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# Copyright (c) 2010, 2011, 2012 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import absolute_import
import functools
import json
import re
import sys
PARSER_C = 'C'
PARSER_PY = 'PYTHON'
try:
import ovs._json
PARSER = PARSER_C
except ImportError:
PARSER = PARSER_PY
__pychecker__ = 'no-stringiter'
SPACES_PER_LEVEL = 2
dumper = functools.partial(json.dumps, separators=(",", ":"))
def to_stream(obj, stream, pretty=False, sort_keys=True):
stream.write(dumper(obj, indent=SPACES_PER_LEVEL if pretty else None,
sort_keys=sort_keys))
def to_file(obj, name, pretty=False, sort_keys=True):
with open(name, "w") as stream:
to_stream(obj, stream, pretty, sort_keys)
def to_string(obj, pretty=False, sort_keys=True):
return dumper(obj, indent=SPACES_PER_LEVEL if pretty else None,
sort_keys=sort_keys)
def from_stream(stream):
p = Parser(check_trailer=True)
while True:
buf = stream.read(4096)
if buf == "" or p.feed(buf) != len(buf):
break
return p.finish()
def from_file(name):
stream = open(name, "r")
try:
return from_stream(stream)
finally:
stream.close()
def from_string(s):
if not isinstance(s, str):
# We assume the input is a string. We will only hit this case for a
# str in Python 2 which is not unicode, so we need to go ahead and
# decode it.
try:
s = str(s, 'utf-8')
except UnicodeDecodeError as e:
seq = ' '.join(["0x%2x" % ord(c)
for c in e.object[e.start:e.end] if ord(c) >= 0x80])
return "not a valid UTF-8 string: invalid UTF-8 sequence %s" % seq
p = Parser(check_trailer=True)
p.feed(s)
return p.finish()
class Parser(object):
# Maximum height of parsing stack. #
MAX_HEIGHT = 1000
def __new__(cls, *args, **kwargs):
if PARSER == PARSER_C:
return ovs._json.Parser(*args, **kwargs)
return super(Parser, cls).__new__(cls)
def __init__(self, check_trailer=False):
self.check_trailer = check_trailer
# Lexical analysis.
self.lex_state = Parser.__lex_start
self.buffer = ""
self.line_number = 0
self.column_number = 0
self.byte_number = 0
# Parsing.
self.parse_state = Parser.__parse_start
self.stack = []
self.member_name = None
# Parse status.
self.done = False
self.error = None
def __lex_start_space(self, c):
pass
def __lex_start_alpha(self, c):
self.buffer = c
self.lex_state = Parser.__lex_keyword
def __lex_start_token(self, c):
self.__parser_input(c)
def __lex_start_number(self, c):
self.buffer = c
self.lex_state = Parser.__lex_number
def __lex_start_string(self, _):
self.lex_state = Parser.__lex_string
def __lex_start_error(self, c):
if ord(c) >= 32 and ord(c) < 128:
self.__error("invalid character '%s'" % c)
else:
self.__error("invalid character U+%04x" % ord(c))
__lex_start_actions = {}
for c in " \t\n\r":
__lex_start_actions[c] = __lex_start_space
for c in "abcdefghijklmnopqrstuvwxyz":
__lex_start_actions[c] = __lex_start_alpha
for c in "[{]}:,":
__lex_start_actions[c] = __lex_start_token
for c in "-0123456789":
__lex_start_actions[c] = __lex_start_number
__lex_start_actions['"'] = __lex_start_string
def __lex_start(self, c):
Parser.__lex_start_actions.get(
c, Parser.__lex_start_error)(self, c)
return True
__lex_alpha = {}
for c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ":
__lex_alpha[c] = True
def __lex_finish_keyword(self):
if self.buffer == "false":
self.__parser_input(False)
elif self.buffer == "true":
self.__parser_input(True)
elif self.buffer == "null":
self.__parser_input(None)
else:
self.__error("invalid keyword '%s'" % self.buffer)
def __lex_keyword(self, c):
if c in Parser.__lex_alpha:
self.buffer += c
return True
else:
self.__lex_finish_keyword()
return False
__number_re = re.compile("(-)?(0|[1-9][0-9]*)"
r"(?:\.([0-9]+))?(?:[eE]([-+]?[0-9]+))?$")
def __lex_finish_number(self):
s = self.buffer
m = Parser.__number_re.match(s)
if m:
sign, integer, fraction, exp = m.groups()
if (exp is not None and
(int(exp) > sys.maxsize or int(exp) < -sys.maxsize - 1)):
self.__error("exponent outside valid range")
return
if fraction is not None and len(fraction.lstrip('0')) == 0:
fraction = None
sig_string = integer
if fraction is not None:
sig_string += fraction
significand = int(sig_string)
pow10 = 0
if fraction is not None:
pow10 -= len(fraction)
if exp is not None:
pow10 += int(exp)
if significand == 0:
self.__parser_input(0)
return
elif significand <= 2 ** 63:
while pow10 > 0 and significand <= 2 ** 63:
significand *= 10
pow10 -= 1
while pow10 < 0 and significand % 10 == 0:
significand //= 10
pow10 += 1
if (pow10 == 0 and
((not sign and significand < 2 ** 63) or
(sign and significand <= 2 ** 63))):
if sign:
self.__parser_input(-significand)
else:
self.__parser_input(significand)
return
value = float(s)
if value == float("inf") or value == float("-inf"):
self.__error("number outside valid range")
return
if value == 0:
