python/ovs/db/parser.py

   1 # Copyright (c) 2010, 2011 Nicira Networks
   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 class Parser(object):
  20     def __init__(self, json, name):
  21         self.name = name
  22         self.json = json
  23         if type(json) != dict:
  24             self.__raise_error("Object expected.")
  25         self.used = set()
  26
  27     def __get(self, name, types, optional, default=None):
  28         if name in self.json:
  29             self.used.add(name)
  30             member = float_to_int(self.json[name])
  31             if is_identifier(member) and "id" in types:
  32                 return member
  33             if len(types) and type(member) not in types:
  34                 self.__raise_error("Type mismatch for member '%s'." % name)
  35             return member
  36         else:
  37             if not optional:
  38                 self.__raise_error("Required '%s' member is missing." % name)
  39             return default
  40
  41     def get(self, name, types):
  42         return self.__get(name, types, False)
  43
  44     def get_optional(self, name, types, default=None):
  45         return self.__get(name, types, True, default)
  46
  47     def __raise_error(self, message):
  48         raise error.Error("Parsing %s failed: %s" % (self.name, message),
  49                           self.json)
  50
  51     def finish(self):
  52         missing = set(self.json) - set(self.used)
  53         if missing:
  54             name = missing.pop()
  55             if len(missing) > 1:
  56                 present = "and %d other members are" % len(missing)
  57             elif missing:
  58                 present = "and 1 other member are"
  59             else:
  60                 present = "is"
  61             self.__raise_error("Member '%s' %s present but not allowed here" %
  62                                (name, present))
  63
  64 def float_to_int(x):
  65     # XXX still needed?
  66     if type(x) == float:
  67         integer = int(x)
  68         if integer == x and -2**53 <= integer < 2**53:
  69             return integer
  70     return x
  71
  72 id_re = re.compile("[_a-zA-Z][_a-zA-Z0-9]*$")
  73 def is_identifier(s):
  74     return type(s) in [str, unicode] and id_re.match(s)
  75
  76 def json_type_to_string(type_):
  77     if type_ == None:
  78         return "null"
  79     elif type_ == bool:
  80         return "boolean"
  81     elif type_ == dict:
  82         return "object"
  83     elif type_ == list:
  84         return "array"
  85     elif type_ in [int, long, float]:
  86         return "number"
  87     elif type_ in [str, unicode]:
  88         return "string"
  89     else:
  90         return "<invalid>"
  91
  92 def unwrap_json(json, name, types, desc):
  93     if (type(json) not in (list, tuple) or len(json) != 2 or json[0] != name or
  94         type(json[1]) not in types):
  95         raise error.Error('expected ["%s", <%s>]' % (name, desc), json)
  96     return json[1]
  97
  98 def parse_json_pair(json):
  99     if type(json) != list or len(json) != 2:
 100         raise error.Error("expected 2-element array", json)
 101     return json
 102