Regex more lazy than

Question

I have the following Regex:

(?<day>\d+). Tag, (?<way>.+)?( \((?<length>\d+?.?\d?)km\))?

And i want to match these three possibilities:

1. Tag, Berlin -> London (500.3km)
2. Tag, London -> Stockholm (183km)
3. Tag, Stockholm (day of rest)

The problem: It doesn't match the length anymore. If I remove the questionsmarks to this:

(?<day>\d+). Tag, (?<way>.+)( \((?<length>\d+?.?\d?)km\))

It matches the first and second one not the third one. I thought I could solve the problem by adding the question mark at the end. But then the last expression becomes lazy. So I add another question mark to the way-expression but it doesn't become more lazy than the last one. So the way is matching the whole length too!

So, is it possible to define different level of lazyness? And if there this doesn't exist, how should i change the pattern to match it right?

Julian

You can't match (day of rest) with (\d+?.?)km. What is the expected output? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Sep 8, 2015 at 8:21
I think the problem is that the .+ in <way> can match the open bracket character (. Maybe use [^\(] instead? — pzelasko
– pzelasko, Commented Sep 8, 2015 at 8:22
@stribizhev: thats right, because it should not match "(day of rest)". If there is a kilometer-expression the length should match it. If there is no kilometer-expression the "way" will match it. And thats the point, the way is always matching everything including the kilometers. — GURKE
– GURKE, Commented Sep 8, 2015 at 8:30
I see, so (?<day>\d+)\.\s+Tag,\s+(?<way>.+?)\s+\((?<length>[^()]+)\) is not a solution, right? What is the regex flavor, BTW? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Sep 8, 2015 at 8:31
@pzelasko: Unfortunately "(day of rest)" should getting matched by the way-expression. So if i forbid the bracket, the day of rest won't get matched. — GURKE
– GURKE, Commented Sep 8, 2015 at 8:32

Wiktor Stribiżew · Accepted Answer · 2015-09-08 08:59:01Z

1

Here is a way to match all the expected elements in your input:

(?<day>\d+)\.\s+Tag,\s+(?<way>(?:[^()]|\((?!\d+(?:\.\d+)?km)[^()]*\))*?)(?:$|\s*(?<length>\(\d+(?:\.\d+)?km\)))

See demo

You can match the whole way that consists of no parenthetical constructs or with them not having integer or float numbers with km right after. Length will be matched only if present. Also note that a literal dot must be escaped (\.).

edited Sep 8, 2015 at 8:59

answered Sep 8, 2015 at 8:34

Wiktor Stribiżew

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4 Comments

GURKE Over a year ago

Hm... nearly. Now the kilometers are also in the way-expression :/ the way only should match "Berlin -> London" without the (500.3km)

Wiktor Stribiżew Over a year ago

Well, I have re-vamped the expression a bit, does it work as expected now?

GURKE Over a year ago

1. Tag, Berlin -> London (500.3km) day: 1 way: Berlin -> London length: 500.3 2. Tag, London -> Stockholm (183km) day: 2 way: London -> Stockholm length: 183 3. Tag, Stockholm (day of rest) day: 3 way: Stockholm (day of rest) length:

GURKE Over a year ago

Thanks a lot for your help, works fine :) Now you have done, seems so easy -.-

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