unknownelement.java

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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */

package org.apache.tools.ant;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.io.IOException;
import org.apache.tools.ant.taskdefs.PreSetDef;

/**
 * Wrapper class that holds all the information necessary to create a task
 * or data type that did not exist when Ant started, or one which
 * has had its definition updated to use a different implementation class.
 *
 */
public class UnknownElement extends Task {

    /**
     * Holds the name of the task/type or nested child element of a
     * task/type that hasn't been defined at parser time or has
     * been redefined since original creation.
     */
    private String elementName;

    /**
     * Holds the namespace of the element.
     */
    private String namespace = "";

    /**
     * Holds the namespace qname of the element.
     */
    private String qname;

    /**
     * The real object after it has been loaded.
     */
    private Object realThing;

    /**
     * List of child elements (UnknownElements).
     */
    private List/*<UnknownElement>*/ children = null;

    /** Specifies if a predefined definition has been done */
    private boolean presetDefed = false;

    /**
     * Creates an UnknownElement for the given element name.
     *
     * @param elementName The name of the unknown element.
     *                    Must not be <code>null</code>.
     */
    public UnknownElement (String elementName) {
        this.elementName = elementName;
    }

    /**
     * @return the list of nested UnknownElements for this UnknownElement.
     */
    public List getChildren() {
        return children;
    }

    /**
     * Returns the name of the XML element which generated this unknown
     * element.
     *
     * @return the name of the XML element which generated this unknown
     *         element.
     */
    public String getTag() {
        return elementName;
    }

    /** Return the namespace of the XML element associated with this component.
     *
     * @return Namespace URI used in the xmlns declaration.
     */
    public String getNamespace() {
        return namespace;
    }

    /**
     * Set the namespace of the XML element associated with this component.
     * This method is typically called by the XML processor.
     * If the namespace is "ant:current", the component helper
     * is used to get the current antlib uri.
     *
     * @param namespace URI used in the xmlns declaration.
     */
    public void setNamespace(String namespace) {
        if (namespace.equals(ProjectHelper.ANT_CURRENT_URI)) {
            ComponentHelper helper = ComponentHelper.getComponentHelper(
                getProject());
            namespace = helper.getCurrentAntlibUri();
        }
        this.namespace = namespace == null ? "" : namespace;
    }

    /** Return the qname of the XML element associated with this component.
     *
     * @return namespace Qname used in the element declaration.
     */
    public String getQName() {
        return qname;
    }

    /** Set the namespace qname of the XML element.
     * This method is typically called by the XML processor.
     *
     * @param qname the qualified name of the element
     */
    public void setQName(String qname) {
        this.qname = qname;
    }


    /**
     * Get the RuntimeConfigurable instance for this UnknownElement, containing
     * the configuration information.
     *
     * @return the configuration info.
     */
    public RuntimeConfigurable getWrapper() {
        return super.getWrapper();
    }

    /**
     * Creates the real object instance and child elements, then configures
     * the attributes and text of the real object. This unknown element
     * is then replaced with the real object in the containing target's list
     * of children.
     *
     * @exception BuildException if the configuration fails
     */
    public void maybeConfigure() throws BuildException {
        if (realThing != null) {
            return;
        }
        configure(makeObject(this, getWrapper()));
    }

    /**
     * Configure the given object from this UnknownElement
     *
     * @param realObject the real object this UnknownElement is representing.
     *
     */
    public void configure(Object realObject) {
        realThing = realObject;

        getWrapper().setProxy(realThing);
        Task task = null;
        if (realThing instanceof Task) {
            task = (Task) realThing;

            task.setRuntimeConfigurableWrapper(getWrapper());

            // For Script example that modifies id'ed tasks in other
            // targets to work. *very* Ugly
            // The reference is replaced by RuntimeConfigurable
            if (getWrapper().getId() != null) {
                this.getOwningTarget().replaceChild(this, (Task) realThing);
            }
       }


