Regular Expressions 101

Explanation

Pro

Definition Group(?(DEFINE) (?<exprs> (?&expr)(\s+(?&bool)\s+((?&expr)|$\s*(?&exprs)\s*$))* ) (?<expr> (?&valleft)\s?(?&comp)\s?(?&valright) ) (?<comp> ((!=)|(==)|(<=)|(>=)|(<)|(>)){1} ) (?<valleft> (?&not)[\w\.]+ ) (?<valright> [\w\.]+ ) (?<bool> (and|or) ) (?<not> (not\s+)?) )

Group exprs(?<exprs> (?&expr)(\s+(?&bool)\s+((?&expr)|$\s*(?&exprs)\s*$))* )

(?&expr)calls group expr as a subroutine

Group 2(\s+(?&bool)\s+((?&expr)|$\s*(?&exprs)\s*$))*

*repeats the group contents below any number of times:

\s+any whitespace character, repeated at least once

(?&bool)calls group bool as a subroutine

\s+any whitespace character, repeated at least once

Group 3((?&expr)|$\s*(?&exprs)\s*$)

1st Alternative(?&expr)

(?&expr)calls group expr as a subroutine

2nd Alternative$\s*(?&exprs)\s*$

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

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

(?&exprs)calls group exprs as a subroutine

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

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

Group expr(?<expr> (?&valleft)\s?(?&comp)\s?(?&valright) )

(?&valleft)calls group valleft as a subroutine

\s?optionally matches any whitespace character

(?&comp)calls group comp as a subroutine

\s?optionally matches any whitespace character

(?&valright)calls group valright as a subroutine

Group comp(?<comp> ((!=)|(==)|(<=)|(>=)|(<)|(>)){1} )

Group 6((!=)|(==)|(<=)|(>=)|(<)|(>)){1}

{1}repeats the group contents below exactly 1 time:

1st Alternative(!=)

Group 7(!=)

!=the literal text !=

2nd Alternative(==)

Group 8(==)

==the literal text ==

3rd Alternative(<=)

Group 9(<=)

<=the literal text <=

4th Alternative(>=)

Group 10(>=)

>=the literal text >=

5th Alternative(<)

Group 11(<)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

6th Alternative(>)

Group 12(>)

>the literal > (62₁₀ / 76₈ / 3E₁₆)

Group valleft(?<valleft> (?&not)[\w\.]+ )

(?&not)calls group not as a subroutine

Character Class[\w\.]+

+matches at least one character from the set below:

\wany word character

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group valright(?<valright> [\w\.]+ )

Character Class[\w\.]+

+matches at least one character from the set below:

\wany word character

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group bool(?<bool> (and|or) )

Group not(?<not> (not\s+)?)

(?&exprs)calls group exprs as a subroutine

Global pattern flags

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

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Unit Test Summary

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Quick Reference

25 tokens

Regular Expression

(?(DEFINE)
    (?<exprs> (?&expr)(\s+(?&bool)\s+((?&expr)|\(\s*(?&exprs)\s*\)))* )
    (?<expr> (?&valleft)\s?(?&comp)\s?(?&valright) )
    (?<comp> ((!=)|(==)|(<=)|(>=)|(<)|(>)){1} )
    (?<valleft> (?&not)[\w\.]+ )
    (?<valright> [\w\.]+ )
    (?<bool> (and|or) )
    (?<not> (not\s+)?)
)
(?&exprs)

Unit Tests

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