我一直在调试一个站点,以查找长页面加载时间的来源,并且将其范围缩小为用于从文本提取URL的正则表达式:
/(?:([\w+.-]+):\/\/|(?:www\.))[^\s<]+/g
在大块文本上运行大约需要3秒钟。我发现,如果我将第一个子句的逆添加到正则表达式(
(?:[^\w+.-]|^)
)的开头,它将几乎立即运行:/(?:[^\w+.-]|^)(?:([\w+.-]++):\/\/|(?:www\.))[^\s<]+/gx
在我看来,添加的子句根本不应该影响正则表达式,因为没有什么可能导致该子句失败(因为这些字符将由“[\w + .-]++”子句匹配)。为什么这会使正则表达式的运行速度如此之快?
编辑
有些人要求我做一个例子。为了简化事情并解决人们在评论中的担忧,我将使用以下两个正则表达式:
# slow one
/(?:([\w+.-]+):\/\/|(?:www\.))[^\s<]+/g
# fast one
/[^\w+.-](?:([\w+.-]+):\/\/|(?:www\.))[^\s<]+/g
启动IRB/Pry,然后在变量中添加一些文本(这是实际搜索内容的精简版本):
text = <<END_OF_TEXT
Unable to deliver message to [email protected]. Error message: request: <soap:Envelope xmlns:soap=";http://schemas.xmlsoap.org/soap/envelope/" xmlns:t=";http://schemas.microsoft.com/exchange/services/year/types" xmlns:m=";http://schemas.microsoft.com/exchange/services/year/messages"><soap:Header><t:RequestServerVersion Version="ExchangeYear"/></soap:Header><soap:Body><m:CreateItem MessageDisposition="SendAndSaveCopy"><m:SavedItemFolderId><t:DistinguishedFolderId Id="stuff"/></m:SavedItemFolderId><m:Items><t:Message><t:MimeContent>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
END_OF_TEXT
在其上使用慢速正则表达式,并注意它的速度:
text.gsub(/(?:([\w+.-]+):\/\/|(?:www\.))[^\s<]+/).to_a
使用快速的正则表达式,并记下它的速度:
text.gsub(/[^\w+.-](?:([\w+.-]+):\/\/|(?:www\.))[^\s<]+/).to_a
我发现这个问题是特定于我在示例中使用的数据类型的(不是很多空格)。如果对更长的RFC 3986运行它,则两个版本的速度都一样快。
最佳答案
第一个模式很慢,因为它以交替开头,而交替的第一个分支则非常允许,因为它允许任意数量的单词,字符,点或连字符。结果,这种交替需要很多时间/步骤才能失败。
第二种模式更快,因为(?:[^\w+.-]|^)
(也是一种替代)就像 anchor 一样工作。的确,即使它是一种替代,它也会被快速测试,因为第一个分支仅匹配一个字符,第二个分支是零宽度的断言。因此,花费更少的时间/步骤来失败。 (特别是因为必须紧跟其后的是一个字字符,一个点或一个hypĥen,这是一个绑定(bind)条件)
但是您可以以更好的方式编写此模式。由于您正在寻找url,因此可以更精确地开始:url可以以“http”,“ftp”,“sftp”,“gopher”,“www”开头(随意添加其他方案(如果需要)。
因此,您可以从以下描述开始:
(?:https?:\/\/|ftp:\/\/|sftp:\/\/|gopher:\/\/|www\.)
为了限制交替的代价(在字符串的每个位置上测试5个分支),您可以使用以下两个技巧:
\b(?:https?:\/\/|ftp:\/\/|sftp:\/\/|gopher:\/\/|www\.)
\b(?=[fghsw])(?:https?:\/\/|ftp:\/\/|sftp:\/\/|gopher:\/\/|www\.)
因此,您可以编写这样的更有效的模式:
/\b(?=[fghsw])(?:https?:\/\/|ftp:\/\/|sftp:\/\/|gopher:\/\/|www\.)[^\s<]+/
简而言之:模式在字符串中的错误位置快速失败时是有效的。
另一种可能的设计,它使用更多的内存,并且需要检查每个匹配项是否都存在捕获组,但这更快。
/[^ghsfw]*+(?:\B[ghsfw][^ghsfw]*)*+|\b((?:https?:\/\/|ftp:\/\/|sftp:\/\/|gopher:\/\/|www\.)[^\s<"&]+)/
(这个想法是将模式分为两个主要分支,第一个描述了您要避免的所有内容,第二个描述了网址。其作用是快速跳转到字符串中的关键位置)
注意:当模式开始变长时,可以使用自由行距模式(或注释模式...)以提高可读性和可维护性:
/(?x)
\b (?=[fghsw])
(?:
https?:\/\/ |
ftp:\/\/ |
sftp:\/\/ |
gopher:\/\/ |
www\.
)
[^\s<]+/
或者您可以使用格式化的字符串和Cary Swoveland在注释中建议的联接。
关于ruby - 缓慢的Ruby Regex通过奇怪的变化变得快速,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/29929866/