componenthelper.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.lang.reflect.Modifier;
import java.lang.reflect.InvocationTargetException;
import java.io.InputStream;
import java.io.IOException;
import java.io.File;
import java.io.StringWriter;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Properties;
import java.util.Set;
import java.util.Stack;
import java.util.List;
import java.util.ArrayList;

import org.apache.tools.ant.taskdefs.Typedef;
import org.apache.tools.ant.taskdefs.Definer;
import org.apache.tools.ant.launch.Launcher;
import org.apache.tools.ant.util.FileUtils;

/**
 * Component creation and configuration.
 *
 * The class is based around handing component
 * definitions in an AntTypeTable.
 *
 * The old task/type methods have been kept
 * for backward compatibly.
 * Project will just delegate its calls to this class.
 *
 * A very simple hook mechanism is provided that allows users to plug
 * in custom code. It is also possible to replace the default behavior
 * ( for example in an app embedding ant )
 *
 * @since Ant1.6
 */
public class ComponentHelper  {
    /** Map from component name to anttypedefinition */
    private AntTypeTable antTypeTable;

    /** Map of tasks generated from antTypeTable */
    private Hashtable taskClassDefinitions = new Hashtable();
    /** flag to rebuild taskClassDefinitions */
    private boolean rebuildTaskClassDefinitions = true;

    /** Map of types generated from antTypeTable */
    private Hashtable typeClassDefinitions = new Hashtable();
    /** flag to rebuild typeClassDefinitions */
    private boolean rebuildTypeClassDefinitions = true;

    /** Set of namespaces that have been checked for antlibs */
    private Set checkedNamespaces = new HashSet();

    /**
     * Stack of antlib contexts used to resolve definitions while
     *   processing antlib
     */
    private Stack antLibStack = new Stack();
    /** current antlib uri */
    private String antLibCurrentUri = null;

    /**
     * this does not appear to be used anywhere in the Ant codebase
     * even via its accessors
     */
    private ComponentHelper next;

    /**
     * Project that owns a component helper
     */
    private Project project;

    /**
     * Error string when the file taskdefs/defaults.properties cannot be found
     */
    private static final String ERROR_NO_TASK_LIST_LOAD = "Can't load default task list";
    /**
     * Error string when the typedefs/defaults.properties cannot be found
     */
    private static final String ERROR_NO_TYPE_LIST_LOAD = "Can't load default type list";

    /**
     * reference under which we register ourselves with a project -{@value}
     */
    public static final String COMPONENT_HELPER_REFERENCE = "ant.ComponentHelper";

    /**
     * string used to control build.syspath policy {@value}
     */
    private static final String BUILD_SYSCLASSPATH_ONLY = "only";

    /**
     * special name of ant's property task -{@value}. There is some
     * contrived work here to enable this early.
     */
    private static final String ANT_PROPERTY_TASK = "property";

    // {tasks, types}
    private static Properties[] defaultDefinitions = new Properties[2];


    /**
     * Find a project component for a specific project, creating
     * it if it does not exist.
     * @param project the project.
     * @return the project component for a specific project.
     */
    public static ComponentHelper getComponentHelper(Project project) {
        if (project == null) {
            return null;
        }
        // Singleton for now, it may change ( per/classloader )
        ComponentHelper ph = (ComponentHelper) project.getReference(
                COMPONENT_HELPER_REFERENCE);
        if (ph != null) {
            return ph;
        }
        ph = new ComponentHelper();
        ph.setProject(project);

        project.addReference(COMPONENT_HELPER_REFERENCE, ph);
        return ph;
    }

    /**
     * Creates a new ComponentHelper instance.
     */
    protected ComponentHelper() {
    }

    /**
     * Set the next chained component helper.
     *
     * @param next the next chained component helper.
     */
    public void setNext(ComponentHelper next) {
        this.next = next;
    }

    /**
     * Get the next chained component helper.
     *
     * @return the next chained component helper.
     */
    public ComponentHelper getNext() {
        return next;
    }

    /**
     * Sets the project for this component helper.
     *
     * @param project the project for this helper.
     */
    public void setProject(Project project) {
        this.project = project;
        antTypeTable = new AntTypeTable(project);
    }

    /**
     * Used with creating child projects. Each child
     * project inherits the component definitions
     * from its parent.
     * @param helper the component helper of the parent project.
     */
    public void initSubProject(ComponentHelper helper) {
        // add the types of the parent project
        AntTypeTable typeTable = helper.antTypeTable;
        for (Iterator i = typeTable.values().iterator(); i.hasNext();) {
            AntTypeDefinition def = (AntTypeDefinition) i.next();
            antTypeTable.put(def.getName(), def);
        }
        // add the parsed namespaces of the parent project
        for (Iterator i = helper.checkedNamespaces.iterator(); i.hasNext();) {
            checkedNamespaces.add(i.next());
        }
    }

