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tdlib-fork/tdutils/td/utils/StringBuilder.cpp

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "td/utils/StringBuilder.h"
#include "td/utils/misc.h"
#include "td/utils/port/thread_local.h"
#include "td/utils/Slice.h"
#include <cstdio>
#include <cstring>
#include <limits>
#include <locale>
#include <memory>
#include <sstream>
#include <utility>
namespace td {
StringBuilder::StringBuilder(MutableSlice slice, bool use_buffer)
: begin_ptr_(slice.begin()), current_ptr_(begin_ptr_), use_buffer_(use_buffer) {
if (slice.size() <= reserved_size) {
auto buffer_size = reserved_size + 100;
buffer_ = std::make_unique<char[]>(buffer_size);
begin_ptr_ = buffer_.get();
current_ptr_ = begin_ptr_;
end_ptr_ = begin_ptr_ + buffer_size - reserved_size;
} else {
end_ptr_ = slice.end() - reserved_size;
}
}
StringBuilder &StringBuilder::operator<<(Slice slice) {
size_t size = slice.size();
if (unlikely(!reserve(size))) {
if (end_ptr_ < current_ptr_) {
return on_error();
}
auto available_size = static_cast<size_t>(end_ptr_ + reserved_size - 1 - current_ptr_);
if (size > available_size) {
error_flag_ = true;
size = available_size;
}
}
std::memcpy(current_ptr_, slice.begin(), size);
current_ptr_ += size;
return *this;
}
template <class T>
static char *print_uint(char *current_ptr, T x) {
if (x < 100) {
if (x < 10) {
*current_ptr++ = static_cast<char>('0' + x);
} else {
*current_ptr++ = static_cast<char>('0' + x / 10);
*current_ptr++ = static_cast<char>('0' + x % 10);
}
return current_ptr;
}
auto begin_ptr = current_ptr;
do {
*current_ptr++ = static_cast<char>('0' + x % 10);
x /= 10;
} while (x > 0);
auto end_ptr = current_ptr - 1;
while (begin_ptr < end_ptr) {
std::swap(*begin_ptr++, *end_ptr--);
}
return current_ptr;
}
template <class T>
static char *print_int(char *current_ptr, T x) {
if (x < 0) {
if (x == std::numeric_limits<T>::min()) {
std::stringstream ss;
ss << x;
auto len = narrow_cast<int>(static_cast<std::streamoff>(ss.tellp()));
ss.read(current_ptr, len);
return current_ptr + len;
}
*current_ptr++ = '-';
x = -x;
}
return print_uint(current_ptr, x);
}
bool StringBuilder::reserve_inner(size_t size) {
if (!use_buffer_) {
return false;
}
size_t old_data_size = current_ptr_ - begin_ptr_;
if (size >= std::numeric_limits<size_t>::max() - reserved_size - old_data_size - 1) {
return false;
}
size_t need_data_size = old_data_size + size;
size_t old_buffer_size = end_ptr_ - begin_ptr_;
if (old_buffer_size >= (std::numeric_limits<size_t>::max() - reserved_size) / 2 - 2) {
return false;
}
size_t new_buffer_size = (old_buffer_size + 1) * 2;
if (new_buffer_size < need_data_size) {
new_buffer_size = need_data_size;
}
if (new_buffer_size < 100) {
new_buffer_size = 100;
}
new_buffer_size += reserved_size;
auto new_buffer = std::make_unique<char[]>(new_buffer_size);
std::memcpy(new_buffer.get(), begin_ptr_, old_data_size);
buffer_ = std::move(new_buffer);
begin_ptr_ = buffer_.get();
current_ptr_ = begin_ptr_ + old_data_size;
end_ptr_ = begin_ptr_ + new_buffer_size - reserved_size;
CHECK(end_ptr_ > current_ptr_);
CHECK(static_cast<size_t>(end_ptr_ - current_ptr_) >= size);
return true;
}
StringBuilder &StringBuilder::operator<<(int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_int(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(unsigned int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_uint(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(long int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_int(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(long unsigned int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_uint(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(long long int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_int(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(long long unsigned int x) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ = print_uint(current_ptr_, x);
return *this;
}
StringBuilder &StringBuilder::operator<<(FixedDouble x) {
if (unlikely(!reserve(std::numeric_limits<double>::max_exponent10 + x.precision + 4))) {
return on_error();
}
static TD_THREAD_LOCAL std::stringstream *ss;
if (init_thread_local<std::stringstream>(ss)) {
auto previous_locale = ss->imbue(std::locale::classic());
ss->setf(std::ios_base::fixed, std::ios_base::floatfield);
} else {
ss->str(std::string());
ss->clear();
}
ss->precision(x.precision);
*ss << x.d;
int len = narrow_cast<int>(static_cast<std::streamoff>(ss->tellp()));
auto left = end_ptr_ + reserved_size - current_ptr_;
if (unlikely(len >= left)) {
error_flag_ = true;
len = left ? narrow_cast<int>(left - 1) : 0;
}
ss->read(current_ptr_, len);
current_ptr_ += len;
return *this;
}
StringBuilder &StringBuilder::operator<<(const void *ptr) {
if (unlikely(!reserve())) {
return on_error();
}
current_ptr_ += std::snprintf(current_ptr_, reserved_size, "%p", ptr);
return *this;
}
} // namespace td