Function match_expr_eval

grep.c:1040–1107

static int match_expr_eval(struct grep_opt *opt, struct grep_expr *x,
			   const char *bol, const char *eol,
			   enum grep_context ctx, ssize_t *col,
			   ssize_t *icol, int collect_hits)
{
	int h = 0;

	switch (x->node) {
	case GREP_NODE_TRUE:
		h = 1;
		break;
	case GREP_NODE_ATOM:
		{
			regmatch_t tmp;
			h = match_one_pattern(x->u.atom, bol, eol, ctx,
					      &tmp, 0);
			if (h && (*col < 0 || tmp.rm_so < *col))
				*col = tmp.rm_so;
		}
		if (x->u.atom->token == GREP_PATTERN_BODY)
			opt->body_hit |= h;
		break;
	case GREP_NODE_NOT:
		/*
		 * Upon visiting a GREP_NODE_NOT, col and icol become swapped.
		 */
		h = !match_expr_eval(opt, x->u.unary, bol, eol, ctx, icol, col,
				     0);
		break;
	case GREP_NODE_AND:
		h = match_expr_eval(opt, x->u.binary.left, bol, eol, ctx, col,
				    icol, 0);
		if (h || opt->columnnum) {
			/*
			 * Don't short-circuit AND when given --column, since a
			 * NOT earlier in the tree may turn this into an OR. In
			 * this case, see the below comment.
			 */
			h &= match_expr_eval(opt, x->u.binary.right, bol, eol,
					     ctx, col, icol, 0);
		}
		break;
	case GREP_NODE_OR:
		if (!(collect_hits || opt->columnnum)) {
			/*
			 * Don't short-circuit OR when given --column (or
			 * collecting hits) to ensure we don't skip a later
			 * child that would produce an earlier match.
			 */
			return (match_expr_eval(opt, x->u.binary.left, bol, eol,
						ctx, col, icol, 0) ||
				match_expr_eval(opt, x->u.binary.right, bol,
						eol, ctx, col, icol, 0));
		}
		h = match_expr_eval(opt, x->u.binary.left, bol, eol, ctx, col,
				    icol, 0);
		if (collect_hits)
			x->u.binary.left->hit |= h;