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#| simple-header
$Id: graph-container.lisp,v 1.12 2005/07/20 20:39:09 moody Exp $
Author: Gary King
DISCUSSION
|#
(in-package #:metabang.graph)
;;; class defs
(defclass* graph-container (iteratable-container-mixin
non-associative-container-mixin
initial-contents-mixin
basic-graph
container-uses-nodes-mixin)
((vertex-pair->edge (make-container 'simple-associative-container
:test #'equal) r))
(:default-initargs
:vertex-class 'graph-container-vertex
:directed-edge-class 'graph-container-directed-edge
:undirected-edge-class 'graph-container-undirected-edge)
(:export-p t)
(:documentation "A graph container is essentially an adjacency list graph representation [?? The Bad name comes from it being implemented with containers... ugh]"))
(defclass* graph-container-edge (basic-edge)
((vertex-1 nil ir "`Vertex-1` is one of the two vertexes that an edge connects. In a directed-edge, `vertex-1` is also the `source-vertex`.")
(vertex-2 nil ir "`Vertex-2` is one of the two vertexes that an edge connects. In a directed edge, `vertex-2` is also the `target-vertex`.")
;(endvertexes nil ir "`Endvertexes` are the two vertices which together comprise an edge.")
)
(:export-slots vertex-1 vertex-2 ;endvertexes
)
(:export-p t)
(:documentation "This is the root class for edges in graph-containers. It adds vertex-1 and vertex-2 slots."))
(defmethod print-object ((object graph-container-edge) stream)
(print-unreadable-object (object stream :type t)
(format stream "<~A ~A ~A>" (vertex-1 object) (vertex-2 object)
(value object))))
(defclass* weighted-edge (weighted-edge-mixin graph-container-edge)
()
(:export-p t)
(:documentation "A weighted edge is both a weighted-edge-mixin and a graph-container-edge."))
(defclass* weighted-directed-edge (weighted-edge-mixin graph-container-directed-edge)
()
(:export-p t)
(:documentation "A weighted edge is a weighted-edge-mixin, a directed-edge-mixin, and a graph-container-edge."))
(defclass* weighted-undirected-edge (weighted-edge-mixin graph-container-undirected-edge)
()
(:export-p t)
(:documentation "A weighted undirected edge is a weighted-edge-mixin, an undirected-edge-mixin, and a graph-container-edge."))
(defclass* graph-container-vertex (basic-vertex)
((vertex-edges nil r))
(:export-p t)
(:default-initargs
:vertex-edges-container-class 'vector-container)
(:documentation "A graph container vertex keeps track of its edges in the the vertex-edges slot. The storage for this defaults to a vector-container but can be changed using the vertex-edges-container-class initarg."))
(defmethod make-vertex-edges-container ((vertex graph-container-vertex)
container-class &rest args)
(apply #'make-container container-class args))
(defmethod initialize-instance :after ((object graph-container-vertex) &key
vertex-edges-container-class)
(setf (slot-value object 'vertex-edges)
(make-vertex-edges-container object vertex-edges-container-class)))
(defmethod make-vertex-container ((graph graph-container) initial-size)
(make-container 'simple-associative-container
:initial-size initial-size
:test (vertex-test graph)))
(defmethod make-edge-container ((graph graph-container) initial-size)
(make-container 'vector-container :initial-size initial-size
:fill-pointer 0))
;;; graph-container-undirected-edge
(defclass* graph-container-undirected-edge (undirected-edge-mixin
graph-container-edge)
()
(:export-p t)
(:documentation "A graph-container-undirected-edge is both an undirected-edge-mixin and a graph-container-edge."))
;;; graph-container-directed-edge
(defclass* graph-container-directed-edge (directed-edge-mixin
graph-container-edge)
()
(:export-p t)
(:documentation "A graph-container-directed-edge is both a directed-edge-mixin and a graph-container-edge."))
