001 package org.maltparser.parser.algorithm.nivre;
002
003 import org.maltparser.core.exception.MaltChainedException;
004 import org.maltparser.core.syntaxgraph.DependencyStructure;
005 import org.maltparser.core.syntaxgraph.node.DependencyNode;
006 import org.maltparser.parser.DependencyParserConfig;
007 import org.maltparser.parser.Oracle;
008 import org.maltparser.parser.ParserConfiguration;
009 import org.maltparser.parser.history.GuideUserHistory;
010 import org.maltparser.parser.history.action.GuideUserAction;
011 /**
012 * @author Johan Hall
013 *
014 */
015 public class ArcEagerOracle extends Oracle {
016
017 public ArcEagerOracle(DependencyParserConfig manager, GuideUserHistory history) throws MaltChainedException {
018 super(manager, history);
019 setGuideName("ArcEager");
020 }
021
022 public GuideUserAction predict(DependencyStructure gold, ParserConfiguration config) throws MaltChainedException {
023 NivreConfig nivreConfig = (NivreConfig)config;
024 DependencyNode stackPeek = nivreConfig.getStack().peek();
025 int stackPeekIndex = stackPeek.getIndex();
026 int inputPeekIndex = nivreConfig.getInput().peek().getIndex();
027
028 if (!stackPeek.isRoot() && gold.getTokenNode(stackPeekIndex).getHead().getIndex() == inputPeekIndex) {
029 return updateActionContainers(ArcEager.LEFTARC, gold.getTokenNode(stackPeekIndex).getHeadEdge().getLabelSet());
030 } else if (gold.getTokenNode(inputPeekIndex).getHead().getIndex() == stackPeekIndex) {
031 return updateActionContainers(ArcEager.RIGHTARC, gold.getTokenNode(inputPeekIndex).getHeadEdge().getLabelSet());
032 } else if (nivreConfig.getRootHandling() == NivreConfig.STRICT && !stackPeek.hasHead()) {
033 return updateActionContainers(ArcEager.SHIFT, null);
034 } else if (gold.getTokenNode(inputPeekIndex).hasLeftDependent() &&
035 gold.getTokenNode(inputPeekIndex).getLeftmostDependent().getIndex() < stackPeekIndex) {
036 return updateActionContainers(ArcEager.REDUCE, null);
037 } else if (gold.getTokenNode(inputPeekIndex).getHead().getIndex() < stackPeekIndex &&
038 (!gold.getTokenNode(inputPeekIndex).getHead().isRoot() || nivreConfig.getRootHandling() == NivreConfig.NORMAL)) {
039 return updateActionContainers(ArcEager.REDUCE, null);
040 } else {
041 return updateActionContainers(ArcEager.SHIFT, null);
042 }
043 }
044
045 public void finalizeSentence(DependencyStructure dependencyGraph) throws MaltChainedException {}
046
047 public void terminate() throws MaltChainedException {}
048 }