class StringScanner

Returns a new StringScanner object whose [stored string] is the given string; sets the [fixed-anchor property]:

scanner = StringScanner.new('foobarbaz')
scanner.string        # => "foobarbaz"
scanner.fixed_anchor? # => false
put_situation(scanner)
# Situation:
#   pos:       0
#   charpos:   0
#   rest:      "foobarbaz"
#   rest_size: 9

static VALUE
strscan_initialize(int argc, VALUE *argv, VALUE self)
{
    struct strscanner *p;
    VALUE str, options;

    p = check_strscan(self);
    rb_scan_args(argc, argv, "11", &str, &options);
    options = rb_check_hash_type(options);
    if (!NIL_P(options)) {
        VALUE fixed_anchor;
        ID keyword_ids[1];
        keyword_ids[0] = rb_intern("fixed_anchor");
        rb_get_kwargs(options, keyword_ids, 0, 1, &fixed_anchor);
        if (fixed_anchor == Qundef) {
            p->fixed_anchor_p = false;
        }
        else {
            p->fixed_anchor_p = RTEST(fixed_anchor);
        }
    }
    else {
        p->fixed_anchor_p = false;
    }
    StringValue(str);
    p->str = str;

    return self;
}

Returns a captured substring or nil; see [Captured Match Values].

When there are captures:

scanner = StringScanner.new('Fri Dec 12 1975 14:39')
scanner.scan(/(?<wday>\w+) (?<month>\w+) (?<day>\d+) /)

• specifier zero: returns the entire matched substring:

  scanner[0]         # => "Fri Dec 12 "
  scanner.pre_match  # => ""
  scanner.post_match # => "1975 14:39"
  

• specifier positive integer. returns the nth capture, or nil if out of range:

  scanner[1] # => "Fri"
  scanner[2] # => "Dec"
  scanner[3] # => "12"
  scanner[4] # => nil
  

• specifier negative integer. counts backward from the last subgroup:

  scanner[-1] # => "12"
  scanner[-4] # => "Fri Dec 12 "
  scanner[-5] # => nil
  

• specifier symbol or string. returns the named subgroup, or nil if no such:

  scanner[:wday]  # => "Fri"
  scanner['wday'] # => "Fri"
  scanner[:month] # => "Dec"
  scanner[:day]   # => "12"
  scanner[:nope]  # => nil
  

When there are no captures, only [0] returns non-nil:

scanner = StringScanner.new('foobarbaz')
scanner.exist?(/bar/)
scanner[0] # => "bar"
scanner[1] # => nil

For a failed match, even [0] returns nil:

scanner.scan(/nope/) # => nil
scanner[0]           # => nil
scanner[1]           # => nil

static VALUE
strscan_aref(VALUE self, VALUE idx)
{
    const char *name;
    struct strscanner *p;
    long i;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p))        return Qnil;

    switch (TYPE(idx)) {
        case T_SYMBOL:
            idx = rb_sym2str(idx);
            /* fall through */
        case T_STRING:
            if (!RTEST(p->regex)) return Qnil;
            RSTRING_GETMEM(idx, name, i);
            i = name_to_backref_number(&(p->regs), p->regex, name, name + i, rb_enc_get(idx));
            break;
        default:
            i = NUM2LONG(idx);
    }

    if (i < 0)
        i += p->regs.num_regs;
    if (i < 0)                 return Qnil;
    if (i >= p->regs.num_regs) return Qnil;
    if (p->regs.beg[i] == -1)  return Qnil;

    return extract_range(p,
                         adjust_register_position(p, p->regs.beg[i]),
                         adjust_register_position(p, p->regs.end[i]));
}

Returns whether the [position] is at the beginning of a line; that is, at the beginning of the [stored string] or immediately after a newline:

scanner = StringScanner.new(MULTILINE_TEXT)
scanner.string
# => "Go placidly amid the noise and haste,\nand remember what peace there may be in silence.\n"
scanner.pos                # => 0
scanner.beginning_of_line? # => true

scanner.scan_until(/,/)    # => "Go placidly amid the noise and haste,"
scanner.beginning_of_line? # => false

scanner.scan(/\n/)         # => "\n"
scanner.beginning_of_line? # => true

scanner.terminate
scanner.beginning_of_line? # => true

scanner.concat('x')
scanner.terminate
scanner.beginning_of_line? # => false

StringScanner#bol? is an alias for StringScanner#beginning_of_line?.

