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Diffstat (limited to 'ext/mbstring/oniguruma/doc/RE')
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diff --git a/ext/mbstring/oniguruma/doc/RE b/ext/mbstring/oniguruma/doc/RE new file mode 100644 index 0000000000..3527b4556f --- /dev/null +++ b/ext/mbstring/oniguruma/doc/RE @@ -0,0 +1,224 @@ +Oniguruma Regular Expressions 2003/07/04 + +syntax: REG_SYNTAX_RUBY (default) + + +1. Syntax elements + + \ escape + | alternation + (...) group + [...] character class + + +2. Characters + + \t horizontal tab (0x09) + \v vertical tab (0x0B) + \n newline (0x0A) + \r return (0x0D) + \b back space (0x08) (* in character class only) + \f form feed (0x0C) + \a bell (0x07) + \e escape (0x1B) + \nnn octal char + \xHH hexadecimal char + \x{7HHHHHHH} wide hexadecimal char + \cx control char + \C-x control char + \M-x meta (x|0x80) + \M-\C-x meta control char + + +3. Character types + + . any character (except newline) + \w word character (alphanumeric, "_" and multibyte char) + \W non-word char + \s whitespace char (\t, \n, \v, \f, \r, \x20) + \S non-whitespace char + \d digit char + \D non-digit char + + +4. Quantifier + + greedy + + ? 1 or 0 times + * 0 or more times + + 1 or more times + {n,m} at least n but not more than m times + {n,} at least n times + {n} n times + + reluctant + + ?? 1 or 0 times + *? 0 or more times + +? 1 or more times + {n,m}? at least n but not more than m times + {n,}? at least n times + + possessive (greedy and does not backtrack after repeated) + + ?+ 1 or 0 times + *+ 0 or more times + ++ 1 or more times + + +5. Anchors + + ^ beginning of the line + $ end of the line + \b word boundary + \B not word boundary + \A beginning of string + \Z end of string, or before newline at the end + \z end of string + \G previous end-of-match position + + +6. POSIX character class ([:xxxxx:], negate [:^xxxxx:]) + + alnum alphabet or digit char + alpha alphabet + ascii code value: [0 - 127] + blank \t, \x20 + cntrl + digit 0-9 + graph + lower + print + punct + space \t, \n, \v, \f, \r, \x20 + upper + xdigit 0-9, a-f, A-F + + +7. Operators in character class + + [...] group (character class in character class) + && intersection + (lowest precedence operator in character class) + + ex. [a-w&&[^c-g]z] ==> ([a-w] and ([^c-g] or z)) ==> [abh-w] + + +8. Extended expressions + + (?#...) comment + (?imx-imx) option on/off + i: ignore case + m: multi-line (dot(.) match newline) + x: extended form + (?imx-imx:subexp) option on/off for subexp + (?:subexp) not captured + (?=subexp) look-ahead + (?!subexp) negative look-ahead + (?<=subexp) look-behind + (?<!subexp) negative look-behind + + Subexp of look-behind must be fixed character length. + But different character length is allowed in top level + alternatives only. + ex. (?<=a|bc) is OK. (?<=aaa(?:b|cd)) is not allowed. + + (?>subexp) don't backtrack + (?<name>subexp) define named group + (name can not include '>', ')', '\' and NUL character) + + +9. Back reference + + \n back reference by group number (n >= 1) + \k<name> back reference by group name + + +10. Subexp call ("Tanaka Akira special") + + \g<name> call by group name + \g<n> call by group number (only if 'n' is not defined as name) + + +----------------------------- +11. Original extensions + + + named group (?<name>...) + + named backref \k<name> + + subexp call \g<name>, \g<group-num> + + +12. Lacked features compare with perl 5.8.0 + + + [:word:] + + \N{name} + + \l,\u,\L,\U, \P, \X, \C + + (?{code}) + + (??{code}) + + (?(condition)yes-pat|no-pat) + + + \Q...\E (* This is effective on REG_SYNTAX_PERL and REG_SYNTAX_JAVA) + + +13. Syntax depend options + + + REG_SYNTAX_RUBY (default) + (?m): dot(.) match newline + + + REG_SYNTAX_PERL, REG_SYNTAX_JAVA + (?s): dot(.) match newline + (?m): ^ match after newline, $ match before newline + + +14. Differences with Japanized GNU regex(version 0.12) of Ruby + + + add look behind + (?<=fixed-char-length-pattern), (?<!fixed-char-length-pattern) + (in negative-look-behind, capture group isn't allowed, + shy group(?:) is allowed.) + + add possessive quantifier. ?+, *+, ++ + + add operations in character class. [], && + + add named group and subexp call. + + octal or hexadecimal number sequence can be treated as + a multibyte code char in char-class, if multibyte encoding is specified. + (ex. [\xa1\xa2], [\xa1\xa7-\xa4\xa1]) + + effect range of isolated option is to next ')'. + ex. (?:(?i)a|b) is interpreted as (?:(?i:a|b)), not (?:(?i:a)|b). + + isolated option is not transparent to previous pattern. + ex. a(?i)* is a syntax error pattern. + + allowed incompleted left brace as an usual char. + ex. /{/, /({)/, /a{2,3/ etc... + + negative POSIX bracket [:^xxxx:] is supported. + + POSIX bracket [:ascii:] is added. + + repeat of look-ahead is not allowd. + ex. /(?=a)*/, /(?!b){5}/ + + +14. Problems + + + Invalid first byte in UTF-8 is allowed. + (which is the same as GNU regex of Ruby) + + /./u =~ "\xa3" + + Of course, although it is possible to validate, + it will become later than now. + + + Zero-length match in infinite repeat stops the repeat, + and captured group status isn't checked as stop condition. + + /()*\1/ =~ "" #=> match + /(?:()|())*\1\2/ =~ "" #=> fail + + /(?:\1a|())*/ =~ "a" #=> match with "" + + + Ignore case option is not effect to an octal or hexadecimal + numbered char, but it becomes effective if it appears in the char class. + This doesn't have consistency, though they are the specifications + which are the same as GNU regex of Ruby. + + /\x61/i.match("A") # => nil + /[\x61]/i.match("A") # => match + +// END |