[libcxx-commits] [libcxx] bec50db - [libc++] Implement P1072R10 (std::basic_string::resize_and_overwrite)
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Jan 6 15:10:41 PST 2022
Author: Nikolas Klauser
Date: 2022-01-07T00:09:16+01:00
New Revision: bec50db2edf63c37ab48b1b9ca1ebb6a9fa47a59
URL: https://github.com/llvm/llvm-project/commit/bec50db2edf63c37ab48b1b9ca1ebb6a9fa47a59
DIFF: https://github.com/llvm/llvm-project/commit/bec50db2edf63c37ab48b1b9ca1ebb6a9fa47a59.diff
LOG: [libc++] Implement P1072R10 (std::basic_string::resize_and_overwrite)
Reviewed By: Quuxplusone, #libc, Mordante
Spies: mzeren-vmw, ckennelly, arichardson, ldionne, Mordante, libcxx-commits, Quuxplusone
Differential Revision: https://reviews.llvm.org/D113013
Added:
libcxx/test/std/strings/basic.string/string.capacity/resize_and_overwrite.pass.cpp
Modified:
libcxx/docs/FeatureTestMacroTable.rst
libcxx/docs/Status/Cxx2bPapers.csv
libcxx/include/string
libcxx/include/version
libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
libcxx/utils/generate_feature_test_macro_components.py
Removed:
################################################################################
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 40e755864c19b..3cfcaa662f650 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -328,6 +328,8 @@ Status
------------------------------------------------- -----------------
``__cpp_lib_string_contains`` ``202011L``
------------------------------------------------- -----------------
+ ``__cpp_lib_string_resize_and_overwrite`` ``202110L``
+ ------------------------------------------------- -----------------
``__cpp_lib_to_underlying`` ``202102L``
================================================= =================
diff --git a/libcxx/docs/Status/Cxx2bPapers.csv b/libcxx/docs/Status/Cxx2bPapers.csv
index 50b11c4347d88..93b2d6befff94 100644
--- a/libcxx/docs/Status/Cxx2bPapers.csv
+++ b/libcxx/docs/Status/Cxx2bPapers.csv
@@ -26,7 +26,7 @@
"`P0288R9 <https://wg21.link/P0288R9>`__","LWG","``any_invocable``","October 2021","",""
"`P0798R8 <https://wg21.link/P0798R8>`__","LWG","Monadic operations for ``std::optional``","October 2021","|Complete|","14.0"
"`P0849R8 <https://wg21.link/P0849R8>`__","LWG","``auto(x)``: ``DECAY_COPY`` in the language","October 2021","|Complete|","14.0"
-"`P1072R10 <https://wg21.link/P1072R10>`__","LWG","``basic_string::resize_and_overwrite``","October 2021","",""
+"`P1072R10 <https://wg21.link/P1072R10>`__","LWG","``basic_string::resize_and_overwrite``","October 2021","|Complete|","14.0"
"`P1147R1 <https://wg21.link/P1147R1>`__","LWG","Printing ``volatile`` Pointers","October 2021","|Complete|","14.0"
"`P1272R4 <https://wg21.link/P1272R4>`__","LWG","Byteswapping for fun&&nuf","October 2021","|Complete|","14.0"
"`P1675R2 <https://wg21.link/P1675R2>`__","LWG","``rethrow_exception`` must be allowed to copy","October 2021","",""
diff --git a/libcxx/include/string b/libcxx/include/string
index 9049d7acbb9bb..1b803bb8bd803 100644
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -158,6 +158,9 @@ public:
void resize(size_type n, value_type c);
void resize(size_type n);
+ template<class Operation>
+ constexpr void resize_and_overwrite(size_type n, Operation op); // since C++23
+
void reserve(size_type res_arg);
void reserve(); // deprecated in C++20
void shrink_to_fit();
@@ -973,6 +976,17 @@ public:
_LIBCPP_INLINE_VISIBILITY void resize(size_type __n) {resize(__n, value_type());}
void reserve(size_type __requested_capacity);
+
+#if _LIBCPP_STD_VER > 20
+ template <class _Op>
+ _LIBCPP_HIDE_FROM_ABI constexpr
