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Jiffle is a raster algebra language that can be used to create new images from logical and mathematical expressions involving source images and user defined variables. It is intended to let users concentrate on algorithms rather than tedious boiler-plate code.

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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();
}