class MatchData

MatchData encapsulates the result of matching a Regexp against string. It is returned by Regexp#match and String#match, and also stored in a global variable returned by Regexp.last_match.

Usage:

url = 'https://docs.ruby-lang.org/en/2.5.0/MatchData.html'
m = url.match(/(\d\.?)+/)   # => #<MatchData "2.5.0" 1:"0">
m.string                    # => "https://docs.ruby-lang.org/en/2.5.0/MatchData.html"
m.regexp                    # => /(\d\.?)+/
# entire matched substring:
m[0]                        # => "2.5.0"

# Working with unnamed captures
m = url.match(%r{([^/]+)/([^/]+)\.html$})
m.captures                  # => ["2.5.0", "MatchData"]
m[1]                        # => "2.5.0"
m.values_at(1, 2)           # => ["2.5.0", "MatchData"]

# Working with named captures
m = url.match(%r{(?<version>[^/]+)/(?<module>[^/]+)\.html$})
m.captures                  # => ["2.5.0", "MatchData"]
m.named_captures            # => {"version"=>"2.5.0", "module"=>"MatchData"}
m[:version]                 # => "2.5.0"
m.values_at(:version, :module)
                            # => ["2.5.0", "MatchData"]
# Numerical indexes are working, too
m[1]                        # => "2.5.0"
m.values_at(1, 2)           # => ["2.5.0", "MatchData"]

Global variables equivalence¶ ↑

Parts of last MatchData (returned by Regexp.last_match) are also aliased as global variables:

$~ is Regexp.last_match;
$& is Regexp.last_match[ 0 ];
$1, $2, and so on are Regexp.last_match[ i ] (captures by number);
$` is Regexp.last_match.pre_match;
$' is Regexp.last_match.post_match;
$+ is Regexp.last_match[ -1 ] (the last capture).

See also “Special global variables” section in Regexp documentation.

Public Instance Methods

matchdata == object → true or false

Returns true if object is another MatchData object whose target string, regexp, match, and captures are the same as self, false otherwise.

Alias for: eql?

matchdata[index] → string or nil click to toggle source

matchdata[start, length] → array

matchdata[range] → array

matchdata[name] → string or nil

When arguments index, +start and length, or range are given, returns match and captures in the style of Array#[]:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0] # => "HX1138"
m[1, 2]  # => ["H", "X"]
m[1..3]  # => ["H", "X", "113"]
m[-3, 2] # => ["X", "113"]

When string or symbol argument name is given, returns the matched substring for the given name:

m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" bar:"ge">
m['foo'] # => "h"
m[:bar]  # => "ge"

If multiple captures have the same name, returns the last matched substring.

m = /(?<foo>.)(?<foo>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" foo:"oge">
m[:foo] #=> "oge"

m = /\W(?<foo>.+)|\w(?<foo>.+)|(?<foo>.+)/.match("hoge")
#<MatchData "hoge" foo:nil foo:"oge" foo:nil>
m[:foo] #=> "oge"

static VALUE
match_aref(int argc, VALUE *argv, VALUE match)
{
    VALUE idx, length;

    match_check(match);
    rb_scan_args(argc, argv, "11", &idx, &length);

    if (NIL_P(length)) {
        if (FIXNUM_P(idx)) {
            return rb_reg_nth_match(FIX2INT(idx), match);
        }
        else {
            int num = namev_to_backref_number(RMATCH_REGS(match), RMATCH(match)->regexp, idx);
            if (num >= 0) {
                return rb_reg_nth_match(num, match);
            }
            else {
                return match_ary_aref(match, idx, Qnil);
            }
        }
    }
    else {
        long beg = NUM2LONG(idx);
        long len = NUM2LONG(length);
        long num_regs = RMATCH_REGS(match)->num_regs;
        if (len < 0) {
            return Qnil;
        }
        if (beg < 0) {
            beg += num_regs;
            if (beg < 0) return Qnil;
        }
        else if (beg > num_regs) {
            return Qnil;
        }
        if (beg+len > num_regs) {
            len = num_regs - beg;
        }
        return match_ary_subseq(match, beg, len, Qnil);
    }
}

begin(n) → integer click to toggle source

begin(name) → integer

Returns the offset (in characters) of the beginning of the specified match.

