strgen_base.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 <http://www.gnu.org/licenses/>.
 */
 
#include "../stdafx.h"
#include "../core/alloc_func.hpp"
#include "../core/endian_func.hpp"
#include "../core/mem_func.hpp"
#include "../error_func.h"
#include "../string_func.h"
#include "../table/control_codes.h"
 
#include "strgen.h"
 
 
#include "../table/strgen_tables.h"
 
#include "../safeguards.h"
 
/* Compiles a list of strings into a compiled string list */
 
static bool _translated;              
static bool _translation;             
const char *_file = "(unknown file)"; 
int _cur_line;                        
int _errors, _warnings, _show_todo;
LanguagePackHeader _lang;             
 
static const CmdStruct *ParseCommandString(const char **str, std::string &param, int *argno, int *casei);
 
Case::Case(int caseidx, const std::string &string) :
    caseidx(caseidx), string(string)
{
}
 
LangString::LangString(const std::string &name, const std::string &english, size_t index, int line) :
    name(name), english(english), index(index), line(line)
{
}
 
void LangString::FreeTranslation()
{
  this->translated.clear();
  this->translated_cases.clear();
}
 
StringData::StringData(size_t tabs) : tabs(tabs), max_strings(tabs * TAB_SIZE)
{
  this->strings.resize(max_strings);
  this->next_string_id = 0;
}
 
void StringData::FreeTranslation()
{
  for (size_t i = 0; i < this->max_strings; i++) {
    LangString *ls = this->strings[i].get();
    if (ls != nullptr) ls->FreeTranslation();
  }
}
 
void StringData::Add(std::unique_ptr<LangString> ls)
{
  this->name_to_string[ls->name] = ls.get();
  this->strings[ls->index].swap(ls);
}
 
LangString *StringData::Find(const std::string_view s)
{
  auto it = this->name_to_string.find(s);
  if (it == this->name_to_string.end()) return nullptr;
 
  return it->second;
}
 
uint StringData::VersionHashStr(uint hash, const char *s) const
{
  for (; *s != '\0'; s++) {
    hash = std::rotl(hash, 3) ^ *s;
    hash = (hash & 1 ? hash >> 1 ^ 0xDEADBEEF : hash >> 1);
  }
  return hash;
}
 
uint StringData::Version() const
{
  uint hash = 0;
 
  for (size_t i = 0; i < this->max_strings; i++) {
    const LangString *ls = this->strings[i].get();
 
    if (ls != nullptr) {
      const CmdStruct *cs;
      const char *s;
      std::string buf;
      int argno;
      int casei;
 
      s = ls->name.c_str();
      hash ^= i * 0x717239;
      hash = (hash & 1 ? hash >> 1 ^ 0xDEADBEEF : hash >> 1);
      hash = this->VersionHashStr(hash, s + 1);
 
      s = ls->english.c_str();
      while ((cs = ParseCommandString(&s, buf, &argno, &casei)) != nullptr) {
        if (cs->flags & C_DONTCOUNT) continue;
 
        hash ^= (cs - _cmd_structs) * 0x1234567;
        hash = (hash & 1 ? hash >> 1 ^ 0xF00BAA4 : hash >> 1);
      }
    }
  }
 
  return hash;
}
 
uint StringData::CountInUse(uint tab) const
{
  int i;
  for (i = TAB_SIZE; --i >= 0;) if (this->strings[(tab * TAB_SIZE) + i] != nullptr) break;
  return i + 1;
}
 
static const char *_cur_ident;
 
/* Used when generating some advanced commands. */
static ParsedCommandStruct _cur_pcs;
static int _cur_argidx;
 
struct Buffer : std::vector<uint8_t> {
  void AppendByte(uint8_t value)
  {
    this->push_back(value);
  }
 
  void AppendUtf8(uint32_t value)
  {
    if (value < 0x80) {
      this->push_back(value);
    } else if (value < 0x800) {
      this->push_back(0xC0 + GB(value,  6, 5));
      this->push_back(0x80 + GB(value,  0, 6));
    } else if (value < 0x10000) {
      this->push_back(0xE0 + GB(value, 12, 4));
      this->push_back(0x80 + GB(value,  6, 6));
      this->push_back(0x80 + GB(value,  0, 6));
    } else if (value < 0x110000) {
      this->push_back(0xF0 + GB(value, 18, 3));
      this->push_back(0x80 + GB(value, 12, 6));
      this->push_back(0x80 + GB(value,  6, 6));
      this->push_back(0x80 + GB(value,  0, 6));
    } else {
      StrgenWarning("Invalid unicode value U+0x{:X}", value);
    }
  }
};
 