static VALUE
strscan_bol_p(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (CURPTR(p) > S_PEND(p)) return Qnil;
    if (p->curr == 0) return Qtrue;
    return (*(CURPTR(p) - 1) == '\n') ? Qtrue : Qfalse;
}

Returns the array of [captured match values] at indexes (1..) if the most recent match attempt succeeded, or nil otherwise:

scanner = StringScanner.new('Fri Dec 12 1975 14:39')
scanner.captures         # => nil

scanner.exist?(/(?<wday>\w+) (?<month>\w+) (?<day>\d+) /)
scanner.captures         # => ["Fri", "Dec", "12"]
scanner.values_at(*0..4) # => ["Fri Dec 12 ", "Fri", "Dec", "12", nil]

scanner.exist?(/Fri/)
scanner.captures         # => []

scanner.scan(/nope/)
scanner.captures         # => nil

static VALUE
strscan_captures(VALUE self)
{
    struct strscanner *p;
    int   i, num_regs;
    VALUE new_ary;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p))        return Qnil;

    num_regs = p->regs.num_regs;
    new_ary  = rb_ary_new2(num_regs);

    for (i = 1; i < num_regs; i++) {
        VALUE str;
        if (p->regs.beg[i] == -1)
            str = Qnil;
        else
            str = extract_range(p,
                                adjust_register_position(p, p->regs.beg[i]),
                                adjust_register_position(p, p->regs.end[i]));
        rb_ary_push(new_ary, str);
    }

    return new_ary;
}

Attempts to [match] the given pattern at the beginning of the [target substring]; does not modify the [positions].

If the match succeeds:

• Returns the matched substring.

• Sets all [match values].

scanner = StringScanner.new('foobarbaz')
scanner.pos = 3
scanner.check('bar') # => "bar"
put_match_values(scanner)
# Basic match values:
#   matched?:       true
#   matched_size:   3
#   pre_match:      "foo"
#   matched  :      "bar"
#   post_match:     "baz"
# Captured match values:
#   size:           1
#   captures:       []
#   named_captures: {}
#   values_at:      ["bar", nil]
#   []:
#     [0]:          "bar"
#     [1]:          nil
# => 0..1
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "barbaz"
#   rest_size: 6

If the match fails:

• Returns nil.

• Clears all [match values].

scanner.check(/nope/)          # => nil
match_values_cleared?(scanner) # => true

static VALUE
strscan_check(VALUE self, VALUE re)
{
    return strscan_do_scan(self, re, 0, 1, 1);
}

Attempts to [match] the given pattern anywhere (at any [position]) in the [target substring]; does not modify the [positions].

If the match succeeds:

• Sets all [match values].

• Returns the matched substring, which extends from the current [position] to the end of the matched substring.

scanner = StringScanner.new('foobarbazbatbam')
scanner.pos = 6
scanner.check_until(/bat/) # => "bazbat"
put_match_values(scanner)
# Basic match values:
#   matched?:       true
#   matched_size:   3
#   pre_match:      "foobarbaz"
#   matched  :      "bat"
#   post_match:     "bam"
# Captured match values:
#   size:           1
#   captures:       []
#   named_captures: {}
#   values_at:      ["bat", nil]
#   []:
#     [0]:          "bat"
#     [1]:          nil
put_situation(scanner)
# Situation:
#   pos:       6
#   charpos:   6
#   rest:      "bazbatbam"
#   rest_size: 9

If the match fails:

• Clears all [match values].

• Returns nil.

scanner.check_until(/nope/)    # => nil
match_values_cleared?(scanner) # => true

static VALUE
strscan_check_until(VALUE self, VALUE re)
{
    return strscan_do_scan(self, re, 0, 1, 0);
}

• Appends the given more_string to the [stored string].

• Returns self.

