componenthelper.java

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                        }
                        if (Task.class.isAssignableFrom(clazz)) {
                            taskClassDefinitions.put(
                                name, antTypeTable.getTypeClass(name));
                        }
                    }
                    rebuildTaskClassDefinitions = false;
                }
            }
        }
        return taskClassDefinitions;
    }


    /**
     * Returns the current type definition hashtable. The returned hashtable is
     * "live" and so should not be modified.
     *
     * @return a map of from type name to implementing class
     *         (String to Class).
     */
    public Hashtable getDataTypeDefinitions() {
        synchronized (typeClassDefinitions) {
            synchronized (antTypeTable) {
                if (rebuildTypeClassDefinitions) {
                    typeClassDefinitions.clear();
                    for (Iterator i = antTypeTable.keySet().iterator();
                         i.hasNext();) {
                        String name = (String) i.next();
                        Class clazz = antTypeTable.getExposedClass(name);
                        if (clazz == null) {
                            continue;
                        }
                        if (!(Task.class.isAssignableFrom(clazz))) {
                            typeClassDefinitions.put(
                                name, antTypeTable.getTypeClass(name));
                        }
                    }
                    rebuildTypeClassDefinitions = false;
                }
            }
        }
        return typeClassDefinitions;
    }

    /**
     * Adds a new datatype definition.
     * 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, but the
     * definition is changed.
     *
     * @param typeName The name of the datatype.
     *                 Must not be <code>null</code>.
     * @param typeClass The full name of the class implementing the datatype.
     *                  Must not be <code>null</code>.
     */
    public void addDataTypeDefinition(String typeName, Class typeClass) {
        AntTypeDefinition def = new AntTypeDefinition();
        def.setName(typeName);
        def.setClass(typeClass);
        updateDataTypeDefinition(def);
        project.log(" +User datatype: " + typeName + "     "
                + typeClass.getName(), Project.MSG_DEBUG);
    }

    /**
     * Describe <code>addDataTypeDefinition</code> method here.
     *
     * @param def an <code>AntTypeDefinition</code> value.
     */
    public void addDataTypeDefinition(AntTypeDefinition def) {
        updateDataTypeDefinition(def);
    }

    /**
     * Returns the current datatype definition hashtable. The returned
     * hashtable is "live" and so should not be modified.
     *
     * @return a map of from datatype name to implementing class
     *         (String to Class).
     */
    public Hashtable getAntTypeTable() {
        return antTypeTable;
    }

    /**
     * Creates a new instance of a task.
     *
     *  Called from Project.createTask(), which can be called by tasks.
     *
     * @param taskType The name of the task to create an instance of.
     *                 Must not be <code>null</code>.
     *
     * @return an instance of the specified task, or <code>null</code> if
     *         the task name is not recognised.
     *
     * @exception BuildException if the task name is recognised but task
     *                           creation fails.
     */
    public Task createTask(String taskType) throws BuildException {
        Task task = createNewTask(taskType);
        if (task == null && taskType.equals(ANT_PROPERTY_TASK)) {
            // quick fix for Ant.java use of property before
            // initializing the project
            addTaskDefinition(ANT_PROPERTY_TASK,
                              org.apache.tools.ant.taskdefs.Property.class);
            task = createNewTask(taskType);
        }
        return task;
    }

    /**
     * Creates a new instance of a task.
     * @since ant1.6
     * @param taskType The name of the task to create an instance of.
     *                 Must not be <code>null</code>.
     *
     * @return an instance of the specified task, or <code>null</code> if
     *         the task name is not recognised.
     *
     * @exception BuildException if the task name is recognised but task
     *                           creation fails.
     */
    private Task createNewTask(String taskType) throws BuildException {
        Class c = getComponentClass(taskType);
        if (c == null || !(Task.class.isAssignableFrom(c))) {
            return null;
        }
        Object obj = createComponent(taskType);
        if (obj == null) {
            return null;
        }
        if (!(obj instanceof Task)) {
            throw new BuildException(
                "Expected a Task from '" + taskType
                + "' but got an instance of " + obj.getClass().getName()
                + " instead");
        }
        Task task = (Task) obj;
        task.setTaskType(taskType);

        // set default value, can be changed by the user
        task.setTaskName(taskType);

        project.log("   +Task: " + taskType, Project.MSG_DEBUG);
        return task;
    }

    /**
     * Creates a new instance of a data type.
     *
     * @param typeName The name of the data type to create an instance of.
     *                 Must not be <code>null</code>.
     *
     * @return an instance of the specified data type, or <code>null</code> if
     *         the data type name is not recognised.
     *
     * @exception BuildException if the data type name is recognised but
     *                           instance creation fails.
     */
    public Object createDataType(String typeName) throws BuildException {
        return createComponent(typeName);
    }

    /**
     * Returns a description of the type of the given element.
     * <p>
     * This is useful for logging purposes.
     *
     * @param element The element to describe.
     *                Must not be <code>null</code>.
     *
     * @return a description of the element type.
     *
     * @since Ant 1.6
     */
    public String getElementName(Object element) {
        return getElementName(element, false);
    }