size_t Utf8Validate(const char *s)
{
  uint32_t c;
 
  if (!HasBit(s[0], 7)) {
    /* 1 byte */
    return 1;
  } else if (GB(s[0], 5, 3) == 6 && IsUtf8Part(s[1])) {
    /* 2 bytes */
    c = GB(s[0], 0, 5) << 6 | GB(s[1], 0, 6);
    if (c >= 0x80) return 2;
  } else if (GB(s[0], 4, 4) == 14 && IsUtf8Part(s[1]) && IsUtf8Part(s[2])) {
    /* 3 bytes */
    c = GB(s[0], 0, 4) << 12 | GB(s[1], 0, 6) << 6 | GB(s[2], 0, 6);
    if (c >= 0x800) return 3;
  } else if (GB(s[0], 3, 5) == 30 && IsUtf8Part(s[1]) && IsUtf8Part(s[2]) && IsUtf8Part(s[3])) {
    /* 4 bytes */
    c = GB(s[0], 0, 3) << 18 | GB(s[1], 0, 6) << 12 | GB(s[2], 0, 6) << 6 | GB(s[3], 0, 6);
    if (c >= 0x10000 && c <= 0x10FFFF) return 4;
  }
 
  return 0;
}
 
 
void EmitSingleChar(Buffer *buffer, char *buf, int value)
{
  if (*buf != '\0') StrgenWarning("Ignoring trailing letters in command");
  buffer->AppendUtf8(value);
}
 
 
/* The plural specifier looks like
 * {NUM} {PLURAL -1 passenger passengers} then it picks either passenger/passengers depending on the count in NUM */
 
/* This is encoded like
 *  CommandByte <ARG#> <NUM> {Length of each string} {each string} */
 
bool ParseRelNum(char **buf, int *value, int *offset)
{
  const char *s = *buf;
  char *end;
  bool rel = false;
 
  while (*s == ' ' || *s == '\t') s++;
  if (*s == '+') {
    rel = true;
    s++;
  }
  int v = std::strtol(s, &end, 0);
  if (end == s) return false;
  if (rel || v < 0) {
    *value += v;
  } else {
    *value = v;
  }
  if (offset != nullptr && *end == ':') {
    /* Take the Nth within */
    s = end + 1;
    *offset = std::strtol(s, &end, 0);
    if (end == s) return false;
  }
  *buf = end;
  return true;
}
 
/* Parse out the next word, or nullptr */
char *ParseWord(char **buf)
{
  char *s = *buf, *r;
 
  while (*s == ' ' || *s == '\t') s++;
  if (*s == '\0') return nullptr;
 
  if (*s == '"') {
    r = ++s;
    /* parse until next " or NUL */
    for (;;) {
      if (*s == '\0') break;
      if (*s == '"') {
        *s++ = '\0';
        break;
      }
      s++;
    }
  } else {
    /* proceed until whitespace or NUL */
    r = s;
    for (;;) {
      if (*s == '\0') break;
      if (*s == ' ' || *s == '\t') {
        *s++ = '\0';
        break;
      }
      s++;
    }
  }
  *buf = s;
  return r;
}
 
/* Forward declaration */
static int TranslateArgumentIdx(int arg, int offset = 0);
 
static void EmitWordList(Buffer *buffer, const std::vector<const char *> &words, uint nw)
{
  /* Maximum word length in bytes, excluding trailing NULL. */
  constexpr uint MAX_WORD_LENGTH = UINT8_MAX - 2;
 
  buffer->AppendByte(nw);
  for (uint i = 0; i < nw; i++) {
    size_t len = strlen(words[i]) + 1;
    if (len >= UINT8_MAX) StrgenFatal("WordList {}/{} string '{}' too long, max bytes {}", i + 1, nw, words[i], MAX_WORD_LENGTH);
    buffer->AppendByte(static_cast<uint8_t>(len));
  }
  for (uint i = 0; i < nw; i++) {
    for (uint j = 0; words[i][j] != '\0'; j++) buffer->AppendByte(words[i][j]);
    buffer->AppendByte(0);
  }
}
 
void EmitPlural(Buffer *buffer, char *buf, int)
{
  int argidx = _cur_argidx;
  int offset = -1;
  int expected = _plural_forms[_lang.plural_form].plural_count;
  std::vector<const char *> words(std::max(expected, MAX_PLURALS), nullptr);
  int nw = 0;
 