(defmethod initialize-instance :after ((object graph-container-directed-edge)
&key source-vertex target-vertex)
(when (and source-vertex (vertex-1 object))
(error "Specify source-vertex or vertex-1, but not both"))
(when (and target-vertex (vertex-2 object))
(error "Specify target-vertex or vertex-2, but not both"))
(when source-vertex
(setf (slot-value object 'vertex-1) source-vertex))
(when target-vertex
(setf (slot-value object 'vertex-2) target-vertex)))
;;; vertex-1 is defined to be the source vertex of an undirected edge
(defmethod source-vertex ((edge graph-container-edge))
(vertex-1 edge))
;;; vertex-2 is defined to be the target vertex of an undirected edge
(defmethod target-vertex ((edge graph-container-edge))
(vertex-2 edge))
(defmethod other-vertex ((edge graph-container-edge)
(v graph-container-vertex))
(cond ((eq v (vertex-1 edge))
(values (vertex-2 edge)))
((eq v (vertex-2 edge))
(values (vertex-1 edge)))
(t (error "Vertex ~A not part of Edge ~A" v edge))))
(defmethod other-vertex ((edge graph-container-edge)
(value t))
(other-vertex edge (find-vertex edge value)))
;;; Managing the vertex-pair->edge table
(defmethod associate-edge-with-pair ((graph graph-container) (edge graph-container-edge))
(push edge (item-at-1 (vertex-pair->edge graph)
(cons (vertex-1 edge) (vertex-2 edge)))))
(defmethod associate-edge-with-pair :after ((graph graph-container) (edge undirected-edge-mixin))
; since it is undirected, index this edge with both endvertex orderings
(push edge (item-at-1 (vertex-pair->edge graph)
(cons (vertex-2 edge) (vertex-1 edge)))))
(defun dissoc-val-from-key-or-delete (container index val)
(let* ((l (delete val (item-at-1 container index) :test #'eq)))
(if (null l)
(delete-item-at container index)
(setf (item-at-1 container index) l))))
(defmethod dissociate-edge-from-pair ((graph graph-container) (edge graph-container-edge))
(dissoc-val-from-key-or-delete (vertex-pair->edge graph)
(cons (vertex-1 edge) (vertex-2 edge)) edge))
(defmethod dissociate-edge-from-pair :after ((graph graph-container) (edge undirected-edge-mixin))
(dissoc-val-from-key-or-delete (vertex-pair->edge graph)
(cons (vertex-2 edge) (vertex-1 edge)) edge))
; Replacing a vertex means carefully reindexing its incident edges in
; the endvertex lookup table for the graph-container.
;; Before replacing the vertex, we forget its related endvertex lookups
(defmethod replace-vertex :before ((graph graph-container) (old basic-vertex) (new basic-vertex))
(iterate-edges old (lambda (e) (dissociate-edge-from-pair graph e))))
;; After replacing the vertex, we fix the endvertex lookups
(defmethod replace-vertex :after ((graph graph-container) (old basic-vertex) (new basic-vertex))
(iterate-edges new (lambda (e) (associate-edge-with-pair graph e))))
(defmethod add-edge ((graph graph-container) (edge graph-container-edge)
&key force-new?)
(declare (ignore force-new?))
(let ((vertex-1 (vertex-1 edge))
(vertex-2 (vertex-2 edge)))
(cond ((eq vertex-1 vertex-2)
(add-edge-to-vertex edge vertex-1))
(t
(add-edge-to-vertex edge vertex-1)
(add-edge-to-vertex edge vertex-2)))
(associate-edge-with-pair graph edge))
edge)
(defmethod add-edge-to-vertex :around ((edge graph-container-edge)
(vertex graph-container-vertex))
(insert-item (vertex-edges vertex) edge))
(defmethod make-node-for-container ((graph graph-container) (node t) &key)
(make-vertex-for-graph graph :element node))
(defmethod find-edge-between-vertexes ((graph graph-container)
(vertex-1 graph-container-vertex)
(vertex-2 graph-container-vertex)
&key error-if-not-found?)
(multiple-value-bind (value found?)
(item-at-1 (vertex-pair->edge graph)
(cons vertex-1 vertex-2))
(when (and error-if-not-found?
(not found?))
(error 'graph-edge-not-found-error
:vertex-1 vertex-1 :vertex-2 vertex-1))
(first value)))
(defmethod find-edge-between-vertexes-if ((graph graph-container)
(vertex-1 graph-container-vertex)
(vertex-2 graph-container-vertex)
fn
&key error-if-not-found?)
