Added non-std string support to tensorflow::StringPiece string conversion operator.

PiperOrigin-RevId: 209050419

2 files changed, 14 insertions, 6 deletions

diff --git a/tensorflow/core/lib/core/stringpiece.h b/tensorflow/core/lib/core/stringpiece.h
index d7ecc44e50..329f115608 100644
--- a/tensorflow/core/lib/core/stringpiece.h
+++ b/tensorflow/core/lib/core/stringpiece.h
@@ -31,6 +31,7 @@ limitations under the License.
 #include <string.h>
 #include <iosfwd>
 #include <string>
+#include <type_traits>
 #include "tensorflow/core/platform/types.h"
 
 namespace tensorflow {
@@ -101,11 +102,18 @@ class StringPiece {
   //   >  0 iff "*this" >  "b"
   int compare(StringPiece b) const;
 
-  // Converts to `std::basic_string`.
-  template <typename A>
-  explicit operator std::basic_string<char, std::char_traits<char>, A>() const {
+  // Converts to various kinds of strings, including `std::basic_string`.
+  template <typename S>
+  explicit operator S() const {
+    static_assert(
+        std::is_same<char, typename S::value_type>::value,
+        "Type mismatch: S must be a string with character type char.");
+    static_assert(
+        std::is_same<std::char_traits<char>, typename S::traits_type>::value,
+        "Type mismatch: S must be a string with traits type "
+        "std::char_traits<char>.");
     if (!data()) return {};
-    return std::basic_string<char, std::char_traits<char>, A>(data(), size());
+    return S(data(), size());
   }
 
  private:
diff --git a/tensorflow/core/lib/core/stringpiece_test.cc b/tensorflow/core/lib/core/stringpiece_test.cc
index 952b9eaaaa..e4b489fe17 100644
--- a/tensorflow/core/lib/core/stringpiece_test.cc
+++ b/tensorflow/core/lib/core/stringpiece_test.cc
@@ -56,8 +56,8 @@ TEST(StringPiece, Ctor) {
 }
 
 TEST(StringPiece, ConversionToString) {
-  EXPECT_EQ("", std::string(StringPiece("")));
-  EXPECT_EQ("foo", std::string(StringPiece("foo")));
+  EXPECT_EQ("", string(StringPiece("")));
+  EXPECT_EQ("foo", string(StringPiece("foo")));
 }
 
 }  // namespace tensorflow