diff options
| -rw-r--r-- | llvm/include/llvm/ADT/StringRef.h | 27 | ||||
| -rw-r--r-- | llvm/unittests/ADT/StringRefTest.cpp | 6 |
2 files changed, 28 insertions, 5 deletions
diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h index 09f9d658c9e..56b75cb34cd 100644 --- a/llvm/include/llvm/ADT/StringRef.h +++ b/llvm/include/llvm/ADT/StringRef.h @@ -84,11 +84,8 @@ namespace llvm { /// Construct a string ref from a pointer and length. LLVM_ATTRIBUTE_ALWAYS_INLINE - /*implicit*/ StringRef(const char *data, size_t length) - : Data(data), Length(length) { - assert((data || length == 0) && - "StringRef cannot be built from a NULL argument with non-null length"); - } + /*implicit*/ constexpr StringRef(const char *data, size_t length) + : Data(data), Length(length) {} /// Construct a string ref from an std::string. LLVM_ATTRIBUTE_ALWAYS_INLINE @@ -839,6 +836,26 @@ namespace llvm { /// @} }; + /// A wrapper around a string literal that serves as a proxy for constructing + /// global tables of StringRefs with the length computed at compile time. + /// Using this class with a non-literal char array is considered undefined + /// behavior. To prevent this, it is recommended that StringLiteral *only* + /// be used in a constexpr context, as such: + /// + /// constexpr StringLiteral S("test"); + /// + /// Note: There is a subtle behavioral difference in the constructor of + /// StringRef and StringLiteral, as illustrated below: + /// + /// constexpr StringLiteral S("a\0b"); // S.size() == 3 + /// StringRef S("a\0b"); // S.size() == 1 + /// + class StringLiteral : public StringRef { + public: + template <size_t N> + constexpr StringLiteral(const char (&Str)[N]) : StringRef(Str, N - 1) {} + }; + /// @name StringRef Comparison Operators /// @{ diff --git a/llvm/unittests/ADT/StringRefTest.cpp b/llvm/unittests/ADT/StringRefTest.cpp index c1cc558b5f7..5b6822ed757 100644 --- a/llvm/unittests/ADT/StringRefTest.cpp +++ b/llvm/unittests/ADT/StringRefTest.cpp @@ -1002,4 +1002,10 @@ TEST(StringRefTest, DropWhileUntil) { EXPECT_EQ("", Taken); } +TEST(StringRefTest, StringLiteral) { + constexpr StringLiteral Strings[] = {"Foo", "Bar"}; + EXPECT_EQ(StringRef("Foo"), Strings[0]); + EXPECT_EQ(StringRef("Bar"), Strings[1]); +} + } // end anonymous namespace |