  /* Parse out the number, if one exists. Otherwise default to prev arg. */
  if (!ParseRelNum(&buf, &argidx, &offset)) argidx--;
 
  const CmdStruct *cmd = _cur_pcs.consuming_commands[argidx];
  if (offset == -1) {
    /* Use default offset */
    if (cmd == nullptr || cmd->default_plural_offset < 0) {
      StrgenFatal("Command '{}' has no (default) plural position", cmd == nullptr ? "<empty>" : cmd->cmd);
    }
    offset = cmd->default_plural_offset;
  }
 
  /* Parse each string */
  for (nw = 0; nw < MAX_PLURALS; nw++) {
    words[nw] = ParseWord(&buf);
    if (words[nw] == nullptr) break;
  }
 
  if (nw == 0) {
    StrgenFatal("{}: No plural words", _cur_ident);
  }
 
  if (expected != nw) {
    if (_translated) {
      StrgenFatal("{}: Invalid number of plural forms. Expecting {}, found {}.", _cur_ident,
        expected, nw);
    } else {
      if ((_show_todo & 2) != 0) StrgenWarning("'{}' is untranslated. Tweaking english string to allow compilation for plural forms", _cur_ident);
      if (nw > expected) {
        nw = expected;
      } else {
        for (; nw < expected; nw++) {
          words[nw] = words[nw - 1];
        }
      }
    }
  }
 
  buffer->AppendUtf8(SCC_PLURAL_LIST);
  buffer->AppendByte(_lang.plural_form);
  buffer->AppendByte(TranslateArgumentIdx(argidx, offset));
  EmitWordList(buffer, words, nw);
}
 
void EmitGender(Buffer *buffer, char *buf, int)
{
  int argidx = _cur_argidx;
  int offset = 0;
  uint nw;
 
  if (buf[0] == '=') {
    buf++;
 
    /* This is a {G=DER} command */
    nw = _lang.GetGenderIndex(buf);
    if (nw >= MAX_NUM_GENDERS) StrgenFatal("G argument '{}' invalid", buf);
 
    /* now nw contains the gender index */
    buffer->AppendUtf8(SCC_GENDER_INDEX);
    buffer->AppendByte(nw);
  } else {
    std::vector<const char *> words(MAX_NUM_GENDERS, nullptr);
 
    /* This is a {G 0 foo bar two} command.
     * If no relative number exists, default to +0 */
    ParseRelNum(&buf, &argidx, &offset);
 
    const CmdStruct *cmd = _cur_pcs.consuming_commands[argidx];
    if (cmd == nullptr || (cmd->flags & C_GENDER) == 0) {
      StrgenFatal("Command '{}' can't have a gender", cmd == nullptr ? "<empty>" : cmd->cmd);
    }
 
    for (nw = 0; nw < MAX_NUM_GENDERS; nw++) {
      words[nw] = ParseWord(&buf);
      if (words[nw] == nullptr) break;
    }
    if (nw != _lang.num_genders) StrgenFatal("Bad # of arguments for gender command");
 
    assert(IsInsideBS(cmd->value, SCC_CONTROL_START, UINT8_MAX));
    buffer->AppendUtf8(SCC_GENDER_LIST);
    buffer->AppendByte(TranslateArgumentIdx(argidx, offset));
    EmitWordList(buffer, words, nw);
  }
}
 
static const CmdStruct *FindCmd(const char *s, int len)
{
  for (const auto &cs : _cmd_structs) {
    if (strncmp(cs.cmd, s, len) == 0 && cs.cmd[len] == '\0') return &cs;
  }
  return nullptr;
}
 
static uint ResolveCaseName(const char *str, size_t len)
{
  /* First get a clean copy of only the case name, then resolve it. */
  char case_str[CASE_GENDER_LEN];
  len = std::min(lengthof(case_str) - 1, len);
  memcpy(case_str, str, len);
  case_str[len] = '\0';
 
  uint8_t case_idx = _lang.GetCaseIndex(case_str);
  if (case_idx >= MAX_NUM_CASES) StrgenFatal("Invalid case-name '{}'", case_str);
  return case_idx + 1;
}
 
