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__all__ = ['BaseResolver', 'Resolver'] 

 

from .error import * 

from .nodes import * 

 

import re 

 

class ResolverError(YAMLError): 

pass 

 

class BaseResolver: 

 

DEFAULT_SCALAR_TAG = 'tag:yaml.org,2002:str' 

DEFAULT_SEQUENCE_TAG = 'tag:yaml.org,2002:seq' 

DEFAULT_MAPPING_TAG = 'tag:yaml.org,2002:map' 

 

yaml_implicit_resolvers = {} 

yaml_path_resolvers = {} 

 

def __init__(self): 

self.resolver_exact_paths = [] 

self.resolver_prefix_paths = [] 

 

@classmethod 

def add_implicit_resolver(cls, tag, regexp, first): 

if not 'yaml_implicit_resolvers' in cls.__dict__: 

implicit_resolvers = {} 

for key in cls.yaml_implicit_resolvers: 

implicit_resolvers[key] = cls.yaml_implicit_resolvers[key][:] 

cls.yaml_implicit_resolvers = implicit_resolvers 

if first is None: 

first = [None] 

for ch in first: 

cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp)) 

 

@classmethod 

def add_path_resolver(cls, tag, path, kind=None): 

# Note: `add_path_resolver` is experimental. The API could be changed. 

# `new_path` is a pattern that is matched against the path from the 

# root to the node that is being considered. `node_path` elements are 

# tuples `(node_check, index_check)`. `node_check` is a node class: 

# `ScalarNode`, `SequenceNode`, `MappingNode` or `None`. `None` 

# matches any kind of a node. `index_check` could be `None`, a boolean 

# value, a string value, or a number. `None` and `False` match against 

# any _value_ of sequence and mapping nodes. `True` matches against 

# any _key_ of a mapping node. A string `index_check` matches against 

# a mapping value that corresponds to a scalar key which content is 

# equal to the `index_check` value. An integer `index_check` matches 

# against a sequence value with the index equal to `index_check`. 

if not 'yaml_path_resolvers' in cls.__dict__: 

cls.yaml_path_resolvers = cls.yaml_path_resolvers.copy() 

new_path = [] 

for element in path: 

if isinstance(element, (list, tuple)): 

if len(element) == 2: 

node_check, index_check = element 

elif len(element) == 1: 

node_check = element[0] 

index_check = True 

else: 

raise ResolverError("Invalid path element: %s" % element) 

else: 

node_check = None 

index_check = element 

if node_check is str: 

node_check = ScalarNode 

elif node_check is list: 

node_check = SequenceNode 

elif node_check is dict: 

node_check = MappingNode 

elif node_check not in [ScalarNode, SequenceNode, MappingNode] \ 

and not isinstance(node_check, str) \ 

and node_check is not None: 

raise ResolverError("Invalid node checker: %s" % node_check) 

if not isinstance(index_check, (str, int)) \ 

and index_check is not None: 

raise ResolverError("Invalid index checker: %s" % index_check) 

new_path.append((node_check, index_check)) 

if kind is str: 

kind = ScalarNode 

elif kind is list: 

kind = SequenceNode 

elif kind is dict: 

kind = MappingNode 

elif kind not in [ScalarNode, SequenceNode, MappingNode] \ 

and kind is not None: 

raise ResolverError("Invalid node kind: %s" % kind) 

cls.yaml_path_resolvers[tuple(new_path), kind] = tag 

 

def descend_resolver(self, current_node, current_index): 

if not self.yaml_path_resolvers: 

return 

exact_paths = {} 

prefix_paths = [] 

if current_node: 

depth = len(self.resolver_prefix_paths) 

for path, kind in self.resolver_prefix_paths[-1]: 

if self.check_resolver_prefix(depth, path, kind, 

current_node, current_index): 

if len(path) > depth: 

prefix_paths.append((path, kind)) 

else: 

exact_paths[kind] = self.yaml_path_resolvers[path, kind] 

else: 

for path, kind in self.yaml_path_resolvers: 

if not path: 

exact_paths[kind] = self.yaml_path_resolvers[path, kind] 

else: 

prefix_paths.append((path, kind)) 

self.resolver_exact_paths.append(exact_paths) 

self.resolver_prefix_paths.append(prefix_paths) 

