常规的前pression环视 [英] regular expression lookaround

问题描述

我不认为这是可能的只是普通的EX pressions，但我不是专家，所以我认为这是值得一问。

我试图做一个大规模的搜索和替换的C＃code，使用.NET正则表达式。我想要做的就是找​​到一行code其中一个特定函数被调用的一个变量，它是DateTime类型。例如：

  axRecord.set_Field（CreatedDate，m_createdDate）;
 

和我想知道这是一个DateTime变量B / C早些时候在code文件将是该行：

 日期时间m_createdDate;
 

但似乎我不能使用一个名为group负后向这样的：

 （小于？=日期时间\ K＆LT; 1＆GT;？+）axRecord.set _ [^] +（LT; 1＆GT; [^）] +）
 

如果我尝试匹配的变量声明和这样的函数调用之间的所有文本：

 日期时间（小于？1＆GT; [^;] +）+ axRecord.set + \ K＆LT;。？。？1＆GT;
 

它会找到第一场比赛 - 第一款基于第一个变量声明 - 但它无法找到任何其他比赛中，因为code的布局是这样的：

 日期时间m_First;
日期时间m_Second;
...
axRecord.set_Field（东西，m_First）;
axRecord.set_Field（somethingElse，m_Second）;
 

和第一场比赛包括第二个变量声明。

有没有一种好方法，只需定期EX pressions做到这一点，还是我不得不求助于脚本在我的逻辑？

解决方案

试试这个：

<$p$p><$c$c>@"(?s)set_Field\(""[^""]*"",\s*(?<vname>\w+)(?<=\bDateTime\s+\k<vname>\b.+)"

通过先进行回顾后，你迫使正则表达式来搜索特定顺序的方法调用：在该变量声明的顺序。你想要做的是首先匹配一个可能的前瞻性的方法调用，然后使用后向验证变量的类型。

我只是做了一个粗略的猜测相匹配的方法调用的部分。像其他人所说，不管你用的是将不得不进行调整以适应您的code正则表达式;有没有通用的解决方案。

I don't think this is possible with just regular expressions, but I'm not an expert so i thought it was worth asking.

I'm trying to do a massive search and replace of C# code, using .NET regex. What I want to do is find a line of code where a specific function is called on a variable that is of type DateTime. e.g:

axRecord.set_Field("CreatedDate", m_createdDate);

and I would know that it's a DateTime variable b/c earlier in that code file would be the line:

DateTime m_createdDate;

but it seems that I can't use a named group in negative lookbehind like:

(?<=DateTime \k<1>.+?)axRecord.set_[^ ]+ (?<1>[^ )]+)

and if I try to match the all the text between the variable declaration and the function call like this:

DateTime (?<1>[^;]+).+?axRecord.set.+?\k<1>

it will find the first match - first based on first variable declared - but then it can't find any other matches, because the code is laid out like this:

DateTime m_First;
DateTime m_Second;
...
axRecord.set_Field("something", m_First);
axRecord.set_Field("somethingElse", m_Second);

and the first match encompasses the second variable declaration.

Is there a good way to do this with just regular expressions, or do I have to resort to scripting in my logic?

解决方案

Try this:

@"(?s)set_Field\(""[^""]*"",\s*(?<vname>\w+)(?<=\bDateTime\s+\k<vname>\b.+)"

By doing the lookbehind first, you're forcing the regex to search for the method calls in a particular order: the order in which the variables are declared. What you want to do is match a likely-looking method call first, then use the lookbehind to verify the type of the variable.

I just made a rough guess at the part that matches the method call. Like the others have said, whatever regex you use is going to have to be tailored to your code; there's no general solution.

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