 
/* returns nullptr on eof
 * else returns command struct */
static const CmdStruct *ParseCommandString(const char **str, std::string &param, int *argno, int *casei)
{
  const char *s = *str, *start;
  char c;
 
  *argno = -1;
  *casei = -1;
 
  /* Scan to the next command, exit if there's no next command. */
  for (; *s != '{'; s++) {
    if (*s == '\0') return nullptr;
  }
  s++; // Skip past the {
 
  if (*s >= '0' && *s <= '9') {
    char *end;
 
    *argno = std::strtoul(s, &end, 0);
    if (*end != ':') StrgenFatal("missing arg #");
    s = end + 1;
  }
 
  /* parse command name */
  start = s;
  do {
    c = *s++;
  } while (c != '}' && c != ' ' && c != '=' && c != '.' && c != 0);
 
  const CmdStruct *cmd = FindCmd(start, s - start - 1);
  if (cmd == nullptr) {
    std::string command(start, s - start - 1);
    StrgenError("Undefined command '{}'", command);
    return nullptr;
  }
 
  if (c == '.') {
    const char *casep = s;
 
    if (!(cmd->flags & C_CASE)) {
      StrgenFatal("Command '{}' can't have a case", cmd->cmd);
    }
 
    do {
      c = *s++;
    } while (c != '}' && c != ' ' && c != '\0');
    *casei = ResolveCaseName(casep, s - casep - 1);
  }
 
  if (c == '\0') {
    StrgenError("Missing }} from command '{}'", start);
    return nullptr;
  }
 
 
  if (c != '}') {
    if (c == '=') s--;
    /* copy params */
    start = s;
    for (;;) {
      c = *s++;
      if (c == '}') break;
      if (c == '\0') {
        StrgenError("Missing }} from command '{}'", start);
        return nullptr;
      }
      param += c;
    }
  }
 
  *str = s;
 
  return cmd;
}
 
StringReader::StringReader(StringData &data, const std::string &file, bool master, bool translation) :
    data(data), file(file), master(master), translation(translation)
{
}
 
ParsedCommandStruct ExtractCommandString(const char *s, bool)
{
  int argno;
  int argidx = 0;
  int casei;
 
  ParsedCommandStruct p;
 
  for (;;) {
    /* read until next command from a. */
    std::string param;
    const CmdStruct *ar = ParseCommandString(&s, param, &argno, &casei);
 
    if (ar == nullptr) break;
 
    /* Sanity checking */
    if (argno != -1 && ar->consumes == 0) StrgenFatal("Non consumer param can't have a paramindex");
 
    if (ar->consumes) {
      if (argno != -1) argidx = argno;
      if (argidx < 0 || (uint)argidx >= p.consuming_commands.max_size()) StrgenFatal("invalid param idx {}", argidx);
      if (p.consuming_commands[argidx] != nullptr && p.consuming_commands[argidx] != ar) StrgenFatal("duplicate param idx {}", argidx);
 
      p.consuming_commands[argidx++] = ar;
    } else if (!(ar->flags & C_DONTCOUNT)) { // Ignore some of them
      p.non_consuming_commands.emplace_back(CmdPair{ar, std::move(param)});
    }
  }
 
  return p;
}
 
 
const CmdStruct *TranslateCmdForCompare(const CmdStruct *a)
{
  if (a == nullptr) return nullptr;
 
  if (strcmp(a->cmd, "STRING1") == 0 ||
      strcmp(a->cmd, "STRING2") == 0 ||
      strcmp(a->cmd, "STRING3") == 0 ||
      strcmp(a->cmd, "STRING4") == 0 ||
      strcmp(a->cmd, "STRING5") == 0 ||
      strcmp(a->cmd, "STRING6") == 0 ||
      strcmp(a->cmd, "STRING7") == 0 ||
      strcmp(a->cmd, "RAW_STRING") == 0) {
    return FindCmd("STRING", 6);
  }
 
  return a;
}
 
 
static bool CheckCommandsMatch(const char *a, const char *b, const char *name)
{
  /* If we're not translating, i.e. we're compiling the base language,
   * it is pointless to do all these checks as it'll always be correct.
   * After all, all checks are based on the base language.
   */
  if (!_translation) return true;
 
  bool result = true;
 
