001    package org.maltparser.parser.algorithm.stack;
002    
003    import java.util.Stack;
004    
005    import org.maltparser.core.exception.MaltChainedException;
006    import org.maltparser.core.syntaxgraph.LabelSet;
007    import org.maltparser.core.syntaxgraph.edge.Edge;
008    import org.maltparser.core.syntaxgraph.node.DependencyNode;
009    import org.maltparser.parser.ParserConfiguration;
010    import org.maltparser.parser.TransitionSystem;
011    import org.maltparser.parser.history.GuideUserHistory;
012    import org.maltparser.parser.history.History;
013    import org.maltparser.parser.history.action.ComplexDecisionAction;
014    import org.maltparser.parser.history.action.GuideUserAction;
015    import org.maltparser.parser.transition.TransitionTable;
016    /**
017     * @author Johan Hall
018     *
019     */
020    public class Projective extends TransitionSystem {
021            protected static final int SHIFT = 1;
022            protected static final int RIGHTARC = 2;
023            protected static final int LEFTARC = 3;
024            
025            public Projective() throws MaltChainedException {
026                    super();
027            }
028            
029            public void apply(GuideUserAction currentAction, ParserConfiguration configuration) throws MaltChainedException {
030                    final StackConfig config = (StackConfig)configuration;
031                    final Stack<DependencyNode> stack = config.getStack();
032                    currentAction.getAction(actionContainers);
033                    Edge e = null;
034                    DependencyNode head = null;
035                    DependencyNode dep = null;
036                    switch (transActionContainer.getActionCode()) {
037                    case LEFTARC:
038                            head = stack.pop(); 
039                            dep = stack.pop();
040                            e = config.getDependencyStructure().addDependencyEdge(head.getIndex(), dep.getIndex());
041                            addEdgeLabels(e);
042                            stack.push(head);
043                            break;
044                    case RIGHTARC:
045                            dep = stack.pop(); 
046                            e = config.getDependencyStructure().addDependencyEdge(stack.peek().getIndex(), dep.getIndex());
047                            addEdgeLabels(e);
048                            break;
049                    default:
050                            final Stack<DependencyNode> input = config.getInput();
051                            if (input.isEmpty()) {
052                                    stack.pop();
053                            } else {
054                                    stack.push(input.pop()); // SHIFT
055                            }
056                            break;
057                    }
058            }
059            
060            public boolean permissible(GuideUserAction currentAction, ParserConfiguration configuration) throws MaltChainedException {
061                    final StackConfig config = (StackConfig)configuration;
062                    currentAction.getAction(actionContainers);
063                    final int trans = transActionContainer.getActionCode();
064                    if ((trans == LEFTARC || trans == RIGHTARC) && !isActionContainersLabeled()) {
065                            return false;
066                    }
067                    final Stack<DependencyNode> stack = config.getStack();
068                    if ((trans == LEFTARC || trans == RIGHTARC) && stack.size() < 2) {
069                            return false;
070                    }
071                    if (trans == LEFTARC && stack.get(stack.size()-2).isRoot()) { 
072                            return false;
073                    }
074                    if (trans == SHIFT && config.getInput().isEmpty()) { 
075                            return false;
076                    }
077                    
078                    return true;
079            }
080            
081            public GuideUserAction getDeterministicAction(GuideUserHistory history, ParserConfiguration config) throws MaltChainedException {
082                    return null;
083            }
084            
085            protected void addAvailableTransitionToTable(TransitionTable ttable) throws MaltChainedException {
086                    ttable.addTransition(SHIFT, "SH", false, null);
087                    ttable.addTransition(RIGHTARC, "RA", true, null);
088                    ttable.addTransition(LEFTARC, "LA", true, null);
089            }
090            
091            protected void initWithDefaultTransitions(GuideUserHistory history) throws MaltChainedException {
092                    GuideUserAction currentAction = new ComplexDecisionAction((History)history);
093                    
094                    transActionContainer.setAction(SHIFT);
095                    for (int i = 0; i < arcLabelActionContainers.length; i++) {
096                            arcLabelActionContainers[i].setAction(-1);
097                    }
098                    currentAction.addAction(actionContainers);
099            }
100            
101            public String getName() {
102                    return "projective";
103            }
104            
105            public GuideUserAction defaultAction(GuideUserHistory history, ParserConfiguration configuration) throws MaltChainedException {
106                    if (((StackConfig)configuration).getInput().isEmpty()) {
107                            LabelSet labelSet = ((StackConfig)configuration).getDependencyGraph().getDefaultRootEdgeLabels();
108                            return updateActionContainers(history, RIGHTARC, labelSet);
109                    }       
110                    return updateActionContainers(history, SHIFT, null);
111            }
112    }