Regular Expressions 101

Pro

@font-facethe literal text @font-face (case sensitive)

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

Comment: Match @font-face and some spaces

Group 1( # Start group 1 \{ # Match { (?: # A non-capturing group [^{}]+ # Match anything except {} one or more times | # Or (?1) # Recurse/rerun the expression of group 1 )* # Repeat 0 or more times \} # Match } )

Comment: Start group 1

\{the literal { (123₁₀ / 173₈ / 7B₁₆)

Comment: Match {

Non-Capturing Group(?: # A non-capturing group [^{}]+ # Match anything except {} one or more times | # Or (?1) # Recurse/rerun the expression of group 1 )*

*repeats the group contents below any number of times:

1st Alternative # A non-capturing group [^{}]+ # Match anything except {} one or more times

Comment: A non-capturing group

Negated Character Class[^{}]+

+matches at least one character outside the set below:

{the literal { (123₁₀ / 173₈ / 7B₁₆)

}the literal } (125₁₀ / 175₈ / 7D₁₆)

Comment: Match anything except {} one or more times

2nd Alternative # Or (?1) # Recurse/rerun the expression of group 1

Comment: Or

(?1)calls group 1 as a subroutine

Comment: Recurse/rerun the expression of group 1

Comment: Repeat 0 or more times

\}the literal } (125₁₀ / 175₈ / 7D₁₆)

Comment: Match }

Comment: End group 1

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

No unit tests · Add a test to get started

25 tokens

Regular Expression

@font-face\s*    # Match @font-face and some spaces
(                # Start group 1
   \{            # Match {
   (?:           # A non-capturing group
      [^{}]+     # Match anything except {} one or more times
      |          # Or
      (?1)       # Recurse/rerun the expression of group 1
   )*            # Repeat 0 or more times
   \}            # Match }
)                # End group 1

Unit Tests

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