Issue #19361: JSON decoder now raises JSONDecodeError instead of ValueError.
diff --git a/Doc/library/json.rst b/Doc/library/json.rst
index 0dad6ad..49bb090 100644
--- a/Doc/library/json.rst
+++ b/Doc/library/json.rst
@@ -250,7 +250,7 @@
will be passed to the constructor of the class.
If the data being deserialized is not a valid JSON document, a
- :exc:`ValueError` will be raised.
+ :exc:`JSONDecodeError` will be raised.
.. function:: loads(s, encoding=None, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)
@@ -261,7 +261,7 @@
*encoding* which is ignored and deprecated.
If the data being deserialized is not a valid JSON document, a
- :exc:`ValueError` will be raised.
+ :exc:`JSONDecodeError` will be raised.
Encoders and Decoders
---------------------
@@ -334,13 +334,16 @@
``'\n'``, ``'\r'`` and ``'\0'``.
If the data being deserialized is not a valid JSON document, a
- :exc:`ValueError` will be raised.
+ :exc:`JSONDecodeError` will be raised.
.. method:: decode(s)
Return the Python representation of *s* (a :class:`str` instance
containing a JSON document)
+ :exc:`JSONDecodeError` will be raised if the given JSON document is not
+ valid.
+
.. method:: raw_decode(s)
Decode a JSON document from *s* (a :class:`str` beginning with a
@@ -469,6 +472,36 @@
mysocket.write(chunk)
+Exceptions
+----------
+
+.. exception:: JSONDecodeError(msg, doc, pos, end=None)
+
+ Subclass of :exc:`ValueError` with the following additional attributes:
+
+ .. attribute:: msg
+
+ The unformatted error message.
+
+ .. attribute:: doc
+
+ The JSON document being parsed.
+
+ .. attribute:: pos
+
+ The start index of *doc* where parsing failed.
+
+ .. attribute:: lineno
+
+ The line corresponding to *pos*.
+
+ .. attribute:: colno
+
+ The column corresponding to *pos*.
+
+ .. versionadded:: 3.5
+
+
Standard Compliance and Interoperability
----------------------------------------
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
index ae18276..453433d 100644
--- a/Doc/whatsnew/3.5.rst
+++ b/Doc/whatsnew/3.5.rst
@@ -230,6 +230,9 @@
of dictionaries alphabetically by key. (Contributed by Berker Peksag in
:issue:`21650`.)
+* JSON decoder now raises :exc:`json.JSONDecodeError` instead of
+ :exc:`ValueError`. (Contributed by Serhiy Storchaka in :issue:`19361`.)
+
os
--
diff --git a/Lib/json/__init__.py b/Lib/json/__init__.py
index 94f7d8c..6ce9880 100644
--- a/Lib/json/__init__.py
+++ b/Lib/json/__init__.py
@@ -98,12 +98,12 @@
__version__ = '2.0.9'
__all__ = [
'dump', 'dumps', 'load', 'loads',
- 'JSONDecoder', 'JSONEncoder',
+ 'JSONDecoder', 'JSONDecodeError', 'JSONEncoder',
]
__author__ = 'Bob Ippolito <bob@redivi.com>'
-from .decoder import JSONDecoder
+from .decoder import JSONDecoder, JSONDecodeError
from .encoder import JSONEncoder
_default_encoder = JSONEncoder(
@@ -311,7 +311,8 @@
raise TypeError('the JSON object must be str, not {!r}'.format(
s.__class__.__name__))
if s.startswith(u'\ufeff'):
- raise ValueError("Unexpected UTF-8 BOM (decode using utf-8-sig)")
+ raise JSONDecodeError("Unexpected UTF-8 BOM (decode using utf-8-sig)",
+ s, 0)
if (cls is None and object_hook is None and
parse_int is None and parse_float is None and
parse_constant is None and object_pairs_hook is None and not kw):
diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
index 59e5f41..0f03f20 100644
--- a/Lib/json/decoder.py
+++ b/Lib/json/decoder.py
@@ -8,7 +8,7 @@
except ImportError:
c_scanstring = None
-__all__ = ['JSONDecoder']
+__all__ = ['JSONDecoder', 'JSONDecodeError']
FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL
@@ -17,32 +17,30 @@
NegInf = float('-inf')
-def linecol(doc, pos):
- if isinstance(doc, bytes):
- newline = b'\n'
- else:
- newline = '\n'
- lineno = doc.count(newline, 0, pos) + 1
- if lineno == 1:
- colno = pos + 1
- else:
- colno = pos - doc.rindex(newline, 0, pos)
- return lineno, colno
+class JSONDecodeError(ValueError):
+ """Subclass of ValueError with the following additional properties:
+ msg: The unformatted error message
+ doc: The JSON document being parsed
+ pos: The start index of doc where parsing failed
+ lineno: The line corresponding to pos
+ colno: The column corresponding to pos
-def errmsg(msg, doc, pos, end=None):
- # Note that this function is called from _json
- lineno, colno = linecol(doc, pos)
- if end is None:
- fmt = '{0}: line {1} column {2} (char {3})'
- return fmt.format(msg, lineno, colno, pos)
- #fmt = '%s: line %d column %d (char %d)'
- #return fmt % (msg, lineno, colno, pos)
- endlineno, endcolno = linecol(doc, end)
- fmt = '{0}: line {1} column {2} - line {3} column {4} (char {5} - {6})'
- return fmt.format(msg, lineno, colno, endlineno, endcolno, pos, end)
- #fmt = '%s: line %d column %d - line %d column %d (char %d - %d)'
- #return fmt % (msg, lineno, colno, endlineno, endcolno, pos, end)
+ """
+ # Note that this exception is used from _json
+ def __init__(self, msg, doc, pos):
+ lineno = doc.count('\n', 0, pos) + 1
+ colno = pos - doc.rfind('\n', 0, pos)
+ errmsg = '%s: line %d column %d (char %d)' % (msg, lineno, colno, pos)
+ ValueError.__init__(self, errmsg)
+ self.msg = msg
+ self.doc = doc
+ self.pos = pos
+ self.lineno = lineno
+ self.colno = colno
+
+ def __reduce__(self):
+ return self.__class__, (self.msg, self.doc, self.pos)
_CONSTANTS = {
@@ -66,7 +64,7 @@
except ValueError:
pass
msg = "Invalid \\uXXXX escape"
- raise ValueError(errmsg(msg, s, pos))
+ raise JSONDecodeError(msg, s, pos)
def py_scanstring(s, end, strict=True,
_b=BACKSLASH, _m=STRINGCHUNK.match):
@@ -84,8 +82,7 @@
while 1:
chunk = _m(s, end)
if chunk is None:
- raise ValueError(
- errmsg("Unterminated string starting at", s, begin))
+ raise JSONDecodeError("Unterminated string starting at", s, begin)
end = chunk.end()
content, terminator = chunk.groups()
# Content is contains zero or more unescaped string characters
@@ -99,22 +96,21 @@
if strict:
#msg = "Invalid control character %r at" % (terminator,)
msg = "Invalid control character {0!r} at".format(terminator)
- raise ValueError(errmsg(msg, s, end))
+ raise JSONDecodeError(msg, s, end)
else:
_append(terminator)
continue
try:
esc = s[end]
except IndexError:
- raise ValueError(
- errmsg("Unterminated string starting at", s, begin))
+ raise JSONDecodeError("Unterminated string starting at", s, begin)
# If not a unicode escape sequence, must be in the lookup table
if esc != 'u':
try:
char = _b[esc]
except KeyError:
msg = "Invalid \\escape: {0!r}".format(esc)
