@c This file was hand-translated to Texinfo from the upstream PCRE
@c documentation file pcresyntax.3, whose copyright notice is:
@c
@c Author: Philip Hazel, University Computing Service
@c Cambridge CB2 3QH, England
@c Last updated: 21 September 2007
@c Copyright (c) 1997-2007 University of Cambridge.
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@c Apart from markup translation, all mention of callouts has been
@c removed, and a few confusing references to PCRE itself or to
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@node Regexp Summary
@subsection Regexp Syntax Summary

This is a quick-reference summary of the regular expression syntax
used in Monotone.

@subsubheading Quoting

@table @code
@item \@var{x}
  where @var{x} is non-alphanumeric is a literal @var{x}
@item \Q...\E
  treat enclosed characters as literal
@end table

@subsubheading Characters

@table @code
@item \a
  alarm, that is, the BEL character (hex 07)
@item \c@var{x}
  ``control-@var{x}'', where @var{x} is any character
@item \e
  escape (hex 1B)
@item \f
  formfeed (hex 0C)
@item \n
  newline (hex 0A)
@item \r
  carriage return (hex 0D)
@item \t
  tab (hex 09)
@item \@var{ddd}
  character with octal code @var{ddd}, or backreference
@item \x@var{hh}
  character with hex code @var{hh}
@item \x@{@var{hhh...}@}
  character with hex code @var{hhh...}
@end table

@subsubheading Character Types

@table @code
@item .
  any character except newline;
               in dotall mode, any character whatsoever
@item \C
  one byte, even in UTF-8 mode (best avoided)
@item \d
  a decimal digit
@item \D
  a character that is not a decimal digit
@item \h
  a horizontal whitespace character
@item \H
  a character that is not a horizontal whitespace character
@item \p@{@var{xx}@}
  a character with the @var{xx} property
@item \P@{@var{xx}@}
  a character without the @var{xx} property
@item \R
  a newline sequence
@item \s
  a whitespace character
@item \S
  a character that is not a whitespace character
@item \v
  a vertical whitespace character
@item \V
  a character that is not a vertical whitespace character
@item \w
  a ``word'' character
@item \W
  a ``non-word'' character
@item \X
  an extended Unicode sequence
@end table

@noindent
@samp{\d}, @samp{\D}, @samp{\s}, @samp{\S}, @samp{\w}, and @samp{\W}
recognize only ASCII characters.

@subsubheading General category property codes for @samp{\p} and @samp{\P}

@table @code
@item C
  Other
@item Cc
  Control
@item Cf
  Format
@item Cn
  Unassigned
@item Co
  Private use
@item Cs
  Surrogate

@item L
  Letter
@item Ll
  Lower case letter
@item Lm
  Modifier letter
@item Lo
  Other letter
@item Lt
  Title case letter
@item Lu
  Upper case letter
@item L&
  Ll, Lu, or Lt

@item M
  Mark
@item Mc
  Spacing mark
@item Me
  Enclosing mark
@item Mn
  Non-spacing mark

@item N
  Number
@item Nd
  Decimal number
@item Nl
  Letter number
@item No
  Other number

@item P
  Punctuation
@item Pc
  Connector punctuation
@item Pd
  Dash punctuation
@item Pe
  Close punctuation
@item Pf
  Final punctuation
@item Pi
  Initial punctuation
@item Po
  Other punctuation
@item Ps
  Open punctuation

@item S
  Symbol
@item Sc
  Currency symbol
@item Sk
  Modifier symbol
@item Sm
  Mathematical symbol
@item So
  Other symbol

@item Z
  Separator
@item Zl
  Line separator
@item Zp
  Paragraph separator
@item Zs
  Space separator
@end table

@subsubheading Script names for @samp{\p} and @samp{\P}

Arabic,
Armenian,
Balinese,
Bengali,
Bopomofo,
Braille,
Buginese,
Buhid,
Canadian_Aboriginal,
Cherokee,
Common,
Coptic,
Cuneiform,
Cypriot,
Cyrillic,
Deseret,
Devanagari,
Ethiopic,
Georgian,
Glagolitic,
Gothic,
Greek,
Gujarati,
Gurmukhi,
Han,
Hangul,
Hanunoo,
Hebrew,
Hiragana,
Inherited,
Kannada,
Katakana,
Kharoshthi,
Khmer,
Lao,
Latin,
Limbu,
Linear_B,
Malayalam,
Mongolian,
Myanmar,
New_Tai_Lue,
Nko,
Ogham,
Old_Italic,
Old_Persian,
Oriya,
Osmanya,
Phags_Pa,
Phoenician,
Runic,
Shavian,
Sinhala,
Syloti_Nagri,
Syriac,
Tagalog,
Tagbanwa,
Tai_Le,
Tamil,
Telugu,
Thaana,
Thai,
Tibetan,
Tifinagh,
Ugaritic,
Yi.

@subsubheading Character Classes

@table @code
@item [...]
  positive character class
@item [^...]
  negative character class
@item [@var{x}-@var{y}]
  range (can be used for hex characters)
@item [[:@var{xxx}:]]
  positive POSIX named set
@item [[:^@var{xxx}:]]
  negative POSIX named set

@item alnum
  alphanumeric
@item alpha
  alphabetic
@item ascii
  0-127
@item blank
  space or tab
@item cntrl
  control character
@item digit
  decimal digit
@item graph
  printing, excluding space
@item lower
  lower case letter
@item print
  printing, including space
@item punct
  printing, excluding alphanumeric
@item space
  whitespace
@item upper
  upper case letter
@item word
  same as @samp{\w}
@item xdigit
  hexadecimal digit
@end table

In PCRE, POSIX character set names recognize only ASCII
characters. You can use @samp{\Q...\E} inside a character class.

