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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2025
//
// 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/SliceBuilder.h"
#include "td/utils/Status.h"
#include <cstring>
#include <utility>
namespace td {
namespace detail {
template <class SliceT>
class ParserImpl {
public:
explicit ParserImpl(SliceT data) : ptr_(data.begin()), end_(data.end()), status_() {
}
ParserImpl(ParserImpl &&other) noexcept : ptr_(other.ptr_), end_(other.end_), status_(std::move(other.status_)) {
other.clear();
}
ParserImpl &operator=(ParserImpl &&other) noexcept {
if (&other == this) {
return *this;
}
ptr_ = other.ptr_;
end_ = other.end_;
status_ = std::move(other.status_);
other.clear();
return *this;
}
ParserImpl(const ParserImpl &) = delete;
ParserImpl &operator=(const ParserImpl &) = delete;
~ParserImpl() = default;
bool empty() const {
return ptr_ == end_;
}
void clear() {
ptr_ = SliceT().begin();
end_ = ptr_;
status_ = Status::OK();
}
SliceT read_till_nofail(char c) {
if (status_.is_error()) {
return SliceT();
}
auto till = static_cast<decltype(ptr_)>(std::memchr(ptr_, c, end_ - ptr_));
if (till == nullptr) {
till = end_;
}
SliceT result(ptr_, till);
ptr_ = till;
return result;
}
SliceT read_till_nofail(Slice str) {
if (status_.is_error()) {
return SliceT();
}
auto best_till = end_;
for (auto c : str) {
auto till = static_cast<decltype(ptr_)>(std::memchr(ptr_, c, end_ - ptr_));
if (till != nullptr && till < best_till) {
best_till = till;
}
}
SliceT result(ptr_, best_till);
ptr_ = best_till;
return result;
}
template <class F>
SliceT read_while(const F &f) {
auto save_ptr = ptr_;
while (ptr_ != end_ && f(*ptr_)) {
ptr_++;
}
return SliceT(save_ptr, ptr_);
}
SliceT read_all() {
auto save_ptr = ptr_;
ptr_ = end_;
return SliceT(save_ptr, ptr_);
}
SliceT read_till(char c) {
if (status_.is_error()) {
return SliceT();
}
SliceT res = read_till_nofail(c);
if (ptr_ == end_ || ptr_[0] != c) {
status_ = Status::Error(PSLICE() << "Read till '" << c << "' failed");
return SliceT();
}
return res;
}
char peek_char() {
if (ptr_ == end_) {
return 0;
}
return *ptr_;
}
char *ptr() {
return ptr_;
}
void skip_nofail(char c) {
if (ptr_ != end_ && ptr_[0] == c) {
ptr_++;
}
}
void skip(char c) {
if (status_.is_error()) {
return;
}
if (ptr_ == end_ || ptr_[0] != c) {
status_ = Status::Error(PSLICE() << "Skip '" << c << "' failed");
return;
}
ptr_++;
}
bool try_skip(char c) {
if (ptr_ != end_ && ptr_[0] == c) {
ptr_++;
return true;
}
return false;
}
bool try_skip(Slice prefix) {
if (prefix.size() > static_cast<size_t>(end_ - ptr_) || prefix != Slice(ptr_, prefix.size())) {
return false;
}
advance(prefix.size());
return true;
}
void skip_till_not(Slice str) {
while (ptr_ != end_) {
if (std::memchr(str.data(), *ptr_, str.size()) == nullptr) {
break;
}
ptr_++;
}
}
void skip_whitespaces() {
skip_till_not(" \t\r\n");
}
SliceT read_word() {
skip_whitespaces();
return read_till_nofail(" \t\r\n");
}
SliceT data() const {
return SliceT(ptr_, end_);
}
Status &status() {
return status_;
}
void advance(size_t diff) {
ptr_ += diff;
CHECK(ptr_ <= end_);
}
private:
decltype(std::declval<SliceT>().begin()) ptr_;
decltype(std::declval<SliceT>().end()) end_;
Status status_;
};
} // namespace detail
using Parser = detail::ParserImpl<MutableSlice>;
using ConstParser = detail::ParserImpl<Slice>;
} // namespace td
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