 

def ascend_resolver(self): 

if not self.yaml_path_resolvers: 

return 

self.resolver_exact_paths.pop() 

self.resolver_prefix_paths.pop() 

 

def check_resolver_prefix(self, depth, path, kind, 

current_node, current_index): 

node_check, index_check = path[depth-1] 

if isinstance(node_check, str): 

if current_node.tag != node_check: 

return 

elif node_check is not None: 

if not isinstance(current_node, node_check): 

return 

if index_check is True and current_index is not None: 

return 

if (index_check is False or index_check is None) \ 

and current_index is None: 

return 

if isinstance(index_check, str): 

if not (isinstance(current_index, ScalarNode) 

and index_check == current_index.value): 

return 

elif isinstance(index_check, int) and not isinstance(index_check, bool): 

if index_check != current_index: 

return 

return True 

 

def resolve(self, kind, value, implicit): 

if kind is ScalarNode and implicit[0]: 

if value == '': 

resolvers = self.yaml_implicit_resolvers.get('', []) 

else: 

resolvers = self.yaml_implicit_resolvers.get(value[0], []) 

resolvers += self.yaml_implicit_resolvers.get(None, []) 

for tag, regexp in resolvers: 

if regexp.match(value): 

return tag 

implicit = implicit[1] 

if self.yaml_path_resolvers: 

exact_paths = self.resolver_exact_paths[-1] 

if kind in exact_paths: 

return exact_paths[kind] 

if None in exact_paths: 

return exact_paths[None] 

if kind is ScalarNode: 

return self.DEFAULT_SCALAR_TAG 

elif kind is SequenceNode: 

return self.DEFAULT_SEQUENCE_TAG 

elif kind is MappingNode: 

return self.DEFAULT_MAPPING_TAG 

 

class Resolver(BaseResolver): 

pass 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:bool', 

re.compile(r'''^(?:yes|Yes|YES|no|No|NO 

|true|True|TRUE|false|False|FALSE 

|on|On|ON|off|Off|OFF)$''', re.X), 

list('yYnNtTfFoO')) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:float', 

re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)\.[0-9_]*(?:[eE][-+][0-9]+)? 

|\.[0-9_]+(?:[eE][-+][0-9]+)? 

|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\.[0-9_]* 

|[-+]?\.(?:inf|Inf|INF) 

|\.(?:nan|NaN|NAN))$''', re.X), 

list('-+0123456789.')) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:int', 

re.compile(r'''^(?:[-+]?0b[0-1_]+ 

|[-+]?0[0-7_]+ 

|[-+]?(?:0|[1-9][0-9_]*) 

|[-+]?0x[0-9a-fA-F_]+ 

|[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$''', re.X), 

list('-+0123456789')) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:merge', 

re.compile(r'^(?:<<)$'), 

['<']) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:null', 

re.compile(r'''^(?: ~ 

|null|Null|NULL 

| )$''', re.X), 

['~', 'n', 'N', '']) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:timestamp', 

re.compile(r'''^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] 

|[0-9][0-9][0-9][0-9] -[0-9][0-9]? -[0-9][0-9]? 

(?:[Tt]|[ \t]+)[0-9][0-9]? 

:[0-9][0-9] :[0-9][0-9] (?:\.[0-9]*)? 

(?:[ \t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$''', re.X), 

list('0123456789')) 

 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:value', 

re.compile(r'^(?:=)$'), 

['=']) 

 

# The following resolver is only for documentation purposes. It cannot work 

# because plain scalars cannot start with '!', '&', or '*'. 

Resolver.add_implicit_resolver( 

'tag:yaml.org,2002:yaml', 

re.compile(r'^(?:!|&|\*)$'), 

list('!&*'))