• Does not affect the [positions] or [match values].

scanner = StringScanner.new('foo')
scanner.string           # => "foo"
scanner.terminate
scanner.concat('barbaz') # => #<StringScanner 3/9 "foo" @ "barba...">
scanner.string           # => "foobarbaz"
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "barbaz"
#   rest_size: 6

static VALUE
strscan_concat(VALUE self, VALUE str)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    StringValue(str);
    rb_str_append(p->str, str);
    return self;
}

Returns whether the [position] is at the end of the [stored string]:

scanner = StringScanner.new('foobarbaz')
scanner.eos? # => false
pos = 3
scanner.eos? # => false
scanner.terminate
scanner.eos? # => true

static VALUE
strscan_eos_p(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    return EOS_P(p) ? Qtrue : Qfalse;
}

Attempts to [match] the given pattern anywhere (at any [position]) n the [target substring]; does not modify the [positions].

If the match succeeds:

• Returns a byte offset: the distance in bytes between the current [position] and the end of the matched substring.

• Sets all [match values].

scanner = StringScanner.new('foobarbazbatbam')
scanner.pos = 6
scanner.exist?(/bat/) # => 6
put_match_values(scanner)
# Basic match values:
#   matched?:       true
#   matched_size:   3
#   pre_match:      "foobarbaz"
#   matched  :      "bat"
#   post_match:     "bam"
# Captured match values:
#   size:           1
#   captures:       []
#   named_captures: {}
#   values_at:      ["bat", nil]
#   []:
#     [0]:          "bat"
#     [1]:          nil
put_situation(scanner)
# Situation:
#   pos:       6
#   charpos:   6
#   rest:      "bazbatbam"
#   rest_size: 9

If the match fails:

• Returns nil.

• Clears all [match values].

scanner.exist?(/nope/)         # => nil
match_values_cleared?(scanner) # => true

static VALUE
strscan_exist_p(VALUE self, VALUE re)
{
    return strscan_do_scan(self, re, 0, 0, 0);
}

Returns whether the [fixed-anchor property] is set.

static VALUE
strscan_fixed_anchor_p(VALUE self)
{
    struct strscanner *p;
    p = check_strscan(self);
    return p->fixed_anchor_p ? Qtrue : Qfalse;
}

Returns a string representation of self that may show:

1. The current [position].

2. The size (in bytes) of the [stored string].

3. The substring preceding the current position.

4. The substring following the current position (which is also the [target substring]).

scanner = StringScanner.new("Fri Dec 12 1975 14:39")
scanner.pos = 11
scanner.inspect # => "#<StringScanner 11/21 \"...c 12 \" @ \"1975 ...\">"

If at beginning-of-string, item 4 above (following substring) is omitted:

scanner.reset
scanner.inspect # => "#<StringScanner 0/21 @ \"Fri D...\">"

If at end-of-string, all items above are omitted:

scanner.terminate
scanner.inspect # => "#<StringScanner fin>"

static VALUE
strscan_inspect(VALUE self)
{
    struct strscanner *p;
    VALUE a, b;

    p = check_strscan(self);
    if (NIL_P(p->str)) {
        a = rb_sprintf("#<%"PRIsVALUE" (uninitialized)>", rb_obj_class(self));
        return a;
    }
    if (EOS_P(p)) {
        a = rb_sprintf("#<%"PRIsVALUE" fin>", rb_obj_class(self));
        return a;
    }
    if (p->curr == 0) {
        b = inspect2(p);
        a = rb_sprintf("#<%"PRIsVALUE" %ld/%ld @ %"PRIsVALUE">",
                       rb_obj_class(self),
                       p->curr, S_LEN(p),
                       b);
        return a;
    }
    a = inspect1(p);
    b = inspect2(p);
    a = rb_sprintf("#<%"PRIsVALUE" %ld/%ld %"PRIsVALUE" @ %"PRIsVALUE">",
                   rb_obj_class(self),
                   p->curr, S_LEN(p),
                   a, b);
    return a;
}

Attempts to [match] the given pattern at the beginning of the [target substring]; does not modify the [positions].

If the match succeeds:

• Sets [match values].

