Expand the loop when to use

Question

I am trying to understand a regex cycle in a regex. What is the big difference between:

MINISTÉRIO[\s\S]*?PÁG

and

MINISTÉRIO(?:[^P]*(?:P(?!ÁG\s:\s\d+\/\d+)[^P]*)(?:[\s\S]*?))PÁG

In this context:

http://regexr.com/3dmlr

Why should I use the second if the first does the SAME?

Thank.

Answer 1

What is Unroll-the-loop?

See Expand the loop method :

This optimization technique is used to optimize re-rotation of a form (expr1|expr2|...)*. This expression is not uncommon, and the use of another repetition within the alternation can also lead to superlinear matching. Superlinear match occurs due to an unreachable expression (a*)*.

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normal * ( *) *

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MINISTÉRIO[\s\S]*?PÁG - , MINISTÉRIO[^P]*(?:P(?!ÁG)[^P]*)*PÁG. . ( PCRE, ). Regex , ). text: , P. , , , , , .

. .*?, .* [^"]*+ quantifiers , , ( [\s\S]*? .*? DOTALL , . ).

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:

• ("String\u0020:\"text\""): "[^"\\]*(?:\\.[^"\\]*)*"

• (/* Comments */): /\*[^*]*\*+(?:[^/*][^*]*\*+)*/

• @<...>@ regex: @<[^>]*(?:>[^@]*)*@