python/ovs/db/parser.py

   1 # Copyright (c) 2010, 2011 Nicira, Inc.
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at:
   6 #
   7 #     http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15 import re
  16
  17 from ovs.db import error
  18
  19
  20 class Parser(object):
  21     def __init__(self, json, name):
  22         self.name = name
  23         self.json = json
  24         if type(json) != dict:
  25             self.__raise_error("Object expected.")
  26         self.used = set()
  27
  28     def __get(self, name, types, optional, default=None):
  29         if name in self.json:
  30             self.used.add(name)
  31             member = float_to_int(self.json[name])
  32             if is_identifier(member) and "id" in types:
  33                 return member
  34             if len(types) and type(member) not in types:
  35                 self.__raise_error("Type mismatch for member '%s'." % name)
  36             return member
  37         else:
  38             if not optional:
  39                 self.__raise_error("Required '%s' member is missing." % name)
  40             return default
  41
  42     def get(self, name, types):
  43         return self.__get(name, types, False)
  44
  45     def get_optional(self, name, types, default=None):
  46         return self.__get(name, types, True, default)
  47
  48     def __raise_error(self, message):
  49         raise error.Error("Parsing %s failed: %s" % (self.name, message),
  50                           self.json)
  51
  52     def finish(self):
  53         missing = set(self.json) - set(self.used)
  54         if missing:
  55             name = missing.pop()
  56             if len(missing) > 1:
  57                 present = "and %d other members are" % len(missing)
  58             elif missing:
  59                 present = "and 1 other member are"
  60             else:
  61                 present = "is"
  62             self.__raise_error("Member '%s' %s present but not allowed here" %
  63                                (name, present))
  64
  65
  66 def float_to_int(x):
  67     # XXX still needed?
  68     if type(x) == float:
  69         integer = int(x)
  70         if integer == x and -2 ** 53 <= integer < 2 ** 53:
  71             return integer
  72     return x
  73
  74
  75 id_re = re.compile("[_a-zA-Z][_a-zA-Z0-9]*$")
  76
  77
  78 def is_identifier(s):
  79     return type(s) in [str, unicode] and id_re.match(s)
  80
  81
  82 def json_type_to_string(type_):
  83     if type_ == None:
  84         return "null"
  85     elif type_ == bool:
  86         return "boolean"
  87     elif type_ == dict:
  88         return "object"
  89     elif type_ == list:
  90         return "array"
  91     elif type_ in [int, long, float]:
  92         return "number"
  93     elif type_ in [str, unicode]:
  94         return "string"
  95     else:
  96         return "<invalid>"
  97
  98
  99 def unwrap_json(json, name, types, desc):
 100     if (type(json) not in (list, tuple) or len(json) != 2 or json[0] != name or
 101         type(json[1]) not in types):
 102         raise error.Error('expected ["%s", <%s>]' % (name, desc), json)
 103     return json[1]
 104
 105
 106 def parse_json_pair(json):
 107     if type(json) != list or len(json) != 2:
 108         raise error.Error("expected 2-element array", json)
 109     return json