metagen/parser.inc.php

<?php

class mtgMetaInfoParser
{
  const T_NonOrdMark         = 1000; //marks start of non 'ord(..)' values
  const T_EOF                = 1001;
  const T_StringConstant     = 1002;
  const T_IntegerConstant    = 1003;
  const T_FloatConstant      = 1004;
  const T_Enum               = 1005;
  const T_RPC                = 1006;
  const T_End                = 1007;
  const T_Identifier         = 1008;
  const T_Struct             = 1009;
  const T_Prop               = 1010;
  const T_Extends            = 1011;
  const T_Func               = 1012;
  const T_RawStringConstant  = 1013;
  const T_Interface          = 1014;
  const T_Implements         = 1015;
  const T_MinType            = 1019; //built-in types begin mark
  const T_string             = 1020;
  const T_uint32             = 1021;
  const T_int32              = 1022;
  const T_uint16             = 1023;
  const T_int16              = 1024;
  const T_uint8              = 1025;
  const T_int8               = 1026;
  const T_float              = 1027;
  const T_uint64             = 1028;
  const T_int64              = 1029;
  const T_bool               = 1030;
  const T_blob               = 1031;
  const T_MaxType            = 1032; //built-in types end mark

  private array $config = array();
  private mtgMetaInfo $current_meta;
  private array $parsed_files = array();
  private array $file_stack = array();
  private ?mtgMetaParsedModule $module = null;
  private string $file = "";
  private string $source = "";
  private int $cursor = 0;
  private int $line = 0;
  //TODO: setting it an 'int' type makes PHPStan produce many 
  //      false positives
  private $T = 0;
  private string $T_value = "";
  /** @var array<string,int>*/
  private $type2T = array();
  /** @var array<int,string>*/
  private $T2descr = array();
  private array $shared_tokens = array();

  function __construct($config = array())
  {
    $this->_initTables();

    self::_addDefaultTokens($config);

    $this->config = $config;
    if(!isset($this->config['include_path']))
      $this->config['include_path'] = array('.');
  }

  private function _initTables()
  {

    $this->type2T = array(
      "string" => self::T_string,
      "uint32" => self::T_uint32,
      "int32" => self::T_int32,
      "uint16" => self::T_uint16,
      "int16" => self::T_int16,
      "uint8" => self::T_uint8,
      "int8" => self::T_int8,
      "float" => self::T_float,
      "double" => self::T_float,
      "uint64" => self::T_uint64,
      "int64" => self::T_int64,
      "bool" => self::T_bool,
      "blob" => self::T_blob,
    );

    $this->T2descr = array_flip($this->type2T);
    $this->T2descr[self::T_EOF] = '<EOF>';
    $this->T2descr[self::T_StringConstant] = '<StringConstant>';
    $this->T2descr[self::T_RawStringConstant] = '<RawStringConstant>';
    $this->T2descr[self::T_IntegerConstant] = '<IntegerConstant>';
    $this->T2descr[self::T_FloatConstant] = '<FloatConstant>';
    $this->T2descr[self::T_Enum] = '<enum>';
    $this->T2descr[self::T_RPC] = '<RPC>';
    $this->T2descr[self::T_End] = '<end>';
    $this->T2descr[self::T_Identifier] = '<Identifier>';
    $this->T2descr[self::T_Struct] = '<struct>';
    $this->T2descr[self::T_Interface] = '<interface>';
    $this->T2descr[self::T_Prop] = '<@prop>';
    $this->T2descr[self::T_Extends] = '<extends>';
    $this->T2descr[self::T_Implements] = '<implements>';
    $this->T2descr[self::T_Func] = '<func>';
  }

  private static function _addDefaultTokens(array &$config)
  {
    if(!isset($config['valid_tokens']))
      $config['valid_tokens'] = array();

