchResultListener* /* listener */) const {
       return Op()(::testing::get<0>(args), ::testing::get<1>(args));
     }
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "are " << GetDesc;
     }
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "aren't " << GetDesc;
     }
   };
 };
 
 class Eq2Matcher : public PairMatchBase<Eq2Matcher, AnyEq> {
  public:
   static const char* Desc() { return "an equal pair"; }
 };
 class Ne2Matcher : public PairMatchBase<Ne2Matcher, AnyNe> {
  public:
   static const char* Desc() { return "an unequal pair"; }
 };
 class Lt2Matcher : public PairMatchBase<Lt2Matcher, AnyLt> {
  public:
   static const char* Desc() { return "a pair where the first < the second"; }
 };
 class Gt2Matcher : public PairMatchBase<Gt2Matcher, AnyGt> {
  public:
   static const char* Desc() { return "a pair where the first > the second"; }
 };
 class Le2Matcher : public PairMatchBase<Le2Matcher, AnyLe> {
  public:
   static const char* Desc() { return "a pair where the first <= the second"; }
 };
 class Ge2Matcher : public PairMatchBase<Ge2Matcher, AnyGe> {
  public:
   static const char* Desc() { return "a pair where the first >= the second"; }
 };
 
 // Implements the Not(...) matcher for a particular argument type T.
 // We do not nest it inside the NotMatcher class template, as that
 // will prevent different instantiations of NotMatcher from sharing
 // the same NotMatcherImpl<T> class.
 template <typename T>
 class NotMatcherImpl : public MatcherInterface<T> {
  public:
   explicit NotMatcherImpl(const Matcher<T>& matcher)
       : matcher_(matcher) {}
 
   virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
     return !matcher_.MatchAndExplain(x, listener);
   }
 
   virtual void DescribeTo(::std::ostream* os) const {
     matcher_.DescribeNegationTo(os);
   }
 
   virtual void DescribeNegationTo(::std::ostream* os) const {
     matcher_.DescribeTo(os);
   }
 
  private:
   const Matcher<T> matcher_;
 
   GTEST_DISALLOW_ASSIGN_(NotMatcherImpl);
 };
 
 // Implements the Not(m) matcher, which matches a value that doesn't
 // match matcher m.
 template <typename InnerMatcher>
 class NotMatcher {
  public:
   explicit NotMatcher(InnerMatcher matcher) : matcher_(matcher) {}
 
   // This template type conversion operator allows Not(m) to be used
   // to match any type m can match.
   template <typename T>
   operator Matcher<T>() const {
     return Matcher<T>(new NotMatcherImpl<T>(SafeMatcherCast<T>(matcher_)));
   }
 
  private:
   InnerMatcher matcher_;
 
   GTEST_DISALLOW_ASSIGN_(NotMatcher);
 };
 
 // Implements the AllOf(m1, m2) matcher for a particular argument type
 // T. We do not nest it inside the BothOfMatcher class template, as
 // that will prevent different instantiations of BothOfMatcher from
 // sharing the same BothOfMatcherImpl<T> class.
 template <typename T>
 class BothOfMatcherImpl : public MatcherInterface<T> {
  public:
   BothOfMatcherImpl(const Matcher<T>& matcher1, const Matcher<T>& matcher2)
       : matcher1_(matcher1), matcher2_(matcher2) {}
 
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "(";
     matcher1_.DescribeTo(os);
     *os << ") and (";
     matcher2_.DescribeTo(os);
     *os << ")";
   }
 
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "(";
     matcher1_.DescribeNegationTo(os);
     *os << ") or (";
     matcher2_.DescribeNegationTo(os);
     *os << ")";
   }
 
   virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
     // If either matcher1_ or matcher2_ doesn't match x, we only need
     // to explain why one of them fails.
     StringMatchResultListener listener1;
     if (!matcher1_.MatchAndExplain(x, &listener1)) {
       *listener << listener1.str();
       return false;
     }
 
     StringMatchResultListener listener2;
     if (!matcher2_.MatchAndExplain(x, &listener2)) {
       *listener << listener2.str();
       return false;
     }
 
     // Otherwise we need to explain why *both* of them match.
     const internal::string s1 = listener1.str();
     const internal::string s2 = listener2.str();
 
     if (s1 == "") {
       *listener << s2;
     } else {
       *listener << s1;
       if (s2 != "") {
         *listener << ", and " << s2;
       }
     }
     return true;
   }
 
  private:
   const Matcher<T> matcher1_;
   const Matcher<T> matcher2_;
 
   GTEST_DISALLOW_ASSIGN_(BothOfMatcherImpl);
 };
 
 #if GTEST_LANG_CXX11
 // MatcherList provides mechanisms for storing a variable number of matchers in
 // a list structure (ListType) and creating a combining matcher from such a
 // list.
 // The template is defined recursively using the following template paramters:
 //   * kSize is the length of the MatcherList.
 //   * Head is the type of the first matcher of the list.
 //   * Tail denotes the types of the remaining matchers of the list.
 template <int kSize, typename Head, typename... Tail>
 struct MatcherList {
   typedef MatcherList<kSize - 1, Tail...> MatcherListTail;
   typedef ::std::pair<Head, typename MatcherListTail::ListType> ListType;
 
   // BuildList stores variadic type values in a nested pair structure.
   // Example:
   // MatcherList<3, int, string, float>::BuildList(5, "foo", 2.0) will return
   // the corresponding result of type pair<int, pair<string, float>>.
   static ListType BuildList(const Head& matcher, const Tail&... tail) {
     return ListType(matcher, MatcherListTail::BuildList(tail...));
   }
 
   // CreateMatcher<T> creates a Matcher<T> from a given list of matchers (built
   // by BuildList()). CombiningMatcher<T> is used to combine the matchers of the
   // list. CombiningMatcher<T> must implement MatcherInterface<T> and have a
   // constructor taking two Matcher<T>s as input.
   template <typename T, template <typename /* T */> class CombiningMatcher>
   static Matcher<T> CreateMatcher(const ListType& matchers) {
     return Matcher<T>(new CombiningMatcher<T>(
         SafeMatcherCast<T>(matchers.first),
         MatcherListTail::template CreateMatcher<T, CombiningMatcher>(
             matchers.second)));
   }
 };
 
 // The following defines the base case for the recursive definition of
 // MatcherList.
 template <typename Matcher1, typename Matcher2>
 struct MatcherList<2, Matcher1, Matcher2> {
   typedef ::std::pair<Matcher1, Matcher2> ListType;
 
   static ListType BuildList(const Matcher1& matcher1,
                             const Matcher2& matcher2) {
     return ::std::pair<Matcher1, Matcher2>(matcher1, matcher2);
   }
 
   template <typename T, template <typename /* T */> class CombiningMatcher>
   static Matcher<T> CreateMatcher(const ListType& matchers) {
     return Matcher<T>(new CombiningMatcher<T>(
         SafeMatcherCast<T>(matchers.first),
         SafeMatcherCast<T>(matchers.second)));
   }
 };
 
 // VariadicMatcher is used for the variadic implementation of
 // AllOf(m_1, m_2, ...) and AnyOf(m_1, m_2, ...).
 // CombiningMatcher<T> is used to recursively combine the provided matchers
 // (of type Args...).
 template <template <typename T> class CombiningMatcher, typename... Args>
 class VariadicMatcher {
  public:
   VariadicMatcher(const Args&... matchers)  // NOLINT
       : matchers_(MatcherListType::BuildList(matchers...)) {}
 
   // This template type conversion operator allows an
   // VariadicMatcher<Matcher1, Matcher2...> object to match any type that
   // all of the provided matchers (Matcher1, Matcher2, ...) can match.
   template <typename T>
   operator Matcher<T>() const {
     return MatcherListType::template CreateMatcher<T, CombiningMatcher>(
         matchers_);
   }
 
  private:
   typedef MatcherList<sizeof...(Args), Args...> MatcherListType;
 
   const typename MatcherListType::ListType matchers_;
 
   GTEST_DISALLOW_ASSIGN_(VariadicMatcher);
 };
 
 template <typename... Args>
 using AllOfMatcher = VariadicMatcher<BothOfMatcherImpl, Args...>;
 
 #endif  // GTEST_LANG_CXX11
 
 // Used for implementing the AllOf(m_1, ..., m_n) matcher, which
 // matches a value that matches all of the matchers m_1, ..., and m_n.
 template <typename Matcher1, typename Matcher2>
 class BothOfMatcher {
  public:
   BothOfMatcher(Matcher1 matcher1, Matcher2 matcher2)
       : matcher1_(matcher1), matcher2_(matcher2) {}
 
   // This template type conversion operator allows a
   // BothOfMatcher<Matcher1, Matcher2> object to match any type that
   // both Matcher1 and Matcher2 can match.
   template <typename T>
   operator Matcher<T>() const {
     return Matcher<T>(new BothOfMatcherImpl<T>(SafeMatcherCast<T>(matcher1_),
                                                SafeMatcherCast<T>(matcher2_)));
   }
 
  private:
   Matcher1 matcher1_;
   Matcher2 matcher2_;
 
   GTEST_DISALLOW_ASSIGN_(BothOfMatcher);
 };
 
 // Implements the AnyOf(m1, m2) matcher for a particular argument type
 // T.  We do not nest it inside the AnyOfMatcher class template, as
 // that will prevent different instantiations of AnyOfMatcher from
 // sharing the same EitherOfMatcherImpl<T> class.
 template <typename T>
 class EitherOfMatcherImpl : public MatcherInterface<T> {
  public:
   EitherOfMatcherImpl(const Matcher<T>& matcher1, const Matcher<T>& matcher2)
       : matcher1_(matcher1), matcher2_(matcher2) {}
 
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "(";
     matcher1_.DescribeTo(os);
     *os << ") or (";
     matcher2_.DescribeTo(os);
     *os << ")";
   }
 
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "(";
     matcher1_.DescribeNegationTo(os);
     *os << ") and (";
     matcher2_.DescribeNegationTo(os);
     *os << ")";
   }
 
   virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
     // If either matcher1_ or matcher2_ matches x, we just need to
     // explain why *one* of them matches.
     StringMatchResultListener listener1;
     if (matcher1_.MatchAndExplain(x, &listener1)) {
       *listener << listener1.str();
       return true;
     }
 
     StringMatchResultListener listener2;
     if (matcher2_.MatchAndExplain(x, &listener2)) {
       *listener << listener2.str();
       return true;
     }
 
     // Otherwise we need to explain why *both* of them fail.
     const internal::string s1 = listener1.str();
     const internal::string s2 = listener2.str();
 
     if (s1 == "") {
       *listener << s2;
     } else {
       *listener << s1;
       if (s2 != "") {
         *listener << ", and " << s2;
       }
     }
     return false;
   }
 
  private:
   const Matcher<T> matcher1_;
   const Matcher<T> matcher2_;
 
   GTEST_DISALLOW_ASSIGN_(EitherOfMatcherImpl);
 };
 
 #if GTEST_LANG_CXX11
 // AnyOfMatcher is used for the variadic implementation of AnyOf(m_1, m_2, ...).
 template <typename... Args>
 using AnyOfMatcher = VariadicMatcher<EitherOfMatcherImpl, Args...>;
 
 #endif  // GTEST_LANG_CXX11
 
 // Used for implementing the AnyOf(m_1, ..., m_n) matcher, which
 // matches a value that matches at least one of the matchers m_1, ...,
 // and m_n.
 template <typename Matcher1, typename Matcher2>
 class EitherOfMatcher {
  public:
   EitherOfMatcher(Matcher1 matcher1, Matcher2 matcher2)
       : matcher1_(matcher1), matcher2_(matcher2) {}
 
   // This template type conversion operator allows a
   // EitherOfMatcher<Matcher1, Matcher2> object to match any type that
   // both Matcher1 and Matcher2 can match.
   template <typename T>
   operator Matcher<T>() const {
     return Matcher<T>(new EitherOfMatcherImpl<T>(
         SafeMatcherCast<T>(matcher1_), SafeMatcherCast<T>(matcher2_)));
   }
 
  private:
   Matcher1 matcher1_;
   Matcher2 matcher2_;
 
   GTEST_DISALLOW_ASSIGN_(EitherOfMatcher);
 };
 
 // Used for implementing Truly(pred), which turns a predicate into a
 // matcher.
 template <typename Predicate>
 class TrulyMatcher {
  public:
   explicit TrulyMatcher(Predicate pred) : predicate_(pred) {}
 
   // This method template allows Truly(pred) to be used as a matcher
   // for type T where T is the argument type of predicate 'pred'.  The
   // argument is passed by reference as the predicate may be
   // interested in the address of the argument.
   template <typename T>
   bool MatchAndExplain(T& x,  // NOLINT
                        MatchResultListener* /* listener */) const {
     // Without the if-statement, MSVC sometimes warns about converting
     // a value to bool (warning 4800).
     //
     // We cannot write 'return !!predicate_(x);' as that doesn't work
     // when predicate_(x) returns a class convertible to bool but
     // having no operator!().
     if (predicate_(x))
       return true;
     return false;
   }
 
   void DescribeTo(::std::ostream* os) const {
     *os << "satisfies the given predicate";
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't satisfy the given predicate";
   }
 
  private:
   Predicate predicate_;
 
   GTEST_DISALLOW_ASSIGN_(TrulyMatcher);
 };
 
 // Used for implementing Matches(matcher), which turns a matcher into
 // a predicate.
 template <typename M>
 class MatcherAsPredicate {
  public:
   explicit MatcherAsPredicate(M matcher) : matcher_(matcher) {}
 
