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Issue #10160: Speed up operator.attrgetter. Patch by Christos Georgiou.

This commit is contained in:
Antoine Pitrou 2010-10-31 15:26:04 +00:00
parent 65b4af34d7
commit e974571d36
4 changed files with 112 additions and 30 deletions
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2
Doc/library/operator.rst
View File

@ -336,6 +336,8 @@ expect a function argument.
b.date)``. Equivalent to::
def attrgetter(*items):
if any(not isinstance(item, str) for item in items):
raise TypeError('attribute name must be a string')
if len(items) == 1:
attr = items[0]
def g(obj):

9
Lib/test/test_operator.py
View File

@ -275,8 +275,7 @@ class OperatorTestCase(unittest.TestCase):
self.assertEqual(f(a), 'arthur')
f = operator.attrgetter('rank')
self.assertRaises(AttributeError, f, a)
f = operator.attrgetter(2)
self.assertRaises(TypeError, f, a)
self.assertRaises(TypeError, operator.attrgetter, 2)
self.assertRaises(TypeError, operator.attrgetter)
# multiple gets
@ -285,7 +284,7 @@ class OperatorTestCase(unittest.TestCase):
record.y = 'Y'
record.z = 'Z'
self.assertEqual(operator.attrgetter('x','z','y')(record), ('X', 'Z', 'Y'))
self.assertRaises(TypeError, operator.attrgetter('x', (), 'y'), record)
self.assertRaises(TypeError, operator.attrgetter, ('x', (), 'y'))
class C(object):
def __getattr__(self, name):
@ -304,6 +303,10 @@ class OperatorTestCase(unittest.TestCase):
self.assertEqual(f(a), ('arthur', 'thomas'))
f = operator.attrgetter('name', 'child.name', 'child.child.name')
self.assertRaises(AttributeError, f, a)
f = operator.attrgetter('child.')
self.assertRaises(AttributeError, f, a)
f = operator.attrgetter('.child')
self.assertRaises(AttributeError, f, a)
a.child.child = A()
a.child.child.name = 'johnson'

2
Misc/NEWS
View File

@ -59,6 +59,8 @@ Core and Builtins
Library
-------
- Issue #10160: Speed up operator.attrgetter. Patch by Christos Georgiou.
- logging: Added style option to basicConfig() to allow %, {} or $-formatting.
- Issue #5729: json.dumps() now supports using a string such as '\t'

