Introduce a BeginEndDistanceIs matcher for containers such as std::forward_list

which lack a size() member.

Also pull in gtest 678.

include/gmock/gmock-matchers.h

@@ -2267,6 +2267,67 @@ class SizeIsMatcher {
   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_LANG_CXX11
+      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.
@@ -3799,6 +3860,17 @@ 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