class Regexp < Object

A Regexp holds a regular expression, used to match a pattern against strings. Regexps are created using the /.../ and %r{...} literals, and by the Regexp.new constructor.

constants

class methods

compile

Regexp.compile( pattern [, options [lang]] ) → aRegexp

Synonym for Regexp.new.

escape

Regexp.escape( aString ) → aNewString

Escapes any characters that would have special meaning in a regular expression. For any string, Regexp.escape(str)=~str will be true.

Regexp.escape('\\*?{}.') → \\\\\*\?\{\}\.

last_match

Regexp.last_match → aMatchData

Returns the MatchData object generated by the last successful pattern match. Equivalent to reading the global variable $~. See the reference for the MatchData class.

new

Regexp.new( pattern [, options [lang]] ) → aRegexp

Constructs a new regular expression from pattern, which can be either a String or a Regexp (in which case that regexp's options are not propagated). If options is a Fixnum, it should be one or more of the constants Regexp::EXTENDED, Regexp::IGNORECASE, and Regexp::POSIXLINE, or-ed together. Otherwise, if options is not nil, the regexp will be case insensitive. The lang parameter enables multibyte support for the regexp: `n', `N' = none, `e', `E' = EUC, `s', `S' = SJIS, `u', `U' = UTF-8.

r1 = Regexp.new('^a-z+:\\s+\w+') → /^a-z+:\s+\w+/ r2 = Regexp.new(r1, true) → /^a-z+:\s+\w+/i r3 = Regexp.new(r2, Regexp::EXTENDED) → /^a-z+:\s+\w+/x

quote

Regexp.quote( aString ) → aNewString

Synonym for Regexp.escape.

instance methods

==

rxp == aRegexp → true or false

Equality—Two regexps are equal if their patterns are identical, they have the same character set code, and their casefold? values are the same.

/abc/ == /abc/x → false /abc/ == /abc/i → false /abc/u == /abc/n → false

===

rxp === aString → true or false

Case Equality—Synonym for Regexp#=~ used in case statements.

a = "HELLO" case a when /^a-z*$/; print "Lower case\n" when /^A-Z*$/; print "Upper case\n" else; print "Mixed case\n" end

produces:

Upper case

=~

rxp =~ aString → anInteger or nil

Match—Matches rxp against aString, returning the offset of the start of the match or nil if the match failed.

/SIT/ =~ "insensitive" → nil /SIT/i =~ "insensitive" → 5

~

~ rxp → anInteger or nil

Match—Matches rxp against the contents of $_. Equivalent to rxp =~ $_.

$_ = "input data" ~ /at/ → 7

casefold?

rxp.casefold? → true or false

Returns the value of the case-insensitive flag.

kcode

rxp.kcode → aString

Returns the character set code for the regexp.

match

rxp.match(aString) → aMatchData or nil

Returns a MatchData object describing the match, or nil if there was no match. This is equivalent to retrieving the value of the special variable $~ following a normal match.

/(.)(.)(.)/.match("abc")[2] → "b"

source

rxp.source → aString

Returns the original string of the pattern.

/ab+c/ix.source → "ab+c"