1 /*

     2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

     3  *

     4  * Redistribution and use in source and binary forms, with or without

     5  * modification, are permitted provided that the following conditions

     6  * are met:

     7  *

     8  *   - Redistributions of source code must retain the above copyright

     9  *     notice, this list of conditions and the following disclaimer.

    10  *

    11  *   - Redistributions in binary form must reproduce the above copyright

    12  *     notice, this list of conditions and the following disclaimer in the

    13  *     documentation and/or other materials provided with the distribution.

    14  *

    15  *   - Neither the name of Oracle nor the names of its

    16  *     contributors may be used to endorse or promote products derived

    17  *     from this software without specific prior written permission.

    18  *

    19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

    20  * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,

    21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

    22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR

    23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,

    24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,

    25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

    26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

    27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

    28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

    29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    30  */

    31 

    32 // Simple sample to demonstrate openjdk asmtools assembler with

    33 // nashorn dynalink linker in a invokedynamic instruction.

    34 //

    35 // To assemble this file, use the following command:

    36 //

    37 //    java -cp <asmtools.jar> org.openjdk.asmtools.Main jasm Main.asm

    38 //

    39 // See also: https://wiki.openjdk.java.net/display/CodeTools/asmtools

    40 //

    41 // NOTE: Uses nashorn internals and so *may* break with later nashorn!

    42 

    43 super public class Main

    44 	version 52:0

    45 {

    46 

    47 

    48 public Method "<init>":"()V"

    49 	stack 1 locals 1

    50 {

    51 		aload_0;

    52 		invokespecial	Method java/lang/Object."<init>":"()V";

    53 		return;

    54 }

    55 

    56 public static Method main:"([Ljava/lang/String;)V"

    57 	stack 2 locals 2

    58 {

    59                 // List l = new ArrayList();

    60 		new	class java/util/ArrayList;

    61 		dup;

    62 		invokespecial	Method java/util/ArrayList."<init>":"()V";

    63 		astore_1;

    64 		aload_1;

    65 

    66                 // l.add("hello");

    67 		ldc	String "hello";

    68 		invokeinterface	InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;

    69 		pop;

    70 

    71                 // l.add("world");

    72 		aload_1;

    73 		ldc	String "world";

    74 		invokeinterface	InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;

    75 		pop;

    76 

    77                 // printLength(l);

    78 		aload_1;

    79 		invokestatic	Method printLength:"(Ljava/lang/Object;)V";

    80 

    81                 // printLength(args); // args is argument of main method

    82 		aload_0;

    83 		invokestatic	Method printLength:"(Ljava/lang/Object;)V";

    84 		return;

    85 }

    86 

    87 private static Method printLength:"(Ljava/lang/Object;)V"

    88 	stack 2 locals 1

    89 {

    90 		getstatic	Field java/lang/System.out:"Ljava/io/PrintStream;";

    91 		aload_0;

    92 

    93                 // Using nashorn embedded dynalink linker with the following invokedynamic

    94                 // 'length' property on a bean - arrays, lists supported

    95 

    96                 invokedynamic   InvokeDynamic REF_invokeStatic:jdk/nashorn/internal/runtime/linker/Bootstrap.bootstrap:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;I)Ljava/lang/invoke/CallSite;":"dyn:getProp|getElem|getMethod:length":"(Ljava/lang/Object;)Ljava/lang/Object;" int 0;

    97 

    98                 // print 'length' value

    99 		invokevirtual	Method java/io/PrintStream.println:"(Ljava/lang/Object;)V";

   100 		return;

   101 }

   102 

   103 } // end Class Main