When non-negative integer argument n is given, returns the offset of the beginning of the nth match:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]       # => "HX1138"
m.begin(0) # => 1
m[3]       # => "113"
m.begin(3) # => 3

m = /(т)(е)(с)/.match('тест')
# => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
m[0]       # => "тес"
m.begin(0) # => 0
m[3]       # => "с"
m.begin(3) # => 2

When string or symbol argument name is given, returns the offset of the beginning for the named match:

m = /(?<foo>.)(.)(?<bar>.)/.match("hoge")
# => #<MatchData "hog" foo:"h" bar:"g">
m[:foo]        # => "h"
m.begin('foo') # => 0
m[:bar]        # => "g"
m.begin(:bar)  # => 2

static VALUE
match_begin(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return Qnil;

    update_char_offset(match);
    return LONG2NUM(RMATCH_EXT(match)->char_offset[i].beg);
}

byteoffset(n) → array click to toggle source

Returns a two-element array containing the beginning and ending byte-based offsets of the nth match. n can be a string or symbol to reference a named capture.

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
m.byteoffset(0)      #=> [1, 7]
m.byteoffset(4)      #=> [6, 7]

m = /(?<foo>.)(.)(?<bar>.)/.match("hoge")
p m.byteoffset(:foo) #=> [0, 1]
p m.byteoffset(:bar) #=> [2, 3]

static VALUE
match_byteoffset(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return rb_assoc_new(Qnil, Qnil);
    return rb_assoc_new(LONG2NUM(BEG(i)), LONG2NUM(END(i)));
}

captures → array click to toggle source

Returns the array of captures, which are all matches except m[0]:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]       # => "HX1138"
m.captures # => ["H", "X", "113", "8"]

Related: MatchData.to_a.

static VALUE
match_captures(VALUE match)
{
    return match_array(match, 1);
}

Also aliased as: deconstruct

deconstruct()

Returns the array of captures, which are all matches except m[0]:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]       # => "HX1138"
m.captures # => ["H", "X", "113", "8"]

Related: MatchData.to_a.

Alias for: captures

deconstruct_keys(array_of_names) → hash click to toggle source

Returns a hash of the named captures for the given names.

m = /(?<hours>\d{2}):(?<minutes>\d{2}):(?<seconds>\d{2})/.match("18:37:22")
m.deconstruct_keys([:hours, :minutes]) # => {:hours => "18", :minutes => "37"}
m.deconstruct_keys(nil) # => {:hours => "18", :minutes => "37", :seconds => "22"}

Returns an empty hash if no named captures were defined:

m = /(\d{2}):(\d{2}):(\d{2})/.match("18:37:22")
m.deconstruct_keys(nil) # => {}

static VALUE
match_deconstruct_keys(VALUE match, VALUE keys)
{
    VALUE h;
    long i;

    match_check(match);

    if (NIL_P(RMATCH(match)->regexp)) {
        return rb_hash_new_with_size(0);
    }

    if (NIL_P(keys)) {
        h = rb_hash_new_with_size(onig_number_of_names(RREGEXP_PTR(RMATCH(match)->regexp)));

        struct MEMO *memo;
        memo = MEMO_NEW(h, match, 1);

        onig_foreach_name(RREGEXP_PTR(RMATCH(match)->regexp), match_named_captures_iter, (void*)memo);

        return h;
    }

    Check_Type(keys, T_ARRAY);

    if (onig_number_of_names(RREGEXP_PTR(RMATCH(match)->regexp)) < RARRAY_LEN(keys)) {
        return rb_hash_new_with_size(0);
    }

    h = rb_hash_new_with_size(RARRAY_LEN(keys));

    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE key = RARRAY_AREF(keys, i);
        VALUE name;

        Check_Type(key, T_SYMBOL);

        name = rb_sym2str(key);

        int num = NAME_TO_NUMBER(RMATCH_REGS(match), RMATCH(match)->regexp, RMATCH(match)->regexp,
                         RSTRING_PTR(name), RSTRING_END(name));

        if (num >= 0) {
            rb_hash_aset(h, key, rb_reg_nth_match(num, match));
        }
        else {
            return h;
        }
    }

    return h;
}

end(n) → integer click to toggle source

end(name) → integer

Returns the offset (in characters) of the end of the specified match.