    $config['valid_tokens'][] = 'class_id';
    $config['valid_tokens'][] = 'shared_tokens';
    $config['valid_tokens'][] = 'enum_override';
    $config['valid_tokens'][] = 'enum_replace';
  }

  function parse(mtgMetaInfo $meta, $raw_file)
  {
    $this->current_meta = $meta;

    $file = realpath($raw_file);
    if($file === false)
      throw new Exception("No such file '$raw_file'");

    $this->_parse($file);
  }

  private function _parse($file)
  {
    if(isset($this->parsed_files[$file]))
      return;
    $module = new mtgMetaParsedModule($file);
    $this->parsed_files[$file] = $module;
    $this->file_stack[] = $file;
    $source = file_get_contents($file);

    try
    {
      if($source === false)
        throw new Exception("Could not read file '$file'");

      $this->_resolveIncludes($module, $source);
    }
    catch(Exception $e)
    {
      throw new Exception(end($this->file_stack) . " : " . $e->getMessage());
    }

    array_pop($this->file_stack);

    $this->module = $module;
    $this->file = $file;
    $this->source = $source;
    $this->cursor = 0;
    $this->line = 1;
    $this->shared_tokens = array();

    try
    {
      $this->_next();
      while($this->T != self::T_EOF)
      {
        //echo "TOKEN : " . $this->T . " " . $this->T_value . " " . $this->line . "\n";

        if($this->T == self::T_Prop)
          $this->_parseSharedTokens($this->_parsePropTokens());
        else if($this->T == self::T_Enum)
          $this->_parseEnum();
        else if($this->T == self::T_Struct)
          $this->_parseStruct();
        else if($this->T == self::T_Interface)
          $this->_parseInterface();
        else if($this->T == self::T_Func)
          $this->_parseFreeFunc();
        else if($this->T == self::T_RPC)
          $this->_parseRPC();
        else
          $this->_error("Unexpected T ('" . $this->_toStr($this->T) . "' " . $this->T_value . ")");
      }
    }
    catch(Exception $e)
    {
      throw new Exception("$file@{$this->line} : " .  $e->getMessage() . " " . $e->getTraceAsString());
    }
  }

  private function _parseInclude(mtgMetaParsedModule $module, $file)
  {
    $this->_parse($file);

    $module->addInclude($this->parsed_files[$file]);
  }

  private function _parseSharedTokens(array $tokens)
  {
    if(!isset($tokens['shared_tokens']))
      return;

    $this->shared_tokens = json_decode($tokens['shared_tokens'], true);
    if(!is_array($this->shared_tokens))
      $this->_error("Invalid 'shared_tokens' formant, invalid JSON");
  }

  private function _parseType($can_be_multi = false)
  {
    $types = array();

    while(true)
    {
      $type = null;
      
      if($this->T == self::T_Func)
      {
        $origin = new mtgOrigin($this->file, $this->line);
        $func_type = $this->_parseFuncType();
        $type = new mtgTypeRef($func_type, $this->module, $origin);
      }
      else if($this->T == self::T_Identifier)
      {
        $origin = new mtgOrigin($this->file, $this->line);
        $type_name = $this->_parseDotName();
        $type = new mtgTypeRef($type_name, $this->module, $origin);
      }
      else
      {
        $origin = new mtgOrigin($this->file, $this->line);
        $type_name = $this->T_value;
        $type = new mtgTypeRef(new mtgBuiltinType($type_name), $this->module, $origin);
        $this->_next();
      }

      if($this->T == ord('['))
      {
        $origin = new mtgOrigin($this->file, $this->line);
        $this->_next();
        $this->_checkThenNext(ord(']'));
        $type = new mtgTypeRef(new mtgArrType($type), $this->module, $origin);
      }
      $types[] = $type;

      if(!$can_be_multi)
        break;

      if($this->T != ord(','))
        break;
      $this->_next();
    }

    if(sizeof($types) > 1)
      return new mtgTypeRef(new mtgMultiType($types), $this->module, new mtgOrigin($this->file, $this->line));
    else
      return $types[0];
  }

  private function _parseFuncType()
  {
    $ftype = new mtgMetaFunc('');

