/projects/ant-1.8.2/src/main/org/apache/tools/ant/util/facade/FacadeTaskHelper.java

/*

 *  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.util.facade;



import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import org.apache.tools.ant.Project;

import org.apache.tools.ant.types.Path;



/**

 * Helper class for facade implementations - encapsulates treatment of

 * explicit implementation choices, magic properties and

 * implementation specific command line arguments.

 *

 *

 * @since Ant 1.5

 */

public class FacadeTaskHelper {



    /**

     * Command line arguments.

     */

    private List args = new ArrayList();



    /**

     * The explicitly chosen implementation.

     */

    private String userChoice;



    /**

     * The magic property to consult.

     */

    private String magicValue;



    /**

     * The default value.

     */

    private String defaultValue;



    /**

     * User specified path used as classpath when loading the implementation.

     */

    private Path implementationClasspath;



    /**

     * @param defaultValue The default value for the implementation.

     * Must not be null.

     */

    public FacadeTaskHelper(String defaultValue) {

        this(defaultValue, null);

    }



    /**

     * @param defaultValue The default value for the implementation.

     * Must not be null.

     * @param magicValue the value of a magic property that may hold a user.

     * choice.  May be null.

     */

    public FacadeTaskHelper(String defaultValue, String magicValue) {

        this.defaultValue = defaultValue;

        this.magicValue = magicValue;

    }



    /**

     * Used to set the value of the magic property.

     * @param magicValue the value of a magic property that may hold a user.

     */

    public void setMagicValue(String magicValue) {

        this.magicValue = magicValue;

    }



    /**

     * Used for explicit user choices.

     * @param userChoice the explicitly chosen implementation.

     */

    public void setImplementation(String userChoice) {

        this.userChoice = userChoice;

    }



    /**

     * Retrieves the implementation.

     * @return the implementation.

     */

    public String getImplementation() {

        return userChoice != null ? userChoice

                                  : (magicValue != null ? magicValue

                                                        : defaultValue);

    }



    /**

     * Retrieves the explicit user choice.

     * @return the explicit user choice.

     */

    public String getExplicitChoice() {

        return userChoice;

    }



    /**

     * Command line argument.

     * @param arg an argument to add.

     */

    public void addImplementationArgument(ImplementationSpecificArgument arg) {

        args.add(arg);

    }



    /**

     * Retrieves the command line arguments enabled for the current

     * facade implementation.

     * @return an array of command line arguements.

     */

    public String[] getArgs() {

        List tmp = new ArrayList(args.size());

        for (Iterator e = args.iterator(); e.hasNext();) {

            ImplementationSpecificArgument arg =

                ((ImplementationSpecificArgument) e.next());

            String[] curr = arg.getParts(getImplementation());

            for (int i = 0; i < curr.length; i++) {

                tmp.add(curr[i]);

            }

        }

        String[] res = new String[tmp.size()];

        return (String[]) tmp.toArray(res);

    }



    /**

     * Tests whether the implementation has been chosen by the user

     * (either via a magic property or explicitly.

     * @return true if magic or user choice has be set.

     * @since Ant 1.5.2

     */

    public boolean hasBeenSet() {

        return userChoice != null || magicValue != null;

    }



    /**

     * The classpath to use when loading the implementation.

     *

     * @param project the current project

     * @return a Path instance that may be appended to

     * @since Ant 1.8.0

     */

    public Path getImplementationClasspath(Project project) {

        if (implementationClasspath == null) {

            implementationClasspath = new Path(project);

        }

        return implementationClasspath;

    }

}