   // This template operator() allows Matches(m) to be used as a
   // predicate on type T where m is a matcher on type T.
   //
   // The argument x is passed by reference instead of by value, as
   // some matcher may be interested in its address (e.g. as in
   // Matches(Ref(n))(x)).
   template <typename T>
   bool operator()(const T& x) const {
     // We let matcher_ commit to a particular type here instead of
     // when the MatcherAsPredicate object was constructed.  This
     // allows us to write Matches(m) where m is a polymorphic matcher
     // (e.g. Eq(5)).
     //
     // If we write Matcher<T>(matcher_).Matches(x) here, it won't
     // compile when matcher_ has type Matcher<const T&>; if we write
     // Matcher<const T&>(matcher_).Matches(x) here, it won't compile
     // when matcher_ has type Matcher<T>; if we just write
     // matcher_.Matches(x), it won't compile when matcher_ is
     // polymorphic, e.g. Eq(5).
     //
     // MatcherCast<const T&>() is necessary for making the code work
     // in all of the above situations.
     return MatcherCast<const T&>(matcher_).Matches(x);
   }
 
  private:
   M matcher_;
 
   GTEST_DISALLOW_ASSIGN_(MatcherAsPredicate);
 };
 
 // For implementing ASSERT_THAT() and EXPECT_THAT().  The template
 // argument M must be a type that can be converted to a matcher.
 template <typename M>
 class PredicateFormatterFromMatcher {
  public:
   explicit PredicateFormatterFromMatcher(M m) : matcher_(internal::move(m)) {}
 
   // This template () operator allows a PredicateFormatterFromMatcher
   // object to act as a predicate-formatter suitable for using with
   // Google Test's EXPECT_PRED_FORMAT1() macro.
   template <typename T>
   AssertionResult operator()(const char* value_text, const T& x) const {
     // We convert matcher_ to a Matcher<const T&> *now* instead of
     // when the PredicateFormatterFromMatcher object was constructed,
     // as matcher_ may be polymorphic (e.g. NotNull()) and we won't
     // know which type to instantiate it to until we actually see the
     // type of x here.
     //
     // We write SafeMatcherCast<const T&>(matcher_) instead of
     // Matcher<const T&>(matcher_), as the latter won't compile when
     // matcher_ has type Matcher<T> (e.g. An<int>()).
     // We don't write MatcherCast<const T&> either, as that allows
     // potentially unsafe downcasting of the matcher argument.
     const Matcher<const T&> matcher = SafeMatcherCast<const T&>(matcher_);
     StringMatchResultListener listener;
     if (MatchPrintAndExplain(x, matcher, &listener))
       return AssertionSuccess();
 
     ::std::stringstream ss;
     ss << "Value of: " << value_text << "\n"
        << "Expected: ";
     matcher.DescribeTo(&ss);
     ss << "\n  Actual: " << listener.str();
     return AssertionFailure() << ss.str();
   }
 
  private:
   const M matcher_;
 
   GTEST_DISALLOW_ASSIGN_(PredicateFormatterFromMatcher);
 };
 
 // A helper function for converting a matcher to a predicate-formatter
 // without the user needing to explicitly write the type.  This is
 // used for implementing ASSERT_THAT() and EXPECT_THAT().
 // Implementation detail: 'matcher' is received by-value to force decaying.
 template <typename M>
 inline PredicateFormatterFromMatcher<M>
 MakePredicateFormatterFromMatcher(M matcher) {
   return PredicateFormatterFromMatcher<M>(internal::move(matcher));
 }
 
 // Implements the polymorphic floating point equality matcher, which matches
 // two float values using ULP-based approximation or, optionally, a
 // user-specified epsilon.  The template is meant to be instantiated with
 // FloatType being either float or double.
 template <typename FloatType>
 class FloatingEqMatcher {
  public:
   // Constructor for FloatingEqMatcher.
   // The matcher's input will be compared with expected.  The matcher treats two
   // NANs as equal if nan_eq_nan is true.  Otherwise, under IEEE standards,
   // equality comparisons between NANs will always return false.  We specify a
   // negative max_abs_error_ term to indicate that ULP-based approximation will
   // be used for comparison.
   FloatingEqMatcher(FloatType expected, bool nan_eq_nan) :
     expected_(expected), nan_eq_nan_(nan_eq_nan), max_abs_error_(-1) {
   }
 
   // Constructor that supports a user-specified max_abs_error that will be used
   // for comparison instead of ULP-based approximation.  The max absolute
   // should be non-negative.
   FloatingEqMatcher(FloatType expected, bool nan_eq_nan,
                     FloatType max_abs_error)
       : expected_(expected),
         nan_eq_nan_(nan_eq_nan),
         max_abs_error_(max_abs_error) {
     GTEST_CHECK_(max_abs_error >= 0)
         << ", where max_abs_error is" << max_abs_error;
   }
 
   // Implements floating point equality matcher as a Matcher<T>.
   template <typename T>
   class Impl : public MatcherInterface<T> {
    public:
     Impl(FloatType expected, bool nan_eq_nan, FloatType max_abs_error)
         : expected_(expected),
           nan_eq_nan_(nan_eq_nan),
           max_abs_error_(max_abs_error) {}
 
     virtual bool MatchAndExplain(T value,
                                  MatchResultListener* listener) const {
       const FloatingPoint<FloatType> actual(value), expected(expected_);
 
       // Compares NaNs first, if nan_eq_nan_ is true.
       if (actual.is_nan() || expected.is_nan()) {
         if (actual.is_nan() && expected.is_nan()) {
           return nan_eq_nan_;
         }
         // One is nan; the other is not nan.
         return false;
       }
       if (HasMaxAbsError()) {
         // We perform an equality check so that inf will match inf, regardless
         // of error bounds.  If the result of value - expected_ would result in
         // overflow or if either value is inf, the default result is infinity,
         // which should only match if max_abs_error_ is also infinity.
         if (value == expected_) {
           return true;
         }
 
         const FloatType diff = value - expected_;
         if (fabs(diff) <= max_abs_error_) {
           return true;
         }
 
         if (listener->IsInterested()) {
           *listener << "which is " << diff << " from " << expected_;
         }
         return false;
       } else {
         return actual.AlmostEquals(expected);
       }
     }
 
     virtual void DescribeTo(::std::ostream* os) const {
       // os->precision() returns the previously set precision, which we
       // store to restore the ostream to its original configuration
       // after outputting.
       const ::std::streamsize old_precision = os->precision(
           ::std::numeric_limits<FloatType>::digits10 + 2);
       if (FloatingPoint<FloatType>(expected_).is_nan()) {
         if (nan_eq_nan_) {
           *os << "is NaN";
         } else {
           *os << "never matches";
         }
       } else {
         *os << "is approximately " << expected_;
         if (HasMaxAbsError()) {
           *os << " (absolute error <= " << max_abs_error_ << ")";
         }
       }
       os->precision(old_precision);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       // As before, get original precision.
       const ::std::streamsize old_precision = os->precision(
           ::std::numeric_limits<FloatType>::digits10 + 2);
       if (FloatingPoint<FloatType>(expected_).is_nan()) {
         if (nan_eq_nan_) {
           *os << "isn't NaN";
         } else {
           *os << "is anything";
         }
       } else {
         *os << "isn't approximately " << expected_;
         if (HasMaxAbsError()) {
           *os << " (absolute error > " << max_abs_error_ << ")";
         }
       }
       // Restore original precision.
       os->precision(old_precision);
     }
 
    private:
     bool HasMaxAbsError() const {
       return max_abs_error_ >= 0;
     }
 
     const FloatType expected_;
     const bool nan_eq_nan_;
     // max_abs_error will be used for value comparison when >= 0.
     const FloatType max_abs_error_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
   // The following 3 type conversion operators allow FloatEq(expected) and
   // NanSensitiveFloatEq(expected) to be used as a Matcher<float>, a
   // Matcher<const float&>, or a Matcher<float&>, but nothing else.
   // (While Google's C++ coding style doesn't allow arguments passed
   // by non-const reference, we may see them in code not conforming to
   // the style.  Therefore Google Mock needs to support them.)
   operator Matcher<FloatType>() const {
     return MakeMatcher(
         new Impl<FloatType>(expected_, nan_eq_nan_, max_abs_error_));
   }
 
   operator Matcher<const FloatType&>() const {
     return MakeMatcher(
         new Impl<const FloatType&>(expected_, nan_eq_nan_, max_abs_error_));
   }
 
   operator Matcher<FloatType&>() const {
     return MakeMatcher(
         new Impl<FloatType&>(expected_, nan_eq_nan_, max_abs_error_));
   }
 
  private:
   const FloatType expected_;
   const bool nan_eq_nan_;
   // max_abs_error will be used for value comparison when >= 0.
   const FloatType max_abs_error_;
 
   GTEST_DISALLOW_ASSIGN_(FloatingEqMatcher);
 };
 
 // Implements the Pointee(m) matcher for matching a pointer whose
 // pointee matches matcher m.  The pointer can be either raw or smart.
 template <typename InnerMatcher>
 class PointeeMatcher {
  public:
   explicit PointeeMatcher(const InnerMatcher& matcher) : matcher_(matcher) {}
 
   // This type conversion operator template allows Pointee(m) to be
   // used as a matcher for any pointer type whose pointee type is
   // compatible with the inner matcher, where type Pointer can be
   // either a raw pointer or a smart pointer.
   //
   // The reason we do this instead of relying on
   // MakePolymorphicMatcher() is that the latter is not flexible
   // enough for implementing the DescribeTo() method of Pointee().
   template <typename Pointer>
   operator Matcher<Pointer>() const {
     return MakeMatcher(new Impl<Pointer>(matcher_));
   }
 
  private:
   // The monomorphic implementation that works for a particular pointer type.
   template <typename Pointer>
   class Impl : public MatcherInterface<Pointer> {
    public:
     typedef typename PointeeOf<GTEST_REMOVE_CONST_(  // NOLINT
         GTEST_REMOVE_REFERENCE_(Pointer))>::type Pointee;
 
     explicit Impl(const InnerMatcher& matcher)
         : matcher_(MatcherCast<const Pointee&>(matcher)) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "points to a value that ";
       matcher_.DescribeTo(os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "does not point to a value that ";
       matcher_.DescribeTo(os);
     }
 
     virtual bool MatchAndExplain(Pointer pointer,
                                  MatchResultListener* listener) const {
       if (GetRawPointer(pointer) == NULL)
         return false;
 
       *listener << "which points to ";
       return MatchPrintAndExplain(*pointer, matcher_, listener);
     }
 
    private:
     const Matcher<const Pointee&> matcher_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
   const InnerMatcher matcher_;
 
   GTEST_DISALLOW_ASSIGN_(PointeeMatcher);
 };
 
 // Implements the WhenDynamicCastTo<T>(m) matcher that matches a pointer or
 // reference that matches inner_matcher when dynamic_cast<T> is applied.
 // The result of dynamic_cast<To> is forwarded to the inner matcher.
 // If To is a pointer and the cast fails, the inner matcher will receive NULL.
 // If To is a reference and the cast fails, this matcher returns false
 // immediately.
 template <typename To>
 class WhenDynamicCastToMatcherBase {
  public:
   explicit WhenDynamicCastToMatcherBase(const Matcher<To>& matcher)
       : matcher_(matcher) {}
 
   void DescribeTo(::std::ostream* os) const {
     GetCastTypeDescription(os);
     matcher_.DescribeTo(os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     GetCastTypeDescription(os);
     matcher_.DescribeNegationTo(os);
   }
 
  protected:
   const Matcher<To> matcher_;
 
   static string GetToName() {
 #if GTEST_HAS_RTTI
     return GetTypeName<To>();
 #else  // GTEST_HAS_RTTI
     return "the target type";
 #endif  // GTEST_HAS_RTTI
   }
 
  private:
   static void GetCastTypeDescription(::std::ostream* os) {
     *os << "when dynamic_cast to " << GetToName() << ", ";
   }
 
   GTEST_DISALLOW_ASSIGN_(WhenDynamicCastToMatcherBase);
 };
 
 // Primary template.
 // To is a pointer. Cast and forward the result.
 template <typename To>
 class WhenDynamicCastToMatcher : public WhenDynamicCastToMatcherBase<To> {
  public:
   explicit WhenDynamicCastToMatcher(const Matcher<To>& matcher)
       : WhenDynamicCastToMatcherBase<To>(matcher) {}
 
   template <typename From>
   bool MatchAndExplain(From from, MatchResultListener* listener) const {
     // TODO(sbenza): Add more detail on failures. ie did the dyn_cast fail?
     To to = dynamic_cast<To>(from);
     return MatchPrintAndExplain(to, this->matcher_, listener);
   }
 };
 
 // Specialize for references.
 // In this case we return false if the dynamic_cast fails.
 template <typename To>
 class WhenDynamicCastToMatcher<To&> : public WhenDynamicCastToMatcherBase<To&> {
  public:
   explicit WhenDynamicCastToMatcher(const Matcher<To&>& matcher)
       : WhenDynamicCastToMatcherBase<To&>(matcher) {}
 
   template <typename From>
   bool MatchAndExplain(From& from, MatchResultListener* listener) const {
     // We don't want an std::bad_cast here, so do the cast with pointers.
     To* to = dynamic_cast<To*>(&from);
     if (to == NULL) {
       *listener << "which cannot be dynamic_cast to " << this->GetToName();
       return false;
     }
     return MatchPrintAndExplain(*to, this->matcher_, listener);
   }
 };
 
