src/main/org/apache/tools/ant/types/EnumeratedAttribute.java

/*
 * The Apache Software License, Version 1.1
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 * reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 * 1. Redistributions of source code must retain the above copyright
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.tools.ant.types;

import org.apache.tools.ant.BuildException;

/**
 * Helper class for attributes that can only take one of a fixed list
 * of values.
 *
 * <p>See {@link org.apache.tools.ant.taskdefs.FixCRLF FixCRLF} for an
 * example.
 *
 * @author <a href="mailto:stefan.bodewig@epost.de">Stefan Bodewig</a> 
 */
public abstract class EnumeratedAttribute {

    /**
     * The selected value in this enumeration.
     */
    protected String value;

    /**
     * the index of the selected value in the array.
     */
    private int index = -1;

    /**
     * This is the only method a subclass needs to implement.
     *
     * @return an array holding all possible values of the enumeration.
     * The order of elements must be fixed so that <tt>indexOfValue(String)</tt>
     * always return the same index for the same value.
     */
    public abstract String[] getValues();

    /** bean constructor */
    protected EnumeratedAttribute(){
    }

    /**
     * Invoked by {@link org.apache.tools.ant.IntrospectionHelper IntrospectionHelper}.
     */
    public final void setValue(String value) throws BuildException {
        int index = indexOfValue(value);
        if (index == -1) {
            throw new BuildException(value + " is not a legal value for this attribute");
        }
        this.index = index;
        this.value = value;
    }

    /**
     * Is this value included in the enumeration?
     */
    public final boolean containsValue(String value) {
        return (indexOfValue(value) != -1);
    }

    /**
     * get the index of a value in this enumeration.
     * @param value the string value to look for.
     * @return the index of the value in the array of strings
     * or -1 if it cannot be found.
     * @see #getValues()
     */
    public final int indexOfValue(String value){
        String[] values = getValues();
        if (values == null || value == null) {
            return -1;
        }
        for (int i = 0; i < values.length; i++){
            if (value.equals(values[i])){
                return i;
            }
        }
        return -1;
    }

    /**
     * @return the selected value.
     */
    public final String getValue() {
        return value;
    }

    /**
     * @return the index of the selected value in the array.
     * @see #getValues()
     */
    public final int getIndex() {
        return index;
    }
}