        // configure attributes of the object and it's children. If it is
        // a task container, defer the configuration till the task container
        // attempts to use the task

        if (task != null) {
            task.maybeConfigure();
        } else {
            getWrapper().maybeConfigure(getProject());
        }

        handleChildren(realThing, getWrapper());
    }

    /**
     * Handles output sent to System.out by this task or its real task.
     *
     * @param output The output to log. Should not be <code>null</code>.
     */
    protected void handleOutput(String output) {
        if (realThing instanceof Task) {
            ((Task) realThing).handleOutput(output);
        } else {
            super.handleOutput(output);
        }
    }

    /**
     * Delegate to realThing if present and if it as task.
     * @see Task#handleInput(byte[], int, int)
     * @param buffer the buffer into which data is to be read.
     * @param offset the offset into the buffer at which data is stored.
     * @param length the amount of data to read.
     *
     * @return the number of bytes read.
     *
     * @exception IOException if the data cannot be read.
     * @since Ant 1.6
     */
    protected int handleInput(byte[] buffer, int offset, int length)
        throws IOException {
        if (realThing instanceof Task) {
            return ((Task) realThing).handleInput(buffer, offset, length);
        } else {
            return super.handleInput(buffer, offset, length);
        }

    }
    /**
     * Handles output sent to System.out by this task or its real task.
     *
     * @param output The output to log. Should not be <code>null</code>.
     */
    protected void handleFlush(String output) {
        if (realThing instanceof Task) {
            ((Task) realThing).handleFlush(output);
        } else {
            super.handleFlush(output);
        }
    }

    /**
     * Handles error output sent to System.err by this task or its real task.
     *
     * @param output The error output to log. Should not be <code>null</code>.
     */
    protected void handleErrorOutput(String output) {
        if (realThing instanceof Task) {
            ((Task) realThing).handleErrorOutput(output);
        } else {
            super.handleErrorOutput(output);
        }
    }


    /**
     * Handles error output sent to System.err by this task or its real task.
     *
     * @param output The error output to log. Should not be <code>null</code>.
     */
    protected void handleErrorFlush(String output) {
        if (realThing instanceof Task) {
            ((Task) realThing).handleErrorOutput(output);
        } else {
            super.handleErrorOutput(output);
        }
    }

    /**
     * Executes the real object if it's a task. If it's not a task
     * (e.g. a data type) then this method does nothing.
     */
    public void execute() {
        if (realThing == null) {
            // plain impossible to get here, maybeConfigure should
            // have thrown an exception.
            throw new BuildException("Could not create task of type: "
                                     + elementName, getLocation());
        }
        try {
            if (realThing instanceof Task) {
                ((Task) realThing).execute();
            }
        } finally {
        	// Finished executing the task
            // null it (unless it has an ID) to allow
            // GC do its job
            // If this UE is used again, a new "realthing" will be made
            if (getWrapper().getId() == null) {
                realThing = null;
                getWrapper().setProxy(null);
            }
        }
    }

    /**
     * Adds a child element to this element.
     *
     * @param child The child element to add. Must not be <code>null</code>.
     */
    public void addChild(UnknownElement child) {
        if (children == null) {
            children = new ArrayList();
        }
        children.add(child);
    }

    /**
     * Creates child elements, creates children of the children
     * (recursively), and sets attributes of the child elements.
     *
     * @param parent The configured object for the parent.
     *               Must not be <code>null</code>.
     *
     * @param parentWrapper The wrapper containing child wrappers
     *                      to be configured. Must not be <code>null</code>
     *                      if there are any children.
     *
     * @exception BuildException if the children cannot be configured.
     */
    protected void handleChildren(
        Object parent,
        RuntimeConfigurable parentWrapper)
        throws BuildException {
        if (parent instanceof TypeAdapter) {
            parent = ((TypeAdapter) parent).getProxy();
        }

        String parentUri = getNamespace();
        Class parentClass = parent.getClass();
        IntrospectionHelper ih = IntrospectionHelper.getHelper(getProject(), parentClass);