- raise ValueError(errmsg(msg, s, end))
+ raise JSONDecodeError(msg, s, end)
end += 1
else:
uni = _decode_uXXXX(s, end)
@@ -163,8 +159,8 @@
pairs = object_hook(pairs)
return pairs, end + 1
elif nextchar != '"':
- raise ValueError(errmsg(
- "Expecting property name enclosed in double quotes", s, end))
+ raise JSONDecodeError(
+ "Expecting property name enclosed in double quotes", s, end)
end += 1
while True:
key, end = scanstring(s, end, strict)
@@ -174,7 +170,7 @@
if s[end:end + 1] != ':':
end = _w(s, end).end()
if s[end:end + 1] != ':':
- raise ValueError(errmsg("Expecting ':' delimiter", s, end))
+ raise JSONDecodeError("Expecting ':' delimiter", s, end)
end += 1
try:
@@ -188,7 +184,7 @@
try:
value, end = scan_once(s, end)
except StopIteration as err:
- raise ValueError(errmsg("Expecting value", s, err.value)) from None
+ raise JSONDecodeError("Expecting value", s, err.value) from None
pairs_append((key, value))
try:
nextchar = s[end]
@@ -202,13 +198,13 @@
if nextchar == '}':
break
elif nextchar != ',':
- raise ValueError(errmsg("Expecting ',' delimiter", s, end - 1))
+ raise JSONDecodeError("Expecting ',' delimiter", s, end - 1)
end = _w(s, end).end()
nextchar = s[end:end + 1]
end += 1
if nextchar != '"':
- raise ValueError(errmsg(
- "Expecting property name enclosed in double quotes", s, end - 1))
+ raise JSONDecodeError(
+ "Expecting property name enclosed in double quotes", s, end - 1)
if object_pairs_hook is not None:
result = object_pairs_hook(pairs)
return result, end
@@ -232,7 +228,7 @@
try:
value, end = scan_once(s, end)
except StopIteration as err:
- raise ValueError(errmsg("Expecting value", s, err.value)) from None
+ raise JSONDecodeError("Expecting value", s, err.value) from None
_append(value)
nextchar = s[end:end + 1]
if nextchar in _ws:
@@ -242,7 +238,7 @@
if nextchar == ']':
break
elif nextchar != ',':
- raise ValueError(errmsg("Expecting ',' delimiter", s, end - 1))
+ raise JSONDecodeError("Expecting ',' delimiter", s, end - 1)
try:
if s[end] in _ws:
end += 1
@@ -343,7 +339,7 @@
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
end = _w(s, end).end()
if end != len(s):
- raise ValueError(errmsg("Extra data", s, end, len(s)))
+ raise JSONDecodeError("Extra data", s, end)
return obj
def raw_decode(self, s, idx=0):
@@ -358,5 +354,5 @@
try:
obj, end = self.scan_once(s, idx)
except StopIteration as err:
- raise ValueError(errmsg("Expecting value", s, err.value)) from None
+ raise JSONDecodeError("Expecting value", s, err.value) from None
return obj, end
diff --git a/Lib/test/test_json/__init__.py b/Lib/test/test_json/__init__.py
index 2cf1032..0807e6f 100644
--- a/Lib/test/test_json/__init__.py
+++ b/Lib/test/test_json/__init__.py
@@ -9,12 +9,15 @@
# import json with and without accelerations
cjson = support.import_fresh_module('json', fresh=['_json'])
pyjson = support.import_fresh_module('json', blocked=['_json'])
+# JSONDecodeError is cached inside the _json module
+cjson.JSONDecodeError = cjson.decoder.JSONDecodeError = json.JSONDecodeError
# create two base classes that will be used by the other tests
class PyTest(unittest.TestCase):
json = pyjson
loads = staticmethod(pyjson.loads)
dumps = staticmethod(pyjson.dumps)