+ void resize_and_overwrite(size_type __n, _Op __op) {
+ __resize_default_init(__n);
+ pointer __data = data();
+ __erase_to_end(_VSTD::move(__op)(__data, __n));
+ }
+#endif
+
_LIBCPP_INLINE_VISIBILITY void __resize_default_init(size_type __n);
_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_INLINE_VISIBILITY
diff --git a/libcxx/include/version b/libcxx/include/version
index 6774e3151a6c2..39f1b8eb19ef1 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -155,6 +155,7 @@ __cpp_lib_stacktrace 202011L <stacktrace>
__cpp_lib_starts_ends_with 201711L <string> <string_view>
__cpp_lib_stdatomic_h 202011L <stdatomic.h>
__cpp_lib_string_contains 202011L <string> <string_view>
+__cpp_lib_string_resize_and_overwrite 202110L <string>
__cpp_lib_string_udls 201304L <string>
__cpp_lib_string_view 201803L <string> <string_view>
201606L // C++17
@@ -375,6 +376,7 @@ __cpp_lib_void_t 201411L <type_traits>
// # define __cpp_lib_stacktrace 202011L
// # define __cpp_lib_stdatomic_h 202011L
# define __cpp_lib_string_contains 202011L
+# define __cpp_lib_string_resize_and_overwrite 202110L
# define __cpp_lib_to_underlying 202102L
#endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
index 1657440104999..21167f64294bf 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
@@ -23,6 +23,7 @@
__cpp_lib_nonmember_container_access 201411L [C++17]
__cpp_lib_starts_ends_with 201711L [C++20]
__cpp_lib_string_contains 202011L [C++2b]
+ __cpp_lib_string_resize_and_overwrite 202110L [C++2b]
__cpp_lib_string_udls 201304L [C++14]
__cpp_lib_string_view 201606L [C++17]
201803L [C++20]
@@ -61,6 +62,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should not be defined before c++14"
# endif
@@ -99,6 +104,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++14"
# endif
@@ -146,6 +155,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++17"
# endif
@@ -214,6 +227,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++20"
# endif
@@ -285,6 +302,13 @@
# error "__cpp_lib_string_contains should have the value 202011L in c++2b"
# endif
+# ifndef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should be defined in c++2b"
+# endif
+# if __cpp_lib_string_resize_and_overwrite != 202110L
+# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++2b"
# endif
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
index e0f225009e41b..ad50bb1c769b3 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
@@ -144,6 +144,7 @@
__cpp_lib_starts_ends_with 201711L [C++20]
__cpp_lib_stdatomic_h 202011L [C++2b]
__cpp_lib_string_contains 202011L [C++2b]
+ __cpp_lib_string_resize_and_overwrite 202110L [C++2b]
__cpp_lib_string_udls 201304L [C++14]
__cpp_lib_string_view 201606L [C++17]
201803L [C++20]
@@ -676,6 +677,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifdef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should not be defined before c++14"
# endif
@@ -1309,6 +1314,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++14"
# endif
@@ -2128,6 +2137,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++17"
# endif
@@ -3274,6 +3287,10 @@
# error "__cpp_lib_string_contains should not be defined before c++2b"
# endif
+# ifdef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should not be defined before c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++20"
# endif
@@ -4564,6 +4581,13 @@
# error "__cpp_lib_string_contains should have the value 202011L in c++2b"
# endif
+# ifndef __cpp_lib_string_resize_and_overwrite
+# error "__cpp_lib_string_resize_and_overwrite should be defined in c++2b"
+# endif
+# if __cpp_lib_string_resize_and_overwrite != 202110L