 // Implements the Field() matcher for matching a field (i.e. member
 // variable) of an object.
 template <typename Class, typename FieldType>
 class FieldMatcher {
  public:
   FieldMatcher(FieldType Class::*field,
                const Matcher<const FieldType&>& matcher)
       : field_(field), matcher_(matcher) {}
 
   void DescribeTo(::std::ostream* os) const {
     *os << "is an object whose given field ";
     matcher_.DescribeTo(os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "is an object whose given field ";
     matcher_.DescribeNegationTo(os);
   }
 
   template <typename T>
   bool MatchAndExplain(const T& value, MatchResultListener* listener) const {
     return MatchAndExplainImpl(
         typename ::testing::internal::
             is_pointer<GTEST_REMOVE_CONST_(T)>::type(),
         value, listener);
   }
 
  private:
   // The first argument of MatchAndExplainImpl() is needed to help
   // Symbian's C++ compiler choose which overload to use.  Its type is
   // true_type iff the Field() matcher is used to match a pointer.
   bool MatchAndExplainImpl(false_type /* is_not_pointer */, const Class& obj,
                            MatchResultListener* listener) const {
     *listener << "whose given field is ";
     return MatchPrintAndExplain(obj.*field_, matcher_, listener);
   }
 
   bool MatchAndExplainImpl(true_type /* is_pointer */, const Class* p,
                            MatchResultListener* listener) const {
     if (p == NULL)
       return false;
 
     *listener << "which points to an object ";
     // Since *p has a field, it must be a class/struct/union type and
     // thus cannot be a pointer.  Therefore we pass false_type() as
     // the first argument.
     return MatchAndExplainImpl(false_type(), *p, listener);
   }
 
   const FieldType Class::*field_;
   const Matcher<const FieldType&> matcher_;
 
   GTEST_DISALLOW_ASSIGN_(FieldMatcher);
 };
 
 // Implements the Property() matcher for matching a property
 // (i.e. return value of a getter method) of an object.
 template <typename Class, typename PropertyType>
 class PropertyMatcher {
  public:
   // The property may have a reference type, so 'const PropertyType&'
   // may cause double references and fail to compile.  That's why we
   // need GTEST_REFERENCE_TO_CONST, which works regardless of
   // PropertyType being a reference or not.
   typedef GTEST_REFERENCE_TO_CONST_(PropertyType) RefToConstProperty;
 
   PropertyMatcher(PropertyType (Class::*property)() const,
                   const Matcher<RefToConstProperty>& matcher)
       : property_(property), matcher_(matcher) {}
 
   void DescribeTo(::std::ostream* os) const {
     *os << "is an object whose given property ";
     matcher_.DescribeTo(os);
   }
 
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "is an object whose given property ";
     matcher_.DescribeNegationTo(os);
   }
 
   template <typename T>
   bool MatchAndExplain(const T&value, MatchResultListener* listener) const {
     return MatchAndExplainImpl(
         typename ::testing::internal::
             is_pointer<GTEST_REMOVE_CONST_(T)>::type(),
         value, listener);
   }
 
  private:
   // The first argument of MatchAndExplainImpl() is needed to help
   // Symbian's C++ compiler choose which overload to use.  Its type is
   // true_type iff the Property() matcher is used to match a pointer.
   bool MatchAndExplainImpl(false_type /* is_not_pointer */, const Class& obj,
                            MatchResultListener* listener) const {
     *listener << "whose given property is ";
     // Cannot pass the return value (for example, int) to MatchPrintAndExplain,
     // which takes a non-const reference as argument.
 #if defined(_PREFAST_ ) && _MSC_VER == 1800
     // Workaround bug in VC++ 2013's /analyze parser.
     // https://connect.microsoft.com/VisualStudio/feedback/details/1106363/internal-compiler-error-with-analyze-due-to-failure-to-infer-move
     posix::Abort();  // To make sure it is never run.
     return false;
 #else
     RefToConstProperty result = (obj.*property_)();
     return MatchPrintAndExplain(result, matcher_, listener);
 #endif
   }
 
   bool MatchAndExplainImpl(true_type /* is_pointer */, const Class* p,
                            MatchResultListener* listener) const {
     if (p == NULL)
       return false;
 
     *listener << "which points to an object ";
     // Since *p has a property method, it must be a class/struct/union
     // type and thus cannot be a pointer.  Therefore we pass
     // false_type() as the first argument.
     return MatchAndExplainImpl(false_type(), *p, listener);
   }
 
   PropertyType (Class::*property_)() const;
   const Matcher<RefToConstProperty> matcher_;
 
   GTEST_DISALLOW_ASSIGN_(PropertyMatcher);
 };
 
 // Type traits specifying various features of different functors for ResultOf.
 // The default template specifies features for functor objects.
 // Functor classes have to typedef argument_type and result_type
 // to be compatible with ResultOf.
 template <typename Functor>
 struct CallableTraits {
   typedef typename Functor::result_type ResultType;
   typedef Functor StorageType;
 
   static void CheckIsValid(Functor /* functor */) {}
   template <typename T>
   static ResultType Invoke(Functor f, T arg) { return f(arg); }
 };
 
 // Specialization for function pointers.
 template <typename ArgType, typename ResType>
 struct CallableTraits<ResType(*)(ArgType)> {
   typedef ResType ResultType;
   typedef ResType(*StorageType)(ArgType);
 
   static void CheckIsValid(ResType(*f)(ArgType)) {
     GTEST_CHECK_(f != NULL)
         << "NULL function pointer is passed into ResultOf().";
   }
   template <typename T>
   static ResType Invoke(ResType(*f)(ArgType), T arg) {
     return (*f)(arg);
   }
 };
 
 // Implements the ResultOf() matcher for matching a return value of a
 // unary function of an object.
 template <typename Callable>
 class ResultOfMatcher {
  public:
   typedef typename CallableTraits<Callable>::ResultType ResultType;
 
   ResultOfMatcher(Callable callable, const Matcher<ResultType>& matcher)
       : callable_(callable), matcher_(matcher) {
     CallableTraits<Callable>::CheckIsValid(callable_);
   }
 
   template <typename T>
   operator Matcher<T>() const {
     return Matcher<T>(new Impl<T>(callable_, matcher_));
   }
 
  private:
   typedef typename CallableTraits<Callable>::StorageType CallableStorageType;
 
   template <typename T>
   class Impl : public MatcherInterface<T> {
    public:
     Impl(CallableStorageType callable, const Matcher<ResultType>& matcher)
         : callable_(callable), matcher_(matcher) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "is mapped by the given callable to a value that ";
       matcher_.DescribeTo(os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "is mapped by the given callable to a value that ";
       matcher_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(T obj, MatchResultListener* listener) const {
       *listener << "which is mapped by the given callable to ";
       // Cannot pass the return value (for example, int) to
       // MatchPrintAndExplain, which takes a non-const reference as argument.
       ResultType result =
           CallableTraits<Callable>::template Invoke<T>(callable_, obj);
       return MatchPrintAndExplain(result, matcher_, listener);
     }
 
    private:
     // Functors often define operator() as non-const method even though
     // they are actualy stateless. But we need to use them even when
     // 'this' is a const pointer. It's the user's responsibility not to
     // use stateful callables with ResultOf(), which does't guarantee
     // how many times the callable will be invoked.
     mutable CallableStorageType callable_;
     const Matcher<ResultType> matcher_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };  // class Impl
 
   const CallableStorageType callable_;
   const Matcher<ResultType> matcher_;
 
   GTEST_DISALLOW_ASSIGN_(ResultOfMatcher);
 };
 
 // Implements a matcher that checks the size of an STL-style container.
 template <typename SizeMatcher>
 class SizeIsMatcher {
  public:
   explicit SizeIsMatcher(const SizeMatcher& size_matcher)
        : size_matcher_(size_matcher) {
   }
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(new Impl<Container>(size_matcher_));
   }
 
   template <typename Container>
   class Impl : public MatcherInterface<Container> {
    public:
     typedef internal::StlContainerView<
          GTEST_REMOVE_REFERENCE_AND_CONST_(Container)> ContainerView;
     typedef typename ContainerView::type::size_type SizeType;
     explicit Impl(const SizeMatcher& size_matcher)
         : size_matcher_(MatcherCast<SizeType>(size_matcher)) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "size ";
       size_matcher_.DescribeTo(os);
     }
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "size ";
       size_matcher_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(Container container,
                                  MatchResultListener* listener) const {
       SizeType size = container.size();
       StringMatchResultListener size_listener;
       const bool result = size_matcher_.MatchAndExplain(size, &size_listener);
       *listener
           << "whose size " << size << (result ? " matches" : " doesn't match");
       PrintIfNotEmpty(size_listener.str(), listener->stream());
       return result;
     }
 
    private:
     const Matcher<SizeType> size_matcher_;
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
  private:
   const SizeMatcher size_matcher_;
   GTEST_DISALLOW_ASSIGN_(SizeIsMatcher);
 };
 
 // Implements a matcher that checks the begin()..end() distance of an STL-style
 // container.
 template <typename DistanceMatcher>
 class BeginEndDistanceIsMatcher {
  public:
   explicit BeginEndDistanceIsMatcher(const DistanceMatcher& distance_matcher)
       : distance_matcher_(distance_matcher) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(new Impl<Container>(distance_matcher_));
   }
 
   template <typename Container>
   class Impl : public MatcherInterface<Container> {
    public:
     typedef internal::StlContainerView<
         GTEST_REMOVE_REFERENCE_AND_CONST_(Container)> ContainerView;
     typedef typename std::iterator_traits<
         typename ContainerView::type::const_iterator>::difference_type
         DistanceType;
     explicit Impl(const DistanceMatcher& distance_matcher)
         : distance_matcher_(MatcherCast<DistanceType>(distance_matcher)) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "distance between begin() and end() ";
       distance_matcher_.DescribeTo(os);
     }
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "distance between begin() and end() ";
       distance_matcher_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(Container container,
                                  MatchResultListener* listener) const {
 #if GTEST_HAS_STD_BEGIN_AND_END_
       using std::begin;
       using std::end;
       DistanceType distance = std::distance(begin(container), end(container));
 #else
       DistanceType distance = std::distance(container.begin(), container.end());
 #endif
       StringMatchResultListener distance_listener;
       const bool result =
           distance_matcher_.MatchAndExplain(distance, &distance_listener);
       *listener << "whose distance between begin() and end() " << distance
                 << (result ? " matches" : " doesn't match");
       PrintIfNotEmpty(distance_listener.str(), listener->stream());
       return result;
     }
 
    private:
     const Matcher<DistanceType> distance_matcher_;
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
  private:
   const DistanceMatcher distance_matcher_;
   GTEST_DISALLOW_ASSIGN_(BeginEndDistanceIsMatcher);
 };
 
 // Implements an equality matcher for any STL-style container whose elements
 // support ==. This matcher is like Eq(), but its failure explanations provide
 // more detailed information that is useful when the container is used as a set.
 // The failure message reports elements that are in one of the operands but not
 // the other. The failure messages do not report duplicate or out-of-order
 // elements in the containers (which don't properly matter to sets, but can
 // occur if the containers are vectors or lists, for example).
 //
 // Uses the container's const_iterator, value_type, operator ==,
 // begin(), and end().
 template <typename Container>
 class ContainerEqMatcher {
  public:
   typedef internal::StlContainerView<Container> View;
   typedef typename View::type StlContainer;
   typedef typename View::const_reference StlContainerReference;
 
   // We make a copy of expected in case the elements in it are modified
   // after this matcher is created.
   explicit ContainerEqMatcher(const Container& expected)
       : expected_(View::Copy(expected)) {
     // Makes sure the user doesn't instantiate this class template
     // with a const or reference type.
     (void)testing::StaticAssertTypeEq<Container,
         GTEST_REMOVE_REFERENCE_AND_CONST_(Container)>();
   }
 
   void DescribeTo(::std::ostream* os) const {
     *os << "equals ";
     UniversalPrint(expected_, os);
   }
   void DescribeNegationTo(::std::ostream* os) const {
     *os << "does not equal ";
     UniversalPrint(expected_, os);
   }
 
   template <typename LhsContainer>
   bool MatchAndExplain(const LhsContainer& lhs,
                        MatchResultListener* listener) const {
     // GTEST_REMOVE_CONST_() is needed to work around an MSVC 8.0 bug
     // that causes LhsContainer to be a const type sometimes.
     typedef internal::StlContainerView<GTEST_REMOVE_CONST_(LhsContainer)>
         LhsView;
     typedef typename LhsView::type LhsStlContainer;
     StlContainerReference lhs_stl_container = LhsView::ConstReference(lhs);
     if (lhs_stl_container == expected_)
       return true;
 
     ::std::ostream* const os = listener->stream();
     if (os != NULL) {
       // Something is different. Check for extra values first.
       bool printed_header = false;
       for (typename LhsStlContainer::const_iterator it =
                lhs_stl_container.begin();
            it != lhs_stl_container.end(); ++it) {
         if (internal::ArrayAwareFind(expected_.begin(), expected_.end(), *it) ==
             expected_.end()) {
           if (printed_header) {
             *os << ", ";
           } else {
             *os << "which has these unexpected elements: ";
             printed_header = true;
           }
           UniversalPrint(*it, os);
         }
       }
 
       // Now check for missing values.
       bool printed_header2 = false;
       for (typename StlContainer::const_iterator it = expected_.begin();
            it != expected_.end(); ++it) {
         if (internal::ArrayAwareFind(
                 lhs_stl_container.begin(), lhs_stl_container.end(), *it) ==
             lhs_stl_container.end()) {
           if (printed_header2) {
             *os << ", ";
           } else {
             *os << (printed_header ? ",\nand" : "which")
                 << " doesn't have these expected elements: ";
             printed_header2 = true;
           }
           UniversalPrint(*it, os);
         }
       }
     }
 
     return false;
   }
 
  private:
   const StlContainer expected_;
 
