1 files changed, 19 insertions, 6 deletions
diff --git a/googlemock/include/gmock/gmock-matchers.h b/googlemock/include/gmock/gmock-matchers.h
index 95bc22c5..6e8bc036 100644
--- a/googlemock/include/gmock/gmock-matchers.h
+++ b/googlemock/include/gmock/gmock-matchers.h
@@ -43,15 +43,14 @@
 #include <algorithm>
 #include <iterator>
 #include <limits>
-#include <memory>
 #include <ostream>  // NOLINT
 #include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
+#include "gtest/gtest.h"
 #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
@@ -339,15 +338,29 @@ class MatcherBase {
   virtual ~MatcherBase() {}
 
  private:
-  std::shared_ptr<const MatcherInterface<GTEST_REFERENCE_TO_CONST_(T)>> impl_;
+  // 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<GTEST_REFERENCE_TO_CONST_(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 std::shared_ptr to const
-// MatcherInterface<T>.  Don't inherit from Matcher!
+// 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:
@@ -1573,7 +1586,7 @@ class MatchesRegexMatcher {
   }
 
  private:
-  const std::shared_ptr<const RE> regex_;
+  const internal::linked_ptr<const RE> regex_;
   const bool full_match_;
 
   GTEST_DISALLOW_ASSIGN_(MatchesRegexMatcher);