When non-negative integer argument n is given, returns the offset of the end of the nth match:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]     # => "HX1138"
m.end(0) # => 7
m[3]     # => "113"
m.end(3) # => 6

m = /(т)(е)(с)/.match('тест')
# => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
m[0]     # => "тес"
m.end(0) # => 3
m[3]     # => "с"
m.end(3) # => 3

When string or symbol argument name is given, returns the offset of the end for the named match:

m = /(?<foo>.)(.)(?<bar>.)/.match("hoge")
# => #<MatchData "hog" foo:"h" bar:"g">
m[:foo]      # => "h"
m.end('foo') # => 1
m[:bar]      # => "g"
m.end(:bar)  # => 3

static VALUE
match_end(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return Qnil;

    update_char_offset(match);
    return LONG2NUM(RMATCH_EXT(match)->char_offset[i].end);
}

eql? == object -> true or false click to toggle source

Returns true if object is another MatchData object whose target string, regexp, match, and captures are the same as self, false otherwise.

static VALUE
match_equal(VALUE match1, VALUE match2)
{
    const struct re_registers *regs1, *regs2;

    if (match1 == match2) return Qtrue;
    if (!RB_TYPE_P(match2, T_MATCH)) return Qfalse;
    if (!RMATCH(match1)->regexp || !RMATCH(match2)->regexp) return Qfalse;
    if (!rb_str_equal(RMATCH(match1)->str, RMATCH(match2)->str)) return Qfalse;
    if (!rb_reg_equal(match_regexp(match1), match_regexp(match2))) return Qfalse;
    regs1 = RMATCH_REGS(match1);
    regs2 = RMATCH_REGS(match2);
    if (regs1->num_regs != regs2->num_regs) return Qfalse;
    if (memcmp(regs1->beg, regs2->beg, regs1->num_regs * sizeof(*regs1->beg))) return Qfalse;
    if (memcmp(regs1->end, regs2->end, regs1->num_regs * sizeof(*regs1->end))) return Qfalse;
    return Qtrue;
}

Also aliased as: ==

hash → integer click to toggle source

Returns the integer hash value for self, based on the target string, regexp, match, and captures.

See also Object#hash.

static VALUE
match_hash(VALUE match)
{
    const struct re_registers *regs;
    st_index_t hashval;

    match_check(match);
    hashval = rb_hash_start(rb_str_hash(RMATCH(match)->str));
    hashval = rb_hash_uint(hashval, reg_hash(match_regexp(match)));
    regs = RMATCH_REGS(match);
    hashval = rb_hash_uint(hashval, regs->num_regs);
    hashval = rb_hash_uint(hashval, rb_memhash(regs->beg, regs->num_regs * sizeof(*regs->beg)));
    hashval = rb_hash_uint(hashval, rb_memhash(regs->end, regs->num_regs * sizeof(*regs->end)));
    hashval = rb_hash_end(hashval);
    return ST2FIX(hashval);
}

inspect → string click to toggle source

Returns a string representation of self:

m = /.$/.match("foo")
# => #<MatchData "o">
m.inspect # => "#<MatchData \"o\">"

m = /(.)(.)(.)/.match("foo")
# => #<MatchData "foo" 1:"f" 2:"o" 3:"o">
m.inspect # => "#<MatchData \"foo\" 1:\"f\" 2:\"o\

m = /(.)(.)?(.)/.match("fo")
# => #<MatchData "fo" 1:"f" 2:nil 3:"o">
m.inspect # => "#<MatchData \"fo\" 1:\"f\" 2:nil 3:\"o\">"

Related: MatchData#to_s.