    /**
     * Factory method to create the components.
     *
     * This should be called by UnknownElement.
     *
     * @param ue The Unknown Element creating this component.
     * @param ns Namespace URI. Also available as ue.getNamespace().
     * @param componentType The component type,
     *                       Also available as ue.getComponentName().
     * @return the created component.
     * @throws BuildException if an error occurs.
     */
    public Object createComponent(UnknownElement ue,
                                  String ns,
                                  String componentType)
        throws BuildException {
        Object component = createComponent(componentType);
        if (component instanceof Task) {
            Task task = (Task) component;
            task.setLocation(ue.getLocation());
            task.setTaskType(componentType);
            task.setTaskName(ue.getTaskName());
            task.setOwningTarget(ue.getOwningTarget());
            task.init();
        }
        return component;
    }

    /**
     * Create an object for a component.
     *
     * @param componentName the name of the component, if
     *                      the component is in a namespace, the
     *                      name is prefixed with the namespace uri and ":".
     * @return the class if found or null if not.
     */
    public Object createComponent(String componentName) {
        AntTypeDefinition def = getDefinition(componentName);
        return (def == null) ? null : def.create(project);
    }

    /**
     * Return the class of the component name.
     *
     * @param componentName the name of the component, if
     *                      the component is in a namespace, the
     *                      name is prefixed with the namespace uri and ":".
     * @return the class if found or null if not.
     */
    public Class getComponentClass(String componentName) {
        AntTypeDefinition def = getDefinition(componentName);
        return (def == null) ? null : def.getExposedClass(project);
    }

    /**
     * Return the antTypeDefinition for a componentName.
     * @param componentName the name of the component.
     * @return the ant definition or null if not present.
     */
    public AntTypeDefinition getDefinition(String componentName) {
        checkNamespace(componentName);
        return antTypeTable.getDefinition(componentName);
    }

    /**
     * This method is initialization code implementing the original ant component
     * loading from /org/apache/tools/ant/taskdefs/default.properties
     * and /org/apache/tools/ant/types/default.properties.
     */
    public void initDefaultDefinitions() {
        initTasks();
        initTypes();
    }

    /**
     * Adds a new task definition to the project.
     * Attempting to override an existing definition with an
     * equivalent one (i.e. with the same classname) results in
     * a verbose log message. Attempting to override an existing definition
     * with a different one results in a warning log message.
     *
     * @param taskName The name of the task to add.
     *                 Must not be <code>null</code>.
     * @param taskClass The full name of the class implementing the task.
     *                  Must not be <code>null</code>.
     *
     * @exception BuildException if the class is unsuitable for being an Ant
     *                           task. An error level message is logged before
     *                           this exception is thrown.
     *
     * @see #checkTaskClass(Class)
     */
    public void addTaskDefinition(String taskName, Class taskClass) {
        checkTaskClass(taskClass);
        AntTypeDefinition def = new AntTypeDefinition();
        def.setName(taskName);
        def.setClassLoader(taskClass.getClassLoader());
        def.setClass(taskClass);
        def.setAdapterClass(TaskAdapter.class);
        def.setClassName(taskClass.getName());
        def.setAdaptToClass(Task.class);
        updateDataTypeDefinition(def);
    }

    /**
     * Checks whether or not a class is suitable for serving as Ant task.
     * Ant task implementation classes must be public, concrete, and have
     * a no-arg constructor.
     *
     * @param taskClass The class to be checked.
     *                  Must not be <code>null</code>.
     *
     * @exception BuildException if the class is unsuitable for being an Ant
     *                           task. An error level message is logged before
     *                           this exception is thrown.
     */
    public void checkTaskClass(final Class taskClass) throws BuildException {
        if (!Modifier.isPublic(taskClass.getModifiers())) {
            final String message = taskClass + " is not public";
            project.log(message, Project.MSG_ERR);
            throw new BuildException(message);
        }
        if (Modifier.isAbstract(taskClass.getModifiers())) {
            final String message = taskClass + " is abstract";
            project.log(message, Project.MSG_ERR);
            throw new BuildException(message);
        }
        try {
            taskClass.getConstructor((Class[]) null);
            // don't have to check for public, since
            // getConstructor finds public constructors only.
        } catch (NoSuchMethodException e) {
            final String message = "No public no-arg constructor in "
                    + taskClass;
            project.log(message, Project.MSG_ERR);
            throw new BuildException(message);
        }
        if (!Task.class.isAssignableFrom(taskClass)) {
            TaskAdapter.checkTaskClass(taskClass, project);
        }
    }

    /**
     * Returns the current task definition hashtable. The returned hashtable is
     * "live" and so should not be modified.
     *
     * @return a map of from task name to implementing class
     *         (String to Class).
     */
    public Hashtable getTaskDefinitions() {
        synchronized (taskClassDefinitions) {
            synchronized (antTypeTable) {
                if (rebuildTaskClassDefinitions) {
                    taskClassDefinitions.clear();
                    for (Iterator i = antTypeTable.keySet().iterator();
                         i.hasNext();) {
                        String name = (String) i.next();
                        Class clazz = antTypeTable.getExposedClass(name);
                        if (clazz == null) {
                            continue;