コード例 #1
0
  /**
   * Parse a set.
   *
   * @param token the initial token.
   * @return the root of the generated parse subtree.
   * @throws Exception if an error occurred.
   */
  private ICodeNode parseSet(Token token) throws Exception {
    ICodeNode rootNode = ICodeFactory.createICodeNode(SETS);
    int tempInteger = 0;
    token = nextToken(); // consume left bracket

    while (token.getType() != RIGHT_BRACKET) {

      if (token.getType() == INTEGER) {
        tempInteger = (int) token.getValue();
        rootNode.addChild(parseTerm(token));
        token = currentToken();
      } else if (token.getType() == IDENTIFIER) {
        ICodeNode var = parseFactor(token);
        rootNode.addChild(var);
        token = currentToken();
      }
      if (token.getType() == COMMA) {
        token = nextToken(); // consume next token
        if (token.getType() == COMMA) {
          errorHandler.flag(token, EXTRA_COMMA, this);
        }
      } else if (token.getType() == RIGHT_BRACKET) { // do nothing
      } else if (token.getType() == SEMICOLON) {
        errorHandler.flag(token, MISSING_CLOSE_SQUARE_BRACKET, this);
        break;
      } else if (token.getType() == DOT_DOT) {
        token = nextToken(); // consume the integer.
        // Create a STRING_CONSTANT node as the root node.
        ICodeNode node = ICodeFactory.createICodeNode(SUBRANGE);
        // denotes the maximum value of the range.
        if (token.getType() != INTEGER) {
          errorHandler.flag(token, MISSING_MAX_VAL_SUBRANGE, this);
        } else {
          int value = (int) token.getValue();
          node.setAttribute(VALUE, value);
        }
        rootNode.addChild(node);
        token = nextToken();

      } else {
        errorHandler.flag(token, MISSING_COMMA, this);
      }
    }
    if (token.getType() != SEMICOLON) {
      token = nextToken(); // consume right bracket
    }
    return rootNode;
  }
コード例 #2
0
  /**
   * Parse a factor.
   *
   * @param token the initial token.
   * @return the root of the generated parse subtree.
   * @throws Exception if an error occurred.
   */
  private ICodeNode parseFactor(Token token) throws Exception {
    TokenType tokenType = token.getType();
    ICodeNode rootNode = null;

    switch ((PascalTokenType) tokenType) {
      case IDENTIFIER:
        {
          // Look up the identifier in the symbol table stack.
          // Flag the identifier as undefined if it's not found.
          String name = token.getText().toLowerCase();
          SymTabEntry id = symTabStack.lookup(name);
          if (id == null) {
            errorHandler.flag(token, IDENTIFIER_UNDEFINED, this);
            id = symTabStack.enterLocal(name);
          }

          rootNode = ICodeFactory.createICodeNode(VARIABLE);
          rootNode.setAttribute(ID, id);
          id.appendLineNumber(token.getLineNumber());

          token = nextToken(); // consume the identifier
          break;
        }

      case INTEGER:
        {
          // Create an INTEGER_CONSTANT node as the root node.
          rootNode = ICodeFactory.createICodeNode(INTEGER_CONSTANT);
          rootNode.setAttribute(VALUE, token.getValue());

          token = nextToken(); // consume the number
          break;
        }

      case REAL:
        {
          // Create an REAL_CONSTANT node as the root node.
          rootNode = ICodeFactory.createICodeNode(REAL_CONSTANT);
          rootNode.setAttribute(VALUE, token.getValue());

          token = nextToken(); // consume the number
          break;
        }

      case STRING:
        {
          String value = (String) token.getValue();

          // Create a STRING_CONSTANT node as the root node.
          rootNode = ICodeFactory.createICodeNode(STRING_CONSTANT);
          rootNode.setAttribute(VALUE, value);

          token = nextToken(); // consume the string
          break;
        }

      case NOT:
        {
          token = nextToken(); // consume the NOT

          // Create a NOT node as the root node.
          rootNode = ICodeFactory.createICodeNode(ICodeNodeTypeImpl.NOT);

          // Parse the factor.  The NOT node adopts the
          // factor node as its child.
          rootNode.addChild(parseFactor(token));

          break;
        }

      case LEFT_PAREN:
        {
          token = nextToken(); // consume the (

          // Parse an expression and make its node the root node.
          rootNode = parseExpression(token);

          // Look for the matching ) token.
          token = currentToken();
          if (token.getType() == RIGHT_PAREN) {
            token = nextToken(); // consume the )
          } else {
            errorHandler.flag(token, MISSING_RIGHT_PAREN, this);
          }

          break;
        }
      case LEFT_BRACKET:
        {
          rootNode = parseSet(token);

          break;
        }

      default:
        {
          errorHandler.flag(token, UNEXPECTED_TOKEN, this);
          break;
        }
    }

    return rootNode;
  }