static VALUE
match_inspect(VALUE match)
{
    VALUE cname = rb_class_path(rb_obj_class(match));
    VALUE str;
    int i;
    struct re_registers *regs = RMATCH_REGS(match);
    int num_regs = regs->num_regs;
    struct backref_name_tag *names;
    VALUE regexp = RMATCH(match)->regexp;

    if (regexp == 0) {
        return rb_sprintf("#<%"PRIsVALUE":%p>", cname, (void*)match);
    }
    else if (NIL_P(regexp)) {
        return rb_sprintf("#<%"PRIsVALUE": %"PRIsVALUE">",
                          cname, rb_reg_nth_match(0, match));
    }

    names = ALLOCA_N(struct backref_name_tag, num_regs);
    MEMZERO(names, struct backref_name_tag, num_regs);

    onig_foreach_name(RREGEXP_PTR(regexp),
            match_inspect_name_iter, names);

    str = rb_str_buf_new2("#<");
    rb_str_append(str, cname);

    for (i = 0; i < num_regs; i++) {
        VALUE v;
        rb_str_buf_cat2(str, " ");
        if (0 < i) {
            if (names[i].name)
                rb_str_buf_cat(str, (const char *)names[i].name, names[i].len);
            else {
                rb_str_catf(str, "%d", i);
            }
            rb_str_buf_cat2(str, ":");
        }
        v = rb_reg_nth_match(i, match);
        if (NIL_P(v))
            rb_str_buf_cat2(str, "nil");
        else
            rb_str_buf_append(str, rb_str_inspect(v));
    }
    rb_str_buf_cat2(str, ">");

    return str;
}

length()

Returns size of the match array:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.size # => 5

Alias for: size

match(n) → string or nil click to toggle source

match(name) → string or nil

Returns the matched substring corresponding to the given argument.

When non-negative argument n is given, returns the matched substring for the nth match:

m = /(.)(.)(\d+)(\d)(\w)?/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8" 5:nil>
m.match(0) # => "HX1138"
m.match(4) # => "8"
m.match(5) # => nil

When string or symbol argument name is given, returns the matched substring for the given name:

m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" bar:"ge">
m.match('foo') # => "h"
m.match(:bar)  # => "ge"

static VALUE
match_nth(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    backref_number_check(regs, i);

    long start = BEG(i), end = END(i);
    if (start < 0)
        return Qnil;

    return rb_str_subseq(RMATCH(match)->str, start, end - start);
}

match_length(n) → integer or nil click to toggle source

match_length(name) → integer or nil

Returns the length (in characters) of the matched substring corresponding to the given argument.

When non-negative argument n is given, returns the length of the matched substring for the nth match:

m = /(.)(.)(\d+)(\d)(\w)?/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8" 5:nil>
m.match_length(0) # => 6
m.match_length(4) # => 1
m.match_length(5) # => nil

When string or symbol argument name is given, returns the length of the matched substring for the named match:

m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" bar:"ge">
m.match_length('foo') # => 1
m.match_length(:bar)  # => 2

static VALUE
match_nth_length(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return Qnil;

    update_char_offset(match);
    const struct rmatch_offset *const ofs =
        &RMATCH_EXT(match)->char_offset[i];
    return LONG2NUM(ofs->end - ofs->beg);
}

named_captures(symbolize_names: false) → hash click to toggle source

Returns a hash of the named captures; each key is a capture name; each value is its captured string or nil:

m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" bar:"ge">
m.named_captures # => {"foo"=>"h", "bar"=>"ge"}

m = /(?<a>.)(?<b>.)/.match("01")
# => #<MatchData "01" a:"0" b:"1">
m.named_captures #=> {"a" => "0", "b" => "1"}

m = /(?<a>.)(?<b>.)?/.match("0")
# => #<MatchData "0" a:"0" b:nil>
m.named_captures #=> {"a" => "0", "b" => nil}

m = /(?<a>.)(?<a>.)/.match("01")
# => #<MatchData "01" a:"0" a:"1">
m.named_captures #=> {"a" => "1"}

