[gnumeric] Criteria: "=" and "<>" are special.

[Morten Welinder <mortenw src gnome org>]

commit c350537706f6784ce9d00767c91a4a2366ea6f81
Author: Morten Welinder <terra gnome org>
Date:   Tue Apr 16 14:58:40 2013 -0400

    Criteria: "=" and "<>" are special.
    
    These test for emptiness.  Another great XL design!

 ChangeLog   |  3 +++
 NEWS        |  1 +
 src/value.c | 18 ++++++++++++++++--
 3 files changed, 20 insertions(+), 2 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index dfc3186..cada49b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,9 @@
 
        * src/value.c (parse_criteria): Anchor only at start.  Fixes
        #661800.
+       (parse_criteria): Handle criteria "=" and "<>" (with no value
+       after the operator) special.  These test for empty and non-empty
+       values.  Fixes #686156.
 
        * src/gutils.c (gnm_regcomp_XL): Split argument "full" into
        "anchor_start" and "anchor_end".  All callers changed.
diff --git a/NEWS b/NEWS
index c53dd15..f68e454 100644
--- a/NEWS
+++ b/NEWS
@@ -46,6 +46,7 @@ Morten:
        * Fix XL import of names with array constants.  [#654211]
        * Fix XL import of booleans/error/empties in array constants.
        * Fix database criteria anchoring.  [#661800]
+       * Fix database criterias "=" and "<>" for emptiness test.  [#686156]
 
 --------------------------------------------------------------------------
 Gnumeric 1.12.1
diff --git a/src/value.c b/src/value.c
index cc9d697..517cd04 100644
--- a/src/value.c
+++ b/src/value.c
@@ -1573,6 +1573,18 @@ criteria_test_match (GnmValue const *x, GnmCriteria *crit)
                GO_REG_OK;
 }
 
+static gboolean
+criteria_test_empty (GnmValue const *x, GnmCriteria *crit)
+{
+       return VALUE_IS_EMPTY (x);
+}
+
+static gboolean
+criteria_test_nonempty (GnmValue const *x, GnmCriteria *crit)
+{
+       return !VALUE_IS_EMPTY (x);
+}
+
 /*
  * Finds a column index of a field.
  */
@@ -1718,13 +1730,15 @@ parse_criteria (GnmValue const *crit_val, GODateConventions const *date_conv)
                res->fun = criteria_test_greater_or_equal;
                len = 2;
        } else if (strncmp (criteria, "<>", 2) == 0) {
-               res->fun = criteria_test_unequal;
+               /* "<>" by itself is special: */
+               res->fun = (criteria[2] == 0) ? criteria_test_nonempty : criteria_test_unequal;
                len = 2;
        } else if (*criteria == '<') {
                res->fun = criteria_test_less;
                len = 1;
        } else if (*criteria == '=') {
-               res->fun = criteria_test_equal;
+               /* "=" by itself is special: */
+               res->fun = (criteria[1] == 0) ? criteria_test_empty : criteria_test_equal;
                len = 1;
        } else if (*criteria == '>') {
                res->fun = criteria_test_greater;