StackConfig.java

package org.maltparser.parser.algorithm.stack;

import java.util.Stack;
import org.maltparser.core.exception.MaltChainedException;
import org.maltparser.core.symbol.SymbolTable;
import org.maltparser.core.symbol.SymbolTableHandler;
import org.maltparser.core.syntaxgraph.DependencyGraph;
import org.maltparser.core.syntaxgraph.DependencyStructure;
import org.maltparser.core.syntaxgraph.edge.Edge;
import org.maltparser.core.syntaxgraph.node.DependencyNode;
import org.maltparser.parser.ParserConfiguration;
import org.maltparser.parser.ParsingException;

/**
 * @author Johan Hall
 *
 */
public class StackConfig extends ParserConfiguration {

    private Stack<DependencyNode> stack;
    private Stack<DependencyNode> input;
    private DependencyStructure dependencyGraph;
    private int lookahead;

    public StackConfig(SymbolTableHandler symbolTableHandler) throws MaltChainedException {
        super();
        stack = new Stack<DependencyNode>();
        input = new Stack<DependencyNode>();
        dependencyGraph = new DependencyGraph(symbolTableHandler);
    }

    public Stack<DependencyNode> getStack() {
        return stack;
    }

    public Stack<DependencyNode> getInput() {
        return input;
    }

    public DependencyStructure getDependencyStructure() {
        return dependencyGraph;
    }

    public boolean isTerminalState() {
        return input.isEmpty() && stack.size() == 1;
    }

    public DependencyNode getStackNode(int index) throws MaltChainedException {
        if (index < 0) {
            throw new ParsingException("Stack index must be non-negative in feature specification. ");
        }
        if (stack.size() - index > 0) {
            return stack.get(stack.size() - 1 - index);
        }
        return null;
    }

    private DependencyNode getBufferNode(int index) throws MaltChainedException {
        if (index < 0) {
            throw new ParsingException("Input index must be non-negative in feature specification. ");
        }
        if (input.size() - index > 0) {
            return input.get(input.size() - 1 - index);
        }
        return null;
    }

    public DependencyNode getLookaheadNode(int index) throws MaltChainedException {
        return getBufferNode(lookahead + index);
    }

    public DependencyNode getInputNode(int index) throws MaltChainedException {
        if (index < lookahead) {
            return getBufferNode(index);
        }
        return null;
    }

    public void setDependencyGraph(DependencyStructure source) throws MaltChainedException {
        dependencyGraph.clear();
        for (int index : source.getTokenIndices()) {
            DependencyNode gnode = source.getTokenNode(index);
            DependencyNode pnode = dependencyGraph.addTokenNode(gnode.getIndex());
            for (SymbolTable table : gnode.getLabelTypes()) {
                pnode.addLabel(table, gnode.getLabelSymbol(table));
            }

            if (gnode.hasHead()) {
                Edge s = gnode.getHeadEdge();
                Edge t = dependencyGraph.addDependencyEdge(s.getSource().getIndex(), s.getTarget().getIndex());

                for (SymbolTable table : s.getLabelTypes()) {
                    t.addLabel(table, s.getLabelSymbol(table));
                }
            }
        }
        for (SymbolTable table : source.getDefaultRootEdgeLabels().keySet()) {
            dependencyGraph.setDefaultRootEdgeLabel(table, source.getDefaultRootEdgeLabelSymbol(table));
        }
    }

    public void lookaheadIncrement() {
        lookahead++;
    }

    public void lookaheadDecrement() {
        if (lookahead > 0) {
            lookahead--;
        }
    }

    public DependencyStructure getDependencyGraph() {
        return dependencyGraph;
    }

    public void initialize(ParserConfiguration parserConfiguration) throws MaltChainedException {
        if (parserConfiguration != null) {
            StackConfig config = (StackConfig) parserConfiguration;
            Stack<DependencyNode> sourceStack = config.getStack();
            Stack<DependencyNode> sourceInput = config.getInput();
            setDependencyGraph(config.getDependencyGraph());
            for (int i = 0, n = sourceStack.size(); i < n; i++) {
                stack.add(dependencyGraph.getDependencyNode(sourceStack.get(i).getIndex()));
            }
            for (int i = 0, n = sourceInput.size(); i < n; i++) {
                input.add(dependencyGraph.getDependencyNode(sourceInput.get(i).getIndex()));
            }
        } else {
            stack.push(dependencyGraph.getDependencyRoot());
            for (int i = dependencyGraph.getHighestTokenIndex(); i > 0; i--) {
                final DependencyNode node = dependencyGraph.getDependencyNode(i);
                if (node != null && !node.hasHead()) {
                    input.push(node);
                }
            }
        }
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        StackConfig that = (StackConfig) obj;

        if (lookahead != that.lookahead) {
            return false;
        }
        if (stack.size() != that.getStack().size()) {
            return false;
        }
        if (input.size() != that.getInput().size()) {
            return false;
        }
        if (dependencyGraph.nEdges() != that.getDependencyGraph().nEdges()) {
            return false;
        }
        for (int i = 0; i < stack.size(); i++) {
            if (stack.get(i).getIndex() != that.getStack().get(i).getIndex()) {
                return false;
            }
        }
        for (int i = 0; i < input.size(); i++) {
            if (input.get(i).getIndex() != that.getInput().get(i).getIndex()) {
                return false;
            }
        }
        return dependencyGraph.getEdges().equals(that.getDependencyGraph().getEdges());
    }

    public void clear() throws MaltChainedException {
        dependencyGraph.clear();
        stack.clear();
        input.clear();
        historyNode = null;
        lookahead = 0;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append(stack.size());
        sb.append(", ");
        sb.append(input.size());
        sb.append(", ");
        sb.append(dependencyGraph.nEdges());
        return sb.toString();
    }
}