Imported Upstream version 4.6.2

ipapython/graph.py

@@ -0,0 +1,88 @@
+#
+# Copyright (C) 2015-2017  FreeIPA Contributors see COPYING for license
+#
+from collections import deque
+
+
+class Graph(object):
+    """
+    Simple oriented graph structure
+
+    G = (V, E) where G is graph, V set of vertices and E list of edges.
+    E = (tail, head) where tail and head are vertices
+    """
+
+    def __init__(self):
+        self.vertices = set()
+        self.edges = []
+        self._adj = dict()
+
+    def add_vertex(self, vertex):
+        self.vertices.add(vertex)
+        self._adj[vertex] = []
+
+    def add_edge(self, tail, head):
+        if tail not in self.vertices:
+            raise ValueError("tail is not a vertex")
+
+        if head not in self.vertices:
+            raise ValueError("head is not a vertex")
+
+        self.edges.append((tail, head))
+        self._adj[tail].append(head)
+
+    def remove_edge(self, tail, head):
+        try:
+            self.edges.remove((tail, head))
+        except KeyError:
+            raise ValueError(
+                "graph does not contain edge: ({0}, {1})".format(tail, head)
+            )
+        self._adj[tail].remove(head)
+
+    def remove_vertex(self, vertex):
+        try:
+            self.vertices.remove(vertex)
+        except KeyError:
+            raise ValueError(
+                "graph does not contain vertex: {0}".format(vertex)
+            )
+
+        # delete _adjacencies
+        del self._adj[vertex]
+        for adj in self._adj.values():
+            adj[:] = [v for v in adj if v != vertex]
+
+        # delete edges
+        self.edges = [
+            e for e in self.edges if e[0] != vertex and e[1] != vertex
+        ]
+
+    def get_tails(self, head):
+        """
+        Get list of vertices where a vertex is on the right side of an edge
+        """
+        return [e[0] for e in self.edges if e[1] == head]
+
+    def get_heads(self, tail):
+        """
+        Get list of vertices where a vertex is on the left side of an edge
+        """
+        return [e[1] for e in self.edges if e[0] == tail]
+
+    def bfs(self, start=None):
+        """
+        Breadth-first search traversal of the graph from `start` vertex.
+        Return a set of all visited vertices
+        """
+        if not start:
+            start = next(iter(self.vertices))
+        visited = set()
+        queue = deque([start])
+
+        while queue:
+            vertex = queue.popleft()
+            if vertex not in visited:
+                visited.add(vertex)
+                queue.extend(set(self._adj.get(vertex, [])) - visited)
+        return visited