# Suppress negative zero.
value = 0
self.__parser_input(value)
elif re.match("-?0[0-9]", s):
self.__error("leading zeros not allowed")
elif re.match("-([^0-9]|$)", s):
self.__error("'-' must be followed by digit")
elif re.match(r"-?(0|[1-9][0-9]*)\.([^0-9]|$)", s):
self.__error("decimal point must be followed by digit")
elif re.search("e[-+]?([^0-9]|$)", s):
self.__error("exponent must contain at least one digit")
else:
self.__error("syntax error in number")
def __lex_number(self, c):
if c in ".0123456789eE-+":
self.buffer += c
return True
else:
self.__lex_finish_number()
return False
__4hex_re = re.compile("[0-9a-fA-F]{4}")
def __lex_4hex(self, s):
if len(s) < 4:
self.__error("quoted string ends within \\u escape")
elif not Parser.__4hex_re.match(s):
self.__error("malformed \\u escape")
elif s == "0000":
self.__error("null bytes not supported in quoted strings")
else:
return int(s, 16)
@staticmethod
def __is_leading_surrogate(c):
"""Returns true if 'c' is a Unicode code point for a leading
surrogate."""
return c >= 0xd800 and c <= 0xdbff
@staticmethod
def __is_trailing_surrogate(c):
"""Returns true if 'c' is a Unicode code point for a trailing
surrogate."""
return c >= 0xdc00 and c <= 0xdfff
@staticmethod
def __utf16_decode_surrogate_pair(leading, trailing):
"""Returns the unicode code point corresponding to leading surrogate
'leading' and trailing surrogate 'trailing'. The return value will not
make any sense if 'leading' or 'trailing' are not in the correct ranges
for leading or trailing surrogates."""
# Leading surrogate: 110110wwwwxxxxxx
# Trailing surrogate: 110111xxxxxxxxxx
# Code point: 000uuuuuxxxxxxxxxxxxxxxx
w = (leading >> 6) & 0xf
u = w + 1
x0 = leading & 0x3f
x1 = trailing & 0x3ff
return (u << 16) | (x0 << 10) | x1
__unescape = {'"': u'"',
"\\": u"\\",
"/": u"/",
"b": u"\b",
"f": u"\f",
"n": u"\n",
"r": u"\r",
"t": u"\t"}
def __lex_finish_string(self):
inp = self.buffer
out = u""
while len(inp):
backslash = inp.find('\\')
if backslash == -1:
out += inp
break
out += inp[:backslash]
inp = inp[backslash + 1:]
if inp == "":
self.__error("quoted string may not end with backslash")
return
replacement = Parser.__unescape.get(inp[0])
if replacement is not None:
out += replacement
inp = inp[1:]
continue
elif inp[0] != u'u':
self.__error("bad escape \\%s" % inp[0])
return
c0 = self.__lex_4hex(inp[1:5])
if c0 is None:
return
inp = inp[5:]
if Parser.__is_leading_surrogate(c0):
if inp[:2] != u'\\u':
self.__error("malformed escaped surrogate pair")
return
c1 = self.__lex_4hex(inp[2:6])
if c1 is None:
return
if not Parser.__is_trailing_surrogate(c1):
self.__error("second half of escaped surrogate pair is "
"not trailing surrogate")
return
code_point = Parser.__utf16_decode_surrogate_pair(c0, c1)
inp = inp[6:]
else:
code_point = c0
out += chr(code_point)
self.__parser_input('string', out)
def __lex_string_escape(self, c):
self.buffer += c
self.lex_state = Parser.__lex_string
return True
def __lex_string(self, c):
if c == '\\':
self.buffer += c
self.lex_state = Parser.__lex_string_escape
elif c == '"':
self.__lex_finish_string()
elif ord(c) >= 0x20:
self.buffer += c
else:
self.__error("U+%04X must be escaped in quoted string" % ord(c))
return True
def __lex_input(self, c):
eat = self.lex_state(self, c)
assert eat is True or eat is False
return eat
def __parse_start(self, token, unused_string):
if token == '{':
self.__push_object()
elif token == '[':
self.__push_array()
else:
self.__error("syntax error at beginning of input")
def __parse_end(self, unused_token, unused_string):
self.__error("trailing garbage at end of input")
def __parse_object_init(self, token, string):
if token == '}':
