class Regex::MatchData

Overview

Regex::MatchData is the type of the special variable $~, and is the type returned by Regex#match and String#match. It encapsulates all the results of a regular expression match.

if md = "Crystal".match(/[p-s]/)
  md.string # => "Crystal"
  md[0]     # => "r"
  md[1]?    # => nil
end

Many Regex::MatchData methods deal with capture groups, and accept an integer argument to select the desired capture group. Capture groups are numbered starting from 1, so that 0 can be used to refer to the entire regular expression without needing to capture it explicitly.

Defined in:

regex/match_data.cr

Instance Method Summary

Instance methods inherited from class Reference

==(other : self)
==(other) ==, dup dup, hash hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference)
same?(other : Nil) same?, to_s(io : IO) : Nil to_s

Class methods inherited from class Reference

new new

Instance methods inherited from class Object

!=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try

Class methods inherited from class Object

from_json(string_or_io, root : String) : self
from_json(string_or_io) : self from_json, from_yaml(string_or_io) : self from_yaml

Instance Method Detail

def ==(other : Regex::MatchData) #

[View source]
def [](n) #

Returns the match of the nth capture group, or raises an IndexError if there is no nth capture group.

"Crystal".match(/r(ys)/).not_nil![1] # => "ys"
"Crystal".match(/r(ys)/).not_nil![2] # raises IndexError

[View source]
def [](group_name : String) #

Returns the match of the capture group named by group_name, or raises an ArgumentError if there is no such named capture group.

"Crystal".match(/r(?<ok>ys)/).not_nil!["ok"] # => "ys"
"Crystal".match(/r(?<ok>ys)/).not_nil!["ng"] # raises ArgumentError

[View source]
def []?(group_name : String) #

Returns the match of the capture group named by group_name, or nil if there is no such named capture group.

"Crystal".match(/r(?<ok>ys)/).not_nil!["ok"]? # => "ys"
"Crystal".match(/r(?<ok>ys)/).not_nil!["ng"]? # => nil

[View source]
def []?(n) #

Returns the match of the nth capture group, or nil if there isn't an nth capture group.

When n is 0, returns the match for the entire Regex.

"Crystal".match(/r(ys)/).not_nil![0]? # => "rys"
"Crystal".match(/r(ys)/).not_nil![1]? # => "ys"
"Crystal".match(/r(ys)/).not_nil![2]? # => nil

[View source]
def begin(n = 0) #

Return the position of the first character of the nth match.

When n is 0 or not given, uses the match of the entire Regex. Otherwise, uses the match of the nth capture group.

"Crystal".match(/r/).not_nil!.begin(0)     # => 1
"Crystal".match(/r(ys)/).not_nil!.begin(1) # => 2
"クリスタル".match(/リ(ス)/).not_nil!.begin(0)    # => 1

[View source]
def byte_begin(n = 0) #

Return the position of the first byte of the nth match.

When n is 0 or not given, uses the match of the entire Regex. Otherwise, uses the match of the nth capture group.

"Crystal".match(/r/).not_nil!.byte_begin(0)     # => 1
"Crystal".match(/r(ys)/).not_nil!.byte_begin(1) # => 2
"クリスタル".match(/リ(ス)/).not_nil!.byte_begin(0)    # => 3

[View source]
def byte_end(n = 0) #

Return the position of the next byte after the match.

When n is 0 or not given, uses the match of the entire Regex. Otherwise, uses the match of the nth capture group.

"Crystal".match(/r/).not_nil!.byte_end(0)     # => 2
"Crystal".match(/r(ys)/).not_nil!.byte_end(1) # => 4
"クリスタル".match(/リ(ス)/).not_nil!.byte_end(0)    # => 9

[View source]
def clone #

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def dup #

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def end(n = 0) #

Return the position of the next character after the match.

When n is 0 or not given, uses the match of the entire Regex. Otherwise, uses the match of the nth capture group.

"Crystal".match(/r/).not_nil!.end(0)     # => 2
"Crystal".match(/r(ys)/).not_nil!.end(1) # => 4
"クリスタル".match(/リ(ス)/).not_nil!.end(0)    # => 3

[View source]
def inspect(io : IO) #

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def post_match #

Returns the part of the original string after the match. If the match ends at the end of the string, returns the empty string.

"Crystal".match(/yst/).not_nil!.post_match # => "al"

[View source]
def pre_match #

Returns the part of the original string before the match. If the match starts at the start of the string, returns the empty string.

"Crystal".match(/yst/).not_nil!.pre_match # => "Cr"

[View source]
def regex : Regex #

Returns the original regular expression.

"Crystal".match(/[p-s]/).not_nil!.regex # => /[p-s]/

[View source]
def size : Int32 #

Returns the number of capture groups, including named capture groups.

"Crystal".match(/[p-s]/).not_nil!.size          # => 0
"Crystal".match(/r(ys)/).not_nil!.size          # => 1
"Crystal".match(/r(ys)(?<ok>ta)/).not_nil!.size # => 2

[View source]
def string : String #

Returns the original string.

"Crystal".match(/[p-s]/).not_nil!.string # => "Crystal"

[View source]
def to_s(io : IO) #

[View source]