.. _py-dg/GraphInterface:

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dg/GraphInterface
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.. default-domain:: py

.. py:currentmodule:: mod
.. cpp:namespace:: mod

.. class:: DGVertex

    A descriptor of either a vertex in a derivation graph, or a null vertex.

    .. method:: __init__()

        Constructs a null descriptor.
    .. :method:: __bool__()

        :returns: ``not isNull()``
        :rtype: bool
    .. method:: isNull()

        :returns: whether this is a null descriptor or not.
        :rtype: bool
    .. attribute:: id

        (Read-only) The index of the vertex. It will be in the range :math:`[0, numVertices + numEdges[`.

        :type: int
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: dg

        (Read-only) The derivation graph the vertex belongs to.

        :type: DG
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: inDegree

        (Read-only) The in-degree of the vertex, including multiplicity of target multisets.

        :type: int
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: inEdges

        (Read-only) A range of in-hyperedges for this vertex.

        :type: DGInEdgeRange
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: outDegree

        (Read-only) The out-degree of the vertex, including multiplicity of source multisets.

        :type: int
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: outEdges

        (Read-only) A range of out-hyperedges for this vertex.

        :type: DGOutEdgeRange
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: graph

        (Read-only) The graph label of the vertex.

        :type: Graph
        :raises: :class:`LogicError` if it is a null descriptor.
.. class:: DGHyperEdge

    A descriptor of either a hyperedge in a derivation graph, or a null edge.

    .. method:: __init__()

        Constructs a null descriptor.
    .. :method:: __bool__()

        :returns: ``not isNull()``
        :rtype: bool
    .. method:: isNull()

        :returns: whether this is a null descriptor or not.
        :rtype: bool
    .. attribute:: id

        (Read-only) The index of the hyperedge. It will be in the range :math:`[0, numVertices + numEdges[`.

        :type: int
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: dg

        (Read-only) The derivation graph the edge belongs to.

        :type: DG
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: numSources

        (Read-only) The number of sources of the hyperedge.

        :type: int
    .. attribute:: sources

        (Read-only) The sources of the hyperedge.

        :type: DGSourceRange
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: numTargets

        (Read-only) The number of targets of the hyperedge.

        :type: int
    .. attribute:: targets

        (Read-only) The targets of the hyperedge.

        :type: DGTargetRange
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: rules

        (Read-only) The rules associated with the hyperedge.

        :type: DGRuleRange
        :raises: :class:`LogicError` if it is a null descriptor.
    .. attribute:: inverse

        (Read-only) A descriptor for the inverse hyperedge of this one, if it exists.
        Otherwise a null descriptor is returned.

        :type: DGHyperEdge
        :raises: :class:`LogicError` if it is a null descriptor.
        :raises: :class:`LogicError` if not ``dg.locked``.
    .. method:: print(printer=GraphPrinter(), nomatchColour="gray", matchColour="", verbosity=0)

        Print the derivations represented by the hyperedge.
        All possible Double-Pushout diagrams are printed.

        :param GraphPrinter printer: the printer to use for the figures.
        :param str matchColour: the TikZ colour to use for the rule and its image in the bottom span.
        :param int verbosity: see :cpp:func:`dg::DG::HyperEdge::print`.
        :returns: A list with file data for each DPO diagram printed.
            Each element is a pair of filename prefixes, where the first entry is completed by appending ``_derL``, ``_derK``, or ``_derR``.
            The second entry is completed similarly by appending ``_derG``, ``_derD``, or ``_derH``.
        :rtype: list[tuple[str, str]]
        :raises: :class:`LogicError` if it is a null descriptor.
        :raises: :class:`LogicError` if it has no rules.