示例#1
0
文件: Parser.cs 项目: bnantz/NCS-V1-1
        private BooleanExpression ParseSimpleExpression()
        {
            BooleanExpression expression = null;

            switch (this.token)
            {
                case TokenType.LeftParenthesis:
                    this.MoveNext();
                    BooleanExpression c = this.ParseOrOperator();
                    this.AssertTokenType(TokenType.RightParenthesis);
                    expression = c;
                    break;
                case TokenType.Identity:
                    this.MoveNext();
                    expression = new IdentityExpression(this.ParseWordExpression());
                    break;
                case TokenType.Role:
                    this.MoveNext();
                    expression = new RoleExpression(this.ParseWordExpression());
                    break;
                case TokenType.Not:
                    this.MoveNext();
                    expression = new NotOperator(this.ParseOrOperator());
                    break;
                default:
                    TokenType[] types = new TokenType[]
                        {
                            TokenType.LeftParenthesis,
                            TokenType.Identity,
                            TokenType.Role,
                            TokenType.Not
                        };

                    throw new SyntaxException(
                        SR.UnexpectedTokenMessage(
                            ConcatTokenNames(types),
                            this.lexer.Current,
                            this.GetIndex()),
                        this.GetIndex());
            }

            return expression;
        }