    $this->_next();

    $this->_checkThenNext(ord('('));

    $c = 0;
    while(true)
    {
      if($this->T == ord(')'))
      {
        $this->_next();
        break;
      }
      else if($c > 0)
      {
        $this->_checkThenNext(ord(','));
      }

      $arg_type = $this->_parseType();
      $c++;
      $arg = new mtgMetaField("_$c", $arg_type);
      $ftype->addArg($arg);
    }

    if($this->T == ord(':'))
    {
      $this->_next();
      $ret_type = $this->_parseType(true/*can be multi-type*/);
      $ftype->setReturnType($ret_type);
    }
    return $ftype;
  }

  private function _resolveIncludes(mtgMetaParsedModule $module, &$text)
  { 
    $include_paths = $this->config['include_path'];

    $result = array();
    $lines = explode("\n", $text);
    foreach($lines as $line)
    {
      if(preg_match('~^#include\s+(\S+)~', $line, $m))
      {
        $this->_processInclude($module, $m[1], $include_paths);
        $result[] = "";
      }
      else
        $result[] = $line;
    }
    $text = implode("\n", $result);
  }

  private function _processInclude(mtgMetaParsedModule $module, $include, array $include_paths)
  {
    $file = false;
    foreach($include_paths as $include_path)
    {
      $file = realpath($include_path . "/" . $include);
      if($file !== false)
        break;
    }

    if($file === false)
      throw new Exception("#include {$include} can't be resolved(include path is '". implode(':', $include_paths) . "')");

    $this->_parseInclude($module, $file);
  }

  private function _parseEnumOrValues()
  {
    $values = array();
    while(true)
    {
      if($this->T == self::T_Identifier)          
      {
        $values[] = $this->T_value;
        $this->_next();
        if(!$this->_nextIf(ord('|')))
          break;
      }
      else
        break;
    }

    return $values;
  }

  private function _parseEnum()
  {
    $this->_next();

    $name = $this->_parseDotName();

    $enum = new mtgMetaEnum($name);
    $tokens = $this->shared_tokens;
    if($this->T == self::T_Prop)
      $tokens = array_merge($tokens, $this->_parsePropTokens());
    $enum->setTokens($tokens);

    $or_values = array();
    while(true)
    {
      if($this->_nextIf(self::T_End))
        break;
      $key = $this->_checkThenNext(self::T_Identifier);
      $this->_checkThenNext(ord('='));
      if($this->T == self::T_Identifier)
      {
        $or_values[$key] = $this->_parseEnumOrValues();
      }
      else
      {
        $value = $this->_checkThenNext(self::T_IntegerConstant);
        $enum->addValue($key, $value);
      }
    }
    $enum->addOrValues($or_values);

    //NOTE: special case for enums when we allow to 'override' the original one, 
    //      with additional values 
    if($enum->hasToken('enum_override'))
    {
      $existing = $this->current_meta->findUnit($enum->getMetaId());
      if(!$existing)
        throw new Exception("Not found '{$name}' enum to override values");
      if(!($existing->object instanceof mtgMetaEnum))
        throw new Exception("Not an enum struct '{$name}'");

      $existing->object->override($enum);
    }
    //NOTE: special case for enums when we allow to 'replace' the original one, 
    //      with additional values 
    else if($enum->hasToken('enum_replace'))
    {
      $existing = $this->current_meta->findUnit($enum->getMetaId());
      if(!$existing)
        throw new Exception("Not found '{$name}' enum to replace values");
      if(!($existing->object instanceof mtgMetaEnum))
        throw new Exception("Not an enum struct '{$name}'");