125
Modules/operator.c
View File

@ -383,7 +383,7 @@ attrgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
attrgetterobject *ag;
PyObject *attr;
Py_ssize_t nattrs;
Py_ssize_t nattrs, idx, char_idx;
if (!_PyArg_NoKeywords("attrgetter()", kwds))
return NULL;
@ -392,15 +392,92 @@ attrgetter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
if (nattrs <= 1) {
if (!PyArg_UnpackTuple(args, "attrgetter", 1, 1, &attr))
return NULL;
} else
attr = args;
}
attr = PyTuple_New(nattrs);
if (attr == NULL)
return NULL;
/* prepare attr while checking args */
for (idx = 0; idx < nattrs; ++idx) {
PyObject *item = PyTuple_GET_ITEM(args, idx);
Py_ssize_t item_len;
Py_UNICODE *item_buffer;
int dot_count;
if (!PyUnicode_Check(item)) {
PyErr_SetString(PyExc_TypeError,
"attribute name must be a string");
Py_DECREF(attr);
return NULL;
}
item_len = PyUnicode_GET_SIZE(item);
item_buffer = PyUnicode_AS_UNICODE(item);
/* check whethere the string is dotted */
dot_count = 0;
for (char_idx = 0; char_idx < item_len; ++char_idx) {
if (item_buffer[char_idx] == (Py_UNICODE)'.')
++dot_count;
}
if (dot_count == 0) {
Py_INCREF(item);
PyUnicode_InternInPlace(&item);
PyTuple_SET_ITEM(attr, idx, item);
} else { /* make it a tuple of non-dotted attrnames */
PyObject *attr_chain = PyTuple_New(dot_count + 1);
PyObject *attr_chain_item;
if (attr_chain == NULL) {
Py_DECREF(attr);
return NULL;
}
Py_ssize_t unibuff_from = 0;
Py_ssize_t unibuff_till = 0;
Py_ssize_t attr_chain_idx = 0;
for (; dot_count > 0; --dot_count) {
while (item_buffer[unibuff_till] != (Py_UNICODE)'.') {
++unibuff_till;
}
attr_chain_item = PyUnicode_FromUnicode(
item_buffer + unibuff_from,
unibuff_till - unibuff_from);
if (attr_chain_item == NULL) {
Py_DECREF(attr_chain);
Py_DECREF(attr);
return NULL;
}
PyUnicode_InternInPlace(&attr_chain_item);
PyTuple_SET_ITEM(attr_chain, attr_chain_idx, attr_chain_item);
++attr_chain_idx;
unibuff_till = unibuff_from = unibuff_till + 1;
}
/* now add the last dotless name */
attr_chain_item = PyUnicode_FromUnicode(
item_buffer + unibuff_from,
item_len - unibuff_from);
if (attr_chain_item == NULL) {
Py_DECREF(attr_chain);
Py_DECREF(attr);
return NULL;
}
PyUnicode_InternInPlace(&attr_chain_item);
PyTuple_SET_ITEM(attr_chain, attr_chain_idx, attr_chain_item);
PyTuple_SET_ITEM(attr, idx, attr_chain);
}
}
/* create attrgetterobject structure */
ag = PyObject_GC_New(attrgetterobject, &attrgetter_type);
if (ag == NULL)
if (ag == NULL) {
Py_DECREF(attr);
return NULL;
}
Py_INCREF(attr);
ag->attr = attr;
ag->nattrs = nattrs;
@ -426,33 +503,31 @@ attrgetter_traverse(attrgetterobject *ag, visitproc visit, void *arg)
static PyObject *
dotted_getattr(PyObject *obj, PyObject *attr)
{
char *s, *p;
PyObject *newobj;
if (!PyUnicode_Check(attr)) {
PyErr_SetString(PyExc_TypeError,
"attribute name must be a string");
return NULL;
}
/* attr is either a tuple or instance of str.
Ensured by the setup code of attrgetter_new */
if (PyTuple_CheckExact(attr)) { /* chained getattr */
Py_ssize_t name_idx = 0, name_count;
PyObject *attr_name;
s = _PyUnicode_AsString(attr);
name_count = PyTuple_GET_SIZE(attr);
Py_INCREF(obj);
for (;;) {
PyObject *newobj, *str;
p = strchr(s, '.');
str = p ? PyUnicode_FromStringAndSize(s, (p-s)) :
PyUnicode_FromString(s);
if (str == NULL) {
for (name_idx = 0; name_idx < name_count; ++name_idx) {
attr_name = PyTuple_GET_ITEM(attr, name_idx);
newobj = PyObject_GetAttr(obj, attr_name);
Py_DECREF(obj);
if (newobj == NULL) {
return NULL;
}
newobj = PyObject_GetAttr(obj, str);
Py_DECREF(str);
Py_DECREF(obj);
/* here */
obj = newobj;
}
} else { /* single getattr */
newobj = PyObject_GetAttr(obj, attr);
if (newobj == NULL)
return NULL;
obj = newobj;
if (p == NULL) break;
s = p+1;
}
return obj;
@ -466,8 +541,8 @@ attrgetter_call(attrgetterobject *ag, PyObject *args, PyObject *kw)
if (!PyArg_UnpackTuple(args, "attrgetter", 1, 1, &obj))
return NULL;
if (ag->nattrs == 1)
return dotted_getattr(obj, ag->attr);
if (ag->nattrs == 1) /* ag->attr is always a tuple */
return dotted_getattr(obj, PyTuple_GET_ITEM(ag->attr, 0));
assert(PyTuple_Check(ag->attr));
assert(PyTuple_GET_SIZE(ag->attr) == nattrs);