311 lines
10 KiB
Python
311 lines
10 KiB
Python
|
import string
|
||
|
|
import types
|
||
|
|
|
||
|
|
## json.py implements a JSON (http://json.org) reader and writer.
|
||
|
|
## Copyright (C) 2005 Patrick D. Logan
|
||
|
|
## Contact mailto:patrickdlogan@stardecisions.com
|
||
|
|
##
|
||
|
|
## This library is free software; you can redistribute it and/or
|
||
|
|
## modify it under the terms of the GNU Lesser General Public
|
||
|
|
## License as published by the Free Software Foundation; either
|
||
|
|
## version 2.1 of the License, or (at your option) any later version.
|
||
|
|
##
|
||
|
|
## This library is distributed in the hope that it will be useful,
|
||
|
|
## but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
||
|
|
## Lesser General Public License for more details.
|
||
|
|
##
|
||
|
|
## You should have received a copy of the GNU Lesser General Public
|
||
|
|
## License along with this library; if not, write to the Free Software
|
||
|
|
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||
|
|
|
||
|
|
|
||
|
|
class _StringGenerator(object):
|
||
|
|
def __init__(self, string):
|
||
|
|
self.string = string
|
||
|
|
self.index = -1
|
||
|
|
def peek(self):
|
||
|
|
i = self.index + 1
|
||
|
|
if i < len(self.string):
|
||
|
|
return self.string[i]
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
def next(self):
|
||
|
|
self.index += 1
|
||
|
|
if self.index < len(self.string):
|
||
|
|
return self.string[self.index]
|
||
|
|
else:
|
||
|
|
raise StopIteration
|
||
|
|
def all(self):
|
||
|
|
return self.string
|
||
|
|
|
||
|
|
class WriteException(Exception):
|
||
|
|
pass
|
||
|
|
|
||
|
|
class ReadException(Exception):
|
||
|
|
pass
|
||
|
|
|
||
|
|
class JsonReader(object):
|
||
|
|
hex_digits = {'A': 10,'B': 11,'C': 12,'D': 13,'E': 14,'F':15}
|
||
|
|
escapes = {'t':'\t','n':'\n','f':'\f','r':'\r','b':'\b'}
|
||
|
|
|
||
|
|
def read(self, s):
|
||
|
|
self._generator = _StringGenerator(s)
|
||
|
|
result = self._read()
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _read(self):
|
||
|
|
self._eatWhitespace()
|
||
|
|
peek = self._peek()
|
||
|
|
if peek is None:
|
||
|
|
raise ReadException, "Nothing to read: '%s'" % self._generator.all()
|
||
|
|
if peek == '{':
|
||
|
|
return self._readObject()
|
||
|
|
elif peek == '[':
|
||
|
|
return self._readArray()
|
||
|
|
elif peek == '"':
|
||
|
|
return self._readString()
|
||
|
|
elif peek == '-' or peek.isdigit():
|
||
|
|
return self._readNumber()
|
||
|
|
elif peek == 't':
|
||
|
|
return self._readTrue()
|
||
|
|
elif peek == 'f':
|
||
|
|
return self._readFalse()
|
||
|
|
elif peek == 'n':
|
||
|
|
return self._readNull()
|
||
|
|
elif peek == '/':
|
||
|
|
self._readComment()
|
||
|
|
return self._read()
|
||
|
|
else:
|
||
|
|
raise ReadException, "Input is not valid JSON: '%s'" % self._generator.all()
|
||
|
|
|
||
|
|
def _readTrue(self):
|
||
|
|
self._assertNext('t', "true")
|
||
|
|
self._assertNext('r', "true")
|
||
|
|
self._assertNext('u', "true")
|
||
|
|
self._assertNext('e', "true")
|
||
|
|
return True
|
||
|
|
|
||
|
|
def _readFalse(self):
|
||
|
|
self._assertNext('f', "false")
|
||
|
|
self._assertNext('a', "false")
|
||
|
|
self._assertNext('l', "false")
|
||
|
|
self._assertNext('s', "false")
|
||
|
|
self._assertNext('e', "false")
|
||
|
|
return False
|
||
|
|
|
||
|
|
def _readNull(self):
|
||
|
|
self._assertNext('n', "null")
|
||
|
|
self._assertNext('u', "null")
|
||
|
|
self._assertNext('l', "null")
|
||
|
|
self._assertNext('l', "null")
|
||
|
|
return None
|
||
|
|
|
||
|
|
def _assertNext(self, ch, target):
|
||
|
|
if self._next() != ch:
|
||
|
|
raise ReadException, "Trying to read %s: '%s'" % (target, self._generator.all())
|
||
|
|
|
||
|
|
def _readNumber(self):
|
||
|
|
isfloat = False
|
||
|
|
result = self._next()
|
||
|
|
peek = self._peek()
|
||
|
|
while peek is not None and (peek.isdigit() or peek == "."):
|
||
|
|
isfloat = isfloat or peek == "."
