78 lines
2.2 KiB
Java
78 lines
2.2 KiB
Java
package org.insa.graph.io;
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import java.io.DataInputStream;
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import java.io.IOException;
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import java.util.ArrayList;
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import org.insa.graph.Graph;
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import org.insa.graph.Node;
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import org.insa.graph.Path;
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/**
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* Implementation of {@link PathReader} to read paths in binary format.
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*
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*/
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public class BinaryPathReader extends BinaryReader implements PathReader {
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// Map version and magic number targeted for this reader.
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protected static final int VERSION = 1;
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protected static final int MAGIC_NUMBER = 0xdecafe;
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/**
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* Create a new BinaryPathReader that read from the given input stream.
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*
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* @param dis Input stream to read from.
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*/
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public BinaryPathReader(DataInputStream dis) {
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super(MAGIC_NUMBER, VERSION, dis);
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}
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@Override
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public Path readPath(Graph graph) throws IOException {
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// Read and check magic number and version.
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checkMagicNumberOrThrow(dis.readInt());
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checkVersionOrThrow(dis.readInt());
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// Read map ID and check against graph.
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String mapId = readFixedLengthString(BinaryGraphReader.MAP_ID_FIELD_LENGTH,
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"UTF-8");
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if (!mapId.equals(graph.getMapId())) {
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throw new MapMismatchException(mapId, graph.getMapId());
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}
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// Number of nodes in the path (without first and last).
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int nbNodes = dis.readInt();
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// Skip (duplicate) first and last node
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readNode(graph);
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readNode(graph);
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// Read intermediate nodes:
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ArrayList<Node> nodes = new ArrayList<Node>();
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for (int i = 0; i < nbNodes; ++i) {
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nodes.add(readNode(graph));
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}
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return Path.createFastestPathFromNodes(graph, nodes);
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}
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/**
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* Read a node from the input stream and returns it.
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*
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* @param graph Graph containing the nodes.
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*
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* @return The next node in the input stream.
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*
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* @throws IOException if something occurs while reading the note.
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* @throws IndexOutOfBoundsException if the node is not in the graph.
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*/
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protected Node readNode(Graph graph) throws IOException {
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// Discard zone.
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dis.readUnsignedByte();
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return graph.getNodes().get(read24bits());
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}
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}
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