   GTEST_DISALLOW_ASSIGN_(ContainerEqMatcher);
 };
 
 // A comparator functor that uses the < operator to compare two values.
 struct LessComparator {
   template <typename T, typename U>
   bool operator()(const T& lhs, const U& rhs) const { return lhs < rhs; }
 };
 
 // Implements WhenSortedBy(comparator, container_matcher).
 template <typename Comparator, typename ContainerMatcher>
 class WhenSortedByMatcher {
  public:
   WhenSortedByMatcher(const Comparator& comparator,
                       const ContainerMatcher& matcher)
       : comparator_(comparator), matcher_(matcher) {}
 
   template <typename LhsContainer>
   operator Matcher<LhsContainer>() const {
     return MakeMatcher(new Impl<LhsContainer>(comparator_, matcher_));
   }
 
   template <typename LhsContainer>
   class Impl : public MatcherInterface<LhsContainer> {
    public:
     typedef internal::StlContainerView<
          GTEST_REMOVE_REFERENCE_AND_CONST_(LhsContainer)> LhsView;
     typedef typename LhsView::type LhsStlContainer;
     typedef typename LhsView::const_reference LhsStlContainerReference;
     // Transforms std::pair<const Key, Value> into std::pair<Key, Value>
     // so that we can match associative containers.
     typedef typename RemoveConstFromKey<
         typename LhsStlContainer::value_type>::type LhsValue;
 
     Impl(const Comparator& comparator, const ContainerMatcher& matcher)
         : comparator_(comparator), matcher_(matcher) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "(when sorted) ";
       matcher_.DescribeTo(os);
     }
 
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "(when sorted) ";
       matcher_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(LhsContainer lhs,
                                  MatchResultListener* listener) const {
       LhsStlContainerReference lhs_stl_container = LhsView::ConstReference(lhs);
       ::std::vector<LhsValue> sorted_container(lhs_stl_container.begin(),
                                                lhs_stl_container.end());
       ::std::sort(
            sorted_container.begin(), sorted_container.end(), comparator_);
 
       if (!listener->IsInterested()) {
         // If the listener is not interested, we do not need to
         // construct the inner explanation.
         return matcher_.Matches(sorted_container);
       }
 
       *listener << "which is ";
       UniversalPrint(sorted_container, listener->stream());
       *listener << " when sorted";
 
       StringMatchResultListener inner_listener;
       const bool match = matcher_.MatchAndExplain(sorted_container,
                                                   &inner_listener);
       PrintIfNotEmpty(inner_listener.str(), listener->stream());
       return match;
     }
 
    private:
     const Comparator comparator_;
     const Matcher<const ::std::vector<LhsValue>&> matcher_;
 
     GTEST_DISALLOW_COPY_AND_ASSIGN_(Impl);
   };
 
  private:
   const Comparator comparator_;
   const ContainerMatcher matcher_;
 
   GTEST_DISALLOW_ASSIGN_(WhenSortedByMatcher);
 };
 
 // Implements Pointwise(tuple_matcher, rhs_container).  tuple_matcher
 // must be able to be safely cast to Matcher<tuple<const T1&, const
 // T2&> >, where T1 and T2 are the types of elements in the LHS
 // container and the RHS container respectively.
 template <typename TupleMatcher, typename RhsContainer>
 class PointwiseMatcher {
  public:
   typedef internal::StlContainerView<RhsContainer> RhsView;
   typedef typename RhsView::type RhsStlContainer;
   typedef typename RhsStlContainer::value_type RhsValue;
 
   // Like ContainerEq, we make a copy of rhs in case the elements in
   // it are modified after this matcher is created.
   PointwiseMatcher(const TupleMatcher& tuple_matcher, const RhsContainer& rhs)
       : tuple_matcher_(tuple_matcher), rhs_(RhsView::Copy(rhs)) {
     // Makes sure the user doesn't instantiate this class template
     // with a const or reference type.
     (void)testing::StaticAssertTypeEq<RhsContainer,
         GTEST_REMOVE_REFERENCE_AND_CONST_(RhsContainer)>();
   }
 
   template <typename LhsContainer>
   operator Matcher<LhsContainer>() const {
     return MakeMatcher(new Impl<LhsContainer>(tuple_matcher_, rhs_));
   }
 
   template <typename LhsContainer>
   class Impl : public MatcherInterface<LhsContainer> {
    public:
     typedef internal::StlContainerView<
          GTEST_REMOVE_REFERENCE_AND_CONST_(LhsContainer)> LhsView;
     typedef typename LhsView::type LhsStlContainer;
     typedef typename LhsView::const_reference LhsStlContainerReference;
     typedef typename LhsStlContainer::value_type LhsValue;
     // We pass the LHS value and the RHS value to the inner matcher by
     // reference, as they may be expensive to copy.  We must use tuple
     // instead of pair here, as a pair cannot hold references (C++ 98,
     // 20.2.2 [lib.pairs]).
     typedef ::testing::tuple<const LhsValue&, const RhsValue&> InnerMatcherArg;
 
     Impl(const TupleMatcher& tuple_matcher, const RhsStlContainer& rhs)
         // mono_tuple_matcher_ holds a monomorphic version of the tuple matcher.
         : mono_tuple_matcher_(SafeMatcherCast<InnerMatcherArg>(tuple_matcher)),
           rhs_(rhs) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "contains " << rhs_.size()
           << " values, where each value and its corresponding value in ";
       UniversalPrinter<RhsStlContainer>::Print(rhs_, os);
       *os << " ";
       mono_tuple_matcher_.DescribeTo(os);
     }
     virtual void DescribeNegationTo(::std::ostream* os) const {
       *os << "doesn't contain exactly " << rhs_.size()
           << " values, or contains a value x at some index i"
           << " where x and the i-th value of ";
       UniversalPrint(rhs_, os);
       *os << " ";
       mono_tuple_matcher_.DescribeNegationTo(os);
     }
 
     virtual bool MatchAndExplain(LhsContainer lhs,
                                  MatchResultListener* listener) const {
       LhsStlContainerReference lhs_stl_container = LhsView::ConstReference(lhs);
       const size_t actual_size = lhs_stl_container.size();
       if (actual_size != rhs_.size()) {
         *listener << "which contains " << actual_size << " values";
         return false;
       }
 
       typename LhsStlContainer::const_iterator left = lhs_stl_container.begin();
       typename RhsStlContainer::const_iterator right = rhs_.begin();
       for (size_t i = 0; i != actual_size; ++i, ++left, ++right) {
         const InnerMatcherArg value_pair(*left, *right);
 
         if (listener->IsInterested()) {
           StringMatchResultListener inner_listener;
           if (!mono_tuple_matcher_.MatchAndExplain(
                   value_pair, &inner_listener)) {
             *listener << "where the value pair (";
             UniversalPrint(*left, listener->stream());
             *listener << ", ";
             UniversalPrint(*right, listener->stream());
             *listener << ") at index #" << i << " don't match";
             PrintIfNotEmpty(inner_listener.str(), listener->stream());
             return false;
           }
         } else {
           if (!mono_tuple_matcher_.Matches(value_pair))
             return false;
         }
       }
 
       return true;
     }
 
    private:
     const Matcher<InnerMatcherArg> mono_tuple_matcher_;
     const RhsStlContainer rhs_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
  private:
   const TupleMatcher tuple_matcher_;
   const RhsStlContainer rhs_;
 
   GTEST_DISALLOW_ASSIGN_(PointwiseMatcher);
 };
 
 // Holds the logic common to ContainsMatcherImpl and EachMatcherImpl.
 template <typename Container>
 class QuantifierMatcherImpl : public MatcherInterface<Container> {
  public:
   typedef GTEST_REMOVE_REFERENCE_AND_CONST_(Container) RawContainer;
   typedef StlContainerView<RawContainer> View;
   typedef typename View::type StlContainer;
   typedef typename View::const_reference StlContainerReference;
   typedef typename StlContainer::value_type Element;
 
   template <typename InnerMatcher>
   explicit QuantifierMatcherImpl(InnerMatcher inner_matcher)
       : inner_matcher_(
            testing::SafeMatcherCast<const Element&>(inner_matcher)) {}
 
   // Checks whether:
   // * All elements in the container match, if all_elements_should_match.
   // * Any element in the container matches, if !all_elements_should_match.
   bool MatchAndExplainImpl(bool all_elements_should_match,
                            Container container,
                            MatchResultListener* listener) const {
     StlContainerReference stl_container = View::ConstReference(container);
     size_t i = 0;
     for (typename StlContainer::const_iterator it = stl_container.begin();
          it != stl_container.end(); ++it, ++i) {
       StringMatchResultListener inner_listener;
       const bool matches = inner_matcher_.MatchAndExplain(*it, &inner_listener);
 
       if (matches != all_elements_should_match) {
         *listener << "whose element #" << i
                   << (matches ? " matches" : " doesn't match");
         PrintIfNotEmpty(inner_listener.str(), listener->stream());
         return !all_elements_should_match;
       }
     }
     return all_elements_should_match;
   }
 
  protected:
   const Matcher<const Element&> inner_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(QuantifierMatcherImpl);
 };
 
 // Implements Contains(element_matcher) for the given argument type Container.
 // Symmetric to EachMatcherImpl.
 template <typename Container>
 class ContainsMatcherImpl : public QuantifierMatcherImpl<Container> {
  public:
   template <typename InnerMatcher>
   explicit ContainsMatcherImpl(InnerMatcher inner_matcher)
       : QuantifierMatcherImpl<Container>(inner_matcher) {}
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "contains at least one element that ";
     this->inner_matcher_.DescribeTo(os);
   }
 
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't contain any element that ";
     this->inner_matcher_.DescribeTo(os);
   }
 
   virtual bool MatchAndExplain(Container container,
                                MatchResultListener* listener) const {
     return this->MatchAndExplainImpl(false, container, listener);
   }
 
  private:
   GTEST_DISALLOW_ASSIGN_(ContainsMatcherImpl);
 };
 
 // Implements Each(element_matcher) for the given argument type Container.
 // Symmetric to ContainsMatcherImpl.
 template <typename Container>
 class EachMatcherImpl : public QuantifierMatcherImpl<Container> {
  public:
   template <typename InnerMatcher>
   explicit EachMatcherImpl(InnerMatcher inner_matcher)
       : QuantifierMatcherImpl<Container>(inner_matcher) {}
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "only contains elements that ";
     this->inner_matcher_.DescribeTo(os);
   }
 
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "contains some element that ";
     this->inner_matcher_.DescribeNegationTo(os);
   }
 
   virtual bool MatchAndExplain(Container container,
                                MatchResultListener* listener) const {
     return this->MatchAndExplainImpl(true, container, listener);
   }
 
  private:
   GTEST_DISALLOW_ASSIGN_(EachMatcherImpl);
 };
 
 // Implements polymorphic Contains(element_matcher).
 template <typename M>
 class ContainsMatcher {
  public:
   explicit ContainsMatcher(M m) : inner_matcher_(m) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(new ContainsMatcherImpl<Container>(inner_matcher_));
   }
 
  private:
   const M inner_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(ContainsMatcher);
 };
 
 // Implements polymorphic Each(element_matcher).
 template <typename M>
 class EachMatcher {
  public:
   explicit EachMatcher(M m) : inner_matcher_(m) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(new EachMatcherImpl<Container>(inner_matcher_));
   }
 
  private:
   const M inner_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(EachMatcher);
 };
 
 // Implements Key(inner_matcher) for the given argument pair type.
 // Key(inner_matcher) matches an std::pair whose 'first' field matches
 // inner_matcher.  For example, Contains(Key(Ge(5))) can be used to match an
 // std::map that contains at least one element whose key is >= 5.
 template <typename PairType>
 class KeyMatcherImpl : public MatcherInterface<PairType> {
  public:
   typedef GTEST_REMOVE_REFERENCE_AND_CONST_(PairType) RawPairType;
   typedef typename RawPairType::first_type KeyType;
 
   template <typename InnerMatcher>
   explicit KeyMatcherImpl(InnerMatcher inner_matcher)
       : inner_matcher_(
           testing::SafeMatcherCast<const KeyType&>(inner_matcher)) {
   }
 
   // Returns true iff 'key_value.first' (the key) matches the inner matcher.
   virtual bool MatchAndExplain(PairType key_value,
                                MatchResultListener* listener) const {
     StringMatchResultListener inner_listener;
     const bool match = inner_matcher_.MatchAndExplain(key_value.first,
                                                       &inner_listener);
     const internal::string explanation = inner_listener.str();
     if (explanation != "") {
       *listener << "whose first field is a value " << explanation;
     }
     return match;
   }
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "has a key that ";
     inner_matcher_.DescribeTo(os);
   }
 
   // Describes what the negation of this matcher does.
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "doesn't have a key that ";
     inner_matcher_.DescribeTo(os);
   }
 
  private:
   const Matcher<const KeyType&> inner_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(KeyMatcherImpl);
 };
 
 // Implements polymorphic Key(matcher_for_key).
 template <typename M>
 class KeyMatcher {
  public:
   explicit KeyMatcher(M m) : matcher_for_key_(m) {}
 
   template <typename PairType>
   operator Matcher<PairType>() const {
     return MakeMatcher(new KeyMatcherImpl<PairType>(matcher_for_key_));
   }
 
  private:
   const M matcher_for_key_;
 
   GTEST_DISALLOW_ASSIGN_(KeyMatcher);
 };
 
