Mathias Agopian
5a5168a191
We add rvalue version of append/insert/replace so that calling
those on a temporary yields to a temporary.
Also add string literal versions of those so that we can
append/insert/replace a literal without allocation, e.g.:
`CString foo = CString{ bar }.append("baz");`
This will not end-up creating a temporary CString for "baz".
118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <utils/CString.h>
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#include <utils/compiler.h>
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#include <utils/ostream.h>
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#include <algorithm>
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#include <cstdlib>
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#include <memory>
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namespace utils {
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UTILS_NOINLINE
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CString::CString(const char* cstr, size_t const length) {
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if (length && cstr) {
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Data* const p = static_cast<Data*>(std::malloc(sizeof(Data) + length + 1));
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p->length = size_type(length);
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mCStr = reinterpret_cast<value_type*>(p + 1);
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// we don't use memcpy here to avoid a call to libc, the generated code is pretty good.
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std::uninitialized_copy_n(cstr, length, mCStr);
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mCStr[length] = '\0';
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}
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}
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CString::CString(size_t const length) {
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if (length) {
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Data* const p = static_cast<Data*>(std::malloc(sizeof(Data) + length + 1));
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p->length = size_type(length);
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mCStr = reinterpret_cast<value_type*>(p + 1);
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std::fill_n(mCStr, length, 0);
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mCStr[length] = '\0';
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}
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}
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CString::CString(const char* cstr)
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: CString(cstr, size_type(cstr ? strlen(cstr) : 0)) {
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}
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CString::CString(const CString& rhs)
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: CString(rhs.c_str(), rhs.size()) {
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}
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CString& CString::operator=(const CString& rhs) {
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if (this != &rhs) {
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auto *const p = mData ? mData - 1 : nullptr;
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new(this) CString(rhs);
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std::free(p);
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}
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return *this;
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}
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CString::~CString() noexcept {
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if (mData) {
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std::free(mData - 1);
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}
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}
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CString& CString::replace(size_type const pos, size_type len, char const* str, size_t const l) & noexcept {
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assert(pos <= size());
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len = std::min(len, size() - pos);
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// The new size of the string, after the replacement.
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const size_type newSize = size() - len + l;
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// Allocate enough memory to hold the new string.
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Data* const p = static_cast<Data*>(std::malloc(sizeof(Data) + newSize + 1));
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assert(p);
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p->length = newSize;
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value_type* newStr = reinterpret_cast<value_type*>(p + 1);
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const value_type* beginning = mCStr;
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const value_type* replacementStart = mCStr + pos;
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const value_type* replacementEnd = replacementStart + len;
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const value_type* end = beginning + size();
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value_type* ptr = newStr;
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ptr = std::uninitialized_copy(beginning, replacementStart, ptr);
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ptr = std::uninitialized_copy_n(str, l, ptr);
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ptr = std::uninitialized_copy(replacementEnd, end, ptr);
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// null-terminator
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*ptr = 0;
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std::swap(mCStr, newStr);
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if (newStr) {
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std::free(reinterpret_cast<Data*>(newStr) - 1);
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}
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return *this;
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}
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#if !defined(NDEBUG)
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io::ostream& operator<<(io::ostream& out, const CString& rhs) {
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return out << rhs.c_str_safe();
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}
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#endif
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} // namespace utils
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