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json.py
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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