Ruby中的动态正则表达式

我想找到一种方法让我从一个字符串（从数据库中取出）动态创建一个正则表达式对象，然后用它来过滤另一个字符串。这个例子是从git提交消息中提取数据，但理论上任何有效的正则表达式都可以作为字符串出现在数据库中。Ruby中的动态正则表达式

会发生什么

>> string = "[ALERT] Project: Revision ...123456 committed by Me <[email protected]>\n on 2009- 07-28 21:21:47\n\n Fixed typo\n" 
>> r = Regexp.new("[A-Za-z]+: Revision ...[\w]+ committed by [A-Za-z\s]+") 
>> string[r] 
=> nil

我希望发生

>> string = "[ALERT] Project: Revision ...123456 committed by Me <[email protected]>\n on 2009- 07-28 21:21:47\n\n Fixed typo\n" 
>> string[/[A-Za-z]+: Revision ...[\w]+ committed by [A-Za-z\s]+/] 
=> "Project: Revision 123456 committed by Me"

来源

2009-08-01 davidsmalley

你唯一缺少的一件事是什么：

>> Regexp.new "\w" 
=> /w/ 
>> Regexp.new "\\w" 
=> /\w/

反斜杠在字符串转义字符。如果你想要一个文字反斜杠，你必须加倍。

>> string = "[ALERT] Project: Revision ...123456 committed by Me <[email protected]>\n on 2009- 07-28 21:21:47\n\n Fixed typo\n" 
=> "[ALERT] Project: Revision ...123456 committed by Me <[email protected]>\n on 2009- 07-28 21:21:47\n\n Fixed typo\n" 
>> r = Regexp.new("[A-Za-z]+: Revision ...[\\w]+ committed by [A-Za-z\\s]+") 
=> /[A-Za-z]+: Revision ...[\w]+ committed by [A-Za-z\s]+/ 
>> string[r] 
=> "Project: Revision ...123456 committed by Me "

通常情况下，如果你愿意粘贴从“破”行，而不仅仅是输入输出，你可能看准了w和s不正确转义

来源

2009-08-01 08:07:27 Gareth

完美，感谢 - 我知道我必须做一些微妙的错误。 – davidsmalley 2009-08-01 08:13:57

选项1：

# Escape the slashes: 
r = Regexp.new("[A-Za-z]+: Revision ...[\\w]+ committed by [A-Za-z\\s]+")

缺点：手动逸出所有已知的转义字符

选项2：

# Use slashes in constructor 
r = Regexp.new(/[A-Za-z]+: Revision ...[\w]+ committed by [A-Za-z\s]+/)

缺点：无

来源

2009-08-01 08:08:14 Swanand

对于选项2 - 构造函数的参数总是字符串，因为正在从数据库中提取正则表达式，所以在这种情况下不起作用。 – davidsmalley 2009-08-01 08:16:58

Ruby中的动态正则表达式

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