|
||
|
|
result = result + self._next()
|
||
|
|
peek = self._peek()
|
||
|
|
try:
|
||
|
|
if isfloat:
|
||
|
|
return float(result)
|
||
|
|
else:
|
||
|
|
return int(result)
|
||
|
|
except ValueError:
|
||
|
|
raise ReadException, "Not a valid JSON number: '%s'" % result
|
||
|
|
|
||
|
|
def _readString(self):
|
||
|
|
result = ""
|
||
|
|
assert self._next() == '"'
|
||
|
|
try:
|
||
|
|
while self._peek() != '"':
|
||
|
|
ch = self._next()
|
||
|
|
if ch == "\\":
|
||
|
|
ch = self._next()
|
||
|
|
if ch in 'brnft':
|
||
|
|
ch = self.escapes[ch]
|
||
|
|
elif ch == "u":
|
||
|
|
ch4096 = self._next()
|
||
|
|
ch256 = self._next()
|
||
|
|
ch16 = self._next()
|
||
|
|
ch1 = self._next()
|
||
|
|
n = 4096 * self._hexDigitToInt(ch4096)
|
||
|
|
n += 256 * self._hexDigitToInt(ch256)
|
||
|
|
n += 16 * self._hexDigitToInt(ch16)
|
||
|
|
n += self._hexDigitToInt(ch1)
|
||
|
|
ch = unichr(n)
|
||
|
|
elif ch not in '"/\\':
|
||
|
|
raise ReadException, "Not a valid escaped JSON character: '%s' in %s" % (ch, self._generator.all())
|
||
|
|
result = result + ch
|
||
|
|
except StopIteration:
|
||
|
|
raise ReadException, "Not a valid JSON string: '%s'" % self._generator.all()
|
||
|
|
assert self._next() == '"'
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _hexDigitToInt(self, ch):
|
||
|
|
try:
|
||
|
|
result = self.hex_digits[ch.upper()]
|
||
|
|
except KeyError:
|
||
|
|
try:
|
||
|
|
result = int(ch)
|
||
|
|
except ValueError:
|
||
|
|
raise ReadException, "The character %s is not a hex digit." % ch
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _readComment(self):
|
||
|
|
assert self._next() == "/"
|
||
|
|
second = self._next()
|
||
|
|
if second == "/":
|
||
|
|
self._readDoubleSolidusComment()
|
||
|
|
elif second == '*':
|
||
|
|
self._readCStyleComment()
|
||
|
|
else:
|
||
|
|
raise ReadException, "Not a valid JSON comment: %s" % self._generator.all()
|
||
|
|
|
||
|
|
def _readCStyleComment(self):
|
||
|
|
try:
|
||
|
|
done = False
|
||
|
|
while not done:
|
||
|
|
ch = self._next()
|
||
|
|
done = (ch == "*" and self._peek() == "/")
|
||
|
|
if not done and ch == "/" and self._peek() == "*":
|
||
|
|
raise ReadException, "Not a valid JSON comment: %s, '/*' cannot be embedded in the comment." % self._generator.all()
|
||
|
|
self._next()
|
||
|
|
except StopIteration:
|
||
|
|
raise ReadException, "Not a valid JSON comment: %s, expected */" % self._generator.all()
|
||
|
|
|
||
|
|
def _readDoubleSolidusComment(self):
|
||
|
|
try:
|
||
|
|
ch = self._next()
|
||
|
|
while ch != "\r" and ch != "\n":
|
||
|
|
ch = self._next()
|
||
|
|
except StopIteration:
|
||
|
|
pass
|
||
|
|
|
||
|
|
def _readArray(self):
|
||
|
|
result = []
|
||
|
|
assert self._next() == '['
|
||
|
|
done = self._peek() == ']'
|
||
|
|
while not done:
|
||
|
|
item = self._read()
|
||
|
|
result.append(item)
|
||
|
|
self._eatWhitespace()
|
||
|
|
done = self._peek() == ']'
|
||
|
|
if not done:
|
||
|
|
ch = self._next()
|
||
|
|
if ch != ",":
|
||
|
|
raise ReadException, "Not a valid JSON array: '%s' due to: '%s'" % (self._generator.all(), ch)
|
||
|
|
assert ']' == self._next()
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _readObject(self):
|
||
|
|
result = {}
|
||
|
|
assert self._next() == '{'
|
