/*

 * Copyright (c) 2016, 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.

 *

 * 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.

 */

/*

 * @test

 * @bug 7020499

 * @summary Verify that try-with-resources desugaring is not generating unnecessary null checks

 * @library /tools/lib

 * @modules jdk.compiler/com.sun.tools.javac.api

 *          jdk.compiler/com.sun.tools.javac.code

 *          jdk.compiler/com.sun.tools.javac.comp

 *          jdk.compiler/com.sun.tools.javac.main

 *          jdk.compiler/com.sun.tools.javac.tree

 *          jdk.compiler/com.sun.tools.javac.util

 * @build toolbox.ToolBox toolbox.JavacTask TwrAvoidNullCheck

 * @run main TwrAvoidNullCheck

 */

import java.io.IOException;

import java.util.Arrays;

import com.sun.source.util.JavacTask;

import com.sun.tools.javac.api.JavacTool;

import com.sun.tools.javac.comp.AttrContext;

import com.sun.tools.javac.comp.Env;

import com.sun.tools.javac.comp.Lower;

import com.sun.tools.javac.tree.JCTree;

import com.sun.tools.javac.tree.JCTree.JCBinary;

import com.sun.tools.javac.tree.TreeInfo;

import com.sun.tools.javac.tree.TreeMaker;

import com.sun.tools.javac.tree.TreeScanner;

import com.sun.tools.javac.util.Context;

import com.sun.tools.javac.util.Context.Factory;

import com.sun.tools.javac.util.List;

import toolbox.ToolBox;

public class TwrAvoidNullCheck {

    public static void main(String... args) throws IOException {

        new TwrAvoidNullCheck().run();

    }

    void run() throws IOException {

        run("new Test()", false);

        run("null", true);

        run("System.getProperty(\"test\") != null ? new Test() : null", true);

    }

    void run(String resourceSpecification, boolean expected) throws IOException {

        String template = "public class Test implements AutoCloseable {\n" +

                          "    void t() {\n" +

                          "        try (Test resource = RESOURCE) { }\n" +

                          "    }\n" +

                          "    public void close() { }\n" +

                          "}\n";

        String code = template.replace("RESOURCE", resourceSpecification);

        Context ctx = new Context();

        DumpLower.preRegister(ctx);

        Iterable<ToolBox.JavaSource> files = Arrays.asList(new ToolBox.JavaSource(code));

        JavacTask task = JavacTool.create().getTask(null, null, null, null, null, files, ctx);

        task.call();

        boolean hasNullCheck = ((DumpLower) DumpLower.instance(ctx)).hasNullCheck;

        if (hasNullCheck != expected) {

            throw new IllegalStateException("expected: " + expected +

                                            "; actual: " + hasNullCheck +

                                            "; code: " + code);

        }

    }

    static class DumpLower extends Lower {

        public static void preRegister(Context ctx) {

            ctx.put(lowerKey, new Factory<Lower>() {

                @Override

                public Lower make(Context c) {

                    return new DumpLower(c);

                }

            });

        }

        public DumpLower(Context context) {

            super(context);

        }

        boolean hasNullCheck;

        @Override

        public List<JCTree> translateTopLevelClass(Env<AttrContext> env, JCTree cdef, TreeMaker make) {

            List<JCTree> result = super.translateTopLevelClass(env, cdef, make);

            new TreeScanner() {

                @Override

                public void visitBinary(JCBinary tree) {

                    hasNullCheck |= tree.operator.getSimpleName().contentEquals("!=") &&

                                    "resource".equals(String.valueOf(TreeInfo.name(tree.lhs))) &&

                                    TreeInfo.isNull(tree.rhs);

                    super.visitBinary(tree);

                }

            }.scan(result);

            return result;

        }

    }

}