diff options
| author |  Abseil Team <absl-team@google.com> | 2019-07-30 20:47:29 -0700 |
|---|---|---|
| committer |  Andy Soffer <asoffer@google.com> | 2019-07-31 16:07:55 -0400 |
| commit | 14550beb3b7b97195e483fb74b5efb906395c31e (patch) | |
| tree | 2b7a9947d0aee3704bc58587e85f63492bbe12f3 /absl/strings | |
| parent | 52e88ee56b72cf32bc66534d942c7398ce481331 (diff) | |
Export of internal Abseil changes.
--
8f685654a7d04eb8a0cb82d31e44e391e906b609 by Derek Mauro <dmauro@google.com>:
Support constexpr construction of absl::string_view from a
string literal in MSVC 2017+.
Fixes https://github.com/abseil/abseil-cpp/issues/352
PiperOrigin-RevId: 260853160
--
a3c4c5168ce2a491134d7c87cf7fdc75d1ee2533 by Derek Mauro <dmauro@google.com>:
Make SwissTable's at() throw when exceptions are enabled
Fixes https://github.com/abseil/abseil-cpp/issues/355
PiperOrigin-RevId: 260788026
GitOrigin-RevId: 8f685654a7d04eb8a0cb82d31e44e391e906b609
Change-Id: I9ed498e181faa9c9d16e9b1b01404969d99b8ea9
Diffstat (limited to 'absl/strings')
| -rw-r--r-- | absl/strings/string_view.h | 30 | ||||
| -rw-r--r-- | absl/strings/string_view_test.cc | 5 |
2 files changed, 24 insertions, 11 deletions
diff --git a/absl/strings/string_view.h b/absl/strings/string_view.h index f8b20015..65b1772d 100644 --- a/absl/strings/string_view.h +++ b/absl/strings/string_view.h @@ -172,19 +172,9 @@ class string_view { // Implicit constructor of a `string_view` from nul-terminated `str`. When // accepting possibly null strings, use `absl::NullSafeStringView(str)` // instead (see below). -#if ABSL_HAVE_BUILTIN(__builtin_strlen) || \ - (defined(__GNUC__) && !defined(__clang__)) - // GCC has __builtin_strlen according to - // https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Other-Builtins.html, but - // ABSL_HAVE_BUILTIN doesn't detect that, so we use the extra checks above. - // __builtin_strlen is constexpr. constexpr string_view(const char* str) // NOLINT(runtime/explicit) : ptr_(str), - length_(CheckLengthInternal(str ? __builtin_strlen(str) : 0)) {} -#else - constexpr string_view(const char* str) // NOLINT(runtime/explicit) - : ptr_(str), length_(CheckLengthInternal(str ? strlen(str) : 0)) {} -#endif + length_(str ? CheckLengthInternal(StrlenInternal(str)) : 0) {} // Implicit constructor of a `string_view` from a `const char*` and length. constexpr string_view(const char* data, size_type len) @@ -495,6 +485,24 @@ class string_view { return ABSL_ASSERT(len <= kMaxSize), len; } + static constexpr size_type StrlenInternal(const char* str) { +#if defined(_MSC_VER) && _MSC_VER >= 1910 && !defined(__clang__) + // MSVC 2017+ can evaluate this at compile-time. + const char* begin = str; + while (*str != '\0') ++str; + return str - begin; +#elif ABSL_HAVE_BUILTIN(__builtin_strlen) || \ + (defined(__GNUC__) && !defined(__clang__)) + // GCC has __builtin_strlen according to + // https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Other-Builtins.html, but + // ABSL_HAVE_BUILTIN doesn't detect that, so we use the extra checks above. + // __builtin_strlen is constexpr. + return __builtin_strlen(str); +#else + return str ? strlen(str) : 0; +#endif + } + const char* ptr_; size_type length_; }; diff --git a/absl/strings/string_view_test.cc b/absl/strings/string_view_test.cc index 823d8ed4..2380e1a3 100644 --- a/absl/strings/string_view_test.cc +++ b/absl/strings/string_view_test.cc @@ -941,6 +941,11 @@ TEST(StringViewTest, ConstexprCompiles) { #error GCC/clang should have constexpr string_view. #endif +// MSVC 2017+ should be able to construct a constexpr string_view from a cstr. +#if defined(_MSC_VER) && _MSC_VER >= 1910 +#define ABSL_HAVE_CONSTEXPR_STRING_VIEW_FROM_CSTR 1 +#endif + #endif // ABSL_HAVE_STD_STRING_VIEW #ifdef ABSL_HAVE_CONSTEXPR_STRING_VIEW_FROM_CSTR |