capture-group

问题 When I use vim, I often use & to backreference the entire match within substitutions. For example, the following replaces all instances of "foo" with "foobar": %s/foo/&bar/g The benefit here is laziness: I don't have to type the parenthesis in the match and I only have to type one character instead of two for the backreference in the substitution. Perhaps more importantly, I don't have figure out my backrefrences while I'm typing my match, reducing cognitive load. Is there an equivalent to

问题 When I use vim, I often use & to backreference the entire match within substitutions. For example, the following replaces all instances of "foo" with "foobar": %s/foo/&bar/g The benefit here is laziness: I don't have to type the parenthesis in the match and I only have to type one character instead of two for the backreference in the substitution. Perhaps more importantly, I don't have figure out my backrefrences while I'm typing my match, reducing cognitive load. Is there an equivalent to

问题 When I use vim, I often use & to backreference the entire match within substitutions. For example, the following replaces all instances of "foo" with "foobar": %s/foo/&bar/g The benefit here is laziness: I don't have to type the parenthesis in the match and I only have to type one character instead of two for the backreference in the substitution. Perhaps more importantly, I don't have figure out my backrefrences while I'm typing my match, reducing cognitive load. Is there an equivalent to

问题 What I Tried var test = "asdfdas ABCD EFGH"; var regex = /^\S+( [A-Z]{4})+$/; // Also tried: /^\S+( [A-Z]{4})+$/g // And: /^\S+( [A-Z]{4})+?$/g var matches = test.match(regex); I made a JSFiddle. What I Expect The variable matches should become this array: [ "asdfdas ABCD EFGH", " ABCD", " EFGH" ] What I Get The variable matches is actually this array: [ "asdfdas ABCD EFGH", " EFGH" ] My Thoughts My guess is that there's something I'm missing with the capture group and/or $ logic. Any help

问题 I posted this question earlier. But that wasn't quite the end of it. All the rules that applied there still apply. So the strings: "%ABC%" would yield ABC as a result (capture stuff between percent signs) as would "$ABC." (capture stuff after $, giving up when another dollar or dot appears) "$ABC$XYZ" would too, and also give XYZ as a result. To add a bit more to this: "${ABC}" should yield ABC too. (ignore curly braces if present - non capture chars perhaps?). if you have two successive

问题 I want to have multiple capture groups that can be optional and I want to access the strings they correspond to. Something that looks/works like this: let text1 = "something with foo and bar" let text2 = "something with just bar" let regex = NSRegularExpression(pattern: "(foo)? (bar)") for (first?, second) in regex.matches(in:text1) { print(first) // foo print(second) // bar } for (first?, second) in regex.matches(in:text2) { print(first) // nil print(second) // bar } 回答1: Retrieving captured

问题 I have the following text file I would like to parse out to get the individual fields: host_group_web = ( ) host_group_lbnorth = ( lba050 lbhou002 lblon003 ) The fields that I would like to extract are in bold host_group_ web = ( ) host_group_ lbnorth = ( lba505 lbhou002 lblon003 ) host_group_web has no items in between the ( ) , so that portion would be ignored I've named the first group as nodegroup and the items in between the () as nodes I am reading the file line by line, and storing the

问题 I'm porting a library from Ruby to Go, and have just discovered that regular expressions in Ruby are not compatible with Go (google RE2). It's come to my attention that Ruby & Java (plus other languages use PCRE regular expressions (perl compatible, which supports capturing groups)), so I need to re-write my expressions so that they compile ok in Go. For example, I have the following regex: `(?<Year>\d{4})-(?<Month>\d{2})-(?<Day>\d{2})` This should accept input such as: 2001-01-20 The

问题 Are optional non-capturing groups redundant? Is the following regex: (?:wo)?men semantically equivalent to the following regex? (wo)?men 回答1: Your (?:wo)?men and (wo)?men are semantically equivalent, but technically are different, namely, the first is using a non-capturing and the other a capturing group. Thus, the question is why use non-capturing groups when we have capturing ones ? Non-caprturing groups are of help sometimes. To avoid excessive number of backreferences (remember that it is

问题 I'm a regular expression newbie, and I can't quite figure out how to write a single regular expression that would "match" any duplicate consecutive words such as: Paris in the the spring. Not that that is related. Why are you laughing? Are my my regular expressions THAT bad?? Is there a single regular expression that will match ALL of the bold strings above? 回答1: Try this regular expression: \b(\w+)\s+\1\b Here \b is a word boundary and \1 references the captured match of the first group. 回答2