Hash support for std::wstring_view/u16string_view/u32string_view
PiperOrigin-RevId: 519200954
Change-Id: I349023cacab0ac4cbefb8505efd29a5eda1e9067
diff --git a/absl/hash/hash.h b/absl/hash/hash.h
index 956befa..abf8883 100644
--- a/absl/hash/hash.h
+++ b/absl/hash/hash.h
@@ -113,7 +113,9 @@
// * std::string (as well as any instance of std::basic_string that
// uses one of {char, wchar_t, char16_t, char32_t} and its associated
// std::char_traits)
-// * std::string_view
+// * std::string_view (as well as any instance of std::basic_string_view
+// that uses one of {char, wchar_t, char16_t, char32_t} and its associated
+// std::char_traits)
// * All the standard sequence containers (provided the elements are hashable)
// * All the standard associative containers (provided the elements are
// hashable)
diff --git a/absl/hash/hash_test.cc b/absl/hash/hash_test.cc
index 4ed6e50..6727daf 100644
--- a/absl/hash/hash_test.cc
+++ b/absl/hash/hash_test.cc
@@ -53,6 +53,10 @@
#include "absl/numeric/int128.h"
#include "absl/strings/cord_test_helpers.h"
+#ifdef ABSL_HAVE_STD_STRING_VIEW
+#include <string_view>
+#endif
+
namespace {
// Utility wrapper of T for the purposes of testing the `AbslHash` type erasure
@@ -488,6 +492,47 @@
std::u32string(U"Iñtërnâtiônàlizætiøn"))));
}
+TEST(HashValueTest, WStringView) {
+#ifndef ABSL_HAVE_STD_STRING_VIEW
+ GTEST_SKIP();
+#else
+ EXPECT_TRUE((is_hashable<std::wstring_view>::value));
+
+ EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(std::make_tuple(
+ std::wstring_view(), std::wstring_view(L"ABC"), std::wstring_view(L"ABC"),
+ std::wstring_view(L"Some other different string_view"),
+ std::wstring_view(L"Iñtërnâtiônàlizætiøn"))));
+#endif
+}
+
+TEST(HashValueTest, U16StringView) {
+#ifndef ABSL_HAVE_STD_STRING_VIEW
+ GTEST_SKIP();
+#else
+ EXPECT_TRUE((is_hashable<std::u16string_view>::value));
+
+ EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(
+ std::make_tuple(std::u16string_view(), std::u16string_view(u"ABC"),
+ std::u16string_view(u"ABC"),
+ std::u16string_view(u"Some other different string_view"),
+ std::u16string_view(u"Iñtërnâtiônàlizætiøn"))));
+#endif
+}
+
+TEST(HashValueTest, U32StringView) {
+#ifndef ABSL_HAVE_STD_STRING_VIEW
+ GTEST_SKIP();
+#else
+ EXPECT_TRUE((is_hashable<std::u32string_view>::value));
+
+ EXPECT_TRUE(absl::VerifyTypeImplementsAbslHashCorrectly(
+ std::make_tuple(std::u32string_view(), std::u32string_view(U"ABC"),
+ std::u32string_view(U"ABC"),
+ std::u32string_view(U"Some other different string_view"),
+ std::u32string_view(U"Iñtërnâtiônàlizætiøn"))));
+#endif
+}
+
TEST(HashValueTest, StdArray) {
EXPECT_TRUE((is_hashable<std::array<int, 3>>::value));
diff --git a/absl/hash/internal/hash.h b/absl/hash/internal/hash.h
index a22a537..7e534d8 100644
--- a/absl/hash/internal/hash.h
+++ b/absl/hash/internal/hash.h
@@ -56,6 +56,10 @@
#include "absl/types/variant.h"
#include "absl/utility/utility.h"
+#ifdef ABSL_HAVE_STD_STRING_VIEW
+#include <string_view>
+#endif
+
namespace absl {
ABSL_NAMESPACE_BEGIN
@@ -518,7 +522,8 @@
// - `absl::Cord`
// - `std::string` (and std::basic_string<T, std::char_traits<T>, A> for
// any allocator A and any T in {char, wchar_t, char16_t, char32_t})
-// - `absl::string_view` and `std::string_view`
+// - `absl::string_view`, `std::string_view`, `std::wstring_view`,
+// `std::u16string_view`, and `std::u32_string_view`.
//
// For simplicity, we currently support only strings built on `char`, `wchar_t`,
// `char16_t`, or `char32_t`. This support may be broadened, if necessary, but
@@ -544,6 +549,21 @@
str.size());
}
+#ifdef ABSL_HAVE_STD_STRING_VIEW
+
+// Support std::wstring_view, std::u16string_view and std::u32string_view.
+template <typename Char, typename H,
+ typename = absl::enable_if_t<std::is_same<Char, wchar_t>::value ||
+ std::is_same<Char, char16_t>::value ||
+ std::is_same<Char, char32_t>::value>>
+H AbslHashValue(H hash_state, std::basic_string_view<Char> str) {
+ return H::combine(
+ H::combine_contiguous(std::move(hash_state), str.data(), str.size()),
+ str.size());
+}
+
+#endif // ABSL_HAVE_STD_STRING_VIEW
+
// -----------------------------------------------------------------------------
// AbslHashValue for Sequence Containers
// -----------------------------------------------------------------------------