 // Implements Pair(first_matcher, second_matcher) for the given argument pair
 // type with its two matchers. See Pair() function below.
 template <typename PairType>
 class PairMatcherImpl : public MatcherInterface<PairType> {
  public:
   typedef GTEST_REMOVE_REFERENCE_AND_CONST_(PairType) RawPairType;
   typedef typename RawPairType::first_type FirstType;
   typedef typename RawPairType::second_type SecondType;
 
   template <typename FirstMatcher, typename SecondMatcher>
   PairMatcherImpl(FirstMatcher first_matcher, SecondMatcher second_matcher)
       : first_matcher_(
             testing::SafeMatcherCast<const FirstType&>(first_matcher)),
         second_matcher_(
             testing::SafeMatcherCast<const SecondType&>(second_matcher)) {
   }
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     *os << "has a first field that ";
     first_matcher_.DescribeTo(os);
     *os << ", and has a second field that ";
     second_matcher_.DescribeTo(os);
   }
 
   // Describes what the negation of this matcher does.
   virtual void DescribeNegationTo(::std::ostream* os) const {
     *os << "has a first field that ";
     first_matcher_.DescribeNegationTo(os);
     *os << ", or has a second field that ";
     second_matcher_.DescribeNegationTo(os);
   }
 
   // Returns true iff 'a_pair.first' matches first_matcher and 'a_pair.second'
   // matches second_matcher.
   virtual bool MatchAndExplain(PairType a_pair,
                                MatchResultListener* listener) const {
     if (!listener->IsInterested()) {
       // If the listener is not interested, we don't need to construct the
       // explanation.
       return first_matcher_.Matches(a_pair.first) &&
              second_matcher_.Matches(a_pair.second);
     }
     StringMatchResultListener first_inner_listener;
     if (!first_matcher_.MatchAndExplain(a_pair.first,
                                         &first_inner_listener)) {
       *listener << "whose first field does not match";
       PrintIfNotEmpty(first_inner_listener.str(), listener->stream());
       return false;
     }
     StringMatchResultListener second_inner_listener;
     if (!second_matcher_.MatchAndExplain(a_pair.second,
                                          &second_inner_listener)) {
       *listener << "whose second field does not match";
       PrintIfNotEmpty(second_inner_listener.str(), listener->stream());
       return false;
     }
     ExplainSuccess(first_inner_listener.str(), second_inner_listener.str(),
                    listener);
     return true;
   }
 
  private:
   void ExplainSuccess(const internal::string& first_explanation,
                       const internal::string& second_explanation,
                       MatchResultListener* listener) const {
     *listener << "whose both fields match";
     if (first_explanation != "") {
       *listener << ", where the first field is a value " << first_explanation;
     }
     if (second_explanation != "") {
       *listener << ", ";
       if (first_explanation != "") {
         *listener << "and ";
       } else {
         *listener << "where ";
       }
       *listener << "the second field is a value " << second_explanation;
     }
   }
 
   const Matcher<const FirstType&> first_matcher_;
   const Matcher<const SecondType&> second_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(PairMatcherImpl);
 };
 
 // Implements polymorphic Pair(first_matcher, second_matcher).
 template <typename FirstMatcher, typename SecondMatcher>
 class PairMatcher {
  public:
   PairMatcher(FirstMatcher first_matcher, SecondMatcher second_matcher)
       : first_matcher_(first_matcher), second_matcher_(second_matcher) {}
 
   template <typename PairType>
   operator Matcher<PairType> () const {
     return MakeMatcher(
         new PairMatcherImpl<PairType>(
             first_matcher_, second_matcher_));
   }
 
  private:
   const FirstMatcher first_matcher_;
   const SecondMatcher second_matcher_;
 
   GTEST_DISALLOW_ASSIGN_(PairMatcher);
 };
 
 // Implements ElementsAre() and ElementsAreArray().
 template <typename Container>
 class ElementsAreMatcherImpl : public MatcherInterface<Container> {
  public:
   typedef GTEST_REMOVE_REFERENCE_AND_CONST_(Container) RawContainer;
   typedef internal::StlContainerView<RawContainer> View;
   typedef typename View::type StlContainer;
   typedef typename View::const_reference StlContainerReference;
   typedef typename StlContainer::value_type Element;
 
   // Constructs the matcher from a sequence of element values or
   // element matchers.
   template <typename InputIter>
   ElementsAreMatcherImpl(InputIter first, InputIter last) {
     while (first != last) {
       matchers_.push_back(MatcherCast<const Element&>(*first++));
     }
   }
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     if (count() == 0) {
       *os << "is empty";
     } else if (count() == 1) {
       *os << "has 1 element that ";
       matchers_[0].DescribeTo(os);
     } else {
       *os << "has " << Elements(count()) << " where\n";
       for (size_t i = 0; i != count(); ++i) {
         *os << "element #" << i << " ";
         matchers_[i].DescribeTo(os);
         if (i + 1 < count()) {
           *os << ",\n";
         }
       }
     }
   }
 
   // Describes what the negation of this matcher does.
   virtual void DescribeNegationTo(::std::ostream* os) const {
     if (count() == 0) {
       *os << "isn't empty";
       return;
     }
 
     *os << "doesn't have " << Elements(count()) << ", or\n";
     for (size_t i = 0; i != count(); ++i) {
       *os << "element #" << i << " ";
       matchers_[i].DescribeNegationTo(os);
       if (i + 1 < count()) {
         *os << ", or\n";
       }
     }
   }
 
   virtual bool MatchAndExplain(Container container,
                                MatchResultListener* listener) const {
     // To work with stream-like "containers", we must only walk
     // through the elements in one pass.
 
     const bool listener_interested = listener->IsInterested();
 
     // explanations[i] is the explanation of the element at index i.
     ::std::vector<internal::string> explanations(count());
     StlContainerReference stl_container = View::ConstReference(container);
     typename StlContainer::const_iterator it = stl_container.begin();
     size_t exam_pos = 0;
     bool mismatch_found = false;  // Have we found a mismatched element yet?
 
     // Go through the elements and matchers in pairs, until we reach
     // the end of either the elements or the matchers, or until we find a
     // mismatch.
     for (; it != stl_container.end() && exam_pos != count(); ++it, ++exam_pos) {
       bool match;  // Does the current element match the current matcher?
       if (listener_interested) {
         StringMatchResultListener s;
         match = matchers_[exam_pos].MatchAndExplain(*it, &s);
         explanations[exam_pos] = s.str();
       } else {
         match = matchers_[exam_pos].Matches(*it);
       }
 
       if (!match) {
         mismatch_found = true;
         break;
       }
     }
     // If mismatch_found is true, 'exam_pos' is the index of the mismatch.
 
     // Find how many elements the actual container has.  We avoid
     // calling size() s.t. this code works for stream-like "containers"
     // that don't define size().
     size_t actual_count = exam_pos;
     for (; it != stl_container.end(); ++it) {
       ++actual_count;
     }
 
     if (actual_count != count()) {
       // The element count doesn't match.  If the container is empty,
       // there's no need to explain anything as Google Mock already
       // prints the empty container.  Otherwise we just need to show
       // how many elements there actually are.
       if (listener_interested && (actual_count != 0)) {
         *listener << "which has " << Elements(actual_count);
       }
       return false;
     }
 
     if (mismatch_found) {
       // The element count matches, but the exam_pos-th element doesn't match.
       if (listener_interested) {
         *listener << "whose element #" << exam_pos << " doesn't match";
         PrintIfNotEmpty(explanations[exam_pos], listener->stream());
       }
       return false;
     }
 
     // Every element matches its expectation.  We need to explain why
     // (the obvious ones can be skipped).
     if (listener_interested) {
       bool reason_printed = false;
       for (size_t i = 0; i != count(); ++i) {
         const internal::string& s = explanations[i];
         if (!s.empty()) {
           if (reason_printed) {
             *listener << ",\nand ";
           }
           *listener << "whose element #" << i << " matches, " << s;
           reason_printed = true;
         }
       }
     }
     return true;
   }
 
  private:
   static Message Elements(size_t count) {
     return Message() << count << (count == 1 ? " element" : " elements");
   }
 
   size_t count() const { return matchers_.size(); }
 
   ::std::vector<Matcher<const Element&> > matchers_;
 
   GTEST_DISALLOW_ASSIGN_(ElementsAreMatcherImpl);
 };
 
 // Connectivity matrix of (elements X matchers), in element-major order.
 // Initially, there are no edges.
 // Use NextGraph() to iterate over all possible edge configurations.
 // Use Randomize() to generate a random edge configuration.
 class GTEST_API_ MatchMatrix {
  public:
   MatchMatrix(size_t num_elements, size_t num_matchers)
       : num_elements_(num_elements),
         num_matchers_(num_matchers),
         matched_(num_elements_* num_matchers_, 0) {
   }
 
   size_t LhsSize() const { return num_elements_; }
   size_t RhsSize() const { return num_matchers_; }
   bool HasEdge(size_t ilhs, size_t irhs) const {
     return matched_[SpaceIndex(ilhs, irhs)] == 1;
   }
   void SetEdge(size_t ilhs, size_t irhs, bool b) {
     matched_[SpaceIndex(ilhs, irhs)] = b ? 1 : 0;
   }
 
   // Treating the connectivity matrix as a (LhsSize()*RhsSize())-bit number,
   // adds 1 to that number; returns false if incrementing the graph left it
   // empty.
   bool NextGraph();
 
   void Randomize();
 
   string DebugString() const;
 
  private:
   size_t SpaceIndex(size_t ilhs, size_t irhs) const {
     return ilhs * num_matchers_ + irhs;
   }
 
   size_t num_elements_;
   size_t num_matchers_;
 
   // Each element is a char interpreted as bool. They are stored as a
   // flattened array in lhs-major order, use 'SpaceIndex()' to translate
   // a (ilhs, irhs) matrix coordinate into an offset.
   ::std::vector<char> matched_;
 };
 
 typedef ::std::pair<size_t, size_t> ElementMatcherPair;
 typedef ::std::vector<ElementMatcherPair> ElementMatcherPairs;
 
 // Returns a maximum bipartite matching for the specified graph 'g'.
 // The matching is represented as a vector of {element, matcher} pairs.
 GTEST_API_ ElementMatcherPairs
 FindMaxBipartiteMatching(const MatchMatrix& g);
 
 GTEST_API_ bool FindPairing(const MatchMatrix& matrix,
                             MatchResultListener* listener);
 
 // Untyped base class for implementing UnorderedElementsAre.  By
 // putting logic that's not specific to the element type here, we
 // reduce binary bloat and increase compilation speed.
 class GTEST_API_ UnorderedElementsAreMatcherImplBase {
  protected:
   // A vector of matcher describers, one for each element matcher.
   // Does not own the describers (and thus can be used only when the
   // element matchers are alive).
   typedef ::std::vector<const MatcherDescriberInterface*> MatcherDescriberVec;
 
   // Describes this UnorderedElementsAre matcher.
   void DescribeToImpl(::std::ostream* os) const;
 
   // Describes the negation of this UnorderedElementsAre matcher.
   void DescribeNegationToImpl(::std::ostream* os) const;
 
   bool VerifyAllElementsAndMatchersAreMatched(
       const ::std::vector<string>& element_printouts,
       const MatchMatrix& matrix,
       MatchResultListener* listener) const;
 
   MatcherDescriberVec& matcher_describers() {
     return matcher_describers_;
   }
 
   static Message Elements(size_t n) {
     return Message() << n << " element" << (n == 1 ? "" : "s");
   }
 
  private:
   MatcherDescriberVec matcher_describers_;
 
   GTEST_DISALLOW_ASSIGN_(UnorderedElementsAreMatcherImplBase);
 };
 
 // Implements unordered ElementsAre and unordered ElementsAreArray.
 template <typename Container>
 class UnorderedElementsAreMatcherImpl
     : public MatcherInterface<Container>,
       public UnorderedElementsAreMatcherImplBase {
  public:
   typedef GTEST_REMOVE_REFERENCE_AND_CONST_(Container) RawContainer;
   typedef internal::StlContainerView<RawContainer> View;
   typedef typename View::type StlContainer;
   typedef typename View::const_reference StlContainerReference;
   typedef typename StlContainer::const_iterator StlContainerConstIterator;
   typedef typename StlContainer::value_type Element;
 
   // Constructs the matcher from a sequence of element values or
   // element matchers.
   template <typename InputIter>
   UnorderedElementsAreMatcherImpl(InputIter first, InputIter last) {
     for (; first != last; ++first) {
       matchers_.push_back(MatcherCast<const Element&>(*first));
       matcher_describers().push_back(matchers_.back().GetDescriber());
     }
   }
 
   // Describes what this matcher does.
   virtual void DescribeTo(::std::ostream* os) const {
     return UnorderedElementsAreMatcherImplBase::DescribeToImpl(os);
   }
 
