instance method

StringScanner#pre_match

() -> ::String

pre_match → substring

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]));
}

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:

Example

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

See also #post_match #reset #pos= #rest also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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