common: Add a flag for left anchored substring match to recsel.

* common/recsel.c (struct recsel_expr_s): Add field lefta.
(recsel_parse_expr): Parse it.
(recsel_select): Implement selection.
--

This flags makes it for example easy to select keys last updated from
an ldap server:

  gpg --list-filter 'select=origin=ks && -^ url =~ ldap' \
       -k --with-key-origin

1 files changed, 19 insertions, 1 deletions

diff --git a/common/t-recsel.c b/common/t-recsel.c
index 2d5a95d25..ff68e54c3 100644
--- a/common/t-recsel.c
+++ b/common/t-recsel.c
@@ -225,9 +225,27 @@ run_test_2 (void)
   if (!recsel_select (se, test_2_getval, NULL))
     fail (0, 0);
   FREEEXPR();
-  ADDEXPR ("uid =~ @");
+  ADDEXPR ("uid !~ @");
+  if (recsel_select (se, test_2_getval, NULL))
+    fail (0, 0);
+
+  FREEEXPR();
+  ADDEXPR ("uid =~ foo@");
+  if (!recsel_select (se, test_2_getval, NULL))
+    fail (0, 0);
+  FREEEXPR();
+  ADDEXPR ("uid =~ oo@");
+  if (!recsel_select (se, test_2_getval, NULL))
+    fail (0, 0);
+  FREEEXPR();
+  /* Again but with left anchored substring.  */
+  ADDEXPR ("-^ uid =~ foo@");
   if (!recsel_select (se, test_2_getval, NULL))
     fail (0, 0);
+  FREEEXPR();
+  ADDEXPR ("-^ uid =~ oo@");
+  if (recsel_select (se, test_2_getval, NULL))
+    fail (0, 0);
 
   FREEEXPR();
   ADDEXPR ("keyid == 0x12345678");