parsepred.cc

来自「2007年机器人足球世界杯3D仿真组亚军」· CC 代码 · 共 54 行

#include "parser.ih"

rPredicate Parser::parsePred()
{
  rPredicate pred;
  Token tok;

  // LPARENT
  tok = lex();
  if (tok.type != Token::lparent)
    throw parser_error("parser error, expected '('");

  // ID or LPARENT
  tok = lex();
  if (tok.type == Token::lparent)
  {
    // Create list predicate.
    pred = new Predicate(Predicate::type_list);
    lexPushBack(tok);
  } else if (tok.type == Token::id)
    pred = new Predicate(tok.value,Predicate::type_node);
  else
    throw parser_error("parser error, expected '(' or ID");

  // Parse until we lex a RPARENT token.
  while (tok.type != Token::rparent) {
    // RPARENT | PRED | ID
    tok = lex();
    switch (tok.type) {

    case Token::id:
      // add id to predicate.
      pred->push(new Predicate(tok.value,Predicate::type_leave));
      break;

    case Token::lparent:
      // add predicate to predicate.
      lexPushBack(tok);
      pred->push(parsePred());
      break;

    case Token::rparent:
      // done parsing predicate.     
      break;

    default:
      throw parser_error("parser error, expected LPARENT, RPARENT or ID");

    };
  }
 
  return pred;
}