perl6 の正規表現が正規と言えないほど、ぶっ飛んでる構文なのでメモも兼ねて

• Wildcard: .
• Backslashed character
  • digit: \d
  • not digit: \D
  • alpha plus digit: \w
  • not alpha and not digit: \W
  • space: \s
  • not space: \S
  • newline: \n
  • horizontal whitespace: \h
  • vertical whitespace: \v
• Predefined character
  • digit: <digit>
  • alpha plus digit: <alnum>
  • space: <space>
  • alpha: <alpha>, <:L>
  • upper: <:Lu>
  • lower: <:Ll>
• Enumerated character classes
  • enumerate: <[ a b c ]>
  • range: <[ a .. c ]>
  • add: <[ a .. c ] + [ 1 2 3 ]> == <[ a .. c 1 2 3]>
  • remove: <[ a .. c ] - [ b ]> == <[ a c ]>
  • negate: <-[ " ]>
• Quantifiers
  • one or more: +
  • zero or more: *
  • zero or one match: ?
  • general quantifier: ** count
  • general quantifier: ** min..max (This is similar to other languages' {min,max}）
  • modified quantifier: %
    • e.g. / a+ % ',' / will match a or a,a or a,a,a or so on, but will not match a, or a,a,
  • modified quantifier: %%
    • e.g. / a+ %% ',' / will match a or a,a or a,a,a or so on, and also will match a, or a,a,
  • frugal quantifier: ?
    • e.g. / .+? /
  • preventing backtracking: :
    • e.g. / .+: /
• Alternation
  • alternation: ||
  • longest alternation: |
• Anchors
  • start of string: ^
  • end of string: $
  • start of line: ^^
  • end of line: $$
  • word boundary: <|w>（This is similar to other languages' \b）
  • not word boundary: <!|w>
  • left word boundary: <<, «
  • right word boundary: >>, »
• Grouping and Capturing
  • matched object: $/
  • capture: ( )
    • ref: $0, $1, $2, …
  • non capturing group: [ ]
  • named capture: $<name>=[ ], $<name>=( )
    • ref: $<name>
  • capture markers: <( )> (This is similar to other languages' \K）
• Look-around assertions
  • lookahead assertions: <?before pattern>
    • e.g. / foo <?before bar> /
  • negated lookahead assertions: <!before pattern>
  • lookbehind assertions: <?after pattern>
    • e.g. / <?after foo> bar /
  • negated lookbehind assertions: <!after pattern>
• Subrules
  • subrule: my regex name { regex }
  • ref: / <name> /
  • non capturing: / <.name> /
• Regex Adverbs
  • ignorecase: /:i /
  • ratchet: /:r / (This causes the regex engine not to backtrack)
  • sigspace: /:s / (This makes whitespace significant)
• Matching adverbs
  • continue: m:c/ pattern /
  • exhaustive: m:exhaustive/ pattern /, m:ex/ pattern /
  • global: m:global/ pattern /, m:g/ pattern /
  • pos: m:pos/ pattern /, m:p/ pattern /
  • overlap: m:overlap/ pattern /, m:ov/ pattern /