src/script/script_info_dummy.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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/>.
   6  */
   7
   8 /** @file script_info_dummy.cpp Implementation of a dummy Script. */
   9
  10 #include "../stdafx.h"
  11 #include <squirrel.h>
  12
  13 #include "../string_func.h"
  14 #include "../strings_func.h"
  15 #include "../3rdparty/fmt/format.h"
  16
  17 #include "../safeguards.h"
  18
  19 /* The reason this exists in C++, is that a user can trash their ai/ or game/ dir,
  20  *  leaving no Scripts available. The complexity to solve this is insane, and
  21  *  therefore the alternative is used, and make sure there is always a Script
  22  *  available, no matter what the situation is. By defining it in C++, there
  23  *  is simply no way a user can delete it, and therefore safe to use. It has
  24  *  to be noted that this Script is complete invisible for the user, and impossible
  25  *  to select manual. It is a fail-over in case no Scripts are available.
  26  */
  27
  28 /** Run the dummy info.nut. */
  29 void Script_CreateDummyInfo(HSQUIRRELVM vm, const char *type, const char *dir)
  30 {
  31         std::string dummy_script = fmt::format(
  32                         "class Dummy{0} extends {0}Info {{\n"
  33                         "function GetAuthor()      {{ return \"OpenTTD Developers Team\"; }}\n"
  34                         "function GetName()        {{ return \"Dummy{0}\"; }}\n"
  35                         "function GetShortName()   {{ return \"DUMM\"; }}\n"
  36                         "function GetDescription() {{ return \"A Dummy {0} that is loaded when your {1}/ dir is empty\"; }}\n"
  37                         "function GetVersion()     {{ return 1; }}\n"
  38                         "function GetDate()        {{ return \"2008-07-26\"; }}\n"
  39                         "function CreateInstance() {{ return \"Dummy{0}\"; }}\n"
  40                         "}} RegisterDummy{0}(Dummy{0}());\n", type, dir);
  41
  42         sq_pushroottable(vm);
  43
  44         /* Load and run the script */
  45         if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script.c_str(), dummy_script.size(), "dummy", SQTrue))) {
  46                 sq_push(vm, -2);
  47                 if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
  48                         sq_pop(vm, 1);
  49                         return;
  50                 }
  51         }
  52         NOT_REACHED();
  53 }
  54
  55 /**
  56  * Split the given message on newlines ('\n') and escape quotes and (back)slashes,
  57  * so they can be properly interpreted as string constants by the Squirrel compiler.
  58  * @param message The message that we want to sanitize for use in Squirrel code.
  59  * @return Vector with sanitized strings to use as string constant in Squirrel code.
  60  */
  61 static std::vector<std::string> EscapeQuotesAndSlashesAndSplitOnNewLines(const std::string &message)
  62 {
  63         std::vector<std::string> messages;
  64
  65         std::string safe_message;
  66         for (auto c : message) {
  67                 if (c == '\n') {
  68                         messages.emplace_back(std::move(safe_message));
  69                         continue;
  70                 }
  71
  72                 if (c == '"' || c == '\\') safe_message.push_back('\\');
  73                 safe_message.push_back(c);
  74         }
  75         messages.emplace_back(std::move(safe_message));
  76         return messages;
  77 }
  78
  79 /** Run the dummy AI and let it generate an error message. */
  80 void Script_CreateDummy(HSQUIRRELVM vm, StringID string, const char *type)
  81 {
  82         /* We want to translate the error message.
  83          * We do this in three steps:
  84          * 1) We get the error message, escape quotes and slashes, and split on
  85          *    newlines because Log.Error terminates passed strings at newlines.
  86          */
  87         std::string error_message = GetString(string);
  88         std::vector<std::string> messages = EscapeQuotesAndSlashesAndSplitOnNewLines(error_message);
  89
  90         /* 2) We construct the AI's code. This is done by merging a header, body and footer */
  91         std::string dummy_script;
  92         auto back_inserter = std::back_inserter(dummy_script);
  93         /* Just a rough ballpark estimate. */
  94         dummy_script.reserve(error_message.size() + 128 + 64 * messages.size());
  95
  96         fmt::format_to(back_inserter, "class Dummy{0} extends {0}Controller {{\n  function Start()\n  {{\n", type);
  97         for (std::string &message : messages) {
  98                 fmt::format_to(back_inserter, "    {}Log.Error(\"{}\");\n", type, message);
  99         }
 100         dummy_script += "  }\n}\n";
 101
 102         /* 3) Finally we load and run the script */
 103         sq_pushroottable(vm);
 104         if (SQ_SUCCEEDED(sq_compilebuffer(vm, dummy_script.c_str(), dummy_script.size(), "dummy", SQTrue))) {
 105                 sq_push(vm, -2);
 106                 if (SQ_SUCCEEDED(sq_call(vm, 1, SQFalse, SQTrue))) {
 107                         sq_pop(vm, 1);
 108                         return;
 109                 }
 110         }
 111         NOT_REACHED();
 112 }