string_consumer.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */
 
#include "../stdafx.h"
#include "string_consumer.hpp"
 
#include "utf8.hpp"
#include "string_builder.hpp"
 
#include "../string_func.h"
 
#if defined(STRGEN) || defined(SETTINGSGEN)
#include "../error_func.h"
#else
#include "../debug.h"
#endif
 
#include "../safeguards.h"
 
/* static */ const std::string_view StringConsumer::WHITESPACE_NO_NEWLINE = "\t\v\f\r ";
/* static */ const std::string_view StringConsumer::WHITESPACE_OR_NEWLINE = "\t\n\v\f\r ";
 
/* static */ void StringConsumer::LogError(std::string &&msg)
{
#if defined(STRGEN) || defined(SETTINGSGEN)
  FatalErrorI(std::move(msg));
#else
  DebugPrint("misc", 0, std::move(msg));
#endif
}
 
std::optional<uint8_t> StringConsumer::PeekUint8() const
{
  if (this->GetBytesLeft() < 1) return std::nullopt;
  return static_cast<uint8_t>(this->src[this->position]);
}
 
std::optional<uint16_t> StringConsumer::PeekUint16LE() const
{
  if (this->GetBytesLeft() < 2) return std::nullopt;
  return static_cast<uint8_t>(this->src[this->position]) |
    static_cast<uint8_t>(this->src[this->position + 1]) << 8;
}
 
std::optional<uint32_t> StringConsumer::PeekUint32LE() const
{
  if (this->GetBytesLeft() < 4) return std::nullopt;
  return static_cast<uint8_t>(this->src[this->position]) |
    static_cast<uint8_t>(this->src[this->position + 1]) << 8 |
    static_cast<uint8_t>(this->src[this->position + 2]) << 16 |
    static_cast<uint8_t>(this->src[this->position + 3]) << 24;
}
 
std::optional<uint64_t> StringConsumer::PeekUint64LE() const
{
  if (this->GetBytesLeft() < 8) return std::nullopt;
  return static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position])) |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 1])) << 8 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 2])) << 16 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 3])) << 24 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 4])) << 32 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 5])) << 40 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 6])) << 48 |
    static_cast<uint64_t>(static_cast<uint8_t>(this->src[this->position + 7])) << 56;
}
 
std::optional<char> StringConsumer::PeekChar() const
{
  auto result = this->PeekUint8();
  if (!result.has_value()) return {};
  return static_cast<char>(*result);
}
 
std::pair<StringConsumer::size_type, char32_t> StringConsumer::PeekUtf8() const
{
  auto buf = this->src.substr(this->position);
  return DecodeUtf8(buf);
}
 
std::string_view StringConsumer::Peek(size_type len) const
{
  auto buf = this->src.substr(this->position);
  if (len == std::string_view::npos) {
    len = buf.size();
  } else if (len > buf.size()) {
    len = buf.size();
  }
  return buf.substr(0, len);
}
 
void StringConsumer::Skip(size_type len)
{
  if (len == std::string_view::npos) {
    this->position = this->src.size();
  } else if (size_type max_len = GetBytesLeft(); len > max_len) {
    LogError(fmt::format("Source buffer too short: {} > {}", len, max_len));
    this->position = this->src.size();
  } else {
    this->position += len;
  }
}
 
StringConsumer::size_type StringConsumer::Find(std::string_view str) const
{
  assert(!str.empty());
  auto buf = this->src.substr(this->position);
  return buf.find(str);
}
 
StringConsumer::size_type StringConsumer::FindUtf8(char32_t c) const
{
  auto [data, len] = EncodeUtf8(c);
  return this->Find({data, len});
}
 
StringConsumer::size_type StringConsumer::FindCharIn(std::string_view chars) const
{
  assert(!chars.empty());
  auto buf = this->src.substr(this->position);
  return buf.find_first_of(chars);
}
 
StringConsumer::size_type StringConsumer::FindCharNotIn(std::string_view chars) const
{
  assert(!chars.empty());
  auto buf = this->src.substr(this->position);
  return buf.find_first_not_of(chars);
}
 
std::string_view StringConsumer::PeekUntil(std::string_view str, SeparatorUsage sep) const
{
  assert(!str.empty());
  auto buf = this->src.substr(this->position);
  auto len = buf.find(str);
  if (len != std::string_view::npos) {
    switch (sep) {
      case READ_ONE_SEPARATOR:
        if (buf.compare(len, str.size(), str) == 0) len += str.size();
        break;
      case READ_ALL_SEPARATORS:
        while (buf.compare(len, str.size(), str) == 0) len += str.size();
        break;
      default:
        break;
    }
  }
  return buf.substr(0, len);
}
 
std::string_view StringConsumer::PeekUntilUtf8(char32_t c, SeparatorUsage sep) const
{
  auto [data, len] = EncodeUtf8(c);
  return PeekUntil({data, len}, sep);
}
 
std::string_view StringConsumer::ReadUntilUtf8(char32_t c, SeparatorUsage sep)
{
  auto [data, len] = EncodeUtf8(c);
  return ReadUntil({data, len}, sep);
}
 
void StringConsumer::SkipUntilUtf8(char32_t c, SeparatorUsage sep)
{
  auto [data, len] = EncodeUtf8(c);
  return SkipUntil({data, len}, sep);
}
 
void StringConsumer::SkipIntegerBase(int base)
{
  this->SkipIf("-");
  if (base == 0) {
    if (this->ReadIf("0x") || this->ReadIf("0X")) { // boolean short-circuit ensures only one prefix is read
      base = 16;
    } else {
      base = 10;
    }
  }
  switch (base) {
    default:
      assert(false);
      break;
    case 8:
      this->SkipUntilCharNotIn("01234567");
      break;
    case 10:
      this->SkipUntilCharNotIn("0123456789");
      break;
    case 16:
      this->SkipUntilCharNotIn("0123456789abcdefABCDEF");
      break;
  }
}