      $existing->object->replace($enum);
    }
    else
      $this->_addUnit(new mtgMetaInfoUnit($this->file, $enum));
  }

  static private function _isBuiltinType(int $t) : bool
  {
    return $t > self::T_MinType && $t < self::T_MaxType;
  }

  private function _parseFields(callable $next_doer)
  {
    $flds = array();

    while(true)
    {
      if($next_doer())
        break;

      if($this->T == self::T_Identifier)
      {
        $name = $this->T_value;
        $this->_next();
        $this->_checkThenNext(ord(':'));

        if($this->T == self::T_Identifier || 
          $this->T == self::T_Func ||
          self::_isBuiltinType($this->T))
        {
          $type = $this->_parseType();

          $fld = new mtgMetaField($name, $type);

          if($this->T == self::T_Prop)
            $fld->setTokens($this->_parsePropTokens());

          $flds[] = $fld;
        }
        else
          $this->_error("Type expected");
      }
      else
        $this->_error("Unexpected fields T");
    }

    return $flds;
  }

  private function _parseFuncs()
  {
    $end_token = self::T_End;

    $funcs = array();

    while(true)
    {
      $fn = $this->_parseFunc();
      $funcs[] = $fn;

      if($this->T == $end_token)
      {
        $this->_next();
        break;
      }
      
      $this->_next();
    }

    return $funcs;
  }

  private function _parseDotName()
  {
    $dot_name = '';

    while(true)
    {
      if($this->T != self::T_Identifier)
        $this->_error("Unexpected name T");
      
      $dot_name .= $this->T_value;
      $this->_next();
      if($this->T != ord('.'))
        break;
      $dot_name .= '.';
      $this->_next();
    }

    return $dot_name;
  }

  private function _parseFunc()
  {
    $name = $this->_parseDotName();
    $fn = new mtgMetaFunc($name);

    $this->_checkThenNext(ord('('));
    if($this->T == self::T_Prop)
      $fn->setTokens($this->_parsePropTokens());
    $args = $this->_parseFields(function() 
      { return $this->_nextIf(ord(')')); } 
    );
    $fn->setArgs($args);

    $ret_type = null;
    if($this->T == ord(':'))
    {
      $this->_next();
      if($this->T == self::T_Identifier ||
         $this->T == self::T_Func ||
        self::_isBuiltinType($this->T))
      {
        $ret_type = $this->_parseType(true/*can be multi-type*/);
        $fn->setReturnType($ret_type);
      }
      else
        $this->_error("Unexpected func type");
    }

    return $fn;
  }

  private function _addUnit(mtgMetaInfoUnit $unit)
  {
    $this->current_meta->addUnit($unit);
    $this->module->addUnit($unit);
  }

  private function _parseFreeFunc()
  {
    $this->_next();
    $fn = $this->_parseFunc();
    $fn->setTokens(array_merge($this->shared_tokens, $fn->getTokens()));
    $this->_addUnit(new mtgMetaInfoUnit($this->file, $fn));
  }

  private function _parseStruct()
  {
    $this->_next();
    $struct_origin = new mtgOrigin($this->file, $this->line);
    $name = $this->_parseDotName();

    $parent = null;
    if($this->T == self::T_Extends)
    {
      $this->_next();
      $origin = new mtgOrigin($this->file, $this->line);
      $parent_name = $this->_parseDotName();
      $parent = new mtgTypeRef($parent_name, $this->module, $origin);
    }

    $implements = array();
    if($this->T == self::T_Implements)
    {
      do 
      {
        $this->_next();
        $origin = new mtgOrigin($this->file, $this->line);
        $if_name = $this->_parseDotName();
        $implements[] = new mtgTypeRef($if_name, $this->module, $origin);
      } while($this->T == ord(','));
    }

    $s = new mtgMetaStruct($name, array(), $parent, array(), $implements);
    $s->setOrigin($struct_origin);
    $this->_addUnit(new mtgMetaInfoUnit($this->file, $s));

    $tokens = $this->shared_tokens;
    if($this->T == self::T_Prop)
      $tokens = array_merge($tokens, $this->_parsePropTokens());
    $s->setTokens($tokens);

