regex101: PCRE (Legacy) Match Workspace

Pro

(?&valid_text)calls group valid_text as a subroutine

Definition Group(?(DEFINE) (?<valid_text> \A\s*(?&version)\s* (?: (?&element) \s* )+ \s*\Z ) (?<version> version$.+?$; ) (?<element> element\s* (?&element_body); ) (?<element_body> $ (?: [^()]++ | (?&element_body) )* $ ) )

Group valid_text(?<valid_text> \A\s*(?&version)\s* (?: (?&element) \s* )+ \s*\Z )

\Astart of string

\s*any whitespace character, repeated any number of times

(?&version)calls group version as a subroutine

\s*any whitespace character, repeated any number of times

Non-Capturing Group(?: (?&element) \s* )+

+repeats the group contents below at least once:

(?&element)calls group element as a subroutine

\s*any whitespace character, repeated any number of times

\Zend of string, or before its final line terminator

Group version(?<version> version$.+?$; )

versionthe literal text version (case sensitive)

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

.+?any character, repeated at least once

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

; the literal text ;

Group element(?<element> element\s* (?&element_body); )

elementthe literal text element (case sensitive)

\s*any whitespace character, repeated any number of times

(?&element_body)calls group element_body as a subroutine

; the literal text ;

Group element_body(?<element_body> $ (?: [^()]++ | (?&element_body) )* $ )

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Non-Capturing Group(?: [^()]++ | (?&element_body) )*

*repeats the group contents below any number of times:

1st Alternative [^()]++

Negated Character Class[^()]++

++matches at least one character outside the set below:

(the literal ( (40₁₀ / 50₈ / 28₁₆)

)the literal ) (41₁₀ / 51₈ / 29₁₆)

2nd Alternative (?&element_body)

(?&element_body)calls group element_body as a subroutine

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

s modifier: single line. Allows a dot to match line terminators

25 tokens

Regular Expression

(?&valid_text)(?(DEFINE)
    (?<valid_text>
        \A\s*(?&version)\s*
        (?: (?&element) \s* )+
        \s*\Z
    )
    (?<version>
        version\(.+?\);
    )
    (?<element>
        element\s*
        (?&element_body);
    )
    (?<element_body>
        \( (?: [^()]++ | (?&element_body) )* \)
    )
)

Unit Tests

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