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AllowedEdges.java
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AllowedEdges.java
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package org.softwareheritage.graph;
import java.util.ArrayList;
import org.softwareheritage.graph.Graph;
import org.softwareheritage.graph.Node;
/**
* Edge restriction based on node types, used when visiting the graph.
* <p>
* <a href="https://docs.softwareheritage.org/devel/swh-model/data-model.html">Software Heritage
* graph</a> contains multiple node types (contents, directories, revisions, ...) and restricting
* the traversal to specific node types is necessary for many querying operations: <a
* href="https://docs.softwareheritage.org/devel/swh-graph/use-cases.html">use cases</a>.
*
* @author The Software Heritage developers
*/
public class AllowedEdges {
/** Graph on which edge restriction is performed */
Graph graph;
/**
* 2D boolean matrix storing access rights for all combination of src/dst node types (first
* dimension is source, second dimension is destination), when edge restriction is not enforced
* this array is set to null for early bypass.
*/
public boolean[][] restrictedTo;
/**
* Constructor.
*
* @param graph the graph on which to perform edge restriction
* @param edgesFmt a formatted string describing <a
* href="https://docs.softwareheritage.org/devel/swh-graph/api.html#terminology">allowed edges</a>
*/
public AllowedEdges(Graph graph, String edgesFmt) {
this.graph = graph;
int nbNodeTypes = Node.Type.values().length;
this.restrictedTo = new boolean[nbNodeTypes][nbNodeTypes];
// Special values (null, empty, "*")
if (edgesFmt == null || edgesFmt.isEmpty()) {
return;
}
if (edgesFmt.equals("*")) {
// Allows for quick bypass (with simple null check) when no edge restriction
restrictedTo = null;
return;
}
// Format: "src1:dst1,src2:dst2,[...]"
String[] edgeTypes = edgesFmt.split(",");
for (String edgeType : edgeTypes) {
String[] nodeTypes = edgeType.split(":");
if (nodeTypes.length != 2) {
throw new IllegalArgumentException("Cannot parse edge type: " + edgeType);
}
ArrayList<Node.Type> srcTypes = Node.Type.parse(nodeTypes[0]);
ArrayList<Node.Type> dstTypes = Node.Type.parse(nodeTypes[1]);
for (Node.Type srcType : srcTypes) {
for (Node.Type dstType : dstTypes) {
restrictedTo[srcType.ordinal()][dstType.ordinal()] = true;
}
}
}
}
/**
* Checks if a given edge can be followed during graph traversal.
*
* @param srcNodeId edge source node
* @param dstNodeId edge destination node
* @return true if allowed and false otherwise
*/
public boolean isAllowed(long srcNodeId, long dstNodeId) {
Node.Type srcType = graph.getNodeType(srcNodeId);
Node.Type dstType = graph.getNodeType(dstNodeId);
return restrictedTo[srcType.ordinal()][dstType.ordinal()];
}
/**
* Works like {@link AllowedEdges#isAllowed(long, long)} but with node types directly instead of
* node ids.
*
* @see AllowedEdges#isAllowed(long, long)
*/
public boolean isAllowed(Node.Type srcType, Node.Type dstType) {
return restrictedTo[srcType.ordinal()][dstType.ordinal()];
}
}

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