Question

我试图找到一种方法让我从字符串（取自数据库）动态创建一个regexp对象，然后使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存在于数据库中。

会发生什么

>> string = "[ALERT] Project: Revision ...123456 committed by Me <me@me.com>\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

我想要发生什么

>> string = "[ALERT] Project: Revision ...123456 committed by Me <me@me.com>\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"

Answer 1

你只缺少一件事：

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

反斜杠是字符串中的转义字符。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 <me@me.com>\n on 2009-   07-28 21:21:47\n\n    Fixed typo\n"
=> "[ALERT] Project: Revision ...123456 committed by Me <me@me.com>\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，如果您粘贴了“破损”行的输出，而不仅仅是输入，那么您可能已经发现w和s未正确转义< / p>

Answer 2

选项1：

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

缺点：手动转义所有已知转义字符

选项2：

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

缺点：无

Ruby中的动态正则表达式

2 个答案: