1 2__all__ = ['BaseResolver', 'Resolver'] 3 4from .error import * 5from .nodes import * 6 7import re 8 9class ResolverError(YAMLError): 10 pass 11 12class BaseResolver: 13 14 DEFAULT_SCALAR_TAG = 'tag:yaml.org,2002:str' 15 DEFAULT_SEQUENCE_TAG = 'tag:yaml.org,2002:seq' 16 DEFAULT_MAPPING_TAG = 'tag:yaml.org,2002:map' 17 18 yaml_implicit_resolvers = {} 19 yaml_path_resolvers = {} 20 21 def __init__(self): 22 self.resolver_exact_paths = [] 23 self.resolver_prefix_paths = [] 24 25 @classmethod 26 def add_implicit_resolver(cls, tag, regexp, first): 27 if not 'yaml_implicit_resolvers' in cls.__dict__: 28 implicit_resolvers = {} 29 for key in cls.yaml_implicit_resolvers: 30 implicit_resolvers[key] = cls.yaml_implicit_resolvers[key][:] 31 cls.yaml_implicit_resolvers = implicit_resolvers 32 if first is None: 33 first = [None] 34 for ch in first: 35 cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp)) 36 37 @classmethod 38 def add_path_resolver(cls, tag, path, kind=None): 39 # Note: `add_path_resolver` is experimental. The API could be changed. 40 # `new_path` is a pattern that is matched against the path from the 41 # root to the node that is being considered. `node_path` elements are 42 # tuples `(node_check, index_check)`. `node_check` is a node class: 43 # `ScalarNode`, `SequenceNode`, `MappingNode` or `None`. `None` 44 # matches any kind of a node. `index_check` could be `None`, a boolean 45 # value, a string value, or a number. `None` and `False` match against 46 # any _value_ of sequence and mapping nodes. `True` matches against 47 # any _key_ of a mapping node. A string `index_check` matches against 48 # a mapping value that corresponds to a scalar key which content is 49 # equal to the `index_check` value. An integer `index_check` matches 50 # against a sequence value with the index equal to `index_check`. 51 if not 'yaml_path_resolvers' in cls.__dict__: 52 cls.yaml_path_resolvers = cls.yaml_path_resolvers.copy() 53 new_path = [] 54 for element in path: 55 if isinstance(element, (list, tuple)): 56 if len(element) == 2: 57 node_check, index_check = element 58 elif len(element) == 1: 59 node_check = element[0] 60 index_check = True 61 else: 62 raise ResolverError("Invalid path element: %s" % element) 63 else: 64 node_check = None 65 index_check = element 66 if node_check is str: 67 node_check = ScalarNode 68 elif node_check is list: 69 node_check = SequenceNode 70 elif node_check is dict: 71 node_check = MappingNode 72 elif node_check not in [ScalarNode, SequenceNode, MappingNode] \ 73 and not isinstance(node_check, str) \ 74 and node_check is not None: 75 raise ResolverError("Invalid node checker: %s" % node_check) 76 if not isinstance(index_check, (str, int)) \ 77 and index_check is not None: 78 raise ResolverError("Invalid index checker: %s" % index_check) 79 new_path.append((node_check, index_check)) 80 if kind is str: 81 kind = ScalarNode 82 elif kind is list: 83 kind = SequenceNode 84 elif kind is dict: 85 kind = MappingNode 86 elif kind not in [ScalarNode, SequenceNode, MappingNode] \ 87 and kind is not None: 88 raise ResolverError("Invalid node kind: %s" % kind) 89 cls.yaml_path_resolvers[tuple(new_path), kind] = tag 90 91 def descend_resolver(self, current_node, current_index): 92 if not self.yaml_path_resolvers: 93 return 94 exact_paths = {} 95 prefix_paths = [] 96 if current_node: 97 depth = len(self.resolver_prefix_paths) 98 for path, kind in self.resolver_prefix_paths[-1]: 99 if self.check_resolver_prefix(depth, path, kind, 100 current_node, current_index): 101 if len(path) > depth: 102 prefix_paths.append((path, kind)) 103 else: 104 exact_paths[kind] = self.yaml_path_resolvers[path, kind] 105 else: 106 for path, kind in self.yaml_path_resolvers: 107 if not path: 108 exact_paths[kind] = self.yaml_path_resolvers[path, kind] 109 