self.__parser_pop()
else:
self.__parse_object_name(token, string)
def __parse_object_name(self, token, string):
if token == 'string':
self.member_name = string
self.parse_state = Parser.__parse_object_colon
else:
self.__error("syntax error parsing object expecting string")
def __parse_object_colon(self, token, unused_string):
if token == ":":
self.parse_state = Parser.__parse_object_value
else:
self.__error("syntax error parsing object expecting ':'")
def __parse_object_value(self, token, string):
self.__parse_value(token, string, Parser.__parse_object_next)
def __parse_object_next(self, token, unused_string):
if token == ",":
self.parse_state = Parser.__parse_object_name
elif token == "}":
self.__parser_pop()
else:
self.__error("syntax error expecting '}' or ','")
def __parse_array_init(self, token, string):
if token == ']':
self.__parser_pop()
else:
self.__parse_array_value(token, string)
def __parse_array_value(self, token, string):
self.__parse_value(token, string, Parser.__parse_array_next)
def __parse_array_next(self, token, unused_string):
if token == ",":
self.parse_state = Parser.__parse_array_value
elif token == "]":
self.__parser_pop()
else:
self.__error("syntax error expecting ']' or ','")
def __parser_input(self, token, string=None):
self.lex_state = Parser.__lex_start
self.buffer = ""
self.parse_state(self, token, string)
def __put_value(self, value):
top = self.stack[-1]
if isinstance(top, dict):
top[self.member_name] = value
else:
top.append(value)
def __parser_push(self, new_json, next_state):
if len(self.stack) < Parser.MAX_HEIGHT:
if len(self.stack) > 0:
self.__put_value(new_json)
self.stack.append(new_json)
self.parse_state = next_state
else:
self.__error("input exceeds maximum nesting depth %d" %
Parser.MAX_HEIGHT)
def __push_object(self):
self.__parser_push({}, Parser.__parse_object_init)
def __push_array(self):
self.__parser_push([], Parser.__parse_array_init)
def __parser_pop(self):
if len(self.stack) == 1:
self.parse_state = Parser.__parse_end
if not self.check_trailer:
self.done = True
else:
self.stack.pop()
top = self.stack[-1]
if isinstance(top, list):
self.parse_state = Parser.__parse_array_next
else:
self.parse_state = Parser.__parse_object_next
def __parse_value(self, token, string, next_state):
number_types = [int]
number_types.extend([float])
number_types = tuple(number_types)
if token in [False, None, True] or isinstance(token, number_types):
self.__put_value(token)
elif token == 'string':
self.__put_value(string)
else:
if token == '{':
self.__push_object()
elif token == '[':
self.__push_array()
else:
self.__error("syntax error expecting value")
return
self.parse_state = next_state
def __error(self, message):
if self.error is None:
self.error = ("line %d, column %d, byte %d: %s"
% (self.line_number, self.column_number,
self.byte_number, message))
self.done = True
def feed(self, s):
i = 0
while True:
if self.done or i >= len(s):
return i
c = s[i]
if self.__lex_input(c):
self.byte_number += 1
if c == '\n':
self.column_number = 0
self.line_number += 1
else:
self.column_number += 1
i += 1
def is_done(self):
return self.done
def finish(self):
if self.lex_state == Parser.__lex_start:
pass
elif self.lex_state in (Parser.__lex_string,
Parser.__lex_string_escape):
self.__error("unexpected end of input in quoted string")
else:
self.__lex_input(" ")
if self.parse_state == Parser.__parse_start:
self.__error("empty input stream")
elif self.parse_state != Parser.__parse_end:
self.__error("unexpected end of input")
if self.error is None:
assert len(self.stack) == 1
return self.stack.pop()
else:
return self.error
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