+ JSONDecodeError = staticmethod(pyjson.JSONDecodeError)
@unittest.skipUnless(cjson, 'requires _json')
class CTest(unittest.TestCase):
@@ -22,6 +25,7 @@
json = cjson
loads = staticmethod(cjson.loads)
dumps = staticmethod(cjson.dumps)
+ JSONDecodeError = staticmethod(cjson.JSONDecodeError)
# test PyTest and CTest checking if the functions come from the right module
class TestPyTest(PyTest):
diff --git a/Lib/test/test_json/test_decode.py b/Lib/test/test_json/test_decode.py
index 591b2e2..cc83b45 100644
--- a/Lib/test/test_json/test_decode.py
+++ b/Lib/test/test_json/test_decode.py
@@ -63,12 +63,12 @@
def test_extra_data(self):
s = '[1, 2, 3]5'
msg = 'Extra data'
- self.assertRaisesRegex(ValueError, msg, self.loads, s)
+ self.assertRaisesRegex(self.JSONDecodeError, msg, self.loads, s)
def test_invalid_escape(self):
s = '["abc\\y"]'
msg = 'escape'
- self.assertRaisesRegex(ValueError, msg, self.loads, s)
+ self.assertRaisesRegex(self.JSONDecodeError, msg, self.loads, s)
def test_invalid_input_type(self):
msg = 'the JSON object must be str'
@@ -80,10 +80,10 @@
def test_string_with_utf8_bom(self):
# see #18958
bom_json = "[1,2,3]".encode('utf-8-sig').decode('utf-8')
- with self.assertRaises(ValueError) as cm:
+ with self.assertRaises(self.JSONDecodeError) as cm:
self.loads(bom_json)
self.assertIn('BOM', str(cm.exception))
- with self.assertRaises(ValueError) as cm:
+ with self.assertRaises(self.JSONDecodeError) as cm:
self.json.load(StringIO(bom_json))
self.assertIn('BOM', str(cm.exception))
# make sure that the BOM is not detected in the middle of a string
diff --git a/Lib/test/test_json/test_fail.py b/Lib/test/test_json/test_fail.py
index 7caafdb..95ff5b8 100644
--- a/Lib/test/test_json/test_fail.py
+++ b/Lib/test/test_json/test_fail.py
@@ -87,7 +87,7 @@
continue
try:
self.loads(doc)
- except ValueError:
+ except self.JSONDecodeError:
pass
else:
self.fail("Expected failure for fail{0}.json: {1!r}".format(idx, doc))
@@ -124,10 +124,16 @@
('"spam', 'Unterminated string starting at', 0),
]
for data, msg, idx in test_cases:
- self.assertRaisesRegex(ValueError,
- r'^{0}: line 1 column {1} \(char {2}\)'.format(
- re.escape(msg), idx + 1, idx),
- self.loads, data)
+ with self.assertRaises(self.JSONDecodeError) as cm:
+ self.loads(data)
+ err = cm.exception
+ self.assertEqual(err.msg, msg)
+ self.assertEqual(err.pos, idx)
+ self.assertEqual(err.lineno, 1)
+ self.assertEqual(err.colno, idx + 1)
+ self.assertEqual(str(err),
+ '%s: line 1 column %d (char %d)' %
+ (msg, idx + 1, idx))
def test_unexpected_data(self):
test_cases = [
@@ -154,10 +160,16 @@
('{"spam":42,}', 'Expecting property name enclosed in double quotes', 11),
]
for data, msg, idx in test_cases:
- self.assertRaisesRegex(ValueError,
- r'^{0}: line 1 column {1} \(char {2}\)'.format(
- re.escape(msg), idx + 1, idx),
- self.loads, data)
+ with self.assertRaises(self.JSONDecodeError) as cm:
+ self.loads(data)
+ err = cm.exception
+ self.assertEqual(err.msg, msg)
+ self.assertEqual(err.pos, idx)
+ self.assertEqual(err.lineno, 1)
+ self.assertEqual(err.colno, idx + 1)
+ self.assertEqual(str(err),
+ '%s: line 1 column %d (char %d)' %
+ (msg, idx + 1, idx))
def test_extra_data(self):
test_cases = [
@@ -171,11 +183,16 @@
('"spam",42', 'Extra data', 6),
