[ADT] Add a 'find_as' operation to DenseSet.

This operation is analogous to its counterpart in DenseMap: It allows lookup
via cheap-to-construct keys (provided that getHashValue and isEqual are
implemented for the cheap key-type in the DenseMapInfo specialization).

Thanks to Chandler for the review.

llvm-svn: 220168

1 files changed, 38 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/DenseSetTest.cpp b/llvm/unittests/ADT/DenseSetTest.cpp
index 154c5892d5f..5952353034f 100644
--- a/llvm/unittests/ADT/DenseSetTest.cpp
+++ b/llvm/unittests/ADT/DenseSetTest.cpp
@@ -27,4 +27,42 @@ TEST_F(DenseSetTest, DoubleEntrySetTest) {
   EXPECT_EQ(0u, set.count(2));
 }
 
+struct TestDenseSetInfo {
+  static inline unsigned getEmptyKey() { return ~0; }
+  static inline unsigned getTombstoneKey() { return ~0U - 1; }
+  static unsigned getHashValue(const unsigned& Val) { return Val * 37U; }
+  static unsigned getHashValue(const char* Val) {
+    return (unsigned)(Val[0] - 'a') * 37U;
+  }
+  static bool isEqual(const unsigned& LHS, const unsigned& RHS) {
+    return LHS == RHS;
+  }
+  static bool isEqual(const char* LHS, const unsigned& RHS) {
+    return (unsigned)(LHS[0] - 'a') == RHS;
+  }
+};
+
+TEST(DenseSetCustomTest, FindAsTest) {
+  DenseSet<unsigned, TestDenseSetInfo> set;
+  set.insert(0);
+  set.insert(1);
+  set.insert(2);
+
+  // Size tests
+  EXPECT_EQ(3u, set.size());
+
+  // Normal lookup tests
+  EXPECT_EQ(1u, set.count(1));
+  EXPECT_EQ(0u, *set.find(0));
+  EXPECT_EQ(1u, *set.find(1));
+  EXPECT_EQ(2u, *set.find(2));
+  EXPECT_TRUE(set.find(3) == set.end());
+
+  // find_as() tests
+  EXPECT_EQ(0u, *set.find_as("a"));
+  EXPECT_EQ(1u, *set.find_as("b"));
+  EXPECT_EQ(2u, *set.find_as("c"));
+  EXPECT_TRUE(set.find_as("d") == set.end());
+}
+
 }