Function llex

3rd/lua-5.4.3/src/llex.c:445–562

static int llex (LexState *ls, SemInfo *seminfo) {
  luaZ_resetbuffer(ls->buff);
  for (;;) {
    switch (ls->current) {
      case '\n': case '\r': {  /* line breaks */
        inclinenumber(ls);
        break;
      }
      case ' ': case '\f': case '\t': case '\v': {  /* spaces */
        next(ls);
        break;
      }
      case '-': {  /* '-' or '--' (comment) */
        next(ls);
        if (ls->current != '-') return '-';
        /* else is a comment */
        next(ls);
        if (ls->current == '[') {  /* long comment? */
          size_t sep = skip_sep(ls);
          luaZ_resetbuffer(ls->buff);  /* 'skip_sep' may dirty the buffer */
          if (sep >= 2) {
            read_long_string(ls, NULL, sep);  /* skip long comment */
            luaZ_resetbuffer(ls->buff);  /* previous call may dirty the buff. */
            break;
          }
        }
        /* else short comment */
        while (!currIsNewline(ls) && ls->current != EOZ)
          next(ls);  /* skip until end of line (or end of file) */
        break;
      }
      case '[': {  /* long string or simply '[' */
        size_t sep = skip_sep(ls);
        if (sep >= 2) {
          read_long_string(ls, seminfo, sep);
          return TK_STRING;
        }
        else if (sep == 0)  /* '[=...' missing second bracket? */
          lexerror(ls, "invalid long string delimiter", TK_STRING);
        return '[';
      }
      case '=': {
        next(ls);
        if (check_next1(ls, '=')) return TK_EQ;  /* '==' */
        else return '=';
      }
      case '<': {
        next(ls);
        if (check_next1(ls, '=')) return TK_LE;  /* '<=' */
        else if (check_next1(ls, '<')) return TK_SHL;  /* '<<' */
        else return '<';
      }
      case '>': {
        next(ls);
        if (check_next1(ls, '=')) return TK_GE;  /* '>=' */
        else if (check_next1(ls, '>')) return TK_SHR;  /* '>>' */
        else return '>';
      }