   // Describes what the negation of this matcher does.
   virtual void DescribeNegationTo(::std::ostream* os) const {
     return UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(os);
   }
 
   virtual bool MatchAndExplain(Container container,
                                MatchResultListener* listener) const {
     StlContainerReference stl_container = View::ConstReference(container);
     ::std::vector<string> element_printouts;
     MatchMatrix matrix = AnalyzeElements(stl_container.begin(),
                                          stl_container.end(),
                                          &element_printouts,
                                          listener);
 
     const size_t actual_count = matrix.LhsSize();
     if (actual_count == 0 && matchers_.empty()) {
       return true;
     }
     if (actual_count != matchers_.size()) {
       // The element count doesn't match.  If the container is empty,
       // there's no need to explain anything as Google Mock already
       // prints the empty container. Otherwise we just need to show
       // how many elements there actually are.
       if (actual_count != 0 && listener->IsInterested()) {
         *listener << "which has " << Elements(actual_count);
       }
       return false;
     }
 
     return VerifyAllElementsAndMatchersAreMatched(element_printouts,
                                                   matrix, listener) &&
            FindPairing(matrix, listener);
   }
 
  private:
   typedef ::std::vector<Matcher<const Element&> > MatcherVec;
 
   template <typename ElementIter>
   MatchMatrix AnalyzeElements(ElementIter elem_first, ElementIter elem_last,
                               ::std::vector<string>* element_printouts,
                               MatchResultListener* listener) const {
     element_printouts->clear();
     ::std::vector<char> did_match;
     size_t num_elements = 0;
     for (; elem_first != elem_last; ++num_elements, ++elem_first) {
       if (listener->IsInterested()) {
         element_printouts->push_back(PrintToString(*elem_first));
       }
       for (size_t irhs = 0; irhs != matchers_.size(); ++irhs) {
         did_match.push_back(Matches(matchers_[irhs])(*elem_first));
       }
     }
 
     MatchMatrix matrix(num_elements, matchers_.size());
     ::std::vector<char>::const_iterator did_match_iter = did_match.begin();
     for (size_t ilhs = 0; ilhs != num_elements; ++ilhs) {
       for (size_t irhs = 0; irhs != matchers_.size(); ++irhs) {
         matrix.SetEdge(ilhs, irhs, *did_match_iter++ != 0);
       }
     }
     return matrix;
   }
 
   MatcherVec matchers_;
 
   GTEST_DISALLOW_ASSIGN_(UnorderedElementsAreMatcherImpl);
 };
 
 // Functor for use in TransformTuple.
 // Performs MatcherCast<Target> on an input argument of any type.
 template <typename Target>
 struct CastAndAppendTransform {
   template <typename Arg>
   Matcher<Target> operator()(const Arg& a) const {
     return MatcherCast<Target>(a);
   }
 };
 
 // Implements UnorderedElementsAre.
 template <typename MatcherTuple>
 class UnorderedElementsAreMatcher {
  public:
   explicit UnorderedElementsAreMatcher(const MatcherTuple& args)
       : matchers_(args) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     typedef GTEST_REMOVE_REFERENCE_AND_CONST_(Container) RawContainer;
     typedef typename internal::StlContainerView<RawContainer>::type View;
     typedef typename View::value_type Element;
     typedef ::std::vector<Matcher<const Element&> > MatcherVec;
     MatcherVec matchers;
     matchers.reserve(::testing::tuple_size<MatcherTuple>::value);
     TransformTupleValues(CastAndAppendTransform<const Element&>(), matchers_,
                          ::std::back_inserter(matchers));
     return MakeMatcher(new UnorderedElementsAreMatcherImpl<Container>(
                            matchers.begin(), matchers.end()));
   }
 
  private:
   const MatcherTuple matchers_;
   GTEST_DISALLOW_ASSIGN_(UnorderedElementsAreMatcher);
 };
 
 // Implements ElementsAre.
 template <typename MatcherTuple>
 class ElementsAreMatcher {
  public:
   explicit ElementsAreMatcher(const MatcherTuple& args) : matchers_(args) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     typedef GTEST_REMOVE_REFERENCE_AND_CONST_(Container) RawContainer;
     typedef typename internal::StlContainerView<RawContainer>::type View;
     typedef typename View::value_type Element;
     typedef ::std::vector<Matcher<const Element&> > MatcherVec;
     MatcherVec matchers;
     matchers.reserve(::testing::tuple_size<MatcherTuple>::value);
     TransformTupleValues(CastAndAppendTransform<const Element&>(), matchers_,
                          ::std::back_inserter(matchers));
     return MakeMatcher(new ElementsAreMatcherImpl<Container>(
                            matchers.begin(), matchers.end()));
   }
 
  private:
   const MatcherTuple matchers_;
   GTEST_DISALLOW_ASSIGN_(ElementsAreMatcher);
 };
 
 // Implements UnorderedElementsAreArray().
 template <typename T>
 class UnorderedElementsAreArrayMatcher {
  public:
   UnorderedElementsAreArrayMatcher() {}
 
   template <typename Iter>
   UnorderedElementsAreArrayMatcher(Iter first, Iter last)
       : matchers_(first, last) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(
         new UnorderedElementsAreMatcherImpl<Container>(matchers_.begin(),
                                                        matchers_.end()));
   }
 
  private:
   ::std::vector<T> matchers_;
 
   GTEST_DISALLOW_ASSIGN_(UnorderedElementsAreArrayMatcher);
 };
 
 // Implements ElementsAreArray().
 template <typename T>
 class ElementsAreArrayMatcher {
  public:
   template <typename Iter>
   ElementsAreArrayMatcher(Iter first, Iter last) : matchers_(first, last) {}
 
   template <typename Container>
   operator Matcher<Container>() const {
     return MakeMatcher(new ElementsAreMatcherImpl<Container>(
         matchers_.begin(), matchers_.end()));
   }
 
  private:
   const ::std::vector<T> matchers_;
 
   GTEST_DISALLOW_ASSIGN_(ElementsAreArrayMatcher);
 };
 
 // Given a 2-tuple matcher tm of type Tuple2Matcher and a value second
 // of type Second, BoundSecondMatcher<Tuple2Matcher, Second>(tm,
 // second) is a polymorphic matcher that matches a value x iff tm
 // matches tuple (x, second).  Useful for implementing
 // UnorderedPointwise() in terms of UnorderedElementsAreArray().
 //
 // BoundSecondMatcher is copyable and assignable, as we need to put
 // instances of this class in a vector when implementing
 // UnorderedPointwise().
 template <typename Tuple2Matcher, typename Second>
 class BoundSecondMatcher {
  public:
   BoundSecondMatcher(const Tuple2Matcher& tm, const Second& second)
       : tuple2_matcher_(tm), second_value_(second) {}
 
   template <typename T>
   operator Matcher<T>() const {
     return MakeMatcher(new Impl<T>(tuple2_matcher_, second_value_));
   }
 
   // We have to define this for UnorderedPointwise() to compile in
   // C++98 mode, as it puts BoundSecondMatcher instances in a vector,
   // which requires the elements to be assignable in C++98.  The
   // compiler cannot generate the operator= for us, as Tuple2Matcher
   // and Second may not be assignable.
   //
   // However, this should never be called, so the implementation just
   // need to assert.
   void operator=(const BoundSecondMatcher& /*rhs*/) {
     GTEST_LOG_(FATAL) << "BoundSecondMatcher should never be assigned.";
   }
 
  private:
   template <typename T>
   class Impl : public MatcherInterface<T> {
    public:
     typedef ::testing::tuple<T, Second> ArgTuple;
 
     Impl(const Tuple2Matcher& tm, const Second& second)
         : mono_tuple2_matcher_(SafeMatcherCast<const ArgTuple&>(tm)),
           second_value_(second) {}
 
     virtual void DescribeTo(::std::ostream* os) const {
       *os << "and ";
       UniversalPrint(second_value_, os);
       *os << " ";
       mono_tuple2_matcher_.DescribeTo(os);
     }
 
     virtual bool MatchAndExplain(T x, MatchResultListener* listener) const {
       return mono_tuple2_matcher_.MatchAndExplain(ArgTuple(x, second_value_),
                                                   listener);
     }
 
    private:
     const Matcher<const ArgTuple&> mono_tuple2_matcher_;
     const Second second_value_;
 
     GTEST_DISALLOW_ASSIGN_(Impl);
   };
 
   const Tuple2Matcher tuple2_matcher_;
   const Second second_value_;
 };
 
 // Given a 2-tuple matcher tm and a value second,
 // MatcherBindSecond(tm, second) returns a matcher that matches a
 // value x iff tm matches tuple (x, second).  Useful for implementing
 // UnorderedPointwise() in terms of UnorderedElementsAreArray().
 template <typename Tuple2Matcher, typename Second>
 BoundSecondMatcher<Tuple2Matcher, Second> MatcherBindSecond(
     const Tuple2Matcher& tm, const Second& second) {
   return BoundSecondMatcher<Tuple2Matcher, Second>(tm, second);
 }
 
 // Returns the description for a matcher defined using the MATCHER*()
 // macro where the user-supplied description string is "", if
 // 'negation' is false; otherwise returns the description of the
 // negation of the matcher.  'param_values' contains a list of strings
 // that are the print-out of the matcher's parameters.
 GTEST_API_ string FormatMatcherDescription(bool negation,
                                            const char* matcher_name,
                                            const Strings& param_values);
 
 }  // namespace internal
 
 // ElementsAreArray(first, last)
 // ElementsAreArray(pointer, count)
 // ElementsAreArray(array)
 // ElementsAreArray(container)
 // ElementsAreArray({ e1, e2, ..., en })
 //
 // The ElementsAreArray() functions are like ElementsAre(...), except
 // that they are given a homogeneous sequence rather than taking each
 // element as a function argument. The sequence can be specified as an
 // array, a pointer and count, a vector, an initializer list, or an
 // STL iterator range. In each of these cases, the underlying sequence
 // can be either a sequence of values or a sequence of matchers.
 //
 // All forms of ElementsAreArray() make a copy of the input matcher sequence.
 
 template <typename Iter>
 inline internal::ElementsAreArrayMatcher<
     typename ::std::iterator_traits<Iter>::value_type>
 ElementsAreArray(Iter first, Iter last) {
   typedef typename ::std::iterator_traits<Iter>::value_type T;
   return internal::ElementsAreArrayMatcher<T>(first, last);
 }
 
 template <typename T>
 inline internal::ElementsAreArrayMatcher<T> ElementsAreArray(
     const T* pointer, size_t count) {
   return ElementsAreArray(pointer, pointer + count);
 }
 
 template <typename T, size_t N>
 inline internal::ElementsAreArrayMatcher<T> ElementsAreArray(
     const T (&array)[N]) {
   return ElementsAreArray(array, N);
 }
 
 template <typename Container>
 inline internal::ElementsAreArrayMatcher<typename Container::value_type>
 ElementsAreArray(const Container& container) {
   return ElementsAreArray(container.begin(), container.end());
 }
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 template <typename T>
 inline internal::ElementsAreArrayMatcher<T>
 ElementsAreArray(::std::initializer_list<T> xs) {
   return ElementsAreArray(xs.begin(), xs.end());
 }
 #endif
 
 // UnorderedElementsAreArray(first, last)
 // UnorderedElementsAreArray(pointer, count)
 // UnorderedElementsAreArray(array)
 // UnorderedElementsAreArray(container)
 // UnorderedElementsAreArray({ e1, e2, ..., en })
 //
 // The UnorderedElementsAreArray() functions are like
 // ElementsAreArray(...), but allow matching the elements in any order.
 template <typename Iter>
 inline internal::UnorderedElementsAreArrayMatcher<
     typename ::std::iterator_traits<Iter>::value_type>
 UnorderedElementsAreArray(Iter first, Iter last) {
   typedef typename ::std::iterator_traits<Iter>::value_type T;
   return internal::UnorderedElementsAreArrayMatcher<T>(first, last);
 }
 
 template <typename T>
 inline internal::UnorderedElementsAreArrayMatcher<T>
 UnorderedElementsAreArray(const T* pointer, size_t count) {
   return UnorderedElementsAreArray(pointer, pointer + count);
 }
 
 template <typename T, size_t N>
 inline internal::UnorderedElementsAreArrayMatcher<T>
 UnorderedElementsAreArray(const T (&array)[N]) {
   return UnorderedElementsAreArray(array, N);
 }
 
 template <typename Container>
 inline internal::UnorderedElementsAreArrayMatcher<
     typename Container::value_type>
 UnorderedElementsAreArray(const Container& container) {
   return UnorderedElementsAreArray(container.begin(), container.end());
 }
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 template <typename T>
 inline internal::UnorderedElementsAreArrayMatcher<T>
 UnorderedElementsAreArray(::std::initializer_list<T> xs) {
   return UnorderedElementsAreArray(xs.begin(), xs.end());
 }
 #endif
 
 // _ is a matcher that matches anything of any type.
 //
 // This definition is fine as:
 //
 //   1. The C++ standard permits using the name _ in a namespace that
 //      is not the global namespace or ::std.
 //   2. The AnythingMatcher class has no data member or constructor,
 //      so it's OK to create global variables of this type.
 //   3. c-style has approved of using _ in this case.
 const internal::AnythingMatcher _ = {};
 // Creates a matcher that matches any value of the given type T.
 template <typename T>
 inline Matcher<T> A() { return MakeMatcher(new internal::AnyMatcherImpl<T>()); }
 
 // Creates a matcher that matches any value of the given type T.
 template <typename T>
 inline Matcher<T> An() { return A<T>(); }
 
 // Creates a polymorphic matcher that matches anything equal to x.
 // Note: if the parameter of Eq() were declared as const T&, Eq("foo")
 // wouldn't compile.
 template <typename T>
 inline internal::EqMatcher<T> Eq(T x) { return internal::EqMatcher<T>(x); }
 
 // Constructs a Matcher<T> from a 'value' of type T.  The constructed
 // matcher matches any value that's equal to 'value'.
 template <typename T>
 Matcher<T>::Matcher(T value) { *this = Eq(value); }
 
 // Creates a monomorphic matcher that matches anything with type Lhs
 // and equal to rhs.  A user may need to use this instead of Eq(...)
 // in order to resolve an overloading ambiguity.
 //
 // TypedEq<T>(x) is just a convenient short-hand for Matcher<T>(Eq(x))
 // or Matcher<T>(x), but more readable than the latter.
 //
 // We could define similar monomorphic matchers for other comparison
 // operations (e.g. TypedLt, TypedGe, and etc), but decided not to do
 // it yet as those are used much less than Eq() in practice.  A user
 // can always write Matcher<T>(Lt(5)) to be explicit about the type,
 // for example.
 template <typename Lhs, typename Rhs>
 inline Matcher<Lhs> TypedEq(const Rhs& rhs) { return Eq(rhs); }
 
