from coreapi.compat import string_types

import itypes

# Helper functions to get an expected type from a dictionary.

def dereference(lookup_string, struct):

"""

Dereference a JSON pointer.

http://tools.ietf.org/html/rfc6901

"""

keys = lookup_string.strip('#/').split('/')

node = struct

for key in keys:

node = _get_dict(node, key)

return node

def is_json_pointer(value):

return isinstance(value, dict) and ('$ref' in value) and (len(value) == 1)

def _get_string(item, key, default=''):

value = item.get(key)

return value if isinstance(value, string_types) else default

def _get_dict(item, key, default={}, dereference_using=None):

value = item.get(key)

if isinstance(value, dict):

if dereference_using and is_json_pointer(value):

return dereference(value['$ref'], dereference_using)

return value

return default.copy()

def _get_list(item, key, default=[]):

value = item.get(key)

return value if isinstance(value, list) else list(default)

def _get_bool(item, key, default=False):

value = item.get(key)

return value if isinstance(value, bool) else default

# Helper functions to get an expected type from a list.

def get_dicts(item, dereference_using=None):

ret = [value for value in item if isinstance(value, dict)]

if dereference_using:

return [

dereference(value['$ref'], dereference_using) if is_json_pointer(value) else value

for value in ret

]

return ret

def get_strings(item):

return [value for value in item if isinstance(value, string_types)]

class BaseCodec(itypes.Object):

media_type = None

def load(self, bytes, base_url=None):

raise NotImplementedError() # pragma: nocover

def dump(self, document, **kwargs):

raise NotImplementedError() # pragma: nocover