/**
   * 解析标识符
   *
   * @param token
   * @return 对应符号表项
   * @throws Exception
   */
  private SymTabEntry parseIdentifier(Token token) throws Exception {
    SymTabEntry id = null;

    if (token.getType() == IDENTIFIER) {
      String name = token.getText().toLowerCase();
      id = symTabStack.lookupLocal(name);

      // 申明必须得没有,否则重定义了
      if (id == null) {
        id = symTabStack.enterLocal(name);
        id.setDefinition(definition);
        id.appendLineNumber(token.getLineNumber());
      } else {
        errorHandler.flag(token, IDENTIFIER_REDEFINED, this);
      }

      token = nextToken();
    } else {
      errorHandler.flag(token, MISSING_IDENTIFIER, this);
    }

    return id;
  }
  /**
   * Parse a Triangle SingleDeclarationParser.
   *
   * <p>Single-Declaration ::= const Identifier ~ Expression | var Identifier : Type-Denoter | proc
   * Identifier (Formal-Parameter-Sequence) ~ Single-Command | func Identifier
   * (Formal-Parameter-Sequence) : Type-Denoter ~ Expression | Type Identifier ~ Type-Denoter
   *
   * <p>To be overridden by the specialized command parse subclasses.
   *
   * @param token the initial token.
   * @return the root node of the generated parse tree.
   * @throws Exception if an error occurred.
   */
  public void parse(Token token) throws Exception {
    SingleCommandParser singleCommand = null;
    ExpressionParser expression = null;
    FormalParameterSequenceParser formalParameterSequence = null;
    TypeDenoterParser typeDenoter = null;
    EnumSet<TriangleTokenType> syncSet = null;
    TypeSpec identifierType = TrianglePredefined.undefinedType;
    Token identifierToken = null;
    ICode routineICode = null;

    token = currentToken();

    switch ((TriangleTokenType) token.getType()) {
      case CONST:
        identifierToken = nextToken();
        syncSet = EnumSet.of(TILDE);
        syncSet.addAll(ExpressionParser.FIRST_FOLLOW_SET);
        synchronize(IDENTIFIER, MISSING_IDENTIFIER, syncSet);
        syncSet.remove(TILDE);
        token = synchronize(TILDE, MISSING_TILDE, syncSet);
        expression = new ExpressionParser(this);
        ICodeNode expressionNode = expression.parse(token);

        SymTabEntry constantId = symTabStack.lookupLocal(identifierToken.getText().toLowerCase());
        // Enter the new identifier into the symbol table
        // but don't set how it's defined yet.
        if (constantId == null) {
          constantId = symTabStack.enterLocal(identifierToken.getText().toLowerCase());
          constantId.setDefinition(DefinitionImpl.CONSTANT);
          constantId.setAttribute(CONSTANT_VALUE, expressionNode);
          constantId.appendLineNumber(identifierToken.getLineNumber());
          constantId.setTypeSpec(expressionNode.getTypeSpec());
        } else {
          errorHandler.flag(identifierToken, IDENTIFIER_REDEFINED, this);
        }
        break;
      case VAR:
        identifierToken = nextToken();
        syncSet = EnumSet.of(COLON);
        syncSet.addAll(TypeDenoterParser.FIRST_FOLLOW_SET);
        synchronize(IDENTIFIER, MISSING_IDENTIFIER, syncSet);

        syncSet.remove(COLON);
        token = synchronize(COLON, MISSING_COLON, syncSet);

        typeDenoter = new TypeDenoterParser(this);
        identifierType = typeDenoter.parse(token);

