ant/proposal/sandbox/embed/ProjectComponentHelper.java

/*
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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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package org.apache.tools.ant;

import java.io.File;
import java.io.InputStream;
import java.io.IOException;
import java.util.Hashtable;
import java.util.Vector;
import java.util.Properties;
import java.util.Enumeration;
import java.util.Stack;
import java.lang.reflect.Modifier;


import org.apache.tools.ant.types.FilterSet; 
import org.apache.tools.ant.types.FilterSetCollection; 
import org.apache.tools.ant.util.FileUtils; 

/** 
 * Abstract component creation and configuration. Multiple ComponentHelpers
 * can be registered in a project, either by an embedding application
 * or by taskdef-like tasks.
 *
 * After a ProjectComponentHelper is registered, it'll manage the construction and 
 * configuration of tasks/types/etc. It has full control over how the
 * component is created - and may provide runtime wrapping for components
 * not implementing the Task/DataType interfaces.
 * It works in close relation with TaskAdapter and RuntimeConfigurable
 * to handle delayed evaluation of tasks or custom attribute->task mapping.
 * If it returns a wrapper for Task, the wrapper is required to extend
 * TaskAdapter.
 *
 * The common 'Chain' pattern is used to construct
 * tasks, with the original behavior ( Class registry ) tried last, by the
 * default helper implementation.
 *
 * @author Costin Manolache
 */
public abstract class ProjectComponentHelper  {

    /** Creates an ant component..
     *
     * A factory may have knowledge about the tasks it creates. It can return
     * an object extending TaskAdapter that emulates Task/DataType.
     *
     * @param project the context for task creation.
     * @param role Class name for the expected role ( Task, Type, Filter, etc ). Null for 'any'
     * @param ns namespace if a SAX2 parser is used, null for 'classical' ant
     * @param taskName the (local) name of the task.
     */
    public abstract Object createProjectComponent( Project project,
                                                   String role,
                                                   String ns,
                                                   String taskName )
        throws BuildException;

    /** Return true if we know how to create an Component in the
     *  desired role. Used by ProjectHelpers to check if a given tag
     *  is a type or a task
     *
     *  This is only required to forbid tasks to be at top level.
     *  The current ProjectHelper also uses this internally, but that's
     *  an implementation detail that can be avoided.
     */
    public boolean hasRole( Project project, String role, String ns, String name ) {
        return false;
    }

    
}