||
|
|
done = self._peek() == '}'
|
||
|
|
while not done:
|
||
|
|
key = self._read()
|
||
|
|
if type(key) is not types.StringType:
|
||
|
|
raise ReadException, "Not a valid JSON object key (should be a string): %s" % key
|
||
|
|
self._eatWhitespace()
|
||
|
|
ch = self._next()
|
||
|
|
if ch != ":":
|
||
|
|
raise ReadException, "Not a valid JSON object: '%s' due to: '%s'" % (self._generator.all(), ch)
|
||
|
|
self._eatWhitespace()
|
||
|
|
val = self._read()
|
||
|
|
result[key] = val
|
||
|
|
self._eatWhitespace()
|
||
|
|
done = self._peek() == '}'
|
||
|
|
if not done:
|
||
|
|
ch = self._next()
|
||
|
|
if ch != ",":
|
||
|
|
raise ReadException, "Not a valid JSON array: '%s' due to: '%s'" % (self._generator.all(), ch)
|
||
|
|
assert self._next() == "}"
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _eatWhitespace(self):
|
||
|
|
p = self._peek()
|
||
|
|
while p is not None and p in string.whitespace or p == '/':
|
||
|
|
if p == '/':
|
||
|
|
self._readComment()
|
||
|
|
else:
|
||
|
|
self._next()
|
||
|
|
p = self._peek()
|
||
|
|
|
||
|
|
def _peek(self):
|
||
|
|
return self._generator.peek()
|
||
|
|
|
||
|
|
def _next(self):
|
||
|
|
return self._generator.next()
|
||
|
|
|
||
|
|
class JsonWriter(object):
|
||
|
|
|
||
|
|
def _append(self, s):
|
||
|
|
self._results.append(s)
|
||
|
|
|
||
|
|
def write(self, obj, escaped_forward_slash=False):
|
||
|
|
self._escaped_forward_slash = escaped_forward_slash
|
||
|
|
self._results = []
|
||
|
|
self._write(obj)
|
||
|
|
return "".join(self._results)
|
||
|
|
|
||
|
|
def _write(self, obj):
|
||
|
|
ty = type(obj)
|
||
|
|
if ty is types.DictType:
|
||
|
|
n = len(obj)
|
||
|
|
self._append("{")
|
||
|
|
for k, v in obj.items():
|
||
|
|
self._write(k)
|
||
|
|
self._append(":")
|
||
|
|
self._write(v)
|
||
|
|
n = n - 1
|
||
|
|
if n > 0:
|
||
|
|
self._append(",")
|
||
|
|
self._append("}")
|
||
|
|
elif ty is types.ListType or ty is types.TupleType:
|
||
|
|
n = len(obj)
|
||
|
|
self._append("[")
|
||
|
|
for item in obj:
|
||
|
|
self._write(item)
|
||
|
|
n = n - 1
|
||
|
|
if n > 0:
|
||
|
|
self._append(",")
|
||
|
|
self._append("]")
|
||
|
|
elif ty is types.StringType or ty is types.UnicodeType:
|
||
|
|
self._append('"')
|
||
|
|
obj = obj.replace('\\', r'\\')
|
||
|
|
if self._escaped_forward_slash:
|
||
|
|
obj = obj.replace('/', r'\/')
|
||
|
|
obj = obj.replace('"', r'\"')
|
||
|
|
obj = obj.replace('\b', r'\b')
|
||
|
|
obj = obj.replace('\f', r'\f')
|
||
|
|
obj = obj.replace('\n', r'\n')
|
||
|
|
obj = obj.replace('\r', r'\r')
|
||
|
|
obj = obj.replace('\t', r'\t')
|
||
|
|
self._append(obj)
|
||
|
|
self._append('"')
|
||
|
|
elif ty is types.IntType or ty is types.LongType:
|
||
|
|
self._append(str(obj))
|
||
|
|
elif ty is types.FloatType:
|
||
|
|
self._append("%f" % obj)
|
||
|
|
elif obj is True:
|
||
|
|
self._append("true")
|
||
|
|
elif obj is False:
|
||
|
|
self._append("false")
|
||
|
|
elif obj is None:
|
||
|
|
self._append("null")
|
||
|
|
else:
|
||
|
|
raise WriteException, "Cannot write in JSON: %s" % repr(obj)
|
||
|
|
|
||
|
|
def write(obj, escaped_forward_slash=False):
|
||
|
|
return JsonWriter().write(obj, escaped_forward_slash)
|
||
|
|
|
||
|
|
def read(s):
|
||
|
|
return JsonReader().read(s)
|