    /**
     * Returns a description of the type of the given element.
     * <p>
     * This is useful for logging purposes.
     *
     * @param o     The element to describe.
     *              Must not be <code>null</code>.
     * @param brief whether to use a brief description.
     * @return a description of the element type.
     *
     * @since Ant 1.7
     */
    public String getElementName(Object o, boolean brief) {
        //  PR: I do not know what to do if the object class
        //      has multiple defines
        //      but this is for logging only...
        Class elementClass = o.getClass();
        String elementClassname = elementClass.getName();
        for (Iterator i = antTypeTable.values().iterator(); i.hasNext();) {
            AntTypeDefinition def = (AntTypeDefinition) i.next();
            if (elementClassname.equals(def.getClassName())
                    && (elementClass == def.getExposedClass(project))) {
                String name = def.getName();
                return brief ? name : "The <" + name + "> type";
            }
        }
        return getUnmappedElementName(o.getClass(), brief);
    }

    /**
     * Convenient way to get some element name even when you may not have a
     * Project context.
     * @param p       The optional Project instance.
     * @param o       The element to describe.
     *                Must not be <code>null</code>.
     * @param brief   whether to use a brief description.
     * @return a description of the element type.
     * @since Ant 1.7
     */
    public static String getElementName(Project p, Object o, boolean brief) {
        if (p == null) {
            p = Project.getProject(o);
        }
        return p == null ? getUnmappedElementName(o.getClass(), brief)
                : getComponentHelper(p).getElementName(o, brief);
    }

    private static String getUnmappedElementName(Class c, boolean brief) {
        if (brief) {
            String name = c.getName();
            return name.substring(name.lastIndexOf('.') + 1);
        }
        return c.toString();
    }

    /**
     * Check if definition is a valid definition--it may be a
     * definition of an optional task that does not exist.
     * @param def the definition to test.
     * @return true if exposed type of definition is present.
     */
    private boolean validDefinition(AntTypeDefinition def) {
        return !(def.getTypeClass(project) == null
            || def.getExposedClass(project) == null);
    }

    /**
     * Check if two definitions are the same.
     * @param def  the new definition.
     * @param old the old definition.
     * @return true if the two definitions are the same.
     */
    private boolean sameDefinition(
        AntTypeDefinition def, AntTypeDefinition old) {
        boolean defValid = validDefinition(def);
        boolean sameValidity = (defValid == validDefinition(old));
        //must have same validity; then if they are valid they must also be the same:
        return sameValidity && (!defValid || def.sameDefinition(old, project));
    }

    /**
     * Update the component definition table with a new or
     * modified definition.
     * @param def the definition to update or insert.
     */
    private void updateDataTypeDefinition(AntTypeDefinition def) {
        String name = def.getName();
        synchronized (antTypeTable) {
            rebuildTaskClassDefinitions = true;
            rebuildTypeClassDefinitions = true;
            AntTypeDefinition old = antTypeTable.getDefinition(name);
            if (old != null) {
                if (sameDefinition(def, old)) {
                    return;
                }
                Class oldClass = antTypeTable.getExposedClass(name);
                boolean isTask =
                    (oldClass != null && Task.class.isAssignableFrom(oldClass));
                project.log("Trying to override old definition of "
                    + (isTask ? "task " : "datatype ") + name,
                    (def.similarDefinition(old, project))
                    ? Project.MSG_VERBOSE : Project.MSG_WARN);
            }
            project.log(" +Datatype " + name + " " + def.getClassName(),
                        Project.MSG_DEBUG);
            antTypeTable.put(name, def);
        }
    }

    /**
     * Called at the start of processing an antlib.
     * @param uri the uri that is associated with this antlib.
     */
    public void enterAntLib(String uri) {
        antLibCurrentUri = uri;
        antLibStack.push(uri);
    }

    /**
     * @return the current antlib uri.
     */
    public String getCurrentAntlibUri() {
        return antLibCurrentUri;
    }

    /**
     * Called at the end of processing an antlib.
     */
    public void exitAntLib() {
        antLibStack.pop();
        antLibCurrentUri = (antLibStack.size() == 0)
            ? null : (String) antLibStack.peek();
    }

    /**
     * Load ant's tasks.
     */
    private void initTasks() {
        ClassLoader classLoader = getClassLoader(null);
        Properties props = getDefaultDefinitions(false);
        Enumeration e = props.propertyNames();
        while (e.hasMoreElements()) {
            String name = (String) e.nextElement();
            String className = props.getProperty(name);
            AntTypeDefinition def = new AntTypeDefinition();
            def.setName(name);
            def.setClassName(className);
            def.setClassLoader(classLoader);
            def.setAdaptToClass(Task.class);
            def.setAdapterClass(TaskAdapter.class);
            antTypeTable.put(name, def);
        }
    }

    private ClassLoader getClassLoader(ClassLoader classLoader) {
        String buildSysclasspath = project.getProperty(MagicNames.BUILD_SYSCLASSPATH);
        if (project.getCoreLoader() != null
            && !(BUILD_SYSCLASSPATH_ONLY.equals(buildSysclasspath))) {
            classLoader = project.getCoreLoader();
        }
        return classLoader;
    }

    /**
     * Load default task or type definitions - just the names,
     *  no class loading.
     * Caches results between calls to reduce overhead.
     * @param type true for typedefs, false for taskdefs
     * @return a mapping from definition names to class names
     * @throws BuildException if there was some problem loading
     *                        or parsing the definitions list
     */
    private static synchronized Properties getDefaultDefinitions(boolean type)
        throws BuildException {
        int idx = type ? 1 : 0;
        if (defaultDefinitions[idx] == null) {
            String resource = type