        SymTabEntry variableId = symTabStack.lookupLocal(identifierToken.getText().toLowerCase());
        // Enter the new identifier into the symbol table
        // but don't set how it's defined yet.
        if (variableId == null) {
          variableId = symTabStack.enterLocal(identifierToken.getText().toLowerCase());
          variableId.setDefinition(DefinitionImpl.VARIABLE);
          variableId.appendLineNumber(identifierToken.getLineNumber());
          variableId.setTypeSpec(identifierType);
        } else {
          errorHandler.flag(identifierToken, IDENTIFIER_REDEFINED, this);
        }
        break;
      case PROC:
        identifierToken = nextToken();
        routineICode = ICodeFactory.createICode();
        syncSet = EnumSet.of(LEFT_PAREN);
        syncSet.addAll(FormalParameterSequenceParser.FIRST_FOLLOW_SET);
        token = synchronize(IDENTIFIER, MISSING_IDENTIFIER, syncSet);
        syncSet.remove(LEFT_PAREN);
        token = synchronize(LEFT_PAREN, MISSING_LEFT_PAREN, syncSet);
        SymTabEntry procId = symTabStack.lookupLocal(identifierToken.getText().toLowerCase());
        // Enter the new identifier into the symbol table
        // but don't set how it's defined yet.
        if (procId == null) {
          procId = symTabStack.enterLocal(identifierToken.getText().toLowerCase());
          procId.setTypeSpec(TrianglePredefined.undefinedType);
          procId.setDefinition(DefinitionImpl.PROCEDURE);
          procId.appendLineNumber(identifierToken.getLineNumber());
          procId.setAttribute(ROUTINE_SYMTAB, symTabStack.push());
          procId.setAttribute(ROUTINE_ICODE, routineICode);
        } else {
          errorHandler.flag(identifierToken, IDENTIFIER_REDEFINED, this);
          procId = null;
        }

        formalParameterSequence = new FormalParameterSequenceParser(this);
        ArrayList<SymTabEntry> procParamList = formalParameterSequence.parse(token);
        syncSet = EnumSet.of(TILDE);
        syncSet.addAll(SingleCommandParser.FIRST_FOLLOW_SET);
        token = synchronize(RIGHT_PAREN, MISSING_RIGHT_PAREN, syncSet);
        syncSet.remove(TILDE);
        token = synchronize(TILDE, MISSING_TILDE, syncSet);
        singleCommand = new SingleCommandParser(this);
        routineICode.setRoot(singleCommand.parse(token));
        if (procId != null) {
          procId.setAttribute(ROUTINE_PARMS, procParamList);
        }
        symTabStack.pop();
        break;
      case FUNC:
        identifierToken = nextToken();
        routineICode = ICodeFactory.createICode();
        SymTabEntry funcId = symTabStack.lookupLocal(identifierToken.getText().toLowerCase());
        // Enter the new identifier into the symbol table
        // but don't set how it's defined yet.
        if (funcId == null) {
          funcId = symTabStack.enterLocal(identifierToken.getText().toLowerCase());
          funcId.setDefinition(DefinitionImpl.FUNCTION);
          funcId.appendLineNumber(identifierToken.getLineNumber());
          funcId.setTypeSpec(TrianglePredefined.undefinedType);
          funcId.setAttribute(ROUTINE_SYMTAB, symTabStack.push());
          funcId.setAttribute(ROUTINE_ICODE, routineICode);
        } else {
          errorHandler.flag(identifierToken, IDENTIFIER_REDEFINED, this);
          funcId = null;
        }
        syncSet = EnumSet.of(LEFT_PAREN);
        syncSet.addAll(FormalParameterSequenceParser.FIRST_FOLLOW_SET);
        token = synchronize(IDENTIFIER, MISSING_IDENTIFIER, syncSet);
        syncSet.remove(LEFT_PAREN);
        token = synchronize(LEFT_PAREN, MISSING_LEFT_PAREN, syncSet);
        formalParameterSequence = new FormalParameterSequenceParser(this);
        ArrayList<SymTabEntry> funcParamList = formalParameterSequence.parse(token);
        syncSet = EnumSet.of(COLON);
        syncSet.addAll(TypeDenoterParser.FIRST_FOLLOW_SET);
        synchronize(RIGHT_PAREN, MISSING_RIGHT_PAREN, syncSet);
        syncSet.remove(COLON);
        token = synchronize(COLON, MISSING_COLON, syncSet);
        Token typeToken = currentToken();
        typeDenoter = new TypeDenoterParser(this);
        TypeSpec funcType = typeDenoter.parse(token);
        syncSet = ExpressionParser.FIRST_FOLLOW_SET.clone();
        token = synchronize(TILDE, MISSING_TILDE, syncSet);
        expression = new ExpressionParser(this);
        routineICode.setRoot(expression.parse(token));
        if (funcId != null) {
          funcId.setTypeSpec(funcType);
          funcId.setAttribute(ROUTINE_PARMS, funcParamList);
          if (!routineICode.getRoot().getTypeSpec().equals(funcType)) {
            errorHandler.flag(typeToken, RETURN_TYPE_MISMATCH, this);
          }
        }
        symTabStack.pop();
        break;
      case TYPE:
        identifierToken = nextToken();
        syncSet = EnumSet.of(TILDE);
        syncSet.addAll(TypeDenoterParser.FIRST_FOLLOW_SET);
        synchronize(IDENTIFIER, MISSING_IDENTIFIER, syncSet);
        syncSet.remove(TILDE);
        token = synchronize(TILDE, MISSING_TILDE, syncSet);
        typeDenoter = new TypeDenoterParser(this);
        TypeSpec typeType = typeDenoter.parse(token);
        SymTabEntry typeId = symTabStack.lookupLocal(identifierToken.getText().toLowerCase());
        // Enter the new identifier into the symbol table
        // but don't set how it's defined yet.
        if (typeId == null) {
          typeId = symTabStack.enterLocal(identifierToken.getText().toLowerCase());
          typeId.setDefinition(DefinitionImpl.TYPE);
          typeId.appendLineNumber(identifierToken.getLineNumber());
          typeId.setTypeSpec(typeType);
        } else {
          errorHandler.flag(token, IDENTIFIER_REDEFINED, this);
        }
        break;
      default:
        errorHandler.flag(token, MISSING_DECLARATION, this);
        break;
    }
  }
Example #3
0
  /**
   * Parse type definitions.
   *
   * @param token the initial token.
   * @throws Exception if an error occurred.
   */
  public void parse(Token token) throws Exception {
    token = synchronize(IDENTIFIER_SET);