 // Creates a polymorphic matcher that matches anything >= x.
 template <typename Rhs>
 inline internal::GeMatcher<Rhs> Ge(Rhs x) {
   return internal::GeMatcher<Rhs>(x);
 }
 
 // Creates a polymorphic matcher that matches anything > x.
 template <typename Rhs>
 inline internal::GtMatcher<Rhs> Gt(Rhs x) {
   return internal::GtMatcher<Rhs>(x);
 }
 
 // Creates a polymorphic matcher that matches anything <= x.
 template <typename Rhs>
 inline internal::LeMatcher<Rhs> Le(Rhs x) {
   return internal::LeMatcher<Rhs>(x);
 }
 
 // Creates a polymorphic matcher that matches anything < x.
 template <typename Rhs>
 inline internal::LtMatcher<Rhs> Lt(Rhs x) {
   return internal::LtMatcher<Rhs>(x);
 }
 
 // Creates a polymorphic matcher that matches anything != x.
 template <typename Rhs>
 inline internal::NeMatcher<Rhs> Ne(Rhs x) {
   return internal::NeMatcher<Rhs>(x);
 }
 
 // Creates a polymorphic matcher that matches any NULL pointer.
 inline PolymorphicMatcher<internal::IsNullMatcher > IsNull() {
   return MakePolymorphicMatcher(internal::IsNullMatcher());
 }
 
 // Creates a polymorphic matcher that matches any non-NULL pointer.
 // This is convenient as Not(NULL) doesn't compile (the compiler
 // thinks that that expression is comparing a pointer with an integer).
 inline PolymorphicMatcher<internal::NotNullMatcher > NotNull() {
   return MakePolymorphicMatcher(internal::NotNullMatcher());
 }
 
 // Creates a polymorphic matcher that matches any argument that
 // references variable x.
 template <typename T>
 inline internal::RefMatcher<T&> Ref(T& x) {  // NOLINT
   return internal::RefMatcher<T&>(x);
 }
 
 // Creates a matcher that matches any double argument approximately
 // equal to rhs, where two NANs are considered unequal.
 inline internal::FloatingEqMatcher<double> DoubleEq(double rhs) {
   return internal::FloatingEqMatcher<double>(rhs, false);
 }
 
 // Creates a matcher that matches any double argument approximately
 // equal to rhs, including NaN values when rhs is NaN.
 inline internal::FloatingEqMatcher<double> NanSensitiveDoubleEq(double rhs) {
   return internal::FloatingEqMatcher<double>(rhs, true);
 }
 
 // Creates a matcher that matches any double argument approximately equal to
 // rhs, up to the specified max absolute error bound, where two NANs are
 // considered unequal.  The max absolute error bound must be non-negative.
 inline internal::FloatingEqMatcher<double> DoubleNear(
     double rhs, double max_abs_error) {
   return internal::FloatingEqMatcher<double>(rhs, false, max_abs_error);
 }
 
 // Creates a matcher that matches any double argument approximately equal to
 // rhs, up to the specified max absolute error bound, including NaN values when
 // rhs is NaN.  The max absolute error bound must be non-negative.
 inline internal::FloatingEqMatcher<double> NanSensitiveDoubleNear(
     double rhs, double max_abs_error) {
   return internal::FloatingEqMatcher<double>(rhs, true, max_abs_error);
 }
 
 // Creates a matcher that matches any float argument approximately
 // equal to rhs, where two NANs are considered unequal.
 inline internal::FloatingEqMatcher<float> FloatEq(float rhs) {
   return internal::FloatingEqMatcher<float>(rhs, false);
 }
 
 // Creates a matcher that matches any float argument approximately
 // equal to rhs, including NaN values when rhs is NaN.
 inline internal::FloatingEqMatcher<float> NanSensitiveFloatEq(float rhs) {
   return internal::FloatingEqMatcher<float>(rhs, true);
 }
 
 // Creates a matcher that matches any float argument approximately equal to
 // rhs, up to the specified max absolute error bound, where two NANs are
 // considered unequal.  The max absolute error bound must be non-negative.
 inline internal::FloatingEqMatcher<float> FloatNear(
     float rhs, float max_abs_error) {
   return internal::FloatingEqMatcher<float>(rhs, false, max_abs_error);
 }
 
 // Creates a matcher that matches any float argument approximately equal to
 // rhs, up to the specified max absolute error bound, including NaN values when
 // rhs is NaN.  The max absolute error bound must be non-negative.
 inline internal::FloatingEqMatcher<float> NanSensitiveFloatNear(
     float rhs, float max_abs_error) {
   return internal::FloatingEqMatcher<float>(rhs, true, max_abs_error);
 }
 
 // Creates a matcher that matches a pointer (raw or smart) that points
 // to a value that matches inner_matcher.
 template <typename InnerMatcher>
 inline internal::PointeeMatcher<InnerMatcher> Pointee(
     const InnerMatcher& inner_matcher) {
   return internal::PointeeMatcher<InnerMatcher>(inner_matcher);
 }
 
 // Creates a matcher that matches a pointer or reference that matches
 // inner_matcher when dynamic_cast<To> is applied.
 // The result of dynamic_cast<To> is forwarded to the inner matcher.
 // If To is a pointer and the cast fails, the inner matcher will receive NULL.
 // If To is a reference and the cast fails, this matcher returns false
 // immediately.
 template <typename To>
 inline PolymorphicMatcher<internal::WhenDynamicCastToMatcher<To> >
 WhenDynamicCastTo(const Matcher<To>& inner_matcher) {
   return MakePolymorphicMatcher(
       internal::WhenDynamicCastToMatcher<To>(inner_matcher));
 }
 
 // Creates a matcher that matches an object whose given field matches
 // 'matcher'.  For example,
 //   Field(&Foo::number, Ge(5))
 // matches a Foo object x iff x.number >= 5.
 template <typename Class, typename FieldType, typename FieldMatcher>
 inline PolymorphicMatcher<
   internal::FieldMatcher<Class, FieldType> > Field(
     FieldType Class::*field, const FieldMatcher& matcher) {
   return MakePolymorphicMatcher(
       internal::FieldMatcher<Class, FieldType>(
           field, MatcherCast<const FieldType&>(matcher)));
   // The call to MatcherCast() is required for supporting inner
   // matchers of compatible types.  For example, it allows
   //   Field(&Foo::bar, m)
   // to compile where bar is an int32 and m is a matcher for int64.
 }
 
 // Creates a matcher that matches an object whose given property
 // matches 'matcher'.  For example,
 //   Property(&Foo::str, StartsWith("hi"))
 // matches a Foo object x iff x.str() starts with "hi".
 template <typename Class, typename PropertyType, typename PropertyMatcher>
 inline PolymorphicMatcher<
   internal::PropertyMatcher<Class, PropertyType> > Property(
     PropertyType (Class::*property)() const, const PropertyMatcher& matcher) {
   return MakePolymorphicMatcher(
       internal::PropertyMatcher<Class, PropertyType>(
           property,
           MatcherCast<GTEST_REFERENCE_TO_CONST_(PropertyType)>(matcher)));
   // The call to MatcherCast() is required for supporting inner
   // matchers of compatible types.  For example, it allows
   //   Property(&Foo::bar, m)
   // to compile where bar() returns an int32 and m is a matcher for int64.
 }
 
 // Creates a matcher that matches an object iff the result of applying
 // a callable to x matches 'matcher'.
 // For example,
 //   ResultOf(f, StartsWith("hi"))
 // matches a Foo object x iff f(x) starts with "hi".
 // callable parameter can be a function, function pointer, or a functor.
 // Callable has to satisfy the following conditions:
 //   * It is required to keep no state affecting the results of
 //     the calls on it and make no assumptions about how many calls
 //     will be made. Any state it keeps must be protected from the
 //     concurrent access.
 //   * If it is a function object, it has to define type result_type.
 //     We recommend deriving your functor classes from std::unary_function.
 template <typename Callable, typename ResultOfMatcher>
 internal::ResultOfMatcher<Callable> ResultOf(
     Callable callable, const ResultOfMatcher& matcher) {
   return internal::ResultOfMatcher<Callable>(
           callable,
           MatcherCast<typename internal::CallableTraits<Callable>::ResultType>(
               matcher));
   // The call to MatcherCast() is required for supporting inner
   // matchers of compatible types.  For example, it allows
   //   ResultOf(Function, m)
   // to compile where Function() returns an int32 and m is a matcher for int64.
 }
 
 // String matchers.
 
 // Matches a string equal to str.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::string> >
     StrEq(const internal::string& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::string>(
       str, true, true));
 }
 
 // Matches a string not equal to str.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::string> >
     StrNe(const internal::string& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::string>(
       str, false, true));
 }
 
 // Matches a string equal to str, ignoring case.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::string> >
     StrCaseEq(const internal::string& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::string>(
       str, true, false));
 }
 
 // Matches a string not equal to str, ignoring case.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::string> >
     StrCaseNe(const internal::string& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::string>(
       str, false, false));
 }
 
 // Creates a matcher that matches any string, std::string, or C string
 // that contains the given substring.
 inline PolymorphicMatcher<internal::HasSubstrMatcher<internal::string> >
     HasSubstr(const internal::string& substring) {
   return MakePolymorphicMatcher(internal::HasSubstrMatcher<internal::string>(
       substring));
 }
 
 // Matches a string that starts with 'prefix' (case-sensitive).
 inline PolymorphicMatcher<internal::StartsWithMatcher<internal::string> >
     StartsWith(const internal::string& prefix) {
   return MakePolymorphicMatcher(internal::StartsWithMatcher<internal::string>(
       prefix));
 }
 
 // Matches a string that ends with 'suffix' (case-sensitive).
 inline PolymorphicMatcher<internal::EndsWithMatcher<internal::string> >
     EndsWith(const internal::string& suffix) {
   return MakePolymorphicMatcher(internal::EndsWithMatcher<internal::string>(
       suffix));
 }
 
 // Matches a string that fully matches regular expression 'regex'.
 // The matcher takes ownership of 'regex'.
 inline PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
     const internal::RE* regex) {
   return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, true));
 }
 inline PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
     const internal::string& regex) {
   return MatchesRegex(new internal::RE(regex));
 }
 
 // Matches a string that contains regular expression 'regex'.
 // The matcher takes ownership of 'regex'.
 inline PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
     const internal::RE* regex) {
   return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, false));
 }
 inline PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
     const internal::string& regex) {
   return ContainsRegex(new internal::RE(regex));
 }
 
 #if GTEST_HAS_GLOBAL_WSTRING || GTEST_HAS_STD_WSTRING
 // Wide string matchers.
 
 // Matches a string equal to str.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::wstring> >
     StrEq(const internal::wstring& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::wstring>(
       str, true, true));
 }
 
 // Matches a string not equal to str.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::wstring> >
     StrNe(const internal::wstring& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::wstring>(
       str, false, true));
 }
 
 // Matches a string equal to str, ignoring case.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::wstring> >
     StrCaseEq(const internal::wstring& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::wstring>(
       str, true, false));
 }
 
 // Matches a string not equal to str, ignoring case.
 inline PolymorphicMatcher<internal::StrEqualityMatcher<internal::wstring> >
     StrCaseNe(const internal::wstring& str) {
   return MakePolymorphicMatcher(internal::StrEqualityMatcher<internal::wstring>(
       str, false, false));
 }
 
 // Creates a matcher that matches any wstring, std::wstring, or C wide string
 // that contains the given substring.
 inline PolymorphicMatcher<internal::HasSubstrMatcher<internal::wstring> >
     HasSubstr(const internal::wstring& substring) {
   return MakePolymorphicMatcher(internal::HasSubstrMatcher<internal::wstring>(
       substring));
 }
 
 // Matches a string that starts with 'prefix' (case-sensitive).
 inline PolymorphicMatcher<internal::StartsWithMatcher<internal::wstring> >
     StartsWith(const internal::wstring& prefix) {
   return MakePolymorphicMatcher(internal::StartsWithMatcher<internal::wstring>(
       prefix));
 }
 
 // Matches a string that ends with 'suffix' (case-sensitive).
 inline PolymorphicMatcher<internal::EndsWithMatcher<internal::wstring> >
     EndsWith(const internal::wstring& suffix) {
   return MakePolymorphicMatcher(internal::EndsWithMatcher<internal::wstring>(
       suffix));
 }
 
 #endif  // GTEST_HAS_GLOBAL_WSTRING || GTEST_HAS_STD_WSTRING
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field == the second field.
 inline internal::Eq2Matcher Eq() { return internal::Eq2Matcher(); }
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field >= the second field.
 inline internal::Ge2Matcher Ge() { return internal::Ge2Matcher(); }
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field > the second field.
 inline internal::Gt2Matcher Gt() { return internal::Gt2Matcher(); }
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field <= the second field.
 inline internal::Le2Matcher Le() { return internal::Le2Matcher(); }
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field < the second field.
 inline internal::Lt2Matcher Lt() { return internal::Lt2Matcher(); }
 
 // Creates a polymorphic matcher that matches a 2-tuple where the
 // first field != the second field.
 inline internal::Ne2Matcher Ne() { return internal::Ne2Matcher(); }
 
 // Creates a matcher that matches any value of type T that m doesn't
 // match.
 template <typename InnerMatcher>
 inline internal::NotMatcher<InnerMatcher> Not(InnerMatcher m) {
   return internal::NotMatcher<InnerMatcher>(m);
 }
 
