You’re fortunate because in fact .NET regex does this (which I think is quite unique). Essentially in every Match, each Group stores every Captures that was made. So you can count how many times a repeatable pattern matched an input by: Making it a capturing group Counting how many captures were made by that group … Read more
There is currently a proposal (stage 4) to implement this in native Javascript: RegExp Match Indices for ECMAScript ECMAScript RegExp Match Indices provide additional information about the start and end indices of captured substrings relative to the start of the input string. …We propose the adoption of an additional indices property on the array result … Read more
The answer is, needless to say, YES! You can most certainly write a Java regex pattern to match anbn. It uses a positive lookahead for assertion, and one nested reference for “counting”. Rather than immediately giving out the pattern, this answer will guide readers through the process of deriving it. Various hints are given as … Read more
When you repeat a capturing group, in most flavors, only the last capture is kept; any previous capture is overwritten. In some flavor, e.g. .NET, you can get all intermediate captures, but this is not the case with Javascript. That is, in Javascript, if you have a pattern with N capturing groups, you can only … Read more
Let me try to explain this with an example. Consider the following text: http://stackoverflow.com/ https://stackoverflow.com/questions/tagged/regex Now, if I apply the regex below over it… (https?|ftp)://([^/\r\n]+)(/[^\r\n]*)? … I would get the following result: Match “http://stackoverflow.com/” Group 1: “http” Group 2: “stackoverflow.com” Group 3: “https://stackoverflow.com/” Match “https://stackoverflow.com/questions/tagged/regex” Group 1: “https” Group 2: “stackoverflow.com” Group 3: “https://stackoverflow.com/questions/tagged/regex” But … Read more