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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2026
//
// 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)
//
#pragma once
#include "td/utils/common.h"
#include "td/utils/Slice.h"
#include "td/utils/StackAllocator.h"
#include <cstdlib>
#include <memory>
#include <type_traits>
#include <utility>
namespace td {
class StringBuilder {
public:
explicit StringBuilder(MutableSlice slice, bool use_buffer = false);
StringBuilder() : StringBuilder({}, true) {
}
void clear() {
current_ptr_ = begin_ptr_;
error_flag_ = false;
}
void pop_back() {
CHECK(current_ptr_ > begin_ptr_);
current_ptr_--;
}
void push_back(char c) {
if (unlikely(end_ptr_ <= current_ptr_)) {
if (!reserve_inner(RESERVED_SIZE)) {
error_flag_ = true;
return;
}
}
*current_ptr_++ = c;
}
void append_char(size_t count, char c);
MutableCSlice as_cslice() {
if (current_ptr_ >= end_ptr_ + RESERVED_SIZE) {
std::abort(); // shouldn't happen
}
*current_ptr_ = 0;
return MutableCSlice(begin_ptr_, current_ptr_);
}
size_t size() {
return static_cast<size_t>(current_ptr_ - begin_ptr_);
}
bool is_error() const {
return error_flag_;
}
template <class T>
std::enable_if_t<std::is_same<char *, std::remove_const_t<T>>::value, StringBuilder> &operator<<(T str) {
return *this << Slice(str);
}
template <class T>
std::enable_if_t<std::is_same<const char *, std::remove_const_t<T>>::value, StringBuilder> &operator<<(T str) {
return *this << Slice(str);
}
template <size_t N>
StringBuilder &operator<<(char (&str)[N]) = delete;
template <size_t N>
StringBuilder &operator<<(const char (&str)[N]) {
return *this << Slice(str, N - 1);
}
StringBuilder &operator<<(const wchar_t *str) = delete;
StringBuilder &operator<<(Slice slice);
StringBuilder &operator<<(bool b) {
return *this << (b ? Slice("true") : Slice("false"));
}
StringBuilder &operator<<(char c) {
if (unlikely(!reserve())) {
return on_error();
}
*current_ptr_++ = c;
return *this;
}
StringBuilder &operator<<(unsigned char c) {
return *this << static_cast<unsigned int>(c);
}
StringBuilder &operator<<(signed char c) {
return *this << static_cast<int>(c);
}
StringBuilder &operator<<(int x);
StringBuilder &operator<<(unsigned int x);
StringBuilder &operator<<(long int x);
StringBuilder &operator<<(long unsigned int x);
StringBuilder &operator<<(long long int x);
StringBuilder &operator<<(long long unsigned int x);
struct FixedDouble {
double d;
int precision;
FixedDouble(double d, int precision) : d(d), precision(precision) {
}
};
StringBuilder &operator<<(FixedDouble x);
StringBuilder &operator<<(double x) {
return *this << FixedDouble(x, 6);
}
StringBuilder &operator<<(const void *ptr);
template <class A, class B>
StringBuilder &operator<<(const std::pair<A, B> &p) {
return *this << '[' << p.first << ';' << p.second << ']';
}
template <class T>
StringBuilder &operator<<(const vector<T> &v) {
*this << '{';
if (!v.empty()) {
*this << v[0];
size_t len = v.size();
for (size_t i = 1; i < len; i++) {
*this << ", " << v[i];
}
}
return *this << '}';
}
StringBuilder &operator<<(const vector<bool> &v) {
*this << '{';
if (!v.empty()) {
*this << v[0];
size_t len = v.size();
for (size_t i = 1; i < len; i++) {
*this << ", " << static_cast<bool>(v[i]);
}
}
return *this << '}';
}
private:
char *begin_ptr_;
char *current_ptr_;
char *end_ptr_;
bool error_flag_ = false;
bool use_buffer_ = false;
std::unique_ptr<char[]> buffer_;
static constexpr size_t RESERVED_SIZE = 30;
StringBuilder &on_error() {
error_flag_ = true;
return *this;
}
bool reserve() {
if (end_ptr_ > current_ptr_) {
return true;
}
return reserve_inner(RESERVED_SIZE);
}
bool reserve(size_t size) {
if (end_ptr_ > current_ptr_ && static_cast<size_t>(end_ptr_ - current_ptr_) >= size) {
return true;
}
return reserve_inner(size);
}
bool reserve_inner(size_t size);
};
template <class T>
std::enable_if_t<std::is_arithmetic<T>::value && !std::is_same<std::decay_t<T>, bool>::value, string> to_string(
const T &x) {
const size_t buf_size = 1000;
auto buf = StackAllocator::alloc(buf_size);
StringBuilder sb(buf.as_slice());
sb << x;
return sb.as_cslice().str();
}
} // namespace td
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