]
for data, msg, idx in test_cases:
- self.assertRaisesRegex(ValueError,
- r'^{0}: line 1 column {1} - line 1 column {2}'
- r' \(char {3} - {4}\)'.format(
- re.escape(msg), idx + 1, len(data) + 1, idx, len(data)),
- self.loads, data)
+ with self.assertRaises(self.JSONDecodeError) as cm:
+ self.loads(data)
+ err = cm.exception
+ self.assertEqual(err.msg, msg)
+ self.assertEqual(err.pos, idx)
+ self.assertEqual(err.lineno, 1)
+ self.assertEqual(err.colno, idx + 1)
+ self.assertEqual(str(err),
+ '%s: line 1 column %d (char %d)' %
+ (msg, idx + 1, idx))
def test_linecol(self):
test_cases = [
@@ -185,10 +202,16 @@
('\n \n\n !', 4, 6, 10),
]
for data, line, col, idx in test_cases:
- self.assertRaisesRegex(ValueError,
- r'^Expecting value: line {0} column {1}'
- r' \(char {2}\)$'.format(line, col, idx),
- self.loads, data)
+ with self.assertRaises(self.JSONDecodeError) as cm:
+ self.loads(data)
+ err = cm.exception
+ self.assertEqual(err.msg, 'Expecting value')
+ self.assertEqual(err.pos, idx)
+ self.assertEqual(err.lineno, line)
+ self.assertEqual(err.colno, col)
+ self.assertEqual(str(err),
+ 'Expecting value: line %s column %d (char %d)' %
+ (line, col, idx))
class TestPyFail(TestFail, PyTest): pass
class TestCFail(TestFail, CTest): pass
diff --git a/Lib/test/test_json/test_scanstring.py b/Lib/test/test_json/test_scanstring.py
index 07f4358..2d3ee8a 100644
--- a/Lib/test/test_json/test_scanstring.py
+++ b/Lib/test/test_json/test_scanstring.py
@@ -129,7 +129,7 @@
'"\\ud834\\u0X20"',
]
for s in bad_escapes:
- with self.assertRaises(ValueError, msg=s):
+ with self.assertRaises(self.JSONDecodeError, msg=s):
scanstring(s, 1, True)
def test_overflow(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index 45d27be..7845428 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -218,6 +218,8 @@
Library
-------
+- Issue #19361: JSON decoder now raises JSONDecodeError instead of ValueError.
+
- Issue #18518: timeit now rejects statements which can't be compiled outside
a function or a loop (e.g. "return" or "break").
diff --git a/Modules/_json.c b/Modules/_json.c
index 9430990..0bf475e 100644
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -312,23 +312,22 @@
static void
raise_errmsg(char *msg, PyObject *s, Py_ssize_t end)
{
- /* Use the Python function json.decoder.errmsg to raise a nice
- looking ValueError exception */
- static PyObject *errmsg_fn = NULL;
- PyObject *pymsg;
- if (errmsg_fn == NULL) {
+ /* Use JSONDecodeError exception to raise a nice looking ValueError subclass */
+ static PyObject *JSONDecodeError = NULL;
+ PyObject *exc;
+ if (JSONDecodeError == NULL) {
PyObject *decoder = PyImport_ImportModule("json.decoder");
if (decoder == NULL)
return;
- errmsg_fn = PyObject_GetAttrString(decoder, "errmsg");
+ JSONDecodeError = PyObject_GetAttrString(decoder, "JSONDecodeError");
Py_DECREF(decoder);
- if (errmsg_fn == NULL)
+ if (JSONDecodeError == NULL)
return;
}
- pymsg = PyObject_CallFunction(errmsg_fn, "(zOn)", msg, s, end);
- if (pymsg) {
- PyErr_SetObject(PyExc_ValueError, pymsg);
- Py_DECREF(pymsg);
+ exc = PyObject_CallFunction(JSONDecodeError, "(zOn)", msg, s, end);
+ if (exc) {
+ PyErr_SetObject(JSONDecodeError, exc);
+ Py_DECREF(exc);
}
}