[Python-checkins] r70471 - in python/trunk: Doc/library/json.rst Lib/json/__init__.py Lib/json/decoder.py Lib/json/tests/test_decode.py Lib/json/tests/test_unicode.py Misc/NEWS Modules/_json.c
raymond.hettinger
python-checkins at python.org
Thu Mar 19 20:19:04 CET 2009
Author: raymond.hettinger
Date: Thu Mar 19 20:19:03 2009
New Revision: 70471
Log:
Issue 5381: Add object_pairs_hook to the json module.
Modified:
python/trunk/Doc/library/json.rst
python/trunk/Lib/json/__init__.py
python/trunk/Lib/json/decoder.py
python/trunk/Lib/json/tests/test_decode.py
python/trunk/Lib/json/tests/test_unicode.py
python/trunk/Misc/NEWS
python/trunk/Modules/_json.c
Modified: python/trunk/Doc/library/json.rst
==============================================================================
--- python/trunk/Doc/library/json.rst (original)
+++ python/trunk/Doc/library/json.rst Thu Mar 19 20:19:03 2009
@@ -166,7 +166,7 @@
:func:`dump`.
-.. function:: load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
+.. function:: load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, object_pairs_hook[, **kw]]]]]]]])
Deserialize *fp* (a ``.read()``-supporting file-like object containing a JSON
document) to a Python object.
@@ -182,6 +182,17 @@
*object_hook* will be used instead of the :class:`dict`. This feature can be used
to implement custom decoders (e.g. JSON-RPC class hinting).
+ *object_pairs_hook* is an optional function that will be called with the
+ result of any object literal decode with an ordered list of pairs. The
+ return value of *object_pairs_hook* will be used instead of the
+ :class:`dict`. This feature can be used to implement custom decoders that
+ rely on the order that the key and value pairs are decoded (for example,
+ :func:`collections.OrderedDict` will remember the order of insertion). If
+ *object_hook* is also defined, the *object_pairs_hook* takes priority.
+
+ .. versionchanged:: 2.7
+ Added support for *object_pairs_hook*.
+
*parse_float*, if specified, will be called with the string of every JSON
float to be decoded. By default, this is equivalent to ``float(num_str)``.
This can be used to use another datatype or parser for JSON floats
@@ -202,7 +213,7 @@
class.
-.. function:: loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
+.. function:: loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, object_pairs_hook[, **kw]]]]]]]])
Deserialize *s* (a :class:`str` or :class:`unicode` instance containing a JSON
document) to a Python object.
@@ -218,7 +229,7 @@
Encoders and decoders
---------------------
-.. class:: JSONDecoder([encoding[, object_hook[, parse_float[, parse_int[, parse_constant[, strict]]]]]])
+.. class:: JSONDecoder([encoding[, object_hook[, parse_float[, parse_int[, parse_constant[, strict[, object_pairs_hook]]]]]]])
Simple JSON decoder.
@@ -259,6 +270,17 @@
:class:`dict`. This can be used to provide custom deserializations (e.g. to
support JSON-RPC class hinting).
+ *object_pairs_hook*, if specified will be called with the result of every
+ JSON object decoded with an ordered list of pairs. The return value of
+ *object_pairs_hook* will be used instead of the :class:`dict`. This
+ feature can be used to implement custom decoders that rely on the order
+ that the key and value pairs are decoded (for example,
+ :func:`collections.OrderedDict` will remember the order of insertion). If
+ *object_hook* is also defined, the *object_pairs_hook* takes priority.
+
+ .. versionchanged:: 2.7
+ Added support for *object_pairs_hook*.
+
*parse_float*, if specified, will be called with the string of every JSON
float to be decoded. By default, this is equivalent to ``float(num_str)``.
This can be used to use another datatype or parser for JSON floats
Modified: python/trunk/Lib/json/__init__.py
==============================================================================
--- python/trunk/Lib/json/__init__.py (original)
+++ python/trunk/Lib/json/__init__.py Thu Mar 19 20:19:03 2009
@@ -238,11 +238,12 @@
**kw).encode(obj)
-_default_decoder = JSONDecoder(encoding=None, object_hook=None)
+_default_decoder = JSONDecoder(encoding=None, object_hook=None,
+ object_pairs_hook=None)
def load(fp, encoding=None, cls=None, object_hook=None, parse_float=None,
- parse_int=None, parse_constant=None, **kw):
+ parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
"""Deserialize ``fp`` (a ``.read()``-supporting file-like object containing
a JSON document) to a Python object.