  ParsedCommandStruct templ = ExtractCommandString(b, true);
  ParsedCommandStruct lang = ExtractCommandString(a, true);
 
  /* For each string in templ, see if we find it in lang */
  if (templ.non_consuming_commands.max_size() != lang.non_consuming_commands.max_size()) {
    StrgenWarning("{}: template string and language string have a different # of commands", name);
    result = false;
  }
 
  for (auto &templ_nc : templ.non_consuming_commands) {
    /* see if we find it in lang, and zero it out */
    bool found = false;
    for (auto &lang_nc : lang.non_consuming_commands) {
      if (templ_nc.cmd == lang_nc.cmd && templ_nc.param == lang_nc.param) {
        /* it was found in both. zero it out from lang so we don't find it again */
        lang_nc.cmd = nullptr;
        found = true;
        break;
      }
    }
 
    if (!found) {
      StrgenWarning("{}: command '{}' exists in template file but not in language file", name, templ_nc.cmd->cmd);
      result = false;
    }
  }
 
  /* if we reach here, all non consumer commands match up.
   * Check if the non consumer commands match up also. */
  for (uint i = 0; i < templ.consuming_commands.max_size(); i++) {
    if (TranslateCmdForCompare(templ.consuming_commands[i]) != lang.consuming_commands[i]) {
      StrgenWarning("{}: Param idx #{} '{}' doesn't match with template command '{}'", name, i,
        lang.consuming_commands[i]  == nullptr ? "<empty>" : TranslateCmdForCompare(lang.consuming_commands[i])->cmd,
        templ.consuming_commands[i] == nullptr ? "<empty>" : templ.consuming_commands[i]->cmd);
      result = false;
    }
  }
 
  return result;
}
 
void StringReader::HandleString(char *str)
{
  if (*str == '#') {
    if (str[1] == '#' && str[2] != '#') this->HandlePragma(str + 2);
    return;
  }
 
  /* Ignore comments & blank lines */
  if (*str == ';' || *str == ' ' || *str == '\0') return;
 
  char *s = strchr(str, ':');
  if (s == nullptr) {
    StrgenError("Line has no ':' delimiter");
    return;
  }
 
  char *t;
  /* Trim spaces.
   * After this str points to the command name, and s points to the command contents */
  for (t = s; t > str && (t[-1] == ' ' || t[-1] == '\t'); t--) {}
  *t = 0;
  s++;
 
  /* Check string is valid UTF-8 */
  const char *tmp;
  for (tmp = s; *tmp != '\0';) {
    size_t len = Utf8Validate(tmp);
    if (len == 0) StrgenFatal("Invalid UTF-8 sequence in '{}'", s);
 
    char32_t c;
    Utf8Decode(&c, tmp);
    if (c <= 0x001F || // ASCII control character range
        c == 0x200B || // Zero width space
        (c >= 0xE000 && c <= 0xF8FF) || // Private range
        (c >= 0xFFF0 && c <= 0xFFFF)) { // Specials range
      StrgenFatal("Unwanted UTF-8 character U+{:04X} in sequence '{}'", (int)c, s);
    }
 
    tmp += len;
  }
 
  /* Check if the string has a case..
   * The syntax for cases is IDENTNAME.case */
  char *casep = strchr(str, '.');
  if (casep != nullptr) *casep++ = '\0';
 
  /* Check if this string already exists.. */
  LangString *ent = this->data.Find(str);
 
  if (this->master) {
    if (casep != nullptr) {
      StrgenError("Cases in the base translation are not supported.");
      return;
    }
 
    if (ent != nullptr) {
      StrgenError("String name '{}' is used multiple times", str);
      return;
    }
 
    if (this->data.strings[this->data.next_string_id] != nullptr) {
      StrgenError("String ID 0x{:X} for '{}' already in use by '{}'", this->data.next_string_id, str, this->data.strings[this->data.next_string_id]->name);
      return;
    }
 
    /* Allocate a new LangString */
    this->data.Add(std::make_unique<LangString>(str, s, this->data.next_string_id++, _cur_line));
  } else {
    if (ent == nullptr) {
      StrgenWarning("String name '{}' does not exist in master file", str);
      return;
    }
 
    if (!ent->translated.empty() && casep == nullptr) {
      StrgenError("String name '{}' is used multiple times", str);
      return;
    }
 
