unitstate.java

来自「It is the Speech recognition software. 」· Java 代码 · 共 176 行

/*
 * Copyright 1999-2002 Carnegie Mellon University.  
 * Portions Copyright 2002 Sun Microsystems, Inc.  
 * Portions Copyright 2002 Mitsubishi Electric Research Laboratories.
 * All Rights Reserved.  Use is subject to license terms.
 * 
 * See the file "license.terms" for information on usage and
 * redistribution of this file, and for a DISCLAIMER OF ALL 
 * WARRANTIES.
 *
 */

package edu.cmu.sphinx.linguist.flat;

import edu.cmu.sphinx.linguist.UnitSearchState;
import edu.cmu.sphinx.linguist.acoustic.HMMPosition;
import edu.cmu.sphinx.linguist.acoustic.Unit;
import edu.cmu.sphinx.linguist.acoustic.UnitManager;

/**
 * Represents a unit in an SentenceHMMS
 * 
 */
public class UnitState extends SentenceHMMState implements UnitSearchState {
    private Unit unit;
    private transient StatePath tail;
    private HMMPosition position = HMMPosition.INTERNAL;


    /**
     * Creates a UnitState. Gets the left and right contexts from the
     * unit itself.
     *
     * @param parent the parent state
     * @param which the index of the given state
     * @param unit the unit associated with this state
     */
    public UnitState(PronunciationState parent, int which,  Unit unit) {
	super("U", parent, which);
	this.unit = unit;
	Unit[] units = parent.getPronunciation().getUnits();
	int length = units.length;

	// If the last phone is SIL, then we should be using
	// a word-ending phone for the last phone. Decrementing
	// length will make the phone before SIL the last phone.

	if (units[length-1] == UnitManager.SILENCE && length > 1) {
	    length--;
	}

	if (length == 1) {
	    position = HMMPosition.SINGLE;
	} else if (which == 0) {
	    position = HMMPosition.BEGIN;
	} else if (which == length - 1) {
	    position = HMMPosition.END;
	}
    }

    /**
     * Creates a UnitState with the given unit and HMM position.
     *
     * @param unit the unit associated with this state
     * @param position the HMM position of this unit
     */
    public UnitState(Unit unit, HMMPosition position) {
        this.unit = unit;
        this.position = position;
    }

    /**
     * Gets the unit associated with this state
     *
     * @return the unit
     */
    public Unit getUnit() {
	return unit;
    }


    /**
     * Returns true if this unit is the last unit of the pronunciation
     *
     * @return <code>true</code> if the unit is the last unit
     */
    public boolean isLast() {
        return position == HMMPosition.SINGLE || position == HMMPosition.END;
    }


    /**
     * Gets the name for this state
     *
     * @return the name for this state
     */
    public String getName() {
	return super.getName() + "<" + unit + ">";
    }

    /**
     * Returns the value signature of this unit
     *
     * @return the value signature
     */
    public String getValueSignature() {
	return unit.toString();
    }

    /**
     * Gets the pretty name for this unit sate
     *
     * @return the pretty name 
     */
    public String getPrettyName() {
	return unit.toString();
    }

    /**
     * Retrieves a short label describing the type of this state.
     * Typically, subclasses of SentenceHMMState will implement this
     * method and return a short (5 chars or less) label
     *
     * @return the short label.
     */
    public String getTypeLabel() {
	return "Unit";
    }


    /**
     * Gets the position for this unit
     *
     * @return the position for this unit
     */
    public HMMPosition getPosition() {
	return position;
    }

    /**
     * Returns the tail for this unit state.  This is used during the
     * SentenceHMM contruction process. A UnitState may be expanded
     * into a unit state followed by a tree of HMMStates.  Keeping the
     * tail of the tree here helps us to quickly find the end of this
     * collection of states when we are reusing states.
     *
     * @return the tail state
     */
    public StatePath getTail() {
	return tail;
    }

    /**
     * Sets the tail for this state
     *
     * @param tail the tail for the state
     */
    public void setTail(StatePath tail) {
	this.tail = tail;
    }

    public boolean isUnit() {
	return true;
    }
    /**
     * Returns the state order for this state type
     *
     * @return the state order
     */
    public int getOrder() {
        return 5;
    }
}