| # Copyright 2013 The Chromium Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| import json |
| from collections import Iterable, Mapping |
| |
| class LookupResult(object): |
| '''Returned from APISchemaGraph.Lookup(), and relays whether or not |
| some element was found and what annotation object was associated with it, |
| if any. |
| ''' |
| |
| def __init__(self, found=None, annotation=None): |
| assert found is not None, 'LookupResult was given None value for |found|.' |
| self.found = found |
| self.annotation = annotation |
| |
| def __eq__(self, other): |
| return self.__dict__ == other.__dict__ |
| |
| def __ne__(self, other): |
| return not (self == other) |
| |
| def __repr__(self): |
| return '%s%s' % (type(self).__name__, repr(self.__dict__)) |
| |
| def __str__(self): |
| return repr(self) |
| |
| |
| class _GraphNode(dict): |
| '''Represents some element of an API schema, and allows extra information |
| about that element to be stored on the |_annotation| object. |
| ''' |
| |
| def __init__(self, *args, **kwargs): |
| # Use **kwargs here since Python is picky with ordering of default args |
| # and variadic args in the method signature. The only keyword arg we care |
| # about here is 'annotation'. Intentionally don't pass |**kwargs| into the |
| # superclass' __init__(). |
| dict.__init__(self, *args) |
| self._annotation = kwargs.get('annotation') |
| |
| def __eq__(self, other): |
| # _GraphNode inherits __eq__() from dict, which will not take annotation |
| # objects into account when comparing. |
| return dict.__eq__(self, other) |
| |
| def __ne__(self, other): |
| return not (self == other) |
| |
| |
| def _NameForNode(node): |
| '''Creates a unique id for an object in an API schema, depending on |
| what type of attribute the object is a member of. |
| ''' |
| if 'namespace' in node: return node['namespace'] |
| if 'name' in node: return node['name'] |
| if 'id' in node: return node['id'] |
| if 'type' in node: return node['type'] |
| if '$ref' in node: return node['$ref'] |
| assert False, 'Problems with naming node: %s' % json.dumps(node, indent=3) |
| |
| |
| def _IsObjectList(value): |
| '''Determines whether or not |value| is a list made up entirely of |
| dict-like objects. |
| ''' |
| return (isinstance(value, Iterable) and |
| all(isinstance(node, Mapping) for node in value)) |
| |
| |
| def _CreateGraph(root): |
| '''Recursively moves through an API schema, replacing lists of objects |
| and non-object values with objects. |
| ''' |
| schema_graph = _GraphNode() |
| if _IsObjectList(root): |
| for node in root: |
| name = _NameForNode(node) |
| assert name not in schema_graph, 'Duplicate name in API schema graph.' |
| schema_graph[name] = _GraphNode((key, _CreateGraph(value)) for |
| key, value in node.iteritems()) |
| |
| elif isinstance(root, Mapping): |
| for name, node in root.iteritems(): |
| if not isinstance(node, Mapping): |
| schema_graph[name] = _GraphNode() |
| else: |
| schema_graph[name] = _GraphNode((key, _CreateGraph(value)) for |
| key, value in node.iteritems()) |
| return schema_graph |
| |
| |
| def _Subtract(minuend, subtrahend): |
| ''' A Set Difference adaptation for graphs. Returns a |difference|, |
| which contains key-value pairs found in |minuend| but not in |
| |subtrahend|. |
| ''' |
| difference = _GraphNode() |
| for key in minuend: |
| if key not in subtrahend: |
| # Record all of this key's children as being part of the difference. |
| difference[key] = _Subtract(minuend[key], {}) |
| else: |
| # Note that |minuend| and |subtrahend| are assumed to be graphs, and |
| # therefore should have no lists present, only keys and nodes. |
| rest = _Subtract(minuend[key], subtrahend[key]) |
| if rest: |
| # Record a difference if children of this key differed at some point. |
| difference[key] = rest |
| return difference |
| |
| |
| def _Update(base, addend, annotation=None): |
| '''A Set Union adaptation for graphs. Returns a graph which contains |
| the key-value pairs from |base| combined with any key-value pairs |
| from |addend| that are not present in |base|. |
| ''' |
| for key in addend: |
| if key not in base: |
| # Add this key and the rest of its children. |
| base[key] = _Update(_GraphNode(annotation=annotation), |
| addend[key], |
| annotation=annotation) |
| else: |
| # The key is already in |base|, but check its children. |
| _Update(base[key], addend[key], annotation=annotation) |
| return base |
| |
| |
| |
| class APISchemaGraph(object): |
| '''Provides an interface for interacting with an API schema graph, a |
| nested dict structure that allows for simpler lookups of schema data. |
| ''' |
| |
| def __init__(self, api_schema=None, _graph=None): |
| self._graph = _graph if _graph is not None else _CreateGraph(api_schema) |
| |
| def __eq__(self, other): |
| return self._graph == other._graph |
| |
| def __ne__(self, other): |
| return not (self == other) |
| |
| def Subtract(self, other): |
| '''Returns an APISchemaGraph instance representing keys that are in |
| this graph but not in |other|. |
| ''' |
| return APISchemaGraph(_graph=_Subtract(self._graph, other._graph)) |
| |
| def Update(self, other, annotation=None): |
| '''Modifies this graph by adding keys from |other| that are not |
| already present in this graph. |
| ''' |
| _Update(self._graph, other._graph, annotation=annotation) |
| |
| def Lookup(self, *path): |
| '''Given a list of path components, |path|, checks if the |
| APISchemaGraph instance contains |path|. |
| ''' |
| node = self._graph |
| for path_piece in path: |
| node = node.get(path_piece) |
| if node is None: |
| return LookupResult(found=False, annotation=None) |
| return LookupResult(found=True, annotation=node._annotation) |
| |
| def IsEmpty(self): |
| '''Checks for an empty schema graph. |
| ''' |
| return not self._graph |