    $seen_funcs = false;
    $flds = $this->_parseFields(
      function() use(&$seen_funcs) 
      { 
        if($this->_nextIf(self::T_End))
          return true;
        if($this->_nextIf(self::T_Func)) 
        {
          $seen_funcs = true;
          return true;
        }
      }
    );
    foreach($flds as $fld)
      $s->addField($fld);

    if($seen_funcs)
    {
      $funcs = $this->_parseFuncs();
      foreach($funcs as $fn)
        $s->addFunc($fn);
    }
  }

  private function _parseInterface()
  {
    $this->_next();
    $name = $this->_parseDotName();

    $s = new mtgMetaInterface($name);
    $this->_addUnit(new mtgMetaInfoUnit($this->file, $s));

    $tokens = $this->shared_tokens;
    if($this->T == self::T_Prop)
      $tokens = array_merge($tokens, $this->_parsePropTokens());
    $s->setTokens($tokens);

    if($this->T !== self::T_End)
    {
      $this->_next();
      $funcs = $this->_parseFuncs();
      foreach($funcs as $fn)
        $s->addFunc($fn);
    }
    else
      $this->_next();
  }

  private function _parseRPC()
  {
    $this->_next();
    $code = $this->_checkThenNext(self::T_IntegerConstant);
    $name = $this->_parseDotName();
    $this->_checkThenNext(ord('('));

    $tokens = $this->shared_tokens;
    if($this->T == self::T_Prop)
      $tokens = array_merge($tokens, $this->_parsePropTokens());

    $req_fields = $this->_parseFields(function() 
      { return $this->_nextIf(ord(')')); } 
    );
    $rsp_fields = $this->_parseFields(function() 
      { return $this->_nextIf(self::T_End); } 
    );

    $req = new mtgMetaPacket($code, "RPC_REQ_$name");
    $req->setFields($req_fields);
    $rsp = new mtgMetaPacket($code, "RPC_RSP_$name");
    $rsp->setFields($rsp_fields);

    $rpc = new mtgMetaRPC("RPC_$name", $code, $req, $rsp, $tokens);
    $this->_addUnit(new mtgMetaInfoUnit($this->file, $rpc));
  }

  private function _parsePropTokens()
  {
    $new_line = ord("\n");

    $prop_tokens = array();

    while(true)
    {
      if($this->T != self::T_Prop)
        break;

      $name = ltrim($this->T_value, '@');
      $this->_validatePropToken($name);
      $this->_next();

      $value = null;
      $value_start_line = $this->line;
      if($this->T == ord(':'))
      {
        while(true)
        {
          $this->_next(false/*don't skip new line*/);
          if($this->T == $new_line || 
             $this->T == self::T_Prop)
          {
            //let's skip it
            if($this->T == $new_line)
              $this->_next();
            break;
          }
          else
          {
            $tmp = $this->T_value; 
            if($this->T == self::T_StringConstant)
              $tmp = "\"$tmp\"";
            if($value === null)
              $value = '';
            $value .= $tmp;
          }
        }
      }

      if($value && substr($value, 0, 1) === '{')
      {
        $json = json_decode($value);
        if($json === null)
        {
          //for better line reporting
          $this->line = $value_start_line;
          $this->_error("Bad json");
        }
      } 

      $prop_tokens[$name] = $value;
    }
    return $prop_tokens;
  }

  private function _validatePropToken(string $name)
  {
    if(!isset($this->config['valid_tokens']) || 
       !is_array($this->config['valid_tokens']))
      return;

    if(!in_array($name, $this->config['valid_tokens']))
    {
      throw new Exception("Unknown T '$name'");
    }
  }

  private function _char() : string
  {
    $str = substr($this->source, $this->cursor, 1);
    if($str === false)
      $str = '';
    return $str;
  }

  private function _next($skip_newlines = true)
  {
    while(true)
    {
      $c = $this->_char();
      if($c == '')
      {
        $this->cursor--;
        $this->T = self::T_EOF;
        $this->T_value = $c;
        return;
      }