    // Loop to parse a sequence of type definitions
    // separated by semicolons.
    while (token.getType() == IDENTIFIER) {
      String name = token.getText().toLowerCase();
      SymTabEntry typeId = symTabStack.lookupLocal(name);

      // Enter the new identifier into the symbol table
      // but don't set how it's defined yet.
      if (typeId == null) {
        typeId = symTabStack.enterLocal(name);
        typeId.appendLineNumber(token.getLineNumber());
      } else {
        errorHandler.flag(token, IDENTIFIER_REDEFINED, this);
        typeId = null;
      }

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

      // Synchronize on the = token.
      token = synchronize(EQUALS_SET);
      if (token.getType() == EQUALS) {
        token = nextToken(); // consume the =
      } else {
        errorHandler.flag(token, MISSING_EQUALS, this);
      }

      // Parse the type specification.
      TypeSpecificationParser typeSpecificationParser = new TypeSpecificationParser(this);
      TypeSpec type = typeSpecificationParser.parse(token);

      // Set identifier to be a type and set its type specificationt.
      if (typeId != null) {
        typeId.setDefinition(TYPE);
      }

      // Cross-link the type identifier and the type specification.
      if (type != null && typeId != null) {
        if (type.getIdentifier() == null) {
          type.setIdentifier(typeId);
        }
        typeId.setTypeSpec(type);
      } else {
        token = synchronize(FOLLOW_SET);
      }

      token = currentToken();
      TokenType tokenType = token.getType();

      // Look for one or more semicolons after a definition.
      if (tokenType == SEMICOLON) {
        while (token.getType() == SEMICOLON) {
          token = nextToken(); // consume the ;
        }
      }

      // If at the start of the next definition or declaration,
      // then missing a semicolon.
      else if (NEXT_START_SET.contains(tokenType)) {
        errorHandler.flag(token, MISSING_SEMICOLON, this);
      }

      token = synchronize(IDENTIFIER_SET);
    }
  }