Method cap

extern/re2/re2/regexp.h:340–340

  Rune rune() { DCHECK_EQ(op_, kRegexpLiteral); return rune_; }
  CharClass* cc() { DCHECK_EQ(op_, kRegexpCharClass); return cc_; }
  int cap() { DCHECK_EQ(op_, kRegexpCapture); return cap_; }
  const std::string* name() { DCHECK_EQ(op_, kRegexpCapture); return name_; }
  Rune* runes() { DCHECK_EQ(op_, kRegexpLiteralString); return runes_; }
  int nrunes() { DCHECK_EQ(op_, kRegexpLiteralString); return nrunes_; }