@@ -265,11 +266,11 @@
return loads(fp.read(),
encoding=encoding, cls=cls, object_hook=object_hook,
parse_float=parse_float, parse_int=parse_int,
- parse_constant=parse_constant, **kw)
+ parse_constant=parse_constant, object_pairs_hook=None, **kw)
def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None,
- parse_int=None, parse_constant=None, **kw):
+ parse_int=None, parse_constant=None, object_pairs_hook=None, **kw):
"""Deserialize ``s`` (a ``str`` or ``unicode`` instance containing a JSON
document) to a Python object.
@@ -304,12 +305,14 @@
"""
if (cls is None and encoding is None and object_hook is None and
parse_int is None and parse_float is None and
- parse_constant is None and not kw):
+ parse_constant is None and object_pairs_hook is None and not kw):
return _default_decoder.decode(s)
if cls is None:
cls = JSONDecoder
if object_hook is not None:
kw['object_hook'] = object_hook
+ if object_pairs_hook is not None:
+ kw['object_pairs_hook'] = object_pairs_hook
if parse_float is not None:
kw['parse_float'] = parse_float
if parse_int is not None:
Modified: python/trunk/Lib/json/decoder.py
==============================================================================
--- python/trunk/Lib/json/decoder.py (original)
+++ python/trunk/Lib/json/decoder.py Thu Mar 19 20:19:03 2009
@@ -147,8 +147,9 @@
WHITESPACE_STR = ' \t\n\r'
def JSONObject((s, end), encoding, strict, scan_once, object_hook,
- _w=WHITESPACE.match, _ws=WHITESPACE_STR):
- pairs = {}
+ object_pairs_hook, _w=WHITESPACE.match, _ws=WHITESPACE_STR):
+ pairs = []
+ pairs_append = pairs.append
# Use a slice to prevent IndexError from being raised, the following
# check will raise a more specific ValueError if the string is empty
nextchar = s[end:end + 1]
@@ -187,7 +188,7 @@
value, end = scan_once(s, end)
except StopIteration:
raise ValueError(errmsg("Expecting object", s, end))
- pairs[key] = value
+ pairs_append((key, value))
try:
nextchar = s[end]
@@ -218,6 +219,10 @@
if nextchar != '"':
raise ValueError(errmsg("Expecting property name", s, end - 1))
+ if object_pairs_hook is not None:
+ result = object_pairs_hook(pairs)
+ return result, end
+ pairs = dict(pairs)
if object_hook is not None:
pairs = object_hook(pairs)
return pairs, end
@@ -289,7 +294,8 @@
"""
def __init__(self, encoding=None, object_hook=None, parse_float=None,
- parse_int=None, parse_constant=None, strict=True):
+ parse_int=None, parse_constant=None, strict=True,
+ object_pairs_hook=None):
"""``encoding`` determines the encoding used to interpret any ``str``
objects decoded by this instance (utf-8 by default). It has no
effect when decoding ``unicode`` objects.
@@ -320,6 +326,7 @@
"""
self.encoding = encoding
self.object_hook = object_hook
+ self.object_pairs_hook = object_pairs_hook
self.parse_float = parse_float or float
self.parse_int = parse_int or int
self.parse_constant = parse_constant or _CONSTANTS.__getitem__
Modified: python/trunk/Lib/json/tests/test_decode.py
==============================================================================
--- python/trunk/Lib/json/tests/test_decode.py (original)
+++ python/trunk/Lib/json/tests/test_decode.py Thu Mar 19 20:19:03 2009
@@ -2,6 +2,7 @@
from unittest import TestCase
import json
+from collections import OrderedDict
class TestDecode(TestCase):
def test_decimal(self):