@subsubheading Quantifiers

@table @code
@item ?
  0 or 1, greedy
@item ?+
  0 or 1, possessive
@item ??
  0 or 1, lazy
@item *
  0 or more, greedy
@item *+
  0 or more, possessive
@item *?
  0 or more, lazy
@item +
  1 or more, greedy
@item ++
  1 or more, possessive
@item +?
  1 or more, lazy
@item @{@var{n}@}
  exactly @var{n}
@item @{@var{n},@var{m}@}
  at least @var{n}, no more than @var{m}, greedy
@item @{@var{n},@var{m}@}+
  at least @var{n}, no more than @var{m}, possessive
@item @{@var{n},@var{m}@}?
  at least @var{n}, no more than @var{m}, lazy
@item @{@var{n},@}
  @var{n} or more, greedy
@item @{@var{n},@}+
  @var{n} or more, possessive
@item @{@var{n},@}?
  @var{n} or more, lazy
@end table

@subsubheading Anchors and Simple Assertions

@table @code
@item \b
  word boundary
@item \B
  not a word boundary
@item ^
  start of subject
               also after internal newline in multiline mode
@item \A
  start of subject
@item $
  end of subject
               also before newline at end of subject
               also before internal newline in multiline mode
@item \Z
  end of subject
               also before newline at end of subject
@item \z
  end of subject
@item \G
  first matching position in subject
@end table

@subsubheading Match Point Reset

@table @code
@item \K
  reset start of match
@end table

@subsubheading Alternation

@table @code
@item @var{expr}|@var{expr}|@var{expr}...
@end table

@subsubheading Capturing

@table @code
@item (...)
  capturing group
@item (?<@var{name}>...)
  named capturing group (like Perl)
@item (?'@var{name}'...)
  named capturing group (like Perl)
@item (?P<@var{name}>...)
  named capturing group (like Python)
@item (?:...)
  non-capturing group
@item (?|...)
  non-capturing group; reset group numbers for
  capturing groups in each alternative
@end table

@subsubheading Atomic Groups

@table @code
@item (?>...)
  atomic, non-capturing group
@end table

@subsubheading Comment

@table @code
@item (?#....)
  comment (not nestable)
@end table

@subsubheading Option Setting

@table @code
@item (?i)
  caseless
@item (?J)
  allow duplicate names
@item (?m)
  multiline
@item (?s)
  single line (dotall)
@item (?U)
  default ungreedy (lazy)
@item (?x)
  extended (ignore white space)
@item (?-...)
  unset option(s)
@end table

@subsubheading Lookahead and Lookbehind Assertions

@table @code
@item (?=...)
  positive look ahead
@item (?!...)
  negative look ahead
@item (?<=...)
  positive look behind
@item (?<!...)
  negative look behind
@end table

Each top-level branch of a look behind must be of a fixed length.

@subsubheading Backreferences

@table @code
@item \@var{n}
  reference by number (can be ambiguous)
@item \g@var{n}
  reference by number
@item \g@{@var{n}@}
  reference by number
@item \g@{-@var{n}@}
  relative reference by number
@item \k<@var{name}>
  reference by name (like Perl)
@item \k'@var{name}'
  reference by name (like Perl)
@item \g@{@var{name}@}
  reference by name (like Perl)
@item \k@{@var{name}@}
  reference by name (like .NET)
@item (?P=@var{name})
  reference by name (like Python)
@end table

@subsubheading Subroutine References (possibly recursive)

@table @code
@item (?R)
  recurse whole pattern
@item (?@var{n})
  call subpattern by absolute number
@item (?+@var{n})
  call subpattern by relative number
@item (?-@var{n})
  call subpattern by relative number
@item (?&@var{name})
  call subpattern by name (like Perl)
@item (?P>@var{name})
  call subpattern by name (like Python)
@end table

@subsubheading Conditional Patterns

@table @code
@item (?(@var{condition})@var{yes-pattern})
@item (?(@var{condition})@var{yes-pattern}|@var{no-pattern})

@item (?(@var{n})...
  absolute reference condition
@item (?(+@var{n})...
  relative reference condition
@item (?(-@var{n})...
  relative reference condition
@item (?(<@var{name}>)...
  named reference condition (like Perl)
@item (?('@var{name}')...
  named reference condition (like Perl)
@item (?(@var{name})...
  named reference condition (PCRE only)
@item (?(R)...
  overall recursion condition
@item (?(R@var{n})...
  specific group recursion condition
@item (?(R&@var{name})...
  specific recursion condition
@item (?(DEFINE)...
  define subpattern for reference
@item (?(assert)...
  assertion condition
@end table

@subsubheading Backtracking Control

The following act immediately they are reached:

@table @code
@item (*ACCEPT)
  force successful match
@item (*FAIL)
  force backtrack; synonym @samp{(*F)}
@end table

The following act only when a subsequent match failure causes a backtrack to
reach them. They all force a match failure, but they differ in what happens
afterwards. Those that advance the start-of-match point do so only if the
pattern is not anchored.

@table @code
@item (*COMMIT)
  overall failure, no advance of starting point
@item (*PRUNE)
  advance to next starting character
@item (*SKIP)
  advance start to current matching position
@item (*THEN)
  local failure, backtrack to next alternation
@end table

@subsubheading Newline Conventions

These are recognized only at the very start of the pattern or after a
@samp{(*BSR_...)} option.

@table @code
@item (*CR)
@item (*LF)
@item (*CRLF)
@item (*ANYCRLF)
@item (*ANY)
@end table

@subsubheading What @samp{\R} Matches

These are recognized only at the very start of the pattern or after a
@samp{(*...)} option that sets the newline convention.

@table @code
@item (*BSR_ANYCRLF)
@item (*BSR_UNICODE)
@end table