[PATCH] regex: support non-greedy quantifiers

[Julien Ramseier <j.ramseier@gmail.com>]

Here's a tiny patch to enable non-greedy regex quantifiers.
This is not specified by POSIX, but I think it's a useful
extension, and all the code for supporting it is already present.

I tested this against the TRE and AT&T test suites (from NetBSD)
and didn't found any regressions.
However I don't know all the ins and outs of the implementation
and I may have missed something obvious.

- Julien

diff --git a/src/regex/regcomp.c b/src/regex/regcomp.c
index 5fad98b..cc7d633 100644
--- a/src/regex/regcomp.c
+++ b/src/regex/regcomp.c
@@ -979,6 +979,7 @@ static reg_errcode_t tre_parse(tre_parse_ctx_t *ctx)
 	parse_iter:
 		for (;;) {
 			int min, max;
+			int minimal = 0;
 
 			if (*s!='\\' && *s!='*') {
 				if (!ere)
@@ -1014,11 +1015,16 @@ static reg_errcode_t tre_parse(tre_parse_ctx_t *ctx)
 				if (*s == '?')
 					max = 1;
 				s++;
+				/* Non-greedy */
+				if (ere && *s == '?') {
+					minimal = 1;
+					s++;
+				}
 			}
 			if (max == 0)
 				ctx->n = tre_ast_new_literal(ctx->mem, EMPTY, -1, -1);
 			else
-				ctx->n = tre_ast_new_iter(ctx->mem, ctx->n, min, max, 0);
+				ctx->n = tre_ast_new_iter(ctx->mem, ctx->n, min, max, minimal);
 			if (!ctx->n)
 				return REG_ESPACE;
 		}
-- 
2.7.2