I have a regex like "(?<opening>\[)?(?<body>\w )(?<closing>\])?".
This is in .NET.
Currently both opening and closing are optional and independent.
So the question is: is it possible to make the closing match only if opening was encountered, otherwise treat as a mismatch?
Currently it matches all of possible variants: body, [body, body], [body].
But my aim is to match either body or [body]
P.S. I know it's possible via ((?<opening>\[)(?<body>\w )(?<closing>\])|(?<body>\w )),
but my actual <body> pattern is quite big and complicated to duplicate it like that.
CodePudding user response：
For the current scenario, you can use
(?:(?<o>\[)|(?<!\[))\b(?<body>\w )(?(o)(?<c>])|(?![]\w]))
See the .NET regex demo. Details:
(?:(?<o>\[)|(?<!\[))\b- a word boundary (it works here since the next pattern part matches a word char)(?<body>\w )- Group "body": one or more word chars(?(o)(?<c>])|(?![]\w]))- a conditional construct that, if Group "o" stack is not empty,(?<c>])matches and captures into Group "c" a]char,|- or else (if Group "o" did not match)(?![]\w])- requires that there is no]and a word char immediately to the right of the current location.