145 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// UNSUPPORTED: c++03, c++11, c++14, c++1710// TODO: Change to XFAIL once https://llvm.org/PR40995 is fixed11// UNSUPPORTED: availability-pmr-missing12 13// This test ensures that we properly propagate allocators from stringstream's14// inner string object to the new string returned from .str().15// `str() const&` is specified to preserve the allocator (not copy the string).16// `str() &&` isn't specified, but should preserve the allocator (move the string).17 18#include <cassert>19#include <memory>20#include <memory_resource>21#include <sstream>22#include <string>23#include <string_view>24#include <type_traits>25 26#include "make_string.h"27#include "test_allocator.h"28#include "test_macros.h"29 30template <class CharT>31void test_soccc_behavior() {32 using Alloc = SocccAllocator<CharT>;33 using SS = std::basic_stringstream<CharT, std::char_traits<CharT>, Alloc>;34 using S = std::basic_string<CharT, std::char_traits<CharT>, Alloc>;35 {36 SS ss = SS(std::ios_base::out, Alloc(10));37 38 // [stringbuf.members]/6 specifies that the allocator is copied,39 // not select_on_container_copy_construction'ed.40 //41 S copied = ss.str();42 assert(copied.get_allocator().count_ == 10);43 assert(ss.rdbuf()->get_allocator().count_ == 10);44 assert(copied.empty());45 46 // sanity-check that SOCCC does in fact work47 assert(S(copied).get_allocator().count_ == 11);48 49 // [stringbuf.members]/10 doesn't specify the allocator to use,50 // but copying the allocator as-if-by moving the string makes sense.51 //52 S moved = std::move(ss).str();53 assert(moved.get_allocator().count_ == 10);54 assert(ss.rdbuf()->get_allocator().count_ == 10);55 assert(moved.empty());56 }57}58 59template <class CharT,60 class Base = std::basic_stringbuf<CharT, std::char_traits<CharT>, std::pmr::polymorphic_allocator<CharT>>>61struct StringBuf : Base {62 explicit StringBuf(std::pmr::memory_resource* mr) : Base(std::ios_base::in, mr) {}63 void public_setg(int a, int b, int c) {64 CharT* p = this->eback();65 assert(this->view().data() == p);66 this->setg(p + a, p + b, p + c);67 assert(this->eback() == p + a);68 assert(this->view().data() == p + a);69 }70};71 72template <class CharT>73void test_allocation_is_pilfered() {74 using SS = std::basic_stringstream<CharT, std::char_traits<CharT>, std::pmr::polymorphic_allocator<CharT>>;75 using S = std::pmr::basic_string<CharT>;76 alignas(void*) char buf[80 * sizeof(CharT)];77 const CharT* initial =78 MAKE_CSTRING(CharT, "a very long string that exceeds the small string optimization buffer length");79 {80 std::pmr::set_default_resource(std::pmr::null_memory_resource());81 auto mr1 = std::pmr::monotonic_buffer_resource(buf, sizeof(buf), std::pmr::null_memory_resource());82 SS ss = SS(S(initial, &mr1));83 S s = std::move(ss).str();84 assert(s == initial);85 }86 {87 // Try moving-out-of a stringbuf whose view() is not the entire string.88 // This is libc++'s behavior; libstdc++ doesn't allow such stringbufs to be created.89 //90 std::pmr::set_default_resource(std::pmr::null_memory_resource());91 auto mr1 = std::pmr::monotonic_buffer_resource(buf, sizeof(buf), std::pmr::null_memory_resource());92 auto src = StringBuf<CharT>(&mr1);93 src.str(S(initial, &mr1));94 src.public_setg(2, 6, 40);95 SS ss(std::ios_base::in, &mr1);96 *ss.rdbuf() = std::move(src);97 LIBCPP_ASSERT(ss.view() == std::basic_string_view<CharT>(initial).substr(2, 38));98 S s = std::move(ss).str();99 LIBCPP_ASSERT(s == std::basic_string_view<CharT>(initial).substr(2, 38));100 }101}102 103template <class CharT>104void test_no_foreign_allocations() {105 using SS = std::basic_stringstream<CharT, std::char_traits<CharT>, std::pmr::polymorphic_allocator<CharT>>;106 using S = std::pmr::basic_string<CharT>;107 const CharT* initial =108 MAKE_CSTRING(CharT, "a very long string that exceeds the small string optimization buffer length");109 {110 std::pmr::set_default_resource(std::pmr::null_memory_resource());111 auto mr1 = std::pmr::monotonic_buffer_resource(std::pmr::new_delete_resource());112 auto ss = SS(S(initial, &mr1));113 assert(ss.rdbuf()->get_allocator().resource() == &mr1);114 115 // [stringbuf.members]/6 specifies that the result of `str() const &`116 // does NOT use the default allocator; it uses the original allocator.117 //118 S copied = ss.str();119 assert(copied.get_allocator().resource() == &mr1);120 assert(ss.rdbuf()->get_allocator().resource() == &mr1);121 assert(copied == initial);122 123 // [stringbuf.members]/10 doesn't specify the allocator to use,124 // but copying the allocator as-if-by moving the string makes sense.125 //126 S moved = std::move(ss).str();127 assert(moved.get_allocator().resource() == &mr1);128 assert(ss.rdbuf()->get_allocator().resource() == &mr1);129 assert(moved == initial);130 }131}132 133int main(int, char**) {134 test_soccc_behavior<char>();135 test_allocation_is_pilfered<char>();136 test_no_foreign_allocations<char>();137#ifndef TEST_HAS_NO_WIDE_CHARACTERS138 test_soccc_behavior<wchar_t>();139 test_allocation_is_pilfered<wchar_t>();140 test_no_foreign_allocations<wchar_t>();141#endif142 143 return 0;144}145