jaitools.jiffle.runtime.AbstractJiffleRuntime Maven / Gradle / Ivy

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/*
 * Copyright 2011 Michael Bedward
 * 
 * This file is part of jai-tools.
 *
 * jai-tools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the 
 * License, or (at your option) any later version.
 *
 * jai-tools is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public 
 * License along with jai-tools.  If not, see .
 * 
 */

package jaitools.jiffle.runtime;


/**
 * Provides default implementations of {@link JiffleRuntime} methods plus 
 * some common fields.
 *
 * @author Michael Bedward
 * @since 1.1
 * @version $Id: AbstractJiffleRuntime.java 1505 2011-03-05 11:37:43Z michael.bedward $
 */
public abstract class AbstractJiffleRuntime implements JiffleRuntime {
    
    /** Whether the outside option is set. */
    protected boolean _outsideValueSet = false;
    
    /** 
     * The value to return for out-of-bounds image data requests if the
     * outside option is set.
     */
    protected double _outsideValue;
    
    /** 
     * A stack of integer values used in the evaluation of if statements.
     */
    protected IntegerStack _stk;
    
    /** 
     * Provides runtime function support.
     */
    protected final JiffleFunctions _FN;

    /**
     * Creates a new instance of this class and initializes its 
     * {@link JiffleFunctions} and {@link IntegerStack} objects.
     */
    public AbstractJiffleRuntime() {
        _FN = new JiffleFunctions();
        _stk = new IntegerStack();
    }

    /**
     * {@inheritDoc}
     */
    public Double getVar(String varName) {
        return null;
    }
    
    /**
     * Initializes image-scope variables. These are fields in the runtime class.
     * They are initialized in a separate method rather than the constructor
     * because they may depend on expressions involving values that are not
     * known until the processing area is set (e.g. Jiffle's width() function).
     */
    protected abstract void initImageScopeVars();

    /**
     * Initializes runtime class fields related to Jiffle script options.
     */
    protected abstract void initOptionVars();
}