Add IsEmpty overload for C-style strings

Fixes #3937

PiperOrigin-RevId: 463180144
Change-Id: I21b528acc4c3f3aba4234642be01fcead7fe7f00

1 files changed, 38 insertions, 7 deletions

diff --git a/googlemock/include/gmock/gmock-more-matchers.h b/googlemock/include/gmock/gmock-more-matchers.h
index 47aaf98..d9a9210 100644
--- a/googlemock/include/gmock/gmock-more-matchers.h
+++ b/googlemock/include/gmock/gmock-more-matchers.h
@@ -40,6 +40,9 @@
 #ifndef GOOGLEMOCK_INCLUDE_GMOCK_GMOCK_MORE_MATCHERS_H_
 #define GOOGLEMOCK_INCLUDE_GMOCK_GMOCK_MORE_MATCHERS_H_
 
+#include <ostream>
+#include <string>
+
 #include "gmock/gmock-matchers.h"
 
 namespace testing {
@@ -56,14 +59,42 @@ namespace testing {
 #endif
 #endif
 
-// Defines a matcher that matches an empty container. The container must
-// support both size() and empty(), which all STL-like containers provide.
-MATCHER(IsEmpty, negation ? "isn't empty" : "is empty") {
-  if (arg.empty()) {
-    return true;
+namespace internal {
+
+// Implements the polymorphic IsEmpty matcher, which
+// can be used as a Matcher<T> as long as T is either a container that defines
+// empty() and size() (e.g. std::vector or std::string), or a C-style string.
+class IsEmptyMatcher {
+ public:
+  // Matches anything that defines empty() and size().
+  template <typename MatcheeContainerType>
+  bool MatchAndExplain(const MatcheeContainerType& c,
+                       MatchResultListener* listener) const {
+    if (c.empty()) {
+      return true;
+    }
+    *listener << "whose size is " << c.size();
+    return false;
+  }
+
+  // Matches C-style strings.
+  bool MatchAndExplain(const char* s, MatchResultListener* listener) const {
+    return MatchAndExplain(std::string(s), listener);
   }
-  *result_listener << "whose size is " << arg.size();
-  return false;
+
+  // Describes what this matcher matches.
+  void DescribeTo(std::ostream* os) const { *os << "is empty"; }
+
+  void DescribeNegationTo(std::ostream* os) const { *os << "isn't empty"; }
+};
+
+}  // namespace internal
+
+// Creates a polymorphic matcher that matches an empty container or C-style
+// string. The container must support both size() and empty(), which all
+// STL-like containers provide.
+inline PolymorphicMatcher<internal::IsEmptyMatcher> IsEmpty() {
+  return MakePolymorphicMatcher(internal::IsEmptyMatcher());
 }
 
 // Define a matcher that matches a value that evaluates in boolean