/*

 * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.source.util;

import com.sun.source.tree.*;

/**

 * A simple visitor for tree nodes.

 *

 * @param <R> the return type of this visitor's methods.  Use {@link

 *            Void} for visitors that do not need to return results.

 * @param <P> the type of the additional parameter to this visitor's

 *            methods.  Use {@code Void} for visitors that do not need an

 *            additional parameter.

 *

 * @author Peter von der Ahé

 * @since 1.6

 */

public class SimpleTreeVisitor <R,P> implements TreeVisitor<R,P> {

    /**

     * The default value, returned by the {@link #defaultAction default action}.

     */

    protected final R DEFAULT_VALUE;

    /**

     * Creates a visitor, with a DEFAULT_VALUE of {@code null}.

     */

    protected SimpleTreeVisitor() {

        DEFAULT_VALUE = null;

    }

    /**

     * Creates a visitor, with a specified DEFAULT_VALUE.

     * @param defaultValue the default value to be returned by the default action.

     */

    protected SimpleTreeVisitor(R defaultValue) {

        DEFAULT_VALUE = defaultValue;

    }

    /**

     * The default action, used by all visit methods that are not overridden.

     * @param node the node being visited

     * @param p the parameter value passed to the visit method

     * @return the result value to be returned from the visit method

     */

    protected R defaultAction(Tree node, P p) {

        return DEFAULT_VALUE;

    }

    /**

     * Invokes the appropriate visit method specific to the type of the node.

     * @param node the node on which to dispatch

     * @param p a parameter to be passed to the appropriate visit method

     * @return the value returns from the appropriate visit method

     */

    public final R visit(Tree node, P p) {

        return (node == null) ? null : node.accept(this, p);

    }

    /**

     * Invokes the appropriate visit method on each of a sequence of nodes.

     * @param nodes the nodes on which to dispatch

     * @param p a parameter value to be passed to each appropriate visit method

     * @return the value return from the last of the visit methods, or null

     *      if none were called.

     */

    public final R visit(Iterable<? extends Tree> nodes, P p) {

        R r = null;

        if (nodes != null)

            for (Tree node : nodes)

                r = visit(node, p);

        return r;

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitCompilationUnit(CompilationUnitTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitPackage(PackageTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitImport(ImportTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitClass(ClassTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitMethod(MethodTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitVariable(VariableTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitEmptyStatement(EmptyStatementTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitBlock(BlockTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitDoWhileLoop(DoWhileLoopTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitWhileLoop(WhileLoopTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitForLoop(ForLoopTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitLabeledStatement(LabeledStatementTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitSwitch(SwitchTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.SWITCH_EXPRESSIONS)

    @SuppressWarnings("preview")

    public R visitSwitchExpression(SwitchExpressionTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitCase(CaseTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitSynchronized(SynchronizedTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitTry(TryTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitCatch(CatchTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitConditionalExpression(ConditionalExpressionTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitIf(IfTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitExpressionStatement(ExpressionStatementTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitBreak(BreakTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitContinue(ContinueTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitReturn(ReturnTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitThrow(ThrowTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitAssert(AssertTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitMethodInvocation(MethodInvocationTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitNewClass(NewClassTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitNewArray(NewArrayTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitLambdaExpression(LambdaExpressionTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitParenthesized(ParenthesizedTree node, P p) {

        return defaultAction(node, p);

    }

    /**

     * {@inheritDoc} This implementation calls {@code defaultAction}.

     *

     * @param node {@inheritDoc}

     * @param p {@inheritDoc}

     * @return  the result of {@code defaultAction}

     */

    @Override

    public R visitAssignment(AssignmentTree node, P p) {

        return defaultAction(node, p);