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Experimental new implementation of dictionary comparison. This

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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).
This commit is contained in:
Guido van Rossum 1996-12-05 21:55:55 +00:00
parent 685a38ea94
commit a0a69b8b42
2 changed files with 126 additions and 0 deletions
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63
Objects/mappingobject.c
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@ -642,6 +642,67 @@ getmappingitems(mp)
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 @@ mapping_compare(a, b)
return res;
}
#endif /* !NEWCMP */
static object *
mapping_has_key(mp, args)
register mappingobject *mp;