If keyword argument symbolize_names is given a true value, the keys in the resulting hash are Symbols:

m = /(?<a>.)(?<a>.)/.match("01")
# => #<MatchData "01" a:"0" a:"1">
m.named_captures(symbolize_names: true) #=> {:a => "1"}

static VALUE
match_named_captures(int argc, VALUE *argv, VALUE match)
{
    VALUE hash;
    struct MEMO *memo;

    match_check(match);
    if (NIL_P(RMATCH(match)->regexp))
        return rb_hash_new();

    VALUE opt;
    VALUE symbolize_names = 0;

    rb_scan_args(argc, argv, "0:", &opt);

    if (!NIL_P(opt)) {
        static ID keyword_ids[1];

        VALUE symbolize_names_val;

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern_const("symbolize_names");
        }
        rb_get_kwargs(opt, keyword_ids, 0, 1, &symbolize_names_val);
        if (!UNDEF_P(symbolize_names_val) && RTEST(symbolize_names_val)) {
            symbolize_names = 1;
        }
    }

    hash = rb_hash_new();
    memo = MEMO_NEW(hash, match, symbolize_names);

    onig_foreach_name(RREGEXP(RMATCH(match)->regexp)->ptr, match_named_captures_iter, (void*)memo);

    return hash;
}

names → array_of_names click to toggle source

Returns an array of the capture names (see Named Captures):

m = /(?<foo>.)(?<bar>.)(?<baz>.)/.match("hoge")
# => #<MatchData "hog" foo:"h" bar:"o" baz:"g">
m.names # => ["foo", "bar", "baz"]

m = /foo/.match('foo') # => #<MatchData "foo">
m.names # => [] # No named captures.

Equivalent to:

m = /(?<foo>.)(?<bar>.)(?<baz>.)/.match("hoge")
m.regexp.names # => ["foo", "bar", "baz"]

static VALUE
match_names(VALUE match)
{
    match_check(match);
    if (NIL_P(RMATCH(match)->regexp))
        return rb_ary_new_capa(0);
    return rb_reg_names(RMATCH(match)->regexp);
}

offset(n) → [start_offset, end_offset] click to toggle source

offset(name) → [start_offset, end_offset]

Returns a 2-element array containing the beginning and ending offsets (in characters) of the specified match.

When non-negative integer argument n is given, returns the starting and ending offsets of the nth match:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]        # => "HX1138"
m.offset(0) # => [1, 7]
m[3]        # => "113"
m.offset(3) # => [3, 6]

m = /(т)(е)(с)/.match('тест')
# => #<MatchData "тес" 1:"т" 2:"е" 3:"с">
m[0]        # => "тес"
m.offset(0) # => [0, 3]
m[3]        # => "с"
m.offset(3) # => [2, 3]

When string or symbol argument name is given, returns the starting and ending offsets for the named match:

m = /(?<foo>.)(.)(?<bar>.)/.match("hoge")
# => #<MatchData "hog" foo:"h" bar:"g">
m[:foo]         # => "h"
m.offset('foo') # => [0, 1]
m[:bar]         # => "g"
m.offset(:bar)  # => [2, 3]

static VALUE
match_offset(VALUE match, VALUE n)
{
    int i = match_backref_number(match, n);
    struct re_registers *regs = RMATCH_REGS(match);

    match_check(match);
    backref_number_check(regs, i);

    if (BEG(i) < 0)
        return rb_assoc_new(Qnil, Qnil);

    update_char_offset(match);
    return rb_assoc_new(LONG2NUM(RMATCH_EXT(match)->char_offset[i].beg),
                        LONG2NUM(RMATCH_EXT(match)->char_offset[i].end));
}

post_match → str click to toggle source

Returns the substring of the target string from the end of the first match in self (that is, self[0]) to the end of the string; equivalent to regexp global variable $':

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]         # => "HX1138"
m.post_match # => ": The Movie"\

Related: MatchData.pre_match.

VALUE
rb_reg_match_post(VALUE match)
{
    VALUE str;
    long pos;
    struct re_registers *regs;

    if (NIL_P(match)) return Qnil;
    match_check(match);
    regs = RMATCH_REGS(match);
    if (BEG(0) == -1) return Qnil;
    str = RMATCH(match)->str;
    pos = END(0);
    str = rb_str_subseq(str, pos, RSTRING_LEN(str) - pos);
    return str;
}

pre_match → string click to toggle source

Returns the substring of the target string from its beginning up to the first match in self (that is, self[0]); equivalent to regexp global variable $`:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m[0]        # => "HX1138"
m.pre_match # => "T"

Related: MatchData#post_match.