    /* make sure that the commands match */
    if (!CheckCommandsMatch(s, ent->english.c_str(), str)) return;
 
    if (casep != nullptr) {
      ent->translated_cases.emplace_back(ResolveCaseName(casep, strlen(casep)), s);
    } else {
      ent->translated = s;
      /* If the string was translated, use the line from the
       * translated language so errors in the translated file
       * are properly referenced to. */
      ent->line = _cur_line;
    }
  }
}
 
void StringReader::HandlePragma(char *str)
{
  if (!memcmp(str, "plural ", 7)) {
    _lang.plural_form = atoi(str + 7);
    if (_lang.plural_form >= lengthof(_plural_forms)) {
      StrgenFatal("Invalid pluralform {}", _lang.plural_form);
    }
  } else {
    StrgenFatal("unknown pragma '{}'", str);
  }
}
 
static void StripTrailingWhitespace(std::string &str)
{
  str.erase(str.find_last_not_of("\r\n ") + 1);
}
 
void StringReader::ParseFile()
{
  _warnings = _errors = 0;
 
  _translation = this->translation;
  _file = this->file.c_str();
 
  /* Abusing _show_todo to replace "warning" with "info" for translations. */
  _show_todo &= 3;
  if (!this->translation) _show_todo |= 4;
 
  /* For each new file we parse, reset the genders, and language codes. */
  MemSetT(&_lang, 0);
  strecpy(_lang.digit_group_separator, ",");
  strecpy(_lang.digit_group_separator_currency, ",");
  strecpy(_lang.digit_decimal_separator, ".");
 
  _cur_line = 1;
  while (this->data.next_string_id < this->data.max_strings) {
    std::optional<std::string> line = this->ReadLine();
    if (!line.has_value()) return;
 
    StripTrailingWhitespace(line.value());
    this->HandleString(line.value().data());
    _cur_line++;
  }
 
  if (this->data.next_string_id == this->data.max_strings) {
    StrgenError("Too many strings, maximum allowed is {}", this->data.max_strings);
  }
}
 
void HeaderWriter::WriteHeader(const StringData &data)
{
  int last = 0;
  for (size_t i = 0; i < data.max_strings; i++) {
    if (data.strings[i] != nullptr) {
      this->WriteStringID(data.strings[i]->name, (int)i);
      last = (int)i;
    }
  }
 
  this->WriteStringID("STR_LAST_STRINGID", last);
}
 
static int TranslateArgumentIdx(int argidx, int offset)
{
  int sum;
 
  if (argidx < 0 || (uint)argidx >= _cur_pcs.consuming_commands.max_size()) {
    StrgenFatal("invalid argidx {}", argidx);
  }
  const CmdStruct *cs = _cur_pcs.consuming_commands[argidx];
  if (cs != nullptr && cs->consumes <= offset) {
    StrgenFatal("invalid argidx offset {}:{}", argidx, offset);
  }
 
  if (_cur_pcs.consuming_commands[argidx] == nullptr) {
    StrgenFatal("no command for this argidx {}", argidx);
  }
 
  for (int i = sum = 0; i < argidx; i++) {
    cs = _cur_pcs.consuming_commands[i];
 
    sum += (cs != nullptr) ? cs->consumes : 1;
  }
 
  return sum + offset;
}
 
static void PutArgidxCommand(Buffer *buffer)
{
  buffer->AppendUtf8(SCC_ARG_INDEX);
  buffer->AppendByte(TranslateArgumentIdx(_cur_argidx));
}
 
 
static void PutCommandString(Buffer *buffer, const char *str)
{
  _cur_argidx = 0;
 
  while (*str != '\0') {
    /* Process characters as they are until we encounter a { */
    if (*str != '{') {
      buffer->AppendByte(*str++);
      continue;
    }
 
    std::string param;
    int argno;
    int casei;
    const CmdStruct *cs = ParseCommandString(&str, param, &argno, &casei);
    if (cs == nullptr) break;
 
    if (casei != -1) {
      buffer->AppendUtf8(SCC_SET_CASE); // {SET_CASE}
      buffer->AppendByte(casei);
    }
 
    /* For params that consume values, we need to handle the argindex properly */
    if (cs->consumes > 0) {
      /* Check if we need to output a move-param command */
      if (argno != -1 && argno != _cur_argidx) {
        _cur_argidx = argno;
        PutArgidxCommand(buffer);
      }
 