else: 110 prefix_paths.append((path, kind)) 111 self.resolver_exact_paths.append(exact_paths) 112 self.resolver_prefix_paths.append(prefix_paths) 113 114 def ascend_resolver(self): 115 if not self.yaml_path_resolvers: 116 return 117 self.resolver_exact_paths.pop() 118 self.resolver_prefix_paths.pop() 119 120 def check_resolver_prefix(self, depth, path, kind, 121 current_node, current_index): 122 node_check, index_check = path[depth-1] 123 if isinstance(node_check, str): 124 if current_node.tag != node_check: 125 return 126 elif node_check is not None: 127 if not isinstance(current_node, node_check): 128 return 129 if index_check is True and current_index is not None: 130 return 131 if (index_check is False or index_check is None) \ 132 and current_index is None: 133 return 134 if isinstance(index_check, str): 135 if not (isinstance(current_index, ScalarNode) 136 and index_check == current_index.value): 137 return 138 elif isinstance(index_check, int) and not isinstance(index_check, bool): 139 if index_check != current_index: 140 return 141 return True 142 143 def resolve(self, kind, value, implicit): 144 if kind is ScalarNode and implicit[0]: 145 if value == '': 146 resolvers = self.yaml_implicit_resolvers.get('', []) 147 else: 148 resolvers = self.yaml_implicit_resolvers.get(value[0], []) 149 wildcard_resolvers = self.yaml_implicit_resolvers.get(None, []) 150 for tag, regexp in resolvers + wildcard_resolvers: 151 if regexp.match(value): 152 return tag 153 implicit = implicit[1] 154 if self.yaml_path_resolvers: 155 exact_paths = self.resolver_exact_paths[-1] 156 if kind in exact_paths: 157 return exact_paths[kind] 158 if None in exact_paths: 159 return exact_paths[None] 160 if kind is ScalarNode: 161 return self.DEFAULT_SCALAR_TAG 162 elif kind is SequenceNode: 163 return self.DEFAULT_SEQUENCE_TAG 164 elif kind is MappingNode: 165 return self.DEFAULT_MAPPING_TAG 166 167class Resolver(BaseResolver): 168 pass 169 170Resolver.add_implicit_resolver( 171 'tag:yaml.org,2002:bool', 172 re.compile(r'''^(?:yes|Yes|YES|no|No|NO 173 |true|True|TRUE|false|False|FALSE 174 |on|On|ON|off|Off|OFF)$''', re.X), 175 list('yYnNtTfFoO')) 176 177Resolver.add_implicit_resolver( 178 'tag:yaml.org,2002:float', 179 re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)\.[0-9_]*(?:[eE][-+][0-9]+)? 180 |\.[0-9][0-9_]*(?:[eE][-+][0-9]+)? 181 |[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\.[0-9_]* 182 |[-+]?\.(?:inf|Inf|INF) 183 |\.(?:nan|NaN|NAN))$''', re.X), 184 list('-+0123456789.')) 185 186Resolver.add_implicit_resolver( 187 'tag:yaml.org,2002:int', 188 re.compile(r'''^(?:[-+]?0b[0-1_]+ 189 |[-+]?0[0-7_]+ 190 |[-+]?(?:0|[1-9][0-9_]*) 191 |[-+]?0x[0-9a-fA-F_]+ 192 |[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$''', re.X), 193 list('-+0123456789')) 194 195Resolver.add_implicit_resolver( 196 'tag:yaml.org,2002:merge', 197 re.compile(r'^(?:<<)$'), 198 ['<']) 199 200Resolver.add_implicit_resolver( 201 'tag:yaml.org,2002:null', 202 re.compile(r'''^(?: ~ 203 |null|Null|NULL 204 | )$''', re.X), 205 ['~', 'n', 'N', '']) 206 207Resolver.add_implicit_resolver( 208 'tag:yaml.org,2002:timestamp', 209 re.compile(r'''^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9] 210 |[0-9][0-9][0-9][0-9] -[0-9][0-9]? -[0-9][0-9]? 211 (?:[Tt]|[ \t]+)[0-9][0-9]? 212 :[0-9][0-9] :[0-9][0-9] (?:\.[0-9]*)? 213 (?:[ \t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$''', re.X), 214 list('0123456789')) 215 216Resolver.add_implicit_resolver( 217 'tag:yaml.org,2002:value', 218 re.compile(r'^(?:=)$'), 219 ['=']) 220 221# The following resolver is only for documentation purposes. It cannot work 222# because plain scalars cannot start with '!', '&', or '*'. 223Resolver.add_implicit_resolver( 224 'tag:yaml.org,2002:yaml', 225 re.compile(r'^(?:!|&|\*)$'), 226 list('!&*')) 227 228