VALUE
rb_reg_match_pre(VALUE match)
{
    VALUE str;
    struct re_registers *regs;

    if (NIL_P(match)) return Qnil;
    match_check(match);
    regs = RMATCH_REGS(match);
    if (BEG(0) == -1) return Qnil;
    str = rb_str_subseq(RMATCH(match)->str, 0, BEG(0));
    return str;
}

regexp → regexp click to toggle source

Returns the regexp that produced the match:

m = /a.*b/.match("abc") # => #<MatchData "ab">
m.regexp                # => /a.*b/

static VALUE
match_regexp(VALUE match)
{
    VALUE regexp;
    match_check(match);
    regexp = RMATCH(match)->regexp;
    if (NIL_P(regexp)) {
        VALUE str = rb_reg_nth_match(0, match);
        regexp = rb_reg_regcomp(rb_reg_quote(str));
        RB_OBJ_WRITE(match, &RMATCH(match)->regexp, regexp);
    }
    return regexp;
}

size → integer click to toggle source

Returns size of the match array:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.size # => 5

static VALUE
match_size(VALUE match)
{
    match_check(match);
    return INT2FIX(RMATCH_REGS(match)->num_regs);
}

Also aliased as: length

string → string click to toggle source

Returns the target string if it was frozen; otherwise, returns a frozen copy of the target string:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.string # => "THX1138."

static VALUE
match_string(VALUE match)
{
    match_check(match);
    return RMATCH(match)->str;  /* str is frozen */
}

to_a → array click to toggle source

Returns the array of matches:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.to_a # => ["HX1138", "H", "X", "113", "8"]

Related: MatchData#captures.

static VALUE
match_to_a(VALUE match)
{
    return match_array(match, 0);
}

to_s → string click to toggle source

Returns the matched string:

m = /(.)(.)(\d+)(\d)/.match("THX1138.")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.to_s # => "HX1138"

m = /(?<foo>.)(.)(?<bar>.+)/.match("hoge")
# => #<MatchData "hoge" foo:"h" bar:"ge">
m.to_s # => "hoge"

Related: MatchData.inspect.

static VALUE
match_to_s(VALUE match)
{
    VALUE str = rb_reg_last_match(match_check(match));

    if (NIL_P(str)) str = rb_str_new(0,0);
    return str;
}

values_at(*indexes) → array click to toggle source

Returns match and captures at the given indexes, which may include any mixture of:

Integers.
Ranges.
Names (strings and symbols).

Examples:

m = /(.)(.)(\d+)(\d)/.match("THX1138: The Movie")
# => #<MatchData "HX1138" 1:"H" 2:"X" 3:"113" 4:"8">
m.values_at(0, 2, -2) # => ["HX1138", "X", "113"]
m.values_at(1..2, -1) # => ["H", "X", "8"]

m = /(?<a>\d+) *(?<op>[+\-*\/]) *(?<b>\d+)/.match("1 + 2")
# => #<MatchData "1 + 2" a:"1" op:"+" b:"2">
m.values_at(0, 1..2, :a, :b, :op)
# => ["1 + 2", "1", "+", "1", "2", "+"]

static VALUE
match_values_at(int argc, VALUE *argv, VALUE match)
{
    VALUE result;
    int i;

    match_check(match);
    result = rb_ary_new2(argc);

    for (i=0; i<argc; i++) {
        if (FIXNUM_P(argv[i])) {
            rb_ary_push(result, rb_reg_nth_match(FIX2INT(argv[i]), match));
        }
        else {
            int num = namev_to_backref_number(RMATCH_REGS(match), RMATCH(match)->regexp, argv[i]);
            if (num >= 0) {
                rb_ary_push(result, rb_reg_nth_match(num, match));
            }
            else {
                match_ary_aref(match, argv[i], result);
            }
        }
    }
    return result;
}