Course of Raku / Regexes and grammars / Regexes / Alternations / Exercises / http or https

Solution: http or https

Here is a possible solution to the task.

Code

say 'https://example' ~~ / http | https /;

🦋 You can find the source code in the file http-or-https.raku.

Output

｢https｣

Comments

1. Both http and https could match at the start, but | uses longest-token matching.

2. So the longer https wins, even though http is written first.

An alternative solution

The two words differ only by a trailing s, so instead of an alternation you can make that s optional with the ? quantifier:

say 'https://example' ~~ / https? /; # ｢https｣

The ? binds only to the atom right before it — the s — not to the whole word, so https? reads as http followed by an optional s. That single pattern matches both http and https, and being greedy it takes the s whenever it is there.

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