Files
clang-p2996/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.move.pass.cpp
Amirreza Ashouri 838f2890fd [libc++] Eliminate extra allocations from std::move(oss).str() (#67294)
Add test coverage for the new behaviors, especially to verify that the
returned string uses the correct allocator.
Fixes https://github.com/llvm/llvm-project/issues/64644

Migrated from https://reviews.llvm.org/D157776 — @philnik777  @pfusik 
@ldionne @mordante 
 please take another look!
2023-10-17 11:38:12 +02:00

92 lines
2.5 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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
// <sstream>
// template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
// class basic_stringbuf
// basic_string<charT, traits, Allocator> str() &&;
#include <sstream>
#include <cassert>
#include "make_string.h"
#include "test_macros.h"
#define STR(S) MAKE_STRING(CharT, S)
template <class CharT>
static void test() {
{
std::basic_stringbuf<CharT> buf(STR("testing"));
std::basic_string<CharT> s = std::move(buf).str();
assert(s == STR("testing"));
assert(buf.view().empty());
}
{
std::basic_stringbuf<CharT> buf;
std::basic_string<CharT> s = std::move(buf).str();
assert(s.empty());
assert(buf.view().empty());
}
{
std::basic_stringbuf<CharT> buf(STR("a very long string that exceeds the small string optimization buffer length"));
const CharT* p = buf.view().data();
std::basic_string<CharT> s = std::move(buf).str();
assert(s.data() == p); // the allocation was pilfered
assert(buf.view().empty());
}
}
struct StringBuf : std::stringbuf {
using basic_stringbuf::basic_stringbuf;
void public_setg(int a, int b, int c) {
char* p = eback();
this->setg(p + a, p + b, p + c);
}
};
static void test_altered_sequence_pointers() {
{
auto src = StringBuf("hello world", std::ios_base::in);
src.public_setg(4, 6, 9);
std::stringbuf dest;
dest = std::move(src);
std::string view = std::string(dest.view());
std::string str = std::move(dest).str();
assert(view == str);
LIBCPP_ASSERT(str == "o wor");
assert(dest.str().empty());
assert(dest.view().empty());
}
{
auto src = StringBuf("hello world", std::ios_base::in);
src.public_setg(4, 6, 9);
std::stringbuf dest;
dest.swap(src);
std::string view = std::string(dest.view());
std::string str = std::move(dest).str();
assert(view == str);
LIBCPP_ASSERT(str == "o wor");
assert(dest.str().empty());
assert(dest.view().empty());
}
}
int main(int, char**) {
test<char>();
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
test<wchar_t>();
#endif
test_altered_sequence_pointers();
return 0;
}