Experimental new implementation of dictionary comparison. This
defines that a shorter dictionary is always smaller than a longer one.
For dictionaries of the same size, the smallest differing element
determines the outcome (which yields the same results as before,
without explicit sorting).
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 274abda..023de8f 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -642,6 +642,67 @@
return mapping_items((mappingobject *)mp, (object *)NULL);
}
+#define NEWCMP
+
+#ifdef NEWCMP
+
+/* Subroutine which returns the smallest key in a for which b's value
+ is different or absent. The value is returned too, through the
+ pval argument. No reference counts are incremented. */
+
+static object *
+characterize(a, b, pval)
+ mappingobject *a;
+ mappingobject *b;
+ object **pval;
+{
+ object *diff = NULL;
+ int i;
+
+ *pval = NULL;
+ for (i = 0; i < a->ma_size; i++) {
+ if (a->ma_table[i].me_value != NULL) {
+ object *key = a->ma_table[i].me_key;
+ object *aval, *bval;
+ if (diff != NULL && cmpobject(key, diff) > 0)
+ continue;
+ aval = a->ma_table[i].me_value;
+ bval = mappinglookup((object *)b, key);
+ if (bval == NULL || cmpobject(aval, bval) != 0) {
+ diff = key;
+ *pval = aval;
+ }
+ }
+ }
+ return diff;
+}
+
+static int
+mapping_compare(a, b)
+ mappingobject *a, *b;
+{
+ object *adiff, *bdiff, *aval, *bval;
+ int res;
+
+ /* Compare lengths first */
+ if (a->ma_used < b->ma_used)
+ return -1; /* a is shorter */
+ else if (a->ma_used > b->ma_used)
+ return 1; /* b is shorter */
+ /* Same length -- check all keys */
+ adiff = characterize(a, b, &aval);
+ if (adiff == NULL)
+ return 0; /* a is a subset with the same length */
+ bdiff = characterize(b, a, &bval);
+ /* bdiff == NULL would be impossible now */
+ res = cmpobject(adiff, bdiff);
+ if (res == 0)
+ res = cmpobject(aval, bval);
+ return res;
+}
+
+#else /* !NEWCMP */
+
static int
mapping_compare(a, b)
mappingobject *a, *b;
@@ -713,6 +774,8 @@
return res;
}
+#endif /* !NEWCMP */
+
static object *
mapping_has_key(mp, args)
register mappingobject *mp;