Source code for graphbrain.backends.backend

class Backend(object):
    """Hypergraph low-level operations."""

    def __init__(self):
        pass

    def close(self):
        raise NotImplementedError()

    def name(self):
        raise NotImplementedError()

    def exists(self, vertex):
        """Checks if the given edge exists in the hypergraph."""
        raise NotImplementedError()

    def add(self, edge, timestamp=-1):
        """Adds an edges to the hypergraph if it does not exist yet."""
        raise NotImplementedError()

    def remove(self, edge):
        """Removes an edges from the hypergraph."""
        raise NotImplementedError()

    def pattern2edges(self, pattern, open_ended):
        """Return all the edges that match a pattern.
        A pattern is a collection of entity ids and wildcards (None)."""
        raise NotImplementedError()

    def star(self, center):
        """Return all the edges that contain a given entity.
        Entity can be atomic or an edge."""
        raise NotImplementedError()

    def symbols_with_root(self, root):
        """Find all edge_symbols with the given root."""
        raise NotImplementedError()

    def edges_with_symbols(self, symbols, root=None):
        """Find all edges containing the given edge_symbols, and optionally a given root"""
        raise NotImplementedError()

    def destroy(self):
        """Erase the hypergraph."""
        raise NotImplementedError()

    def set_attribute(self, vertex, attribute, value):
        """Sets the value of an attribute."""
        raise NotImplementedError()

    def inc_attribute(self, vertex, attribute):
        """Increments an attribute of a vertex."""
        raise NotImplementedError()

    def dec_attribute(self, vertex, attribute):
        """Decrements an attribute of a vertex."""
        raise NotImplementedError()

    def get_str_attribute(self, vertex, attribute, or_else=None):
        """Returns attribute as string."""
        raise NotImplementedError()

    def get_int_attribute(self, vertex, attribute, or_else=None):
        """Returns attribute as integer value."""
        raise NotImplementedError()

    def get_float_attribute(self, vertex, attribute, or_else=None):
        """Returns attribute as float value."""
        raise NotImplementedError()

    def degree(self, vertex):
        """Returns the degree of a vertex."""
        raise NotImplementedError()

    def timestamp(self, vertex):
        """Returns the timestamp of a vertex."""
        raise NotImplementedError()

    def all(self):
        """Returns a lazy sequence of all the vertices in the hypergraph."""
        raise NotImplementedError()

    def all_attributes(self):
        """Returns a lazy sequence with a tuple for each vertex in the hypergraph.
           The first element of the tuple is the vertex itself,
           the second is a dictionary of attribute values (as strings)."""
        raise NotImplementedError()

    def symbol_count(self):
        """Total number of edge_symbols in the hypergraph"""
        raise NotImplementedError()

    def edge_count(self):
        """Total number of edge in the hypergraph"""
        raise NotImplementedError()

    def total_degree(self):
        """Total degree of the hypergraph"""
        raise NotImplementedError()