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Unified Diff: Lib/json/decoder.py

Issue 19361: Specialize exceptions thrown by JSON parser
Patch Set: Created 4 years, 9 months ago
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--- a/Lib/json/decoder.py Sun Nov 30 20:39:04 2014 +0200
+++ b/Lib/json/decoder.py Mon Dec 01 00:17:14 2014 +0200
@@ -8,7 +8,7 @@ try:
except ImportError:
c_scanstring = None
-__all__ = ['JSONDecoder']
+__all__ = ['JSONDecoder', 'JSONDecodeError']
FLAGS = re.VERBOSE | re.MULTILINE | re.DOTALL
@@ -17,32 +17,30 @@ PosInf = float('inf')
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 @@ def _decode_uXXXX(s, pos):
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 @@ def py_scanstring(s, end, strict=True,
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 @@ def py_scanstring(s, end, strict=True,
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 @@ def JSONObject(s_and_end, strict, scan_o
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 @@ def JSONObject(s_and_end, strict, scan_o
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 @@ def JSONObject(s_and_end, strict, scan_o
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 @@ def JSONObject(s_and_end, strict, scan_o
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 @@ def JSONArray(s_and_end, scan_once, _w=W
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 @@ def JSONArray(s_and_end, scan_once, _w=W
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 @@ class JSONDecoder(object):
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 @@ class JSONDecoder(object):
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
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