1 // Copyright 2012 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // DO NOT EDIT. This file is generated by mksyntaxgo from the RE2 distribution. 6 7 /* 8 Package syntax parses regular expressions into parse trees and compiles 9 parse trees into programs. Most clients of regular expressions will use the 10 facilities of package regexp (such as Compile and Match) instead of this package. 11 12 Syntax 13 14 The regular expression syntax understood by this package when parsing with the Perl flag is as follows. 15 Parts of the syntax can be disabled by passing alternate flags to Parse. 16 17 18 Single characters: 19 . any character, possibly including newline (flag s=true) 20 [xyz] character class 21 [^xyz] negated character class 22 \d Perl character class 23 \D negated Perl character class 24 [[:alpha:]] ASCII character class 25 [[:^alpha:]] negated ASCII character class 26 \pN Unicode character class (one-letter name) 27 \p{Greek} Unicode character class 28 \PN negated Unicode character class (one-letter name) 29 \P{Greek} negated Unicode character class 30 31 Composites: 32 xy x followed by y 33 x|y x or y (prefer x) 34 35 Repetitions: 36 x* zero or more x, prefer more 37 x+ one or more x, prefer more 38 x? zero or one x, prefer one 39 x{n,m} n or n+1 or ... or m x, prefer more 40 x{n,} n or more x, prefer more 41 x{n} exactly n x 42 x*? zero or more x, prefer fewer 43 x+? one or more x, prefer fewer 44 x?? zero or one x, prefer zero 45 x{n,m}? n or n+1 or ... or m x, prefer fewer 46 x{n,}? n or more x, prefer fewer 47 x{n}? exactly n x 48 49 Implementation restriction: The counting forms x{n,m}, x{n,}, and x{n} 50 reject forms that create a minimum or maximum repetition count above 1000. 51 Unlimited repetitions are not subject to this restriction. 52 53 Grouping: 54 (re) numbered capturing group (submatch) 55 (?P<name>re) named & numbered capturing group (submatch) 56 (?:re) non-capturing group 57 (?flags) set flags within current group; non-capturing 58 (?flags:re) set flags during re; non-capturing 59 60 Flag syntax is xyz (set) or -xyz (clear) or xy-z (set xy, clear z). The flags are: 61 62 i case-insensitive (default false) 63 m multi-line mode: ^ and $ match begin/end line in addition to begin/end text (default false) 64 s let . match \n (default false) 65 U ungreedy: swap meaning of x* and x*?, x+ and x+?, etc (default false) 66 67 Empty strings: 68 ^ at beginning of text or line (flag m=true) 69 $ at end of text (like \z not Perl's \Z) or line (flag m=true) 70 \A at beginning of text 71 \b at ASCII word boundary (\w on one side and \W, \A, or \z on the other) 72 \B not at ASCII word boundary 73 \z at end of text 74 75 Escape sequences: 76 \a bell (== \007) 77 \f form feed (== \014) 78 \t horizontal tab (== \011) 79 \n newline (== \012) 80 \r carriage return (== \015) 81 \v vertical tab character (== \013) 82 \* literal *, for any punctuation character * 83 \123 octal character code (up to three digits) 84 \x7F hex character code (exactly two digits) 85 \x{10FFFF} hex character code 86 \Q...\E literal text ... even if ... has punctuation 87 88 Character class elements: 89 x single character 90 A-Z character range (inclusive) 91 \d Perl character class 92 [:foo:] ASCII character class foo 93 \p{Foo} Unicode character class Foo 94 \pF Unicode character class F (one-letter name) 95 96 Named character classes as character class elements: 97 [\d] digits (== \d) 98 [^\d] not digits (== \D) 99 [\D] not digits (== \D) 100 [^\D] not not digits (== \d) 101 [[:name:]] named ASCII class inside character class (== [:name:]) 102 [^[:name:]] named ASCII class inside negated character class (== [:^name:]) 103 [\p{Name}] named Unicode property inside character class (== \p{Name}) 104 [^\p{Name}] named Unicode property inside negated character class (== \P{Name}) 105 106 Perl character classes (all ASCII-only): 107 \d digits (== [0-9]) 108 \D not digits (== [^0-9]) 109 \s whitespace (== [\t\n\f\r ]) 110 \S not whitespace (== [^\t\n\f\r ]) 111 \w word characters (== [0-9A-Za-z_]) 112 \W not word characters (== [^0-9A-Za-z_]) 113 114 ASCII character classes: 115 [[:alnum:]] alphanumeric (== [0-9A-Za-z]) 116 [[:alpha:]] alphabetic (== [A-Za-z]) 117 [[:ascii:]] ASCII (== [\x00-\x7F]) 118 [[:blank:]] blank (== [\t ]) 119 [[:cntrl:]] control (== [\x00-\x1F\x7F]) 120 [[:digit:]] digits (== [0-9]) 121 [[:graph:]] graphical (== [!-~] == [A-Za-z0-9!"#$%&'()*+,\-./:;<=>?@[\\\]^_`{|}~]) 122 [[:lower:]] lower case (== [a-z]) 123 [[:print:]] printable (== [ -~] == [ [:graph:]]) 124 [[:punct:]] punctuation (== [!-/:-@[-`{-~]) 125 [[:space:]] whitespace (== [\t\n\v\f\r ]) 126 [[:upper:]] upper case (== [A-Z]) 127 [[:word:]] word characters (== [0-9A-Za-z_]) 128 [[:xdigit:]] hex digit (== [0-9A-Fa-f]) 129 130 */ 131 package syntax 132