src/main/org/apache/tools/ant/types/Substitution.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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 * 3. The end-user documentation included with the redistribution, if
 *    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,
 *    if and wherever such third-party acknowlegements normally appear.
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 * individuals on behalf of the Apache Software Foundation.  For more
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 */
package org.apache.tools.ant.types;


import java.util.Stack;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.DataType;

/***
 * A regular expression substitution datatype.  It is an expression
 * that is meant to replace a regular expression.
 *
 * <pre>
 *   &lt;substitition [ [id="id"] expression="expression" | refid="id" ] 
 *   /&gt;
 * </pre>
 *
 * @see org.apache.oro.text.regex.Perl5Substitution
 * @author Matthew Inger <a href="mailto:mattinger@mindless.com">mattinger@mindless.com</a>
 */
public class Substitution extends DataType
{
    public final static String DATA_TYPE_NAME = "substitition";

    private String expression;

    public Substitution()
    {
        this.expression = null;
    }

    public void setExpression(String expression)
    {
        this.expression = expression;
    }

    /***
     * Gets the pattern string for this RegularExpression in the
     * given project.
     */
    public String getExpression(Project p)
    {
        if (isReference()) {
            return getRef(p).getExpression(p);
        }

        return expression;
    }

    /***
     * Get the RegularExpression this reference refers to in
     * the given project.  Check for circular references too
     */
    public Substitution getRef(Project p)
    {
        if (!checked)
        {
            Stack stk = new Stack();
            stk.push(this);
            dieOnCircularReference(stk, p);
        }

        
        Object o = ref.getReferencedObject(p);
        if (!(o instanceof Substitution))
        {
            String msg = ref.getRefId() + " doesn\'t denote a substitution";
            throw new BuildException(msg);
        } 
        else 
        {
            return (Substitution) o;
        }
    }

}