tvl-depot/absl/strings/internal/resize_uninitialized.h

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//
// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
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//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
#define ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_
#include <string>
Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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#include <type_traits>
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#include <utility>
#include "absl/base/port.h"
#include "absl/meta/type_traits.h" // for void_t
namespace absl {
namespace strings_internal {
// Is a subclass of true_type or false_type, depending on whether or not
Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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// T has a __resize_default_init member.
template <typename string_type, typename = void>
struct ResizeUninitializedTraits {
using HasMember = std::false_type;
static void Resize(string_type* s, size_t new_size) { s->resize(new_size); }
};
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Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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// __resize_default_init is provided by libc++ >= 8.0 and by Google's internal
// ::string implementation.
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template <typename string_type>
Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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struct ResizeUninitializedTraits<
string_type, absl::void_t<decltype(std::declval<string_type&>()
.__resize_default_init(237))> > {
using HasMember = std::true_type;
static void Resize(string_type* s, size_t new_size) {
s->__resize_default_init(new_size);
}
};
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// Returns true if the std::string implementation supports a resize where
// the new characters added to the std::string are left untouched.
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//
// (A better name might be "STLStringSupportsUninitializedResize", alluding to
// the previous function.)
template <typename string_type>
inline constexpr bool STLStringSupportsNontrashingResize(string_type*) {
Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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return ResizeUninitializedTraits<string_type>::HasMember::value;
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}
// Like str->resize(new_size), except any new characters added to "*str" as a
// result of resizing may be left uninitialized, rather than being filled with
// '0' bytes. Typically used when code is then going to overwrite the backing
// store of the std::string with known data.
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template <typename string_type, typename = void>
inline void STLStringResizeUninitialized(string_type* s, size_t new_size) {
Export of internal Abseil changes. -- e7f892a0b9b313b434c5f9e9a2365b377204b60e by Abseil Team <absl-team@google.com>: Remove internal CaseEqual helper now that we have the equivalent absl::EqualsIgnoreCase. PiperOrigin-RevId: 225189084 -- 722af2c74766d2fe3cee13c8dc886d39aedda597 by Abseil Team <absl-team@google.com>: Add -Wno-extra-semi-stmt to silence that warning. The [-Wno-extra-semi] is already disabled in the build. This change will allow the build to remain consistent across newer versions of clang which are now issuing a new similiar warning [-Wextra-semi-stmt]: https://clang.llvm.org/docs/ReleaseNotes.html#major-new-features https://clang.llvm.org/docs/DiagnosticsReference.html#wextra-semi-stmt PiperOrigin-RevId: 225185101 -- f7fd6244b4efcf0331631a54b7b0cf5f1f691a89 by CJ Johnson <johnsoncj@google.com>: Move using directive in swap implementation PiperOrigin-RevId: 225017825 -- 3005841725df5b9cdb35c8a5319bb4c78b5dc2b7 by Abseil Team <absl-team@google.com>: Update absl/strings/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 224860689 -- eeaf7099924b182472bfea3636ef6d9a39adfc50 by CJ Johnson <johnsoncj@google.com>: Prefer public method over private for InlinedVector allocator access PiperOrigin-RevId: 224825775 -- db9d218e3ca7ab400eef97778b720cb082a03281 by Eric Fiselier <ericwf@google.com>: Take advantage of secret libc++ resize uninitialized function in string. PiperOrigin-RevId: 224817877 GitOrigin-RevId: e7f892a0b9b313b434c5f9e9a2365b377204b60e Change-Id: I051beee37ee03f0570bd2e068355ad75c8bdfcf8
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ResizeUninitializedTraits<string_type>::Resize(s, new_size);
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}
} // namespace strings_internal
} // namespace absl
#endif // ABSL_STRINGS_INTERNAL_RESIZE_UNINITIALIZED_H_