Function lower_subexps

compat/regex/regcomp.c:1318–1338

Lowering pass: Turn each SUBEXP node into the appropriate concatenation of OP_OPEN_SUBEXP, the body of the SUBEXP (if any) and OP_CLOSE_SUBEXP. */

      if (other_idx < BITSET_WORD_BITS)
	  dfa->used_bkref_map &= ~((bitset_word_t) 1 << other_idx);
    }

  return REG_NOERROR;
}

/* Lowering pass: Turn each SUBEXP node into the appropriate concatenation
   of OP_OPEN_SUBEXP, the body of the SUBEXP (if any) and OP_CLOSE_SUBEXP.  */
static reg_errcode_t
lower_subexps (void *extra, bin_tree_t *node)
{
  regex_t *preg = (regex_t *) extra;
  reg_errcode_t err = REG_NOERROR;

  if (node->left && node->left->token.type == SUBEXP)
    {
      node->left = lower_subexp (&err, preg, node->left);
      if (node->left)
	node->left->parent = node;
    }
  if (node->right && node->right->token.type == SUBEXP)
    {
      node->right = lower_subexp (&err, preg, node->right);
      if (node->right)
	node->right->parent = node;