StateSelect.java

/*
 * Copyright (c) 2008-2012, Matthias Mann
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Matthias Mann nor the names of its contributors may
 *       be used to endorse or promote products derived from this software
 *       without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package de.matthiasmann.twl.utils;

import de.matthiasmann.twl.renderer.AnimationState;
import de.matthiasmann.twl.renderer.AnimationState.StateKey;
import java.util.Collection;

/**
 *
 * @author Matthias Mann
 */
public class StateSelect {
    
    private static boolean useOptimizer = false;
    
    private final StateExpression[] expressions;
    private final StateKey[] programKeys;
    private final short[] programCodes;

    public static final StateSelect EMPTY = new StateSelect();
    
    public StateSelect(Collection<StateExpression> expressions) {
        this(expressions.toArray(new StateExpression[expressions.size()]));
    }
    
    public StateSelect(StateExpression ... expressions) {
        this.expressions = expressions;
        
        StateSelectOptimizer sso = useOptimizer
                ? StateSelectOptimizer.optimize(expressions)
                : null;
        
        if(sso != null) {
            programKeys = sso.programKeys;
            programCodes = sso.programCodes;
        } else {
            programKeys = null;
            programCodes = null;
        }
    }

    public static boolean isUseOptimizer() {
        return useOptimizer;
    }

    /**
     * Controls the use of the StateSelectOptimizer.
     * 
     * @param useOptimizer true if the StateSelectOptimizer should be used
     */
    public static void setUseOptimizer(boolean useOptimizer) {
        StateSelect.useOptimizer = useOptimizer;
    }
    
    /**
     * Returns the number of expressions.
     * <p>This is also the return value of {@link #evaluate(de.matthiasmann.twl.renderer.AnimationState) }
     * when no expression matched.</p>
     * @return the number of expressions
     */
    public int getNumExpressions() {
        return expressions.length;
    }
    
    /**
     * Retrives the specified expression
     * @param idx the expression index
     * @return the expression
     * @see #getNumExpressions() 
     */
    public StateExpression getExpression(int idx) {
        return expressions[idx];
    }
    
    /**
     * Evaluates the expression list.
     * 
     * @param as the animation stateor null
     * @return the index of the first matching expression or
     *         {@link #getNumExpressions()} when no expression matches
     */
    public int evaluate(AnimationState as) {
        if(programKeys != null) {
            return evaluateProgram(as);
        }
        return evaluateExpr(as);
    }
    
    private int evaluateExpr(AnimationState as) {
        int i = 0;
        for(int n=expressions.length ; i<n ; i++) {
            if(expressions[i].evaluate(as)) {
                break;
            }
        }
        return i;
    }
    
    private int evaluateProgram(AnimationState as) {
        int pos = 0;
        do {
            if(as == null || !as.getAnimationState(programKeys[pos >> 1])) {
                pos++;
            }
            pos = programCodes[pos];
        } while(pos >= 0);
        return pos & CODE_MASK;
    }

    static final int CODE_RESULT = 0x8000;
    static final int CODE_MASK   = 0x7FFF;
}