Example #1
0
        private ProgramObject parseLowerOrderExpression()
        {
            ProgramObject expression;
            ProgramObject tmp;

            expression = parseHigherOrderExpression();
            while (currentToken.tokenType != TokenType.Then &&
                   currentToken.tokenType != TokenType.Eol &&
                   currentToken.tokenType != TokenType.Eof)
            {
                switch (currentToken.tokenType)
                {
                case TokenType.And:
                    tmp          = expression;
                    currentToken = lexer.nextToken();
                    expression   = new LeftAnd(tmp, parseHigherOrderExpression());
                    break;

                case TokenType.Or:
                    tmp          = expression;
                    currentToken = lexer.nextToken();
                    expression   = new LeftOr(tmp, parseHigherOrderExpression());
                    break;

                case TokenType.Xor:
                    tmp          = expression;
                    currentToken = lexer.nextToken();
                    expression   = new LeftXor(tmp, parseHigherOrderExpression());
                    break;

                case TokenType.OParenthesis:
                    currentToken = lexer.nextToken();
                    expression   = parseParenthesis();
                    break;

                case TokenType.CParenthesis:
                    return(expression);

                default:
                    throw new UnexpectedTokenException(currentToken.value);
                }
            }
            return(expression);
        }
Example #2
0
        private ProgramObject parseHigherOrderExpression()
        {
            ProgramObject expression = null;
            ProgramObject s;

            if (currentToken.tokenType == TokenType.Not || currentToken.tokenType == TokenType.Symbol)
            {
                s = parseSymbol();
                switch (currentToken.tokenType)
                {
                case TokenType.And:
                    currentToken = lexer.nextToken();
                    expression   = new LeftAnd(s, parseHigherOrderExpression());
                    break;

                case TokenType.Or:
                case TokenType.Xor:
                case TokenType.Then:
                case TokenType.OParenthesis:
                case TokenType.CParenthesis:
                case TokenType.Eol:
                case TokenType.Eof:
                    expression = s;
                    break;
                }
            }
            else if (currentToken.tokenType == TokenType.OParenthesis)
            {
                currentToken = lexer.nextToken();
                expression   = parseParenthesis();
            }
            else
            {
                throw new UnexpectedTokenException(currentToken.value);
            }
            return(expression);
        }