Regex for obtaining all key value pairs with delimiter-CodePudding

My input will always look something like this with an arbitrary amount of key/value pairs:

"irrelevant part[identifier]key1=val1;key2=val2;key3=val3"

and the desired end result is [key1, val1, key2, val2, key3, val3]

I'm able to match and get key1=val1;key2=val2;key3=val3 via \[identifier](.*) but am lost on how to grab the pairs delimited by a semi-colon.

CodePudding user response：

Complex regex are powerful but notoriously difficult to comprehend and maintain, and also can get quite slow. You don't seem to need one for your case at all, I would go with something like this:

input
 .dropWhile(_ != ']')
 .tail
 .split(";")
 .map { _.split("=") }
 .collect { case Array(k,v) => k -> v }
 .toMap

CodePudding user response：

You can use a pattern with a \G operator:

val text = "irrelevant part[identifier]key1=val1;key2=val2;key3=val3"
val regex = """(?:\G(?!^);|\[identifier])([\w-] )=([^;]*)""".r
val results = (regex findAllIn text).matchData.map(x => (x.group(1), x.group(2))).toMap
println(results) // => Map(key1 -> val1, key2 -> val2, key3 -> val3)

See this Scala demo and this regex demo. Details:

(?:\G(?!^);|\[identifier]) - either the end of the previous match and then a ; char, or [identifier] char sequence
([\w-] ) - Group 1: one or more word or - chars
= - a = char and
([^;]*) - Group 2: any zero or more chars other than semi-colon.