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diff --git a/src/regexp/syntax/doc.go b/src/regexp/syntax/doc.go new file mode 100644 index 0000000..f6a4b43 --- /dev/null +++ b/src/regexp/syntax/doc.go @@ -0,0 +1,141 @@ +// Copyright 2012 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// DO NOT EDIT. This file is generated by mksyntaxgo from the RE2 distribution. + +/* +Package syntax parses regular expressions into parse trees and compiles +parse trees into programs. Most clients of regular expressions will use the +facilities of package regexp (such as Compile and Match) instead of this package. + +# Syntax + +The regular expression syntax understood by this package when parsing with the Perl flag is as follows. +Parts of the syntax can be disabled by passing alternate flags to Parse. + +Single characters: + + . any character, possibly including newline (flag s=true) + [xyz] character class + [^xyz] negated character class + \d Perl character class + \D negated Perl character class + [[:alpha:]] ASCII character class + [[:^alpha:]] negated ASCII character class + \pN Unicode character class (one-letter name) + \p{Greek} Unicode character class + \PN negated Unicode character class (one-letter name) + \P{Greek} negated Unicode character class + +Composites: + + xy x followed by y + x|y x or y (prefer x) + +Repetitions: + + x* zero or more x, prefer more + x+ one or more x, prefer more + x? zero or one x, prefer one + x{n,m} n or n+1 or ... or m x, prefer more + x{n,} n or more x, prefer more + x{n} exactly n x + x*? zero or more x, prefer fewer + x+? one or more x, prefer fewer + x?? zero or one x, prefer zero + x{n,m}? n or n+1 or ... or m x, prefer fewer + x{n,}? n or more x, prefer fewer + x{n}? exactly n x + +Implementation restriction: The counting forms x{n,m}, x{n,}, and x{n} +reject forms that create a minimum or maximum repetition count above 1000. +Unlimited repetitions are not subject to this restriction. + +Grouping: + + (re) numbered capturing group (submatch) + (?P<name>re) named & numbered capturing group (submatch) + (?:re) non-capturing group + (?flags) set flags within current group; non-capturing + (?flags:re) set flags during re; non-capturing + + Flag syntax is xyz (set) or -xyz (clear) or xy-z (set xy, clear z). The flags are: + + i case-insensitive (default false) + m multi-line mode: ^ and $ match begin/end line in addition to begin/end text (default false) + s let . match \n (default false) + U ungreedy: swap meaning of x* and x*?, x+ and x+?, etc (default false) + +Empty strings: + + ^ at beginning of text or line (flag m=true) + $ at end of text (like \z not \Z) or line (flag m=true) + \A at beginning of text + \b at ASCII word boundary (\w on one side and \W, \A, or \z on the other) + \B not at ASCII word boundary + \z at end of text + +Escape sequences: + + \a bell (== \007) + \f form feed (== \014) + \t horizontal tab (== \011) + \n newline (== \012) + \r carriage return (== \015) + \v vertical tab character (== \013) + \* literal *, for any punctuation character * + \123 octal character code (up to three digits) + \x7F hex character code (exactly two digits) + \x{10FFFF} hex character code + \Q...\E literal text ... even if ... has punctuation + +Character class elements: + + x single character + A-Z character range (inclusive) + \d Perl character class + [:foo:] ASCII character class foo + \p{Foo} Unicode character class Foo + \pF Unicode character class F (one-letter name) + +Named character classes as character class elements: + + [\d] digits (== \d) + [^\d] not digits (== \D) + [\D] not digits (== \D) + [^\D] not not digits (== \d) + [[:name:]] named ASCII class inside character class (== [:name:]) + [^[:name:]] named ASCII class inside negated character class (== [:^name:]) + [\p{Name}] named Unicode property inside character class (== \p{Name}) + [^\p{Name}] named Unicode property inside negated character class (== \P{Name}) + +Perl character classes (all ASCII-only): + + \d digits (== [0-9]) + \D not digits (== [^0-9]) + \s whitespace (== [\t\n\f\r ]) + \S not whitespace (== [^\t\n\f\r ]) + \w word characters (== [0-9A-Za-z_]) + \W not word characters (== [^0-9A-Za-z_]) + +ASCII character classes: + + [[:alnum:]] alphanumeric (== [0-9A-Za-z]) + [[:alpha:]] alphabetic (== [A-Za-z]) + [[:ascii:]] ASCII (== [\x00-\x7F]) + [[:blank:]] blank (== [\t ]) + [[:cntrl:]] control (== [\x00-\x1F\x7F]) + [[:digit:]] digits (== [0-9]) + [[:graph:]] graphical (== [!-~] == [A-Za-z0-9!"#$%&'()*+,\-./:;<=>?@[\\\]^_`{|}~]) + [[:lower:]] lower case (== [a-z]) + [[:print:]] printable (== [ -~] == [ [:graph:]]) + [[:punct:]] punctuation (== [!-/:-@[-`{-~]) + [[:space:]] whitespace (== [\t\n\v\f\r ]) + [[:upper:]] upper case (== [A-Z]) + [[:word:]] word characters (== [0-9A-Za-z_]) + [[:xdigit:]] hex digit (== [0-9A-Fa-f]) + +Unicode character classes are those in unicode.Categories and unicode.Scripts. +*/ +package syntax |