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Ruby中的动态正则表达式

regex ruby

7

davidsmalley · 技术社区 · 17 年前

我试图找到一种方法,让我从一个字符串(取自数据库)动态创建一个regexp对象,然后用它过滤另一个字符串。本例是从git提交消息中提取数据,但理论上,任何有效的regexp都可以作为字符串存在于数据库中。

发生了什么

>> 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

>> 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"

2 回复 | 直到 17 年前

1

11

Gareth 17 年前

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

反斜杠是字符串中的转义字符。如果你想要一个反斜杠,你必须加倍它。

>> 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,如果您粘贴了“断开”行的输出,而不仅仅是输入,您可能已经发现 w 和 s

2

0

Swanand 17 年前

备选案文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

备选案文2:

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

缺点:没有