您可以使用单个正则表达式来解析函数参数吗? [英] Can You Use a Single Regular Expression to Parse Function Parameters?
问题描述
问题
有一个程序文件，该文件在某些位置包含以下代码段.
There is a program file that contains the following code snippet at some point in the file.
...
food($apples$ , $oranges$ , $pears$ , $tomato$){
...
}
...
此函数可以包含任意数量的参数，但是它们必须是用逗号分隔的字符串.所有参数字符串都是小写字母.
This function may contain any number of parameters but they must be strings separated by commas. All the parameter strings are lowercase words.
我希望能够使用正则表达式解析出每个参数.例如，python中的结果列表如下:
I want to be able to parse out each of the parameters using a regular expression. For example the resulting list in python would be as follows:
["apples", "oranges", "pears", "tomato"]
尝试的解决方案
使用python RE模块，我可以将问题分为两部分来实现.
Using the python RE module, I was able to achieve this by breaking the problem into two parts.
-
在代码中找到函数并提取参数列表.
Find the function in the code and extract the list of parameters.
plist = re.search(r'food\((.*)\)', programString).group(1)
使用另一个正则表达式拆分列表.
Split the list using another regular expression.
params = re.findall(r'[a-z]+', plist)
问题
无论如何，我可以使用一个正则表达式而不是两个正则表达式来实现这一点吗?
Is there anyway I could achieve this with one regular expression instead of two?
修改
多亏了蒂姆·皮茨克(Tim Pietzcker)的回答，我才找到了一些相关的问题:
Thanks to Tim Pietzcker's answer I was able to find some related questions:
- Python regular expressions - how to capture multiple groups from a wildcard expression?
- Which regex flavors support captures (as opposed to capturing groups)?
推荐答案
回答您的问题可以在单个正则表达式中完成吗?":是的，但是在Python中不是.
To answer your question "Can it be done in a single regex?": Yes, but not in Python.
如果您想仅使用一个正则表达式来匹配并捕获(分别)示例中未知数量的匹配项，则需要
If you want to match and capture (individually) an unknown number of matches as in your example, using only a single regular expression, then you need a regex engine that supports captures (as opposed to capturing groups). Only .NET and Perl 6 do this currently.
因此在Python中，您需要分两步进行操作(find整个food(...)函数调用，然后findall单独匹配，并按Dingo的建议使用第二个正则表达式).
So in Python, you either need to do it in two steps (find the entire food(...) function call, and then findall individual matches with a second regex as suggested by Dingo).
或者使用像Paul McGuire的pyparsing这样的解析器.
Or use a parser like Paul McGuire's pyparsing.
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