(let ((it (search-for-match (vertex-edges vertex-1)
(lambda (edge)
(and (eq vertex-2 (other-vertex edge vertex-1))
(funcall fn edge))))))
(when (and error-if-not-found? (not it))
(error 'graph-edge-not-found-error
:vertex-1 vertex-1 :vertex-2 vertex-1))
it))
(defmethod find-edge-between-vertexes-if ((graph graph-container)
(value-1 t)
(value-2 t)
fn
&key error-if-not-found?)
(let ((v1 (find-vertex graph value-1 error-if-not-found?))
(v2 (find-vertex graph value-2 error-if-not-found?)))
(or (and v1 v2 (find-edge-between-vertexes-if graph v1 v2 fn))
(when error-if-not-found?
(error 'graph-edge-not-found-error :vertex-1 v1 :vertex-2 v2)))))
(defmethod find-edge ((graph graph-container) (edge graph-container-edge)
&optional error-if-not-found?)
(find-edge-between-vertexes
graph (vertex-1 edge) (vertex-2 edge)
:error-if-not-found? error-if-not-found?))
(defmethod delete-edge ((graph graph-container) (edge graph-container-edge))
(let ((vertex-1 (vertex-1 edge))
(vertex-2 (vertex-2 edge)))
(delete-item (vertex-edges vertex-1) edge)
(delete-item (vertex-edges vertex-2) edge)
(dissociate-edge-from-pair graph edge))
edge)
(defmethod delete-all-edges ((graph graph-container))
(iterate-vertexes
graph
(lambda (vertex)
(empty! (vertex-edges vertex))))
(empty! (vertex-pair->edge graph))
graph)
(defmethod empty! :after ((graph graph-container))
(empty! (vertex-pair->edge graph)))
;;; iteration
(defmethod iterate-edges ((graph graph-container) fn)
(iterate-elements (graph-edges graph) fn))
(defmethod iterate-edges ((vertex graph-container-vertex) fn)
(iterate-elements (vertex-edges vertex) fn))
(defmethod iterate-source-edges ((vertex graph-container-vertex) fn)
(iterate-elements (vertex-edges vertex)
(lambda (edge)
(when (or (undirected-edge-p edge)
(eq vertex (source-vertex edge)))
(funcall fn edge)))))
(defmethod iterate-target-edges ((vertex graph-container-vertex) fn)
(iterate-elements (vertex-edges vertex)
(lambda (edge)
(when (or (undirected-edge-p edge)
(eq vertex (target-vertex edge)))
(funcall fn edge)))))
(defmethod iterate-children ((vertex graph-container-vertex) fn)
(iterate-source-edges vertex
(lambda (edge)
(funcall fn (other-vertex edge vertex)))))
(defmethod iterate-parents ((vertex graph-container-vertex) fn)
(iterate-target-edges vertex
(lambda (edge)
(funcall fn (other-vertex edge vertex)))))
(defmethod iterate-neighbors ((vertex graph-container-vertex) fn)
(iterate-edges vertex
(lambda (edge)
(funcall fn (other-vertex edge vertex)))))
(defmethod vertexes ((edge graph-container-edge))
(collect-using #'iterate-vertexes nil edge))
(defmethod has-children-p ((vertex graph-container-vertex))
(iterate-source-edges vertex
(lambda (edge)
(declare (ignore edge))
(return-from has-children-p t)))
(values nil))
(defmethod has-parent-p ((vertex graph-container-vertex))
(iterate-target-edges vertex
(lambda (edge)
(declare (ignore edge))
(return-from has-parent-p t)))
(values nil))
(defmethod vertices-share-edge-p ((vertex-1 graph-container-vertex)
(vertex-2 graph-container-vertex))
(iterate-target-edges vertex-1
(lambda (e)
(when (or (eq (target-vertex e) vertex-2)
(eq (source-vertex e) vertex-2))
(return-from vertices-share-edge-p t))))
(iterate-source-edges vertex-1
(lambda (e)
(when (or (eq (target-vertex e) vertex-2)
(eq (source-vertex e) vertex-2))
(return-from vertices-share-edge-p t))))
(values nil))
(defmethod edge-count ((graph graph-container))
(size (graph-edges graph)))
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