问C#中的MDX解析器
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Stack Overflow用户

提问于 2011-10-10 06:05:04

回答 2查看 2.3K关注 0票数 2

我需要用我的.Net应用程序解析一个MDX。最初，我使用正则表达式来做这件事，但是表达式变得越来越复杂，一位正则表达式专家建议我使用解析器会更好。

有没有专门针对MDX的解析器？我尝试了Ranet，但由于某些未知的原因，它没有安装在我的机器上(没有显示任何错误消息)。

我需要将MDX的几个部分拆分为字符串。例如，一个字符串中的where子句，另一个字符串中的from子句等。

parsing

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回答 2

Stack Overflow用户

回答已采纳

发布于 2011-10-16 03:14:20

最好的解决方案是找到一个解析器，但总是很难找到满足您特定需求的解析器。因此，如果您最终要编写解析器Ve parser是一个比正则表达式更好的工具，因为它提供了更多的解析功能，您可以生成更好的输出，而且由于您调用的是.net方法，因此它隐含地具有编写解析器的智能。缺点是它仍然没有很好的文档记录，因此您可能会发现在某些特殊情况下很难实现。

项目链接：http://veparser.codeplex.com

NuGet标识符: veparser

如果您需要获取MDX不同部分的文本，以下是部分示例代码：

using VeParser;
using System.Linq;
using System.Collections.Generic;
using System;


public class MDXParser : TokenParser
{
    protected override Parser GetRootParser()
    {
        // read the following line as : fill 'select' property of 'current object(which is a statement)' with the 'new value of selectStatement' after facing a sequence of a select statement and then the symbol of ( and then a delemitied list of identierfiers filling the 'fileds' property of 'current selectStatement object' delemitied by ',' and finally expect the sequence to be finished with a symbol of ')'
        var selectStatement = fill("select", create<selectStatment>( seq(expectKeyword_of("select"), expectSymbol_of("("), deleimitedList(expectSymbol_of(","), fill("fields",identifier) ), expectSymbol_of(")"))));
        // read the following line as : fill the from property of 'current object(which is a statement)' with an expected identifier that is after a 'from' keyword
        var fromStatement = seq(expectKeyword_of("from"), fill("from", identifier));
        // the following statement is incomplete, as I just wanted to show a sample bit, If you are interested I can help you complete the parser until the full documentation become available.
        var whereStatement = fill("where", create<whereStatement>(seq(expectKeyword_of("where"))));
        var statement = create<statement>(seq(selectStatement, fromStatement, whereStatement));

        return statement;
    }

    public statement Parse(string code)
    {
        var keywords = new[] { "select", "where", "from" };
        var symbols = new[] { "(",")", ".", "[", "]" };
        var tokenList = Lexer.Parser(code, keywords, symbols, ignoreWhireSpaces : true);
        // Now we have our string input converted into a list of tokens which actually is a list of words but with some additional information about any word, for example a "select" is marked as keyword
        var parseResult = base.Parse(tokenList.tokens);
        if (parseResult == null)
            throw new Exception("Invalid Code, at the moment Ve Parser does not support any error reporting feature.");
        else
            return (statement)parseResult;
    }
}
public class statement
{
    public selectStatment select;
    public string where;
    public identifier from;
}
public class selectStatment
{
    public List<identifier> fields;
}
public class whereStatement
{

}