Automated g4 rollback of changelist 189060958

PiperOrigin-RevId: 189110935

3 files changed, 81 insertions, 0 deletions

diff --git a/tensorflow/core/lib/core/stringpiece.cc b/tensorflow/core/lib/core/stringpiece.cc
index 5bd79778a6..29b727fc44 100644
--- a/tensorflow/core/lib/core/stringpiece.cc
+++ b/tensorflow/core/lib/core/stringpiece.cc
@@ -17,9 +17,14 @@ limitations under the License.
 
 #include <algorithm>
 #include <iostream>
+#include "tensorflow/core/lib/hash/hash.h"
 
 namespace tensorflow {
 
+size_t StringPieceHasher::operator()(StringPiece s) const {
+  return Hash64(s.data(), s.size());
+}
+
 std::ostream& operator<<(std::ostream& o, StringPiece piece) {
   o.write(piece.data(), piece.size());
   return o;
diff --git a/tensorflow/core/lib/core/stringpiece.h b/tensorflow/core/lib/core/stringpiece.h
index 910e4d9e2a..caa9642774 100644
--- a/tensorflow/core/lib/core/stringpiece.h
+++ b/tensorflow/core/lib/core/stringpiece.h
@@ -35,6 +35,8 @@ limitations under the License.
 
 namespace tensorflow {
 
+struct StringPieceHasher;
+
 class StringPiece {
  public:
   typedef size_t size_type;
@@ -129,6 +131,10 @@ class StringPiece {
   // Intentionally copyable
 };
 
+struct StringPieceHasher {
+  size_t operator()(StringPiece s) const;
+};
+
 inline bool operator==(StringPiece x, StringPiece y) {
   return ((x.size() == y.size()) &&
           (memcmp(x.data(), y.data(), x.size()) == 0));
diff --git a/tensorflow/core/lib/core/stringpiece_test.cc b/tensorflow/core/lib/core/stringpiece_test.cc
index d0dbeb6072..8f17b85b6d 100644
--- a/tensorflow/core/lib/core/stringpiece_test.cc
+++ b/tensorflow/core/lib/core/stringpiece_test.cc
@@ -65,4 +65,74 @@ TEST(StringPiece, Contains) {
   EXPECT_TRUE(!a.contains(d));
 }
 
+TEST(StringPieceHasher, Equality) {
+  StringPieceHasher hasher;
+
+  StringPiece s1("foo");
+  StringPiece s2("bar");
+  StringPiece s3("baz");
+  StringPiece s4("zot");
+
+  EXPECT_TRUE(hasher(s1) != hasher(s2));
+  EXPECT_TRUE(hasher(s1) != hasher(s3));
+  EXPECT_TRUE(hasher(s1) != hasher(s4));
+  EXPECT_TRUE(hasher(s2) != hasher(s3));
+  EXPECT_TRUE(hasher(s2) != hasher(s4));
+  EXPECT_TRUE(hasher(s3) != hasher(s4));
+
+  EXPECT_TRUE(hasher(s1) == hasher(s1));
+  EXPECT_TRUE(hasher(s2) == hasher(s2));
+  EXPECT_TRUE(hasher(s3) == hasher(s3));
+  EXPECT_TRUE(hasher(s4) == hasher(s4));
+}
+
+TEST(StringPieceHasher, HashMap) {
+  string s1("foo");
+  string s2("bar");
+  string s3("baz");
+
+  StringPiece p1(s1);
+  StringPiece p2(s2);
+  StringPiece p3(s3);
+
+  std::unordered_map<StringPiece, int, StringPieceHasher> map;
+
+  map.insert(std::make_pair(p1, 0));
+  map.insert(std::make_pair(p2, 1));
+  map.insert(std::make_pair(p3, 2));
+  EXPECT_EQ(map.size(), 3);
+
+  bool found[3] = {false, false, false};
+  for (auto const& val : map) {
+    int x = val.second;
+    EXPECT_TRUE(x >= 0 && x < 3);
+    EXPECT_TRUE(!found[x]);
+    found[x] = true;
+  }
+  EXPECT_EQ(found[0], true);
+  EXPECT_EQ(found[1], true);
+  EXPECT_EQ(found[2], true);
+
+  auto new_iter = map.find("zot");
+  EXPECT_TRUE(new_iter == map.end());
+
+  new_iter = map.find("bar");
+  EXPECT_TRUE(new_iter != map.end());
+
+  map.erase(new_iter);
+  EXPECT_EQ(map.size(), 2);
+
+  found[0] = false;
+  found[1] = false;
+  found[2] = false;
+  for (const auto& iter : map) {
+    int x = iter.second;
+    EXPECT_TRUE(x >= 0 && x < 3);
+    EXPECT_TRUE(!found[x]);
+    found[x] = true;
+  }
+  EXPECT_EQ(found[0], true);
+  EXPECT_EQ(found[1], false);
+  EXPECT_EQ(found[2], true);
+}
 }  // namespace tensorflow