• Returns the size in bytes of the matched substring.

scanner = StringScanner.new('foobarbaz')
scanner.pos = 3
scanner.match?(/bar/) => 3
put_match_values(scanner)
# Basic match values:
#   matched?:       true
#   matched_size:   3
#   pre_match:      "foo"
#   matched  :      "bar"
#   post_match:     "baz"
# Captured match values:
#   size:           1
#   captures:       []
#   named_captures: {}
#   values_at:      ["bar", nil]
#   []:
#     [0]:          "bar"
#     [1]:          nil
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "barbaz"
#   rest_size: 6

If the match fails:

• Clears match values.

• Returns nil.

• Does not increment positions.

scanner.match?(/nope/)         # => nil
match_values_cleared?(scanner) # => true

static VALUE
strscan_match_p(VALUE self, VALUE re)
{
    return strscan_do_scan(self, re, 0, 0, 1);
}

Returns the matched substring from the most recent [match] attempt if it was successful, or nil otherwise; see [Basic Matched Values]:

scanner = StringScanner.new('foobarbaz')
scanner.matched        # => nil
scanner.pos = 3
scanner.match?(/bar/)  # => 3
scanner.matched        # => "bar"
scanner.match?(/nope/) # => nil
scanner.matched        # => nil

static VALUE
strscan_matched(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p)) return Qnil;
    return extract_range(p,
                         adjust_register_position(p, p->regs.beg[0]),
                         adjust_register_position(p, p->regs.end[0]));
}

Returns true of the most recent [match attempt] was successful, false otherwise; see [Basic Matched Values]:

scanner = StringScanner.new('foobarbaz')
scanner.matched?       # => false
scanner.pos = 3
scanner.exist?(/baz/)  # => 6
scanner.matched?       # => true
scanner.exist?(/nope/) # => nil
scanner.matched?       # => false

static VALUE
strscan_matched_p(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    return MATCHED_P(p) ? Qtrue : Qfalse;
}

Returns the size (in bytes) of the matched substring from the most recent match [match attempt] if it was successful, or nil otherwise; see [Basic Matched Values]:

scanner = StringScanner.new('foobarbaz')
scanner.matched_size   # => nil

pos = 3
scanner.exist?(/baz/)  # => 9
scanner.matched_size   # => 3

scanner.exist?(/nope/) # => nil
scanner.matched_size   # => nil

static VALUE
strscan_matched_size(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p)) return Qnil;
    return LONG2NUM(p->regs.end[0] - p->regs.beg[0]);
}

Returns the array of captured match values at indexes (1..) if the most recent match attempt succeeded, or nil otherwise; see [Captured Match Values]:

scanner = StringScanner.new('Fri Dec 12 1975 14:39')
scanner.named_captures # => {}

pattern = /(?<wday>\w+) (?<month>\w+) (?<day>\d+) /
scanner.match?(pattern)
scanner.named_captures # => {"wday"=>"Fri", "month"=>"Dec", "day"=>"12"}

scanner.string = 'nope'
scanner.match?(pattern)
scanner.named_captures # => {"wday"=>nil, "month"=>nil, "day"=>nil}

scanner.match?(/nosuch/)
scanner.named_captures # => {}

static VALUE
strscan_named_captures(VALUE self)
{
    struct strscanner *p;
    named_captures_data data;
    GET_SCANNER(self, p);
    data.self = self;
    data.captures = rb_hash_new();
    if (!RB_NIL_P(p->regex)) {
        onig_foreach_name(RREGEXP_PTR(p->regex), named_captures_iter, &data);
    }

    return data.captures;
}

Returns the substring string[pos, length]; does not update [match values] or [positions]:

scanner = StringScanner.new('foobarbaz')
scanner.pos = 3
scanner.peek(3)   # => "bar"
scanner.terminate
scanner.peek(3)   # => ""

static VALUE
strscan_peek(VALUE self, VALUE vlen)
{
    struct strscanner *p;
    long len;

    GET_SCANNER(self, p);

    len = NUM2LONG(vlen);
    if (EOS_P(p))
        return str_new(p, "", 0);

    len = minl(len, S_RESTLEN(p));
    return extract_beg_len(p, p->curr, len);
}

Peeks at the current byte and returns it as an integer.

