tdlight/tdtl/td/tl/tl_simple_parser.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// 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 <cassert>
#include <cstdint>
#include <cstring>
#include <string>
namespace td {
namespace tl {
class tl_simple_parser {
const char *data;
const char *data_begin;
std::size_t data_len;
const char *error;
std::size_t error_pos;
void set_error(const char *error_message) {
if (error == NULL) {
assert(error_message != NULL);
error = error_message;
error_pos = static_cast<std::size_t>(data - data_begin);
data = "\x00\x00\x00\x00\x00\x00\x00\x00";
data_len = 0;
} else {
data = "\x00\x00\x00\x00\x00\x00\x00\x00";
assert(data_len == 0);
}
}
void check_len(const std::size_t len) {
if (data_len < len) {
set_error("Not enough data to read");
} else {
data_len -= len;
}
}
tl_simple_parser(const tl_simple_parser &other);
tl_simple_parser &operator=(const tl_simple_parser &other);
public:
tl_simple_parser(const char *data, std::size_t data_len)
: data(data), data_begin(data), data_len(data_len), error(), error_pos() {
}
const char *get_error() const {
return error;
}
std::size_t get_error_pos() const {
return error_pos;
}
std::int32_t fetch_int() {
check_len(sizeof(std::int32_t));
std::int32_t result = *reinterpret_cast<const std::int32_t *>(data);
data += sizeof(std::int32_t);
return result;
}
std::int64_t fetch_long() {
check_len(sizeof(std::int64_t));
std::int64_t result;
std::memcpy(&result, data, sizeof(std::int64_t));
data += sizeof(std::int64_t);
return result;
}
std::string fetch_string() {
check_len(4);
int result_len = static_cast<unsigned char>(data[0]);
if (result_len < 254) {
check_len((result_len >> 2) * 4);
std::string result(data + 1, result_len);
data += ((result_len >> 2) + 1) * 4;
return result;
}
if (result_len == 254) {
result_len = static_cast<unsigned char>(data[1]) + (static_cast<unsigned char>(data[2]) << 8) +
(static_cast<unsigned char>(data[3]) << 16);
check_len(((result_len + 3) >> 2) * 4);
std::string result(data + 4, result_len);
data += ((result_len + 7) >> 2) * 4;
return result;
}
set_error("Can't fetch string, 255 found");
return std::string();
}
void fetch_end() {
if (data_len) {
set_error("Too much data to fetch");
}
}
};
} // namespace tl
} // namespace td