@@ -20,3 +21,18 @@
# exercise the uncommon cases. The array cases are already covered.
rval = json.loads('{ "key" : "value" , "k":"v" }')
self.assertEquals(rval, {"key":"value", "k":"v"})
+
+ def test_object_pairs_hook(self):
+ s = '{"xkd":1, "kcw":2, "art":3, "hxm":4, "qrt":5, "pad":6, "hoy":7}'
+ p = [("xkd", 1), ("kcw", 2), ("art", 3), ("hxm", 4),
+ ("qrt", 5), ("pad", 6), ("hoy", 7)]
+ self.assertEqual(json.loads(s), eval(s))
+ self.assertEqual(json.loads(s, object_pairs_hook = lambda x: x), p)
+ od = json.loads(s, object_pairs_hook = OrderedDict)
+ self.assertEqual(od, OrderedDict(p))
+ self.assertEqual(type(od), OrderedDict)
+ # the object_pairs_hook takes priority over the object_hook
+ self.assertEqual(json.loads(s,
+ object_pairs_hook = OrderedDict,
+ object_hook = lambda x: None),
+ OrderedDict(p))
Modified: python/trunk/Lib/json/tests/test_unicode.py
==============================================================================
--- python/trunk/Lib/json/tests/test_unicode.py (original)
+++ python/trunk/Lib/json/tests/test_unicode.py Thu Mar 19 20:19:03 2009
@@ -1,6 +1,7 @@
from unittest import TestCase
import json
+from collections import OrderedDict
class TestUnicode(TestCase):
def test_encoding1(self):
@@ -54,6 +55,21 @@
s = '"\\u{0:04x}"'.format(i)
self.assertEquals(json.loads(s), u)
+ def test_object_pairs_hook_with_unicode(self):
+ s = u'{"xkd":1, "kcw":2, "art":3, "hxm":4, "qrt":5, "pad":6, "hoy":7}'
+ p = [(u"xkd", 1), (u"kcw", 2), (u"art", 3), (u"hxm", 4),
+ (u"qrt", 5), (u"pad", 6), (u"hoy", 7)]
+ self.assertEqual(json.loads(s), eval(s))
+ self.assertEqual(json.loads(s, object_pairs_hook = lambda x: x), p)
+ od = json.loads(s, object_pairs_hook = OrderedDict)
+ self.assertEqual(od, OrderedDict(p))
+ self.assertEqual(type(od), OrderedDict)
+ # the object_pairs_hook takes priority over the object_hook
+ self.assertEqual(json.loads(s,
+ object_pairs_hook = OrderedDict,
+ object_hook = lambda x: None),
+ OrderedDict(p))
+
def test_default_encoding(self):
self.assertEquals(json.loads(u'{"a": "\xe9"}'.encode('utf-8')),
{'a': u'\xe9'})
Modified: python/trunk/Misc/NEWS
==============================================================================
--- python/trunk/Misc/NEWS (original)
+++ python/trunk/Misc/NEWS Thu Mar 19 20:19:03 2009
@@ -181,6 +181,9 @@
Library
-------
+- Issue #5381: Added object_pairs_hook to the json module. This allows
+ OrderedDicts to be built by the decoder.
+
- Issue #2110: Add support for thousands separator and 'n' type
specifier to Decimal.__format__
Modified: python/trunk/Modules/_json.c
==============================================================================
--- python/trunk/Modules/_json.c (original)
+++ python/trunk/Modules/_json.c Thu Mar 19 20:19:03 2009
@@ -35,6 +35,7 @@
PyObject *encoding;
PyObject *strict;
PyObject *object_hook;
+ PyObject *pairs_hook;
PyObject *parse_float;
PyObject *parse_int;
PyObject *parse_constant;
@@ -44,6 +45,7 @@
{"encoding", T_OBJECT, offsetof(PyScannerObject, encoding), READONLY, "encoding"},
{"strict", T_OBJECT, offsetof(PyScannerObject, strict), READONLY, "strict"},
{"object_hook", T_OBJECT, offsetof(PyScannerObject, object_hook), READONLY, "object_hook"},
+ {"object_pairs_hook", T_OBJECT, offsetof(PyScannerObject, pairs_hook), READONLY, "object_pairs_hook"},
{"parse_float", T_OBJECT, offsetof(PyScannerObject, parse_float), READONLY, "parse_float"},
{"parse_int", T_OBJECT, offsetof(PyScannerObject, parse_int), READONLY, "parse_int"},
{"parse_constant", T_OBJECT, offsetof(PyScannerObject, parse_constant), READONLY, "parse_constant"},
@@ -891,6 +893,7 @@
Py_VISIT(s->encoding);
Py_VISIT(s->strict);
Py_VISIT(s->object_hook);
+ Py_VISIT(s->pairs_hook);
Py_VISIT(s->parse_float);
Py_VISIT(s->parse_int);
Py_VISIT(s->parse_constant);
@@ -906,6 +909,7 @@
Py_CLEAR(s->encoding);
Py_CLEAR(s->strict);
Py_CLEAR(s->object_hook);
+ Py_CLEAR(s->pairs_hook);
Py_CLEAR(s->parse_float);