      /* Output the one from the master string... it's always accurate. */
      cs = _cur_pcs.consuming_commands[_cur_argidx++];
      if (cs == nullptr) {
        StrgenFatal("{}: No argument exists at position {}", _cur_ident, _cur_argidx - 1);
      }
    }
 
    cs->proc(buffer, param.data(), cs->value);
  }
}
 
void LanguageWriter::WriteLength(uint length)
{
  char buffer[2];
  int offs = 0;
  if (length >= 0x4000) {
    StrgenFatal("string too long");
  }
 
  if (length >= 0xC0) {
    buffer[offs++] = (length >> 8) | 0xC0;
  }
  buffer[offs++] = length & 0xFF;
  this->Write((uint8_t*)buffer, offs);
}
 
void LanguageWriter::WriteLang(const StringData &data)
{
  std::vector<uint> in_use;
  for (size_t tab = 0; tab < data.tabs; tab++) {
    uint n = data.CountInUse((uint)tab);
 
    in_use.push_back(n);
    _lang.offsets[tab] = TO_LE16(n);
 
    for (uint j = 0; j != in_use[tab]; j++) {
      const LangString *ls = data.strings[(tab * TAB_SIZE) + j].get();
      if (ls != nullptr && ls->translated.empty()) _lang.missing++;
    }
  }
 
  _lang.ident = TO_LE32(LanguagePackHeader::IDENT);
  _lang.version = TO_LE32(data.Version());
  _lang.missing = TO_LE16(_lang.missing);
  _lang.winlangid = TO_LE16(_lang.winlangid);
 
  this->WriteHeader(&_lang);
  Buffer buffer;
 
  for (size_t tab = 0; tab < data.tabs; tab++) {
    for (uint j = 0; j != in_use[tab]; j++) {
      const LangString *ls = data.strings[(tab * TAB_SIZE) + j].get();
      const std::string *cmdp;
 
      /* For undefined strings, just set that it's an empty string */
      if (ls == nullptr) {
        this->WriteLength(0);
        continue;
      }
 
      _cur_ident = ls->name.c_str();
      _cur_line = ls->line;
 
      /* Produce a message if a string doesn't have a translation. */
      if (_show_todo > 0 && ls->translated.empty()) {
        if ((_show_todo & 2) != 0) {
          StrgenWarning("'{}' is untranslated", ls->name);
        }
        if ((_show_todo & 1) != 0) {
          const char *s = "<TODO> ";
          while (*s != '\0') buffer.AppendByte(*s++);
        }
      }
 
      /* Extract the strings and stuff from the english command string */
      _cur_pcs = ExtractCommandString(ls->english.c_str(), false);
 
      if (!ls->translated_cases.empty() || !ls->translated.empty()) {
        cmdp = &ls->translated;
      } else {
        cmdp = &ls->english;
      }
 
      _translated = cmdp != &ls->english;
 
      if (!ls->translated_cases.empty()) {
        /* Need to output a case-switch.
         * It has this format
         * <0x9E> <NUM CASES> <CASE1> <LEN1> <STRING1> <CASE2> <LEN2> <STRING2> <CASE3> <LEN3> <STRING3> <STRINGDEFAULT>
         * Each LEN is printed using 2 bytes in big endian order. */
        buffer.AppendUtf8(SCC_SWITCH_CASE);
        buffer.AppendByte((uint8_t)ls->translated_cases.size());
 
        /* Write each case */
        for (const Case &c : ls->translated_cases) {
          buffer.AppendByte(c.caseidx);
          /* Make some space for the 16-bit length */
          uint pos = (uint)buffer.size();
          buffer.AppendByte(0);
          buffer.AppendByte(0);
          /* Write string */
          PutCommandString(&buffer, c.string.c_str());
          buffer.AppendByte(0); // terminate with a zero
          /* Fill in the length */
          uint size = (uint)buffer.size() - (pos + 2);
          buffer[pos + 0] = GB(size, 8, 8);
          buffer[pos + 1] = GB(size, 0, 8);
        }
      }
 
      if (!cmdp->empty()) PutCommandString(&buffer, cmdp->c_str());
 
      this->WriteLength((uint)buffer.size());
      this->Write(buffer.data(), buffer.size());
      buffer.clear();
    }
  }
}