s = StringScanner.new('ab')
s.peek_byte         # => 97

static VALUE
strscan_peek_byte(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (EOS_P(p))
        return Qnil;

    return INT2FIX((unsigned char)*CURPTR(p));
}

Returns the substring that follows the matched substring from the most recent match attempt if it was successful, or nil otherwise; see [Basic Match Values]:

scanner = StringScanner.new('foobarbaz')
scanner.post_match     # => nil

scanner.pos = 3
scanner.match?(/bar/)  # => 3
scanner.post_match     # => "baz"

scanner.match?(/nope/) # => nil
scanner.post_match     # => nil

static VALUE
strscan_post_match(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p)) return Qnil;
    return extract_range(p,
                         adjust_register_position(p, p->regs.end[0]),
                         S_LEN(p));
}

Returns the substring that precedes the matched substring from the most recent match attempt if it was successful, or nil otherwise; see [Basic Match Values]:

scanner = StringScanner.new('foobarbaz')
scanner.pre_match      # => nil

scanner.pos = 3
scanner.exist?(/baz/)  # => 6
scanner.pre_match      # => "foobar" # Substring of entire string, not just target string.

scanner.exist?(/nope/) # => nil
scanner.pre_match      # => nil

static VALUE
strscan_pre_match(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p)) return Qnil;
    return extract_range(p,
                         0,
                         adjust_register_position(p, p->regs.beg[0]));
}

Sets both [byte position] and [character position] to zero, and clears [match values]; returns self:

scanner = StringScanner.new('foobarbaz')
scanner.exist?(/bar/)          # => 6
scanner.reset                  # => #<StringScanner 0/9 @ "fooba...">
put_situation(scanner)
# Situation:
#   pos:       0
#   charpos:   0
#   rest:      "foobarbaz"
#   rest_size: 9
# => nil
match_values_cleared?(scanner) # => true

static VALUE
strscan_reset(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    p->curr = 0;
    CLEAR_MATCH_STATUS(p);
    return self;
}

Returns the ‘rest’ of the [stored string] (all after the current [position]), which is the [target substring]:

scanner = StringScanner.new('foobarbaz')
scanner.rest # => "foobarbaz"
scanner.pos = 3
scanner.rest # => "barbaz"
scanner.terminate
scanner.rest # => ""

static VALUE
strscan_rest(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (EOS_P(p)) {
        return str_new(p, "", 0);
    }
    return extract_range(p, p->curr, S_LEN(p));
}

Returns the size (in bytes) of the rest of the [stored string]:

scanner = StringScanner.new('foobarbaz')
scanner.rest      # => "foobarbaz"
scanner.rest_size # => 9
scanner.pos = 3
scanner.rest      # => "barbaz"
scanner.rest_size # => 6
scanner.terminate
scanner.rest      # => ""
scanner.rest_size # => 0

static VALUE
strscan_rest_size(VALUE self)
{
    struct strscanner *p;
    long i;

    GET_SCANNER(self, p);
    if (EOS_P(p)) {
        return INT2FIX(0);
    }
    i = S_RESTLEN(p);
    return INT2FIX(i);
}

Scans one byte and returns it as an integer. This method is not multibyte character sensitive. See also: getch.

static VALUE
strscan_scan_byte(VALUE self)
{
    struct strscanner *p;
    VALUE byte;

    GET_SCANNER(self, p);
    CLEAR_MATCH_STATUS(p);
    if (EOS_P(p))
        return Qnil;

    byte = INT2FIX((unsigned char)*CURPTR(p));
    p->prev = p->curr;
    p->curr++;
    MATCHED(p);
    adjust_registers_to_matched(p);
    return byte;
}

If ‘base` isn’t provided or is ‘10`, then it is equivalent to calling `#scan` with a `[+-]?d+` pattern, and returns an Integer or nil.

If ‘base` is `16`, then it is equivalent to calling `#scan` with a `[+-]?(0x)?+` pattern, and returns an Integer or nil.

The scanned string must be encoded with an ASCII compatible encoding, otherwise Encoding::CompatibilityError will be raised.