      $this->T = ord($c);
      $this->T_value = $c;

      ++$this->cursor;

      switch($c)
      {
        case ' ': case "\r": case "\t": break;
        case "\n": $this->line++; if($skip_newlines) break; else return;
        case '{': case '}': case '(': case ')': case '[': case ']': case '|': return;
        case ',': case ':': case ';': case '=': return;
        case '.':
          if(!ctype_digit($this->_char())) return;
          $this->_error("Floating point constant can't start with .");
          break;
        case '"':
          $this->T_value = "";
          while($this->_char() != '"') 
          {
            if(ord($this->_char()) < ord(' '))
              $this->_error("Illegal character in string constant");
            if($this->_char() == '\\') 
            {
              $this->cursor++;
              switch($this->_char()) 
              {
                case 'n':  $this->T_value .= "\n"; $this->cursor++; break;
                case 't':  $this->T_value .= "\t"; $this->cursor++; break;
                case 'r':  $this->T_value .= "\r"; $this->cursor++; break;
                case '"': $this->T_value .= '"'; $this->cursor++; break;
                case '\\': $this->T_value .= '\\'; $this->cursor++; break;
                default: $this->_error("Unknown escape code in string constant"); break;
              }
            }
            else // printable chars + UTF-8 bytes
            {
              $this->T_value .= $this->_char();
              $this->cursor++;
            }
          }
          $this->T = self::T_StringConstant;
          $this->cursor++;
          return;

        case '`':
          $this->T_value = "";
          while($this->_char() != '`') 
          {
            $this->T_value .= $this->_char();
            $this->cursor++;
          }
          $this->T = self::T_RawStringConstant;
          $this->cursor++;
          return;

        case '/':
          if($this->_char() == '/') 
          {
            $this->cursor++;
            while($this->_char() != '' && $this->_char() != "\n") $this->cursor++;
            break;
          }

        case '#':
          while($this->_char() != '' && $this->_char() != "\n") $this->cursor++;
          break;

        case '@':
          $start = $this->cursor - 1;
          while(ctype_alnum($this->_char()) || $this->_char() == '_')
            $this->cursor++;
          $this->T = self::T_Prop;
          $this->T_value = substr($this->source, $start, $this->cursor - $start);
          return;

        //fall thru
        default:

          if(ctype_alpha($c))
          {
            //collect all chars of an identifier
            $start = $this->cursor - 1;
            while(ctype_alnum($this->_char()) || $this->_char() == '_')
              $this->cursor++;
            $this->T_value = substr($this->source, $start, $this->cursor - $start);

            if(isset($this->type2T[$this->T_value]))
            {
              $this->T = $this->type2T[$this->T_value];
              return;
            }

            if($this->T_value == "true" || $this->T_value == "false") 
            {
              $this->T = self::T_IntegerConstant;
              return;
            }

            //check for declaration keywords:
            if($this->T_value == "struct")      { $this->T = self::T_Struct;     return; }
            if($this->T_value == "interface")   { $this->T = self::T_Interface;  return; }
            if($this->T_value == "enum")        { $this->T = self::T_Enum;       return; }
            if($this->T_value == "RPC")         { $this->T = self::T_RPC;        return; }
            if($this->T_value == "end")         { $this->T = self::T_End;        return; }
            if($this->T_value == "extends")     { $this->T = self::T_Extends;    return; }
            if($this->T_value == "implements")  { $this->T = self::T_Implements; return; }
            if($this->T_value == "func")        { $this->T = self::T_Func;       return; }

