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Tighten-up the lookkey() logic and beautify the code a bit.

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Use less code by moving many of the steps from the initial
lookup into the main search loop.

Beautify the code but keep the overall logic unchanged.
This commit is contained in:
Raymond Hettinger 2013-08-28 20:59:31 -07:00
parent 7c1017bfee
commit afe890923f
1 changed files with 51 additions and 96 deletions
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147
Objects/setobject.c
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@ -79,65 +79,53 @@ NULL if the rich comparison returns an error.
static setentry *
set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash)
{
size_t i, j; /* Unsigned for defined overflow behavior. */
size_t perturb;
setentry *freeslot;
size_t mask = so->mask;
setentry *table = so->table;
setentry *freeslot = NULL;
setentry *entry;
size_t perturb = hash;
size_t mask = so->mask;
size_t i = (size_t)hash & mask; /* Unsigned for defined overflow behavior. */
size_t j = i;
int cmp;
PyObject *startkey;
i = (size_t)hash & mask;
entry = &table[i];
if (entry->key == NULL || entry->key == key)
if (entry->key == NULL)
return entry;
if (entry->hash == hash && entry->key != dummy) {
startkey = entry->key;
Py_INCREF(startkey);
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
Py_DECREF(startkey);
if (cmp < 0)
return NULL;
if (table == so->table && entry->key == startkey) {
if (cmp > 0)
return entry;
}
else {
/* Start over if the compare altered the set */
return set_lookkey(so, key, hash);
}
}
freeslot = (entry->key == dummy) ? entry : NULL;
/* In the loop, key == dummy is by far (factor of 100s)
the least likely outcome, so test for that last. */
j = i;
perturb = hash;
while (1) {
j ^= 1;
entry = &table[j];
if (entry->key == NULL) {
if (freeslot != NULL)
entry = freeslot;
break;
}
if (entry->key == key)
break;
return entry;
if (entry->hash == hash && entry->key != dummy) {
startkey = entry->key;
PyObject *startkey = entry->key;
Py_INCREF(startkey);
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
Py_DECREF(startkey);
if (cmp < 0)
return NULL;
if (table == so->table && entry->key == startkey) {
if (cmp > 0)
break;
}
else {
if (table != so->table || entry->key != startkey)
return set_lookkey(so, key, hash);
}
if (cmp > 0)
return entry;
}
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
entry = &table[j ^ 1];
if (entry->key == NULL)
break;
if (entry->key == key)
return entry;
if (entry->hash == hash && entry->key != dummy) {
PyObject *startkey = entry->key;
Py_INCREF(startkey);
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
Py_DECREF(startkey);
if (cmp < 0)
return NULL;
if (table != so->table || entry->key != startkey)
return set_lookkey(so, key, hash);
if (cmp > 0)
return entry;
}
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
@ -147,33 +135,10 @@ set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash)
perturb >>= PERTURB_SHIFT;
entry = &table[j];
if (entry->key == NULL) {
if (freeslot != NULL)
entry = freeslot;
if (entry->key == NULL)
break;
}
if (entry->key == key)
break;
if (entry->hash == hash && entry->key != dummy) {
startkey = entry->key;
Py_INCREF(startkey);
cmp = PyObject_RichCompareBool(startkey, key, Py_EQ);
Py_DECREF(startkey);
if (cmp < 0)
return NULL;
if (table == so->table && entry->key == startkey) {
if (cmp > 0)
break;
}
else {
return set_lookkey(so, key, hash);
}
}
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
}
return entry;
return freeslot == NULL ? entry : freeslot;
}
/*
@ -184,12 +149,13 @@ set_lookkey(PySetObject *so, PyObject *key, Py_hash_t hash)
static setentry *
set_lookkey_unicode(PySetObject *so, PyObject *key, Py_hash_t hash)
{
size_t i, j; /* Unsigned for defined overflow behavior. */
size_t perturb;
setentry *freeslot;
size_t mask = so->mask;
setentry *table = so->table;
setentry *freeslot = NULL;
setentry *entry;
size_t perturb = hash;
size_t mask = so->mask;
size_t i = (size_t)hash & mask;
size_t j = i;
/* Make sure this function doesn't have to handle non-unicode keys,
including subclasses of str; e.g., one reason to subclass
@ -200,25 +166,22 @@ set_lookkey_unicode(PySetObject *so, PyObject *key, Py_hash_t hash)
return set_lookkey(so, key, hash);
}
i = (size_t)hash & mask;
entry = &table[i];
if (entry->key == NULL || entry->key == key)
if (entry->key == NULL)
return entry;
if (entry->key == dummy)
freeslot = entry;
else {
if (entry->hash == hash && unicode_eq(entry->key, key))
return entry;
freeslot = NULL;
}
j = i;
perturb = hash;
while (1) {
j ^= 1;
entry = &table[j];
if (entry->key == key
|| (entry->hash == hash
&& entry->key != dummy
&& unicode_eq(entry->key, key)))
return entry;
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
entry = &table[j ^ 1];
if (entry->key == NULL)
return freeslot == NULL ? entry : freeslot;
break;
if (entry->key == key
|| (entry->hash == hash
&& entry->key != dummy
@ -233,17 +196,9 @@ set_lookkey_unicode(PySetObject *so, PyObject *key, Py_hash_t hash)
entry = &table[j];
if (entry->key == NULL)
return freeslot == NULL ? entry : freeslot;
if (entry->key == key
|| (entry->hash == hash
&& entry->key != dummy
&& unicode_eq(entry->key, key)))
return entry;
if (entry->key == dummy && freeslot == NULL)
freeslot = entry;
break;
}
assert(0); /* NOT REACHED */
return 0;
return freeslot == NULL ? entry : freeslot;
}
/*