+# error "__cpp_lib_string_resize_and_overwrite should have the value 202110L in c++2b"
+# endif
+
# ifndef __cpp_lib_string_udls
# error "__cpp_lib_string_udls should be defined in c++2b"
# endif
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/resize_and_overwrite.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/resize_and_overwrite.pass.cpp
new file mode 100644
index 0000000000000..36b3a2a6c81a1
--- /dev/null
+++ b/libcxx/test/std/strings/basic.string/string.capacity/resize_and_overwrite.pass.cpp
@@ -0,0 +1,105 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <string>
+
+// template<class Operation>
+// void resize_and_overwrite(size_type n, Operation op)
+
+#include <cassert>
+#include <string>
+
+#include "make_string.h"
+#include "test_macros.h"
+
+template <class S>
+constexpr void test_appending(size_t k, size_t N, size_t new_capacity) {
+ assert(N > k);
+ assert(new_capacity >= N);
+ auto s = S(k, 'a');
+ s.resize_and_overwrite(new_capacity, [&](auto* p, auto n) {
+ assert(n == new_capacity);
+ LIBCPP_ASSERT(s.size() == new_capacity);
+ LIBCPP_ASSERT(s.begin().base() == p);
+ assert(std::all_of(p, p + k, [](const auto ch) { return ch == 'a'; }));
+ std::fill(p + k, p + n, 'b');
+ p[n] = 'c'; // will be overwritten
+ return N;
+ });
+ const S expected = S(k, 'a') + S(N - k, 'b');
+ assert(s == expected);
+ assert(s.c_str()[N] == '\0');
+}
+
+template <class S>
+constexpr void test_truncating(size_t o, size_t N) {
+ assert(N < o);
+ auto s = S(o, 'a');
+ s.resize_and_overwrite(N, [&](auto* p, auto n) {
+ assert(n == N);
+ LIBCPP_ASSERT(s.size() == n);
+ LIBCPP_ASSERT(s.begin().base() == p);
+ assert(std::all_of(p, p + n, [](auto ch) { return ch == 'a'; }));
+ p[n - 1] = 'b';
+ p[n] = 'c'; // will be overwritten
+ return n;
+ });
+ const S expected = S(N - 1, 'a') + S(1, 'b');
+ assert(s == expected);
+ assert(s.c_str()[N] == '\0');
+}
+
+template <class CharT>
+constexpr bool test() {
+ using S = std::basic_string<CharT>;
+ test_appending<S>(10, 15, 15);
+ test_appending<S>(10, 15, 20);
+ test_appending<S>(10, 40, 40);
+ test_appending<S>(10, 40, 50);
+ test_appending<S>(30, 35, 35);
+ test_appending<S>(30, 35, 45);
+ test_appending<S>(10, 15, 30);
+ test_truncating<S>(15, 10);
+ test_truncating<S>(40, 35);
+ test_truncating<S>(40, 10);
+
+ return true;
+}
+
+void test_value_categories() {
+ std::string s;
+ s.resize_and_overwrite(10, [](char*&, size_t&) { return 0; });
+ struct RefQualified {
+ int operator()(char*, size_t) && { return 0; }
+ };
+ s.resize_and_overwrite(10, RefQualified{});
+}
+
+int main(int, char**) {
+ test<char>();
+ test<char8_t>();
+ test<char16_t>();
+ test<char32_t>();
+
+#if defined(__cpp_lib_constexpr_string) && __cpp_lib_constexpr_string >= 201907L
+ static_assert(test<char>());
+ static_assert(test<char8_t>());
+ static_assert(test<char16_t>());
+ static_assert(test<char32_t>());
+#endif
+
+#ifndef TEST_HAS_NO_WIDE_CHARACTERS
+ test<wchar_t>();
+#if defined(__cpp_lib_constexpr_string) && __cpp_lib_constexpr_string >= 201907L
+ static_assert(test<wchar_t>());
+#endif
+#endif
+ return 0;
+}
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 0d43c74a69790..7047f3f4b0cc1 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -624,6 +624,10 @@ def add_version_header(tc):
"name": "__cpp_lib_string_contains",
"values": { "c++2b": 202011 },
"headers": ["string", "string_view"],
+ }, {
+ "name": "__cpp_lib_string_resize_and_overwrite",
+ "values": { "c++2b": 202110 },
+ "headers": ["string"],
}, {
"name": "__cpp_lib_string_udls",
"values": { "c++14": 201304 },
More information about the libcxx-commits
mailing list