Class BaseConstructor
Synopsis
class BaseConstructor
Description
No description yet.
Inheritance
Decsendents: SafeConstructor, BaseLoader, CBaseLoader
Methods
| __init__ | ||
| add_constructor | ||
| add_multi_constructor | ||
| check_data | Mentioned in
| |
| check_state_key | Block special attributes/methods from being set in a newly created object, to prevent user-controlled methods from being called during deserialization | |
| construct_document | ||
| construct_mapping | ||
| construct_object | ||
| construct_pairs | ||
| construct_scalar | ||
| construct_sequence | Mentioned in
| |
| get_data | Mentioned in
| |
| get_single_data |
Source
Lines 19-171 in lib3/yaml/constructor.py.
class BaseConstructor:
yaml_constructors = {}
yaml_multi_constructors = {}
def __init__(self):
self.constructed_objects = {}
self.recursive_objects = {}
self.state_generators = []
self.deep_construct = False
def check_data(self):
# If there are more documents available?
return self.check_node()
def check_state_key(self, key):
"""Block special attributes/methods from being set in a newly created
object, to prevent user-controlled methods from being called during
deserialization"""
if self.get_state_keys_blacklist_regexp().match(key):
raise ConstructorError(None, None,
"blacklisted key '%s' in instance state found" % (key,), None)
def get_data(self):
# Construct and return the next document.
if self.check_node():
return self.construct_document(self.get_node())
def get_single_data(self):
# Ensure that the stream contains a single document and construct it.
node = self.get_single_node()
if node is not None:
return self.construct_document(node)
return None
def construct_document(self, node):
data = self.construct_object(node)
while self.state_generators:
state_generators = self.state_generators
self.state_generators = []
for generator in state_generators:
for dummy in generator:
pass
self.constructed_objects = {}
self.recursive_objects = {}
self.deep_construct = False
return data
def construct_object(self, node, deep=False):
if node in self.constructed_objects:
return self.constructed_objects[node]
if deep:
old_deep = self.deep_construct
self.deep_construct = True
if node in self.recursive_objects:
raise ConstructorError(None, None,
"found unconstructable recursive node", node.start_mark)
self.recursive_objects[node] = None
constructor = None
tag_suffix = None
if node.tag in self.yaml_constructors:
constructor = self.yaml_constructors[node.tag]
else:
for tag_prefix in self.yaml_multi_constructors:
if tag_prefix is not None and node.tag.startswith(tag_prefix):
tag_suffix = node.tag[len(tag_prefix):]
constructor = self.yaml_multi_constructors[tag_prefix]
break
else:
if None in self.yaml_multi_constructors:
tag_suffix = node.tag
constructor = self.yaml_multi_constructors[None]
elif None in self.yaml_constructors:
constructor = self.yaml_constructors[None]
elif isinstance(node, ScalarNode):
constructor = self.__class__.construct_scalar
elif isinstance(node, SequenceNode):
constructor = self.__class__.construct_sequence
elif isinstance(node, MappingNode):
constructor = self.__class__.construct_mapping
if tag_suffix is None:
data = constructor(self, node)
else:
data = constructor(self, tag_suffix, node)
if isinstance(data, types.GeneratorType):
generator = data
data = next(generator)
if self.deep_construct:
for dummy in generator:
pass
else:
self.state_generators.append(generator)
self.constructed_objects[node] = data
del self.recursive_objects[node]
if deep:
self.deep_construct = old_deep
return data
def construct_scalar(self, node):
if not isinstance(node, ScalarNode):
raise ConstructorError(None, None,
"expected a scalar node, but found %s" % node.id,
node.start_mark)
return node.value
def construct_sequence(self, node, deep=False):
if not isinstance(node, SequenceNode):
raise ConstructorError(None, None,
"expected a sequence node, but found %s" % node.id,
node.start_mark)
return [self.construct_object(child, deep=deep)
for child in node.value]
def construct_mapping(self, node, deep=False):
if not isinstance(node, MappingNode):
raise ConstructorError(None, None,
"expected a mapping node, but found %s" % node.id,
node.start_mark)
mapping = {}
for key_node, value_node in node.value:
key = self.construct_object(key_node, deep=deep)
if not isinstance(key, collections.abc.Hashable):
raise ConstructorError("while constructing a mapping", node.start_mark,
"found unhashable key", key_node.start_mark)
value = self.construct_object(value_node, deep=deep)
mapping[key] = value
return mapping
def construct_pairs(self, node, deep=False):
if not isinstance(node, MappingNode):
raise ConstructorError(None, None,
"expected a mapping node, but found %s" % node.id,
node.start_mark)
pairs = []
for key_node, value_node in node.value:
key = self.construct_object(key_node, deep=deep)
value = self.construct_object(value_node, deep=deep)
pairs.append((key, value))
return pairs
@classmethod
def add_constructor(cls, tag, constructor):
if not 'yaml_constructors' in cls.__dict__:
cls.yaml_constructors = cls.yaml_constructors.copy()
cls.yaml_constructors[tag] = constructor
@classmethod
def add_multi_constructor(cls, tag_prefix, multi_constructor):
if not 'yaml_multi_constructors' in cls.__dict__:
cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
cls.yaml_multi_constructors[tag_prefix] = multi_constructor
class SafeConstructor(BaseConstructor):