Package com.google.javascript.jscomp.graph

Class Graph<N,​E>

  • Type Parameters:
    N - Value type that the graph node stores.
    E - Value type that the graph edge stores.
    All Implemented Interfaces:
    AdjacencyGraph<N,​E>
    Direct Known Subclasses:
    DiGraph, UndiGraph
    public abstract class Graph<N,​E>
extends java.lang.Object
implements AdjacencyGraph<N,​E>
    The base generic class for graph-like data structure and algorithms in the compiler.

    Nodes and edges in the graph can store a piece of data that this graph is used to represent. For example, a variable interference graph might store a variable in the node. This piece of data can be accessed with GraphNode.getValue() and Graph.GraphEdge.getValue(). However, in some cases wrapping the nodes and/or edges in a custom class may be preferrable, as this additional piece of data must be explicitly cast down from Annotation to its true type.

    Algorithms and analysis can annotate information on the nodes and edges using GraphNode.getValue() and Graph.GraphEdge.getValue(). For example, a graph coloring algorithm can store the color as an annotation. If multiple analyses are required, it is up to the user of the analysis to save the annotated solution between passes.

    We implemented our own graph data structure (as opposed to using com.google.common.graph ) for three reasons. First, aside from the node's label value, we would like to annotate information on the nodes and edges. Using a map to annotate would introduce too much overhead during fix point analysis. Also, com.google.common.graph does not support labeling of edges. Second, avoiding using an external package limits our dependencies. Third, com.google.common.graph uses WeakRefs which J2CL does not support.

    • Constructor Detail

      • Graph

        public Graph()

    • Method Detail

      • connect

        public abstract void connect​(N n1,
                             E edge,
                             N n2)
        Connects two nodes in the graph with an edge.
        Parameters:
        n1 - First node.
        edge - The edge.
        n2 - Second node.

      • disconnect

        public abstract void disconnect​(N n1,
                                N n2)
        Disconnects two nodes in the graph by removing all edges between them.
        Parameters:
        n1 - First node.
        n2 - Second node.

      • connectIfNotFound

        public final void connectIfNotFound​(N n1,
                                    E edge,
                                    N n2)
        Connects two nodes in the graph with an edge if such edge does not already exists between the nodes.
        Parameters:
        n1 - First node.
        edge - The edge.
        n2 - Second node.

      • createNode

        public abstract GraphNode<N,​E> createNode​(N value)
        Gets a node from the graph given a value. New nodes are created if that value has not been assigned a graph node. Values equality are compared using Object.equals.
        Parameters:
        value - The node's value.
        Returns:
        The corresponding node in the graph.

      • getNodes

        public abstract java.util.Collection<? extends GraphNode<N,​E>> getNodes()
        Gets an immutable list of all nodes.
        Specified by:
        getNodes in interface AdjacencyGraph<N,​E>

      • getEdges

        public abstract java.util.List<? extends Graph.GraphEdge<N,​E>> getEdges()
        Gets an immutable list of all edges.

      • getEdges

        public abstract java.util.List<? extends Graph.GraphEdge<N,​E>> getEdges​(N n1,
                                                                              N n2)
        Retrieves an edge from the graph.
        Parameters:
        n1 - Node one.
        n2 - Node two.
        Returns:
        The list of edges between those two values in the graph.

      • getNodeDegree

        public abstract int getNodeDegree​(N value)
        Gets the degree of a node.
        Parameters:
        value - The node's value.
        Returns:
        The degree of the node.

      • getNeighborNodes

        public abstract java.util.List<GraphNode<N,​E>> getNeighborNodes​(N value)
        Gets the neighboring nodes.
        Parameters:
        value - The node's value.
        Returns:
        A list of neighboring nodes.

      • getFirstEdge

        public abstract Graph.GraphEdge<N,​E> getFirstEdge​(N n1,
                                                        N n2)
        Retrieves any edge from the graph.
        Parameters:
        n1 - Node one.
        n2 - Node two.
        Returns:
        The first edges between those two values in the graph. null if there are none.

      • hasNode

        public final boolean hasNode​(N n)
        Checks whether the node exists in the graph (createNode(Object) has been called with that value).
        Parameters:
        n - Node.
        Returns:
        true if it exist.

      • isConnected

        public abstract boolean isConnected​(N n1,
                                    N n2)
        Checks whether two nodes in the graph are connected.
        Parameters:
        n1 - Node 1.
        n2 - Node 2.
        Returns:
        true if the two nodes are connected.

      • isConnected

        public abstract boolean isConnected​(N n1,
                                    E e,
                                    N n2)
        Checks whether two nodes in the graph are connected by the given edge type.
        Parameters:
        n1 - Node 1.
        e - The edge type.
        n2 - Node 2.

      • clearEdgeAnnotations

        public final void clearEdgeAnnotations()
        Makes each edge's annotation null.

      • pushNodeAnnotations

        public final void pushNodeAnnotations()
        Pushes nodes' annotation values. Restored with popNodeAnnotations(). Nodes' annotation values are cleared.

      • popNodeAnnotations

        public final void popNodeAnnotations()
        Restores nodes' annotation values to state before last pushNodeAnnotations().

      • pushEdgeAnnotations

        public final void pushEdgeAnnotations()
        Pushes edges' annotation values. Restored with popEdgeAnnotations(). Edges' annotation values are cleared.

      • popEdgeAnnotations

        public final void popEdgeAnnotations()
        Restores edges' annotation values to state before last pushEdgeAnnotations().