Py_CLEAR(s->parse_int);
Py_CLEAR(s->parse_constant);
@@ -923,13 +927,17 @@
*/
char *str = PyString_AS_STRING(pystr);
Py_ssize_t end_idx = PyString_GET_SIZE(pystr) - 1;
- PyObject *rval = PyDict_New();
+ PyObject *rval;
+ PyObject *pairs;
+ PyObject *item;
PyObject *key = NULL;
PyObject *val = NULL;
char *encoding = PyString_AS_STRING(s->encoding);
int strict = PyObject_IsTrue(s->strict);
Py_ssize_t next_idx;
- if (rval == NULL)
+
+ pairs = PyList_New(0);
+ if (pairs == NULL)
return NULL;
/* skip whitespace after { */
@@ -962,11 +970,16 @@
if (val == NULL)
goto bail;
- if (PyDict_SetItem(rval, key, val) == -1)
+ item = PyTuple_Pack(2, key, val);
+ if (item == NULL)
goto bail;
-
Py_CLEAR(key);
Py_CLEAR(val);
+ if (PyList_Append(pairs, item) == -1) {
+ Py_DECREF(item);
+ goto bail;
+ }
+ Py_DECREF(item);
idx = next_idx;
/* skip whitespace before } or , */
@@ -992,6 +1005,23 @@
raise_errmsg("Expecting object", pystr, end_idx);
goto bail;
}
+
+ /* if pairs_hook is not None: rval = object_pairs_hook(pairs) */
+ if (s->pairs_hook != Py_None) {
+ val = PyObject_CallFunctionObjArgs(s->pairs_hook, pairs, NULL);
+ if (val == NULL)
+ goto bail;
+ Py_DECREF(pairs);
+ *next_idx_ptr = idx + 1;
+ return val;
+ }
+
+ rval = PyObject_CallFunctionObjArgs((PyObject *)(&PyDict_Type),
+ pairs, NULL);
+ if (rval == NULL)
+ goto bail;
+ Py_CLEAR(pairs);
+
/* if object_hook is not None: rval = object_hook(rval) */
if (s->object_hook != Py_None) {
val = PyObject_CallFunctionObjArgs(s->object_hook, rval, NULL);
@@ -1006,7 +1036,7 @@
bail:
Py_XDECREF(key);
Py_XDECREF(val);
- Py_DECREF(rval);
+ Py_XDECREF(pairs);
return NULL;
}
@@ -1021,12 +1051,16 @@
*/
Py_UNICODE *str = PyUnicode_AS_UNICODE(pystr);
Py_ssize_t end_idx = PyUnicode_GET_SIZE(pystr) - 1;
- PyObject *val = NULL;
- PyObject *rval = PyDict_New();
+ PyObject *rval;
+ PyObject *pairs;
+ PyObject *item;
PyObject *key = NULL;
+ PyObject *val = NULL;
int strict = PyObject_IsTrue(s->strict);
Py_ssize_t next_idx;
- if (rval == NULL)
+
+ pairs = PyList_New(0);
+ if (pairs == NULL)
return NULL;
/* skip whitespace after { */
@@ -1059,11 +1093,16 @@
if (val == NULL)
goto bail;
- if (PyDict_SetItem(rval, key, val) == -1)
+ item = PyTuple_Pack(2, key, val);
+ if (item == NULL)
goto bail;
-
Py_CLEAR(key);
Py_CLEAR(val);
+ if (PyList_Append(pairs, item) == -1) {
+ Py_DECREF(item);
+ goto bail;
+ }
+ Py_DECREF(item);
idx = next_idx;
/* skip whitespace before } or , */
@@ -1091,6 +1130,22 @@
goto bail;
}
+ /* if pairs_hook is not None: rval = object_pairs_hook(pairs) */
+ if (s->pairs_hook != Py_None) {
+ val = PyObject_CallFunctionObjArgs(s->pairs_hook, pairs, NULL);
+ if (val == NULL)
+ goto bail;
+ Py_DECREF(pairs);
+ *next_idx_ptr = idx + 1;
+ return val;
+ }
+
+ rval = PyObject_CallFunctionObjArgs((PyObject *)(&PyDict_Type),
+ pairs, NULL);
+ if (rval == NULL)
+ goto bail;
+ Py_CLEAR(pairs);
+
/* if object_hook is not None: rval = object_hook(rval) */
if (s->object_hook != Py_None) {
val = PyObject_CallFunctionObjArgs(s->object_hook, rval, NULL);
@@ -1105,7 +1160,7 @@
bail:
Py_XDECREF(key);
Py_XDECREF(val);
- Py_DECREF(rval);
+ Py_XDECREF(pairs);
return NULL;
}
@@ -1648,6 +1703,7 @@
s->encoding = NULL;
s->strict = NULL;
s->object_hook = NULL;
+ s->pairs_hook = NULL;
s->parse_float = NULL;
s->parse_int = NULL;
s->parse_constant = NULL;
@@ -1690,6 +1746,9 @@
s->object_hook = PyObject_GetAttrString(ctx, "object_hook");
if (s->object_hook == NULL)
goto bail;
+ s->pairs_hook = PyObject_GetAttrString(ctx, "object_pairs_hook");
+ if (s->object_hook == NULL)
+ goto bail;
s->parse_float = PyObject_GetAttrString(ctx, "parse_float");
if (s->parse_float == NULL)
goto bail;
@@ -1706,6 +1765,7 @@
Py_CLEAR(s->encoding);
Py_CLEAR(s->strict);
Py_CLEAR(s->object_hook);
+ Py_CLEAR(s->pairs_hook);
Py_CLEAR(s->parse_float);
Py_CLEAR(s->parse_int);
Py_CLEAR(s->parse_constant);
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