 // Returns a matcher that matches anything that satisfies the given
 // predicate.  The predicate can be any unary function or functor
 // whose return type can be implicitly converted to bool.
 template <typename Predicate>
 inline PolymorphicMatcher<internal::TrulyMatcher<Predicate> >
 Truly(Predicate pred) {
   return MakePolymorphicMatcher(internal::TrulyMatcher<Predicate>(pred));
 }
 
 // Returns a matcher that matches the container size. The container must
 // support both size() and size_type which all STL-like containers provide.
 // Note that the parameter 'size' can be a value of type size_type as well as
 // matcher. For instance:
 //   EXPECT_THAT(container, SizeIs(2));     // Checks container has 2 elements.
 //   EXPECT_THAT(container, SizeIs(Le(2));  // Checks container has at most 2.
 template <typename SizeMatcher>
 inline internal::SizeIsMatcher<SizeMatcher>
 SizeIs(const SizeMatcher& size_matcher) {
   return internal::SizeIsMatcher<SizeMatcher>(size_matcher);
 }
 
 // Returns a matcher that matches the distance between the container's begin()
 // iterator and its end() iterator, i.e. the size of the container. This matcher
 // can be used instead of SizeIs with containers such as std::forward_list which
 // do not implement size(). The container must provide const_iterator (with
 // valid iterator_traits), begin() and end().
 template <typename DistanceMatcher>
 inline internal::BeginEndDistanceIsMatcher<DistanceMatcher>
 BeginEndDistanceIs(const DistanceMatcher& distance_matcher) {
   return internal::BeginEndDistanceIsMatcher<DistanceMatcher>(distance_matcher);
 }
 
 // Returns a matcher that matches an equal container.
 // This matcher behaves like Eq(), but in the event of mismatch lists the
 // values that are included in one container but not the other. (Duplicate
 // values and order differences are not explained.)
 template <typename Container>
 inline PolymorphicMatcher<internal::ContainerEqMatcher<  // NOLINT
                             GTEST_REMOVE_CONST_(Container)> >
     ContainerEq(const Container& rhs) {
   // This following line is for working around a bug in MSVC 8.0,
   // which causes Container to be a const type sometimes.
   typedef GTEST_REMOVE_CONST_(Container) RawContainer;
   return MakePolymorphicMatcher(
       internal::ContainerEqMatcher<RawContainer>(rhs));
 }
 
 // Returns a matcher that matches a container that, when sorted using
 // the given comparator, matches container_matcher.
 template <typename Comparator, typename ContainerMatcher>
 inline internal::WhenSortedByMatcher<Comparator, ContainerMatcher>
 WhenSortedBy(const Comparator& comparator,
              const ContainerMatcher& container_matcher) {
   return internal::WhenSortedByMatcher<Comparator, ContainerMatcher>(
       comparator, container_matcher);
 }
 
 // Returns a matcher that matches a container that, when sorted using
 // the < operator, matches container_matcher.
 template <typename ContainerMatcher>
 inline internal::WhenSortedByMatcher<internal::LessComparator, ContainerMatcher>
 WhenSorted(const ContainerMatcher& container_matcher) {
   return
       internal::WhenSortedByMatcher<internal::LessComparator, ContainerMatcher>(
           internal::LessComparator(), container_matcher);
 }
 
 // Matches an STL-style container or a native array that contains the
 // same number of elements as in rhs, where its i-th element and rhs's
 // i-th element (as a pair) satisfy the given pair matcher, for all i.
 // TupleMatcher must be able to be safely cast to Matcher<tuple<const
 // T1&, const T2&> >, where T1 and T2 are the types of elements in the
 // LHS container and the RHS container respectively.
 template <typename TupleMatcher, typename Container>
 inline internal::PointwiseMatcher<TupleMatcher,
                                   GTEST_REMOVE_CONST_(Container)>
 Pointwise(const TupleMatcher& tuple_matcher, const Container& rhs) {
   // This following line is for working around a bug in MSVC 8.0,
   // which causes Container to be a const type sometimes (e.g. when
   // rhs is a const int[])..
   typedef GTEST_REMOVE_CONST_(Container) RawContainer;
   return internal::PointwiseMatcher<TupleMatcher, RawContainer>(
       tuple_matcher, rhs);
 }
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 
 // Supports the Pointwise(m, {a, b, c}) syntax.
 template <typename TupleMatcher, typename T>
 inline internal::PointwiseMatcher<TupleMatcher, std::vector<T> > Pointwise(
     const TupleMatcher& tuple_matcher, std::initializer_list<T> rhs) {
   return Pointwise(tuple_matcher, std::vector<T>(rhs));
 }
 
 #endif  // GTEST_HAS_STD_INITIALIZER_LIST_
 
 // UnorderedPointwise(pair_matcher, rhs) matches an STL-style
 // container or a native array that contains the same number of
 // elements as in rhs, where in some permutation of the container, its
 // i-th element and rhs's i-th element (as a pair) satisfy the given
 // pair matcher, for all i.  Tuple2Matcher must be able to be safely
 // cast to Matcher<tuple<const T1&, const T2&> >, where T1 and T2 are
 // the types of elements in the LHS container and the RHS container
 // respectively.
 //
 // This is like Pointwise(pair_matcher, rhs), except that the element
 // order doesn't matter.
 template <typename Tuple2Matcher, typename RhsContainer>
 inline internal::UnorderedElementsAreArrayMatcher<
     typename internal::BoundSecondMatcher<
         Tuple2Matcher, typename internal::StlContainerView<GTEST_REMOVE_CONST_(
                            RhsContainer)>::type::value_type> >
 UnorderedPointwise(const Tuple2Matcher& tuple2_matcher,
                    const RhsContainer& rhs_container) {
   // This following line is for working around a bug in MSVC 8.0,
   // which causes RhsContainer to be a const type sometimes (e.g. when
   // rhs_container is a const int[]).
   typedef GTEST_REMOVE_CONST_(RhsContainer) RawRhsContainer;
 
   // RhsView allows the same code to handle RhsContainer being a
   // STL-style container and it being a native C-style array.
   typedef typename internal::StlContainerView<RawRhsContainer> RhsView;
   typedef typename RhsView::type RhsStlContainer;
   typedef typename RhsStlContainer::value_type Second;
   const RhsStlContainer& rhs_stl_container =
       RhsView::ConstReference(rhs_container);
 
   // Create a matcher for each element in rhs_container.
   ::std::vector<internal::BoundSecondMatcher<Tuple2Matcher, Second> > matchers;
   for (typename RhsStlContainer::const_iterator it = rhs_stl_container.begin();
        it != rhs_stl_container.end(); ++it) {
     matchers.push_back(
         internal::MatcherBindSecond(tuple2_matcher, *it));
   }
 
   // Delegate the work to UnorderedElementsAreArray().
   return UnorderedElementsAreArray(matchers);
 }
 
 #if GTEST_HAS_STD_INITIALIZER_LIST_
 
 // Supports the UnorderedPointwise(m, {a, b, c}) syntax.
 template <typename Tuple2Matcher, typename T>
 inline internal::UnorderedElementsAreArrayMatcher<
     typename internal::BoundSecondMatcher<Tuple2Matcher, T> >
 UnorderedPointwise(const Tuple2Matcher& tuple2_matcher,
                    std::initializer_list<T> rhs) {
   return UnorderedPointwise(tuple2_matcher, std::vector<T>(rhs));
 }
 
 #endif  // GTEST_HAS_STD_INITIALIZER_LIST_
 
 // Matches an STL-style container or a native array that contains at
 // least one element matching the given value or matcher.
 //
 // Examples:
 //   ::std::set<int> page_ids;
 //   page_ids.insert(3);
 //   page_ids.insert(1);
 //   EXPECT_THAT(page_ids, Contains(1));
 //   EXPECT_THAT(page_ids, Contains(Gt(2)));
 //   EXPECT_THAT(page_ids, Not(Contains(4)));
 //
 //   ::std::map<int, size_t> page_lengths;
 //   page_lengths[1] = 100;
 //   EXPECT_THAT(page_lengths,
 //               Contains(::std::pair<const int, size_t>(1, 100)));
 //
 //   const char* user_ids[] = { "joe", "mike", "tom" };
 //   EXPECT_THAT(user_ids, Contains(Eq(::std::string("tom"))));
 template <typename M>
 inline internal::ContainsMatcher<M> Contains(M matcher) {
   return internal::ContainsMatcher<M>(matcher);
 }
 
 // Matches an STL-style container or a native array that contains only
 // elements matching the given value or matcher.
 //
 // Each(m) is semantically equivalent to Not(Contains(Not(m))). Only
 // the messages are different.
 //
 // Examples:
 //   ::std::set<int> page_ids;
 //   // Each(m) matches an empty container, regardless of what m is.
 //   EXPECT_THAT(page_ids, Each(Eq(1)));
 //   EXPECT_THAT(page_ids, Each(Eq(77)));
 //
 //   page_ids.insert(3);
 //   EXPECT_THAT(page_ids, Each(Gt(0)));
 //   EXPECT_THAT(page_ids, Not(Each(Gt(4))));
 //   page_ids.insert(1);
 //   EXPECT_THAT(page_ids, Not(Each(Lt(2))));
 //
 //   ::std::map<int, size_t> page_lengths;
 //   page_lengths[1] = 100;
 //   page_lengths[2] = 200;
 //   page_lengths[3] = 300;
 //   EXPECT_THAT(page_lengths, Not(Each(Pair(1, 100))));
 //   EXPECT_THAT(page_lengths, Each(Key(Le(3))));
 //
 //   const char* user_ids[] = { "joe", "mike", "tom" };
 //   EXPECT_THAT(user_ids, Not(Each(Eq(::std::string("tom")))));
 template <typename M>
 inline internal::EachMatcher<M> Each(M matcher) {
   return internal::EachMatcher<M>(matcher);
 }
 
 // Key(inner_matcher) matches an std::pair whose 'first' field matches
 // inner_matcher.  For example, Contains(Key(Ge(5))) can be used to match an
 // std::map that contains at least one element whose key is >= 5.
 template <typename M>
 inline internal::KeyMatcher<M> Key(M inner_matcher) {
   return internal::KeyMatcher<M>(inner_matcher);
 }
 
 // Pair(first_matcher, second_matcher) matches a std::pair whose 'first' field
 // matches first_matcher and whose 'second' field matches second_matcher.  For
 // example, EXPECT_THAT(map_type, ElementsAre(Pair(Ge(5), "foo"))) can be used
 // to match a std::map<int, string> that contains exactly one element whose key
 // is >= 5 and whose value equals "foo".
 template <typename FirstMatcher, typename SecondMatcher>
 inline internal::PairMatcher<FirstMatcher, SecondMatcher>
 Pair(FirstMatcher first_matcher, SecondMatcher second_matcher) {
   return internal::PairMatcher<FirstMatcher, SecondMatcher>(
       first_matcher, second_matcher);
 }
 
 // Returns a predicate that is satisfied by anything that matches the
 // given matcher.
 template <typename M>
 inline internal::MatcherAsPredicate<M> Matches(M matcher) {
   return internal::MatcherAsPredicate<M>(matcher);
 }
 
 // Returns true iff the value matches the matcher.
 template <typename T, typename M>
 inline bool Value(const T& value, M matcher) {
   return testing::Matches(matcher)(value);
 }
 
 // Matches the value against the given matcher and explains the match
 // result to listener.
 template <typename T, typename M>
 inline bool ExplainMatchResult(
     M matcher, const T& value, MatchResultListener* listener) {
   return SafeMatcherCast<const T&>(matcher).MatchAndExplain(value, listener);
 }
 
 #if GTEST_LANG_CXX11
 // Define variadic matcher versions. They are overloaded in
 // gmock-generated-matchers.h for the cases supported by pre C++11 compilers.
 template <typename... Args>
 inline internal::AllOfMatcher<Args...> AllOf(const Args&... matchers) {
   return internal::AllOfMatcher<Args...>(matchers...);
 }
 
 template <typename... Args>
 inline internal::AnyOfMatcher<Args...> AnyOf(const Args&... matchers) {
   return internal::AnyOfMatcher<Args...>(matchers...);
 }
 
 #endif  // GTEST_LANG_CXX11
 
 // AllArgs(m) is a synonym of m.  This is useful in
 //
 //   EXPECT_CALL(foo, Bar(_, _)).With(AllArgs(Eq()));
 //
 // which is easier to read than
 //
 //   EXPECT_CALL(foo, Bar(_, _)).With(Eq());
 template <typename InnerMatcher>
 inline InnerMatcher AllArgs(const InnerMatcher& matcher) { return matcher; }
 
 // These macros allow using matchers to check values in Google Test
 // tests.  ASSERT_THAT(value, matcher) and EXPECT_THAT(value, matcher)
 // succeed iff the value matches the matcher.  If the assertion fails,
 // the value and the description of the matcher will be printed.
 #define ASSERT_THAT(value, matcher) ASSERT_PRED_FORMAT1(\
     ::testing::internal::MakePredicateFormatterFromMatcher(matcher), value)
 #define EXPECT_THAT(value, matcher) EXPECT_PRED_FORMAT1(\
     ::testing::internal::MakePredicateFormatterFromMatcher(matcher), value)
 
 }  // namespace testing
 
 // Include any custom callback matchers added by the local installation.
 // We must include this header at the end to make sure it can use the
 // declarations from this file.
 #include "gmock/internal/custom/gmock-matchers.h"
 #endif  // GMOCK_INCLUDE_GMOCK_GMOCK_MATCHERS_H_