edu.stanford.nlp.parser.lexparser.ExactGrammarCompactor.java Source code

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Here is the source code for edu.stanford.nlp.parser.lexparser.ExactGrammarCompactor.java

Source

package edu.stanford.nlp.parser.lexparser;

import edu.stanford.nlp.util.logging.Redwood;

import edu.stanford.nlp.trees.PennTreebankLanguagePack;
import edu.stanford.nlp.fsm.TransducerGraph;
import edu.stanford.nlp.fsm.QuasiDeterminizer;
import edu.stanford.nlp.fsm.AutomatonMinimizer;
import edu.stanford.nlp.fsm.FastExactAutomatonMinimizer;

import java.util.List;

/**
 * @author Teg Grenager (grenager@cs.stanford.edu)
 */
public class ExactGrammarCompactor extends GrammarCompactor {

    /** A logger for this class */
    private static Redwood.RedwoodChannels log = Redwood.channels(ExactGrammarCompactor.class);

    TransducerGraph.GraphProcessor quasiDeterminizer = new QuasiDeterminizer();
    AutomatonMinimizer minimizer = new FastExactAutomatonMinimizer();
    TransducerGraph.NodeProcessor ntsp = new TransducerGraph.SetToStringNodeProcessor(
            new PennTreebankLanguagePack());
    TransducerGraph.NodeProcessor otsp = new TransducerGraph.ObjectToSetNodeProcessor();
    TransducerGraph.ArcProcessor isp = new TransducerGraph.InputSplittingProcessor();
    TransducerGraph.ArcProcessor ocp = new TransducerGraph.OutputCombiningProcessor();
    private boolean saveGraphs; // = false;

    public ExactGrammarCompactor(Options op, boolean saveGraphs, boolean verbose) {
        super(op);
        this.saveGraphs = saveGraphs;
        this.verbose = verbose;
        outputType = NORMALIZED_LOG_PROBABILITIES;
    }

    @Override
    protected TransducerGraph doCompaction(TransducerGraph graph, List l1, List l3) {
        TransducerGraph result = graph;
        if (saveGraphs) {
            writeFile(result, "unminimized", (String) result.getEndNodes().iterator().next());
        }
        result = quasiDeterminizer.processGraph(result);
        result = new TransducerGraph(result, ocp); // combine outputs into inputs
        result = minimizer.minimizeFA(result); // minimize the thing
        //result = new  TransducerGraph(graph, otsp); // for debugging
        result = new TransducerGraph(result, ntsp); // pull out strings from sets returned by minimizer
        result = new TransducerGraph(result, isp); // split outputs from inputs
        if (saveGraphs) {
            writeFile(result, "exactminimized", (String) result.getEndNodes().iterator().next());
        }
        // for debugging do comparison of the paths accepted by graph and result
        //log.info(TransducerGraph.testGraphPaths(graph, result, 100));
        return result;
    }

}