diff options
Diffstat (limited to 'bsfs/graph/graph.py')
| -rw-r--r-- | bsfs/graph/graph.py | 99 |
1 files changed, 75 insertions, 24 deletions
diff --git a/bsfs/graph/graph.py b/bsfs/graph/graph.py index b7b9f1c..1b4c212 100644 --- a/bsfs/graph/graph.py +++ b/bsfs/graph/graph.py @@ -1,20 +1,18 @@ -""" -Part of the BlackStar filesystem (bsfs) module. -A copy of the license is provided with the project. -Author: Matthias Baumgartner, 2022 -""" # imports import os import typing # bsfs imports -from bsfs.schema import Schema +from bsfs.query import ast, validate +from bsfs import schema as bsc from bsfs.triple_store import TripleStoreBase from bsfs.utils import URI, typename # inner-module imports +from . import ac from . import nodes as _nodes +from . import resolve # exports __all__: typing.Sequence[str] = ( @@ -25,9 +23,7 @@ __all__: typing.Sequence[str] = ( ## code ## class Graph(): - """The Graph class is - - The Graph class provides a convenient interface to query and access a graph. + """The Graph class provides a convenient interface to query and access a graph. Since it logically builds on the concept of graphs it is easier to navigate than raw triple stores. Naturally, it uses a triple store as *backend*. It also controls actions via access permissions to a *user*. @@ -37,35 +33,40 @@ class Graph(): # link to the triple storage backend. _backend: TripleStoreBase - # user uri. - _user: URI + # access controls. + _ac: ac.AccessControlBase - def __init__(self, backend: TripleStoreBase, user: URI): + def __init__( + self, + backend: TripleStoreBase, + access_control: ac.AccessControlBase, + ): + # store members self._backend = backend - self._user = user + self._ac = access_control # ensure Graph schema requirements self.migrate(self._backend.schema) def __hash__(self) -> int: - return hash((type(self), self._backend, self._user)) + return hash((type(self), self._backend, self._ac)) def __eq__(self, other) -> bool: return isinstance(other, type(self)) \ and self._backend == other._backend \ - and self._user == other._user + and self._ac == other._ac def __repr__(self) -> str: - return f'{typename(self)}(backend={repr(self._backend)}, user={self._user})' + return f'{typename(self)}({repr(self._backend)}, {self._ac})' def __str__(self) -> str: - return f'{typename(self)}({str(self._backend)}, {self._user})' + return f'{typename(self)}({str(self._backend)})' @property - def schema(self) -> Schema: + def schema(self) -> bsc.Schema: """Return the store's local schema.""" return self._backend.schema - def migrate(self, schema: Schema, append: bool = True) -> 'Graph': + def migrate(self, schema: bsc.Schema, append: bool = True) -> 'Graph': """Migrate the current schema to a new *schema*. Appends to the current schema by default; control this via *append*. @@ -73,14 +74,14 @@ class Graph(): """ # check args - if not isinstance(schema, Schema): + if not isinstance(schema, bsc.Schema): raise TypeError(schema) # append to current schema if append: schema = schema + self._backend.schema # add Graph schema requirements with open(os.path.join(os.path.dirname(__file__), 'schema.nt'), mode='rt', encoding='UTF-8') as ifile: - schema = schema + Schema.from_string(ifile.read()) + schema = schema + bsc.from_string(ifile.read()) # migrate schema in backend # FIXME: consult access controls! self._backend.schema = schema @@ -95,19 +96,69 @@ class Graph(): *node_type*) once some data is assigned to them. """ + # get node type type_ = self.schema.node(node_type) # NOTE: Nodes constructor materializes guids. - return _nodes.Nodes(self._backend, self._user, type_, guids) + return _nodes.Nodes(self._backend, self._ac, type_, guids) def node(self, node_type: URI, guid: URI) -> _nodes.Nodes: """Return node *guid* of type *node_type* as a `bsfs.graph.Nodes` instance. - Note that the *guids* need not to exist (however, the *node_type* has + Note that the *guid* need not to exist (however, the *node_type* has to be part of the schema). An inexistent guid will be created (using *node_type*) once some data is assigned to them. """ + return self.nodes(node_type, {guid}) + + def empty(self, node_type: URI) -> _nodes.Nodes: + """Return a `Nodes` instance with type *node_type* but no nodes.""" + return self.nodes(node_type, set()) + + def get( + self, + node_type: URI, + query: typing.Optional[ast.filter.FilterExpression], + ) -> _nodes.Nodes: + """Return a `Nodes` instance over all nodes of type *node_type* that match the *query*.""" + # return Nodes instance + type_ = self.schema.node(node_type) + return _nodes.Nodes(self._backend, self._ac, type_, self.__get(node_type, query)) + + def sorted( + self, + node_type: URI, + query: typing.Optional[ast.filter.FilterExpression], + # FIXME: sort ast + ) -> typing.Iterator[_nodes.Nodes]: + """Return a iterator over `Nodes` instances over all nodes of type *node_type* that match the *query*.""" + # FIXME: Order should be a parameter + # return iterator over Nodes instances + type_ = self.schema.node(node_type) + for guid in self.__get(node_type, query): + yield _nodes.Nodes(self._backend, self._ac, type_, {guid}) + + def all(self, node_type: URI) -> _nodes.Nodes: + """Return all instances of type *node_type*.""" + type_ = self.schema.node(node_type) + return _nodes.Nodes(self._backend, self._ac, type_, self.__get(node_type, None)) + + def __get( + self, + node_type: URI, + query: typing.Optional[ast.filter.FilterExpression], + ) -> typing.Iterator[URI]: + """Build and execute a get query.""" + # get node type type_ = self.schema.node(node_type) - return _nodes.Nodes(self._backend, self._user, type_, {guid}) + # resolve Nodes instances + query = resolve.Filter(self._backend.schema).resolve(type_, query) + # add access controls to query + query = self._ac.filter_read(type_, query) + # validate query + if query is not None: + validate.Filter(self._backend.schema).validate(type_, query) + # query the backend and return the (non-materialized) result + return self._backend.get(type_, query) ## EOF ## |