I want a Perl regular expression to match std::foo but not match std::foo::bar. This is what I have so far:
我想要一个Perl正则表达式匹配std :: foo但不匹配std :: foo :: bar。这是我到目前为止:
/((?<!\w)([A-Za-z0-9_]+)::([A-Za-z0-9_]+))(?!:)/
This matches std::foo::bar as far as std::fo, but I want the whole match to fail for this input, not give a partial match.
这与std :: fo匹配std :: foo :: bar,但是我希望整个匹配对于此输入失败,而不是给出部分匹配。
What regex to I actually want?
我真正想要什么正则表达式?
4 个解决方案
#1
4
This solution uses a possessive quantifer on the foo part of the pattern \w++. That means it will refuse to backtrack after finding a series of "word" characters, even if the rest of the pattern -- the negative look-ahead -- then fails. I've also had to change the negative look-behind to reject word characters or colons : to prevent things like baz::std::foo from matching
该解决方案在模式\ w ++的foo部分使用所有格量化器。这意味着它会在找到一系列“单词”字符后拒绝回溯,即使模式的其余部分 - 负面预测 - 然后失败。我还必须改变负面的后视来拒绝单词字符或冒号:以防止像baz :: std :: foo这样的东西匹配
It is mostly a tidy-up of the answer from Sebastian Proske. It uses \w instead of the literal character class, adds layout using the /x modifier, and removes unnecessary parentheses. It also provides a working example
塞巴斯蒂安·普罗克斯的回答大多是一个整理。它使用\ w而不是文字字符类,使用/ x修饰符添加布局,并删除不必要的括号。它还提供了一个工作示例
use strict;
use warnings 'all';
use feature 'say';
my $s = 'match std::foo but not match std::foo::bar.';
say $1 while $s =~ / (?<![\w:]) ( \w+::\w++) (?!:) /gx;
output
std::foo
#2
1
Other than \b you could also:
除了\ b你还可以:
- use possessive matching to avoid backtracking into
foo:((?<!\w)([A-Za-z0-9_]+)::([A-Za-z0-9_]++))(?!:) - add the word character class to the lookahead, so it can't backtrack into
foo:((?<!\w)([A-Za-z0-9_]+)::([A-Za-z0-9_]+))(?![:\w])
使用所有格匹配来避免回溯到foo:((?
在前瞻中添加单词character class,因此无法回溯到foo :((?
#3
1
Just add \b before the negative lookahead which ensures that there is an word boundary exisst and also don't forget to add : in the first negative lookahead. Otherwise it would match the second part.
只需在负前瞻之前添加\ b,以确保存在一个单词边界,并且不要忘记在第一个负向前瞻中添加:否则它将匹配第二部分。
((?<![:\w])([A-Za-z0-9_]+)::([A-Za-z0-9_]+))\b(?!:)
OR
This would match the import string only if it's not preceded by a non-space character.
仅当导入字符串前面没有非空格字符时,才匹配导入字符串。
(?<!\S)([A-Za-z0-9_]+)::([A-Za-z0-9_]+)\b(?!:)
#4
-1
To match this whole string std::foo::bar instead of partial values We can use this regex
要匹配整个字符串std :: foo :: bar而不是部分值我们可以使用此正则表达式
((\b(.+)\b)+?[::]{2}.+)
It will give you two matches
它会给你两场比赛
std::foostd::foo::bar
#1
4
This solution uses a possessive quantifer on the foo part of the pattern \w++. That means it will refuse to backtrack after finding a series of "word" characters, even if the rest of the pattern -- the negative look-ahead -- then fails. I've also had to change the negative look-behind to reject word characters or colons : to prevent things like baz::std::foo from matching
该解决方案在模式\ w ++的foo部分使用所有格量化器。这意味着它会在找到一系列“单词”字符后拒绝回溯,即使模式的其余部分 - 负面预测 - 然后失败。我还必须改变负面的后视来拒绝单词字符或冒号:以防止像baz :: std :: foo这样的东西匹配
It is mostly a tidy-up of the answer from Sebastian Proske. It uses \w instead of the literal character class, adds layout using the /x modifier, and removes unnecessary parentheses. It also provides a working example
塞巴斯蒂安·普罗克斯的回答大多是一个整理。它使用\ w而不是文字字符类,使用/ x修饰符添加布局,并删除不必要的括号。它还提供了一个工作示例
use strict;
use warnings 'all';
use feature 'say';
my $s = 'match std::foo but not match std::foo::bar.';
say $1 while $s =~ / (?<![\w:]) ( \w+::\w++) (?!:) /gx;
output
std::foo
#2
1
Other than \b you could also:
除了\ b你还可以:
- use possessive matching to avoid backtracking into
foo:((?<!\w)([A-Za-z0-9_]+)::([A-Za-z0-9_]++))(?!:) - add the word character class to the lookahead, so it can't backtrack into
foo:((?<!\w)([A-Za-z0-9_]+)::([A-Za-z0-9_]+))(?![:\w])
使用所有格匹配来避免回溯到foo:((?
在前瞻中添加单词character class,因此无法回溯到foo :((?
#3
1
Just add \b before the negative lookahead which ensures that there is an word boundary exisst and also don't forget to add : in the first negative lookahead. Otherwise it would match the second part.
只需在负前瞻之前添加\ b,以确保存在一个单词边界,并且不要忘记在第一个负向前瞻中添加:否则它将匹配第二部分。
((?<![:\w])([A-Za-z0-9_]+)::([A-Za-z0-9_]+))\b(?!:)
OR
This would match the import string only if it's not preceded by a non-space character.
仅当导入字符串前面没有非空格字符时,才匹配导入字符串。
(?<!\S)([A-Za-z0-9_]+)::([A-Za-z0-9_]+)\b(?!:)
#4
-1
To match this whole string std::foo::bar instead of partial values We can use this regex
要匹配整个字符串std :: foo :: bar而不是部分值我们可以使用此正则表达式
((\b(.+)\b)+?[::]{2}.+)
It will give you two matches
它会给你两场比赛
std::foostd::foo::bar