            //if not it's a user defined identifier
            $this->T = self::T_Identifier;
            return;
          }
          else if(ctype_digit($c) || $c == '-')
          {
            $start = $this->cursor - 1;
            while(ctype_digit($this->_char())) $this->cursor++;
            if($this->_char() == '.')
            {
              $this->cursor++;
              while(ctype_digit($this->_char())) $this->cursor++;
              // see if this float has a scientific notation suffix. Both JSON
              // and C++ (through strtod() we use) have the same format:
              if($this->_char() == 'e' || $this->_char() == 'E') 
              {
                $this->cursor++;
                if($this->_char() == '+' || $this->_char() == '-') $this->cursor++;
                while(ctype_digit($this->_char())) $this->cursor++;
              }
              $this->T = self::T_FloatConstant;
            }
            else
              $this->T = self::T_IntegerConstant;
            $this->T_value = substr($this->source, $start, $this->cursor - $start);
            return;
          }

          $this->_error("Illegal character '$c'");
      }
    }
  }

  private function _nextIf(int $t) : bool
  {
    $yes = $t === $this->T;
    if($yes)
      $this->_next();
    return $yes;
  }

  private function _checkThenNext(int $t) : string
  {
    if($t !== $this->T)
    {
      $this->_error("Expecting '" . $this->_toStr($t) . "' instead got '" . $this->_toStr($this->T) . "'");
    }

    $attr = $this->T_value;
    $this->_next();
    return $attr;
  }

  private function _toStr(int $t) : string
  {
    if($t < self::T_NonOrdMark)
      return chr($t);
    return $this->T2descr[$t];
  }

  private function _error(string $msg)
  {
    throw new Exception($msg . " (T: {$this->T}, attr: {$this->T_value})");
  }
}

class mtgMetaParsedModule
{
  public $file;
  public $units = array();
  public $includes = array();

  function __construct($file)
  {
    $this->file = $file;
  }

  function addUnit(mtgMetaInfoUnit $unit)
  {
    $this->units[$unit->object->getMetaId()] = $unit;
  }

  function findUnit($id)
  {
    if(isset($this->units[$id]))
      return $this->units[$id];

    foreach($this->includes as $include)
    {
      if(isset($include->units[$id]))
        return $include->units[$id];
    }

    return null;
  }

  function addInclude(mtgMetaParsedModule $include)
  {
    $this->includes[] = $include;
  }
}

function mtg_parse_meta(array $meta_srcs, $valid_tokens = null, $inc_path = null)
{
  if($inc_path === null)
  {
    //let's autodetect include path
    $inc_path = array();
    foreach($meta_srcs as $src)
    {
      if(is_dir($src))
        $inc_path[] = $src;
      else if(is_file($src))
        $inc_path[] = dirname($src);
    }
  }

  $meta_parser = new mtgMetaInfoParser(
    array(
      'include_path' => $inc_path, 
      'valid_tokens' => $valid_tokens
    )
  );
  $meta = new mtgMetaInfo();
  foreach($meta_srcs as $src)
    mtg_load_meta($meta, $meta_parser, $src);

  $meta->validate();

  mtgTypeRef::checkAllResolved();

  return $meta;
}

function mtg_load_meta(mtgMetaInfo $meta, mtgMetaInfoParser $meta_parser, $dir_or_file)
{
  $files = array();
  if(is_dir($dir_or_file))
    $files = mtg_find_meta_files($dir_or_file);
  else if(is_file($dir_or_file))
    $files[] = $dir_or_file;
  else
    throw new Exception("Bad meta source '$dir_or_file'");

  foreach($files as $file)
    $meta_parser->parse($meta, $file);
}

function mtg_find_meta_files($dir)
{
  $items = scandir($dir);
  if($items === false)
    throw new Exception("Directory '$dir' is invalid");

  $files = array();
  foreach($items as $item)
  {
    if($item[0] == '.')
      continue;

    if(strpos($item, ".meta") !== (strlen($item)-5))
      continue;

    $file = $dir . '/' . $item;
    if(is_file($file) && !is_dir($file))
      $files[] = $file;
  }
  return $files;
}