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-rw-r--r--json.py310
1 files changed, 310 insertions, 0 deletions
diff --git a/json.py b/json.py
new file mode 100644
index 0000000..a28a13e
--- /dev/null
+++ b/json.py
@@ -0,0 +1,310 @@
+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)