# File strscan/lib/strscan/strscan.rb, line 15
def scan_integer(base: 10)
  case base
  when 10
    scan_base10_integer
  when 16
    scan_base16_integer
  else
    raise ArgumentError, "Unsupported integer base: #{base.inspect}, expected 10 or 16"
  end
end

Returns the count of captures if the most recent match attempt succeeded, nil otherwise; see [Captures Match Values]:

scanner = StringScanner.new('Fri Dec 12 1975 14:39')
scanner.size                        # => nil

pattern = /(?<wday>\w+) (?<month>\w+) (?<day>\d+) /
scanner.match?(pattern)
scanner.values_at(*0..scanner.size) # => ["Fri Dec 12 ", "Fri", "Dec", "12", nil]
scanner.size                        # => 4

scanner.match?(/nope/)              # => nil
scanner.size                        # => nil

static VALUE
strscan_size(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p))        return Qnil;
    return INT2FIX(p->regs.num_regs);
}

Returns the [stored string]:

scanner = StringScanner.new('foobar')
scanner.string # => "foobar"
scanner.concat('baz')
scanner.string # => "foobarbaz"

static VALUE
strscan_get_string(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    return p->str;
}

Replaces the [stored string] with the given other_string:

• Sets both [positions] to zero.

• Clears [match values].

• Returns other_string.

scanner = StringScanner.new('foobar')
scanner.scan(/foo/)
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "bar"
#   rest_size: 3
match_values_cleared?(scanner) # => false

scanner.string = 'baz'         # => "baz"
put_situation(scanner)
# Situation:
#   pos:       0
#   charpos:   0
#   rest:      "baz"
#   rest_size: 3
match_values_cleared?(scanner) # => true

static VALUE
strscan_set_string(VALUE self, VALUE str)
{
    struct strscanner *p = check_strscan(self);

    StringValue(str);
    p->str = str;
    p->curr = 0;
    CLEAR_MATCH_STATUS(p);
    return str;
}

Sets the [position] to its value previous to the recent successful [match] attempt:

scanner = StringScanner.new('foobarbaz')
scanner.scan(/foo/)
put_situation(scanner)
# Situation:
#   pos:       3
#   charpos:   3
#   rest:      "barbaz"
#   rest_size: 6
scanner.unscan
# => #<StringScanner 0/9 @ "fooba...">
put_situation(scanner)
# Situation:
#   pos:       0
#   charpos:   0
#   rest:      "foobarbaz"
#   rest_size: 9

Raises an exception if match values are clear:

scanner.scan(/nope/)           # => nil
match_values_cleared?(scanner) # => true
scanner.unscan                 # Raises StringScanner::Error.

static VALUE
strscan_unscan(VALUE self)
{
    struct strscanner *p;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p))
        rb_raise(ScanError, "unscan failed: previous match record not exist");
    p->curr = p->prev;
    CLEAR_MATCH_STATUS(p);
    return self;
}

Returns an array of captured substrings, or nil of none.

For each specifier, the returned substring is [specifier]; see [].

scanner = StringScanner.new('Fri Dec 12 1975 14:39')
pattern = /(?<wday>\w+) (?<month>\w+) (?<day>\d+) /
scanner.match?(pattern)
scanner.values_at(*0..3)               # => ["Fri Dec 12 ", "Fri", "Dec", "12"]
scanner.values_at(*%i[wday month day]) # => ["Fri", "Dec", "12"]

static VALUE
strscan_values_at(int argc, VALUE *argv, VALUE self)
{
    struct strscanner *p;
    long i;
    VALUE new_ary;

    GET_SCANNER(self, p);
    if (! MATCHED_P(p))        return Qnil;

    new_ary = rb_ary_new2(argc);
    for (i = 0; i<argc; i++) {
        rb_ary_push(new_ary, strscan_aref(self, argv[i]));
    }

    return new_ary;
}

Returns a shallow copy of self; the [stored string] in the copy is the same string as in self.

static VALUE
strscan_init_copy(VALUE vself, VALUE vorig)
{
    struct strscanner *self, *orig;

    self = check_strscan(vself);
    orig = check_strscan(vorig);
    if (self != orig) {
        self->flags = orig->flags;
        self->str = orig->str;
        self->prev = orig->prev;
        self->curr = orig->curr;
        if (rb_reg_region_copy(&self->regs, &orig->regs))
            rb_memerror();
        RB_GC_GUARD(vorig);
    }

    return vself;
}