samples/Main.asm

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 * modification, are permitted provided that the following conditions
 * are met:
 *
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 *     notice, this list of conditions and the following disclaimer.
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 *   - Redistributions in binary form must reproduce the above copyright
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 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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// Simple sample to demonstrate openjdk asmtools assembler with
// nashorn dynalink linker in a invokedynamic instruction.
//
// To assemble this file, use the following command:
//
//    java -cp <asmtools.jar> org.openjdk.asmtools.Main jasm Main.asm
//
// See also: https://wiki.openjdk.java.net/display/CodeTools/asmtools
//
// NOTE: Uses dynalink API defined by JEP-276 (http://openjdk.java.net/jeps/276)

super public class Main
	version 52:0
{

private static final Field linker:"Ljdk/dynalink/DynamicLinker;";

/*
   static {
        // create dynalink linker factory
        final DynamicLinkerFactory factory = new DynamicLinkerFactory();

        // create standard linker that can handle Java POJOs
        linker = factory.createLinker();
   }
*/
static Method "<clinit>":"()V"
        stack 2 locals 1
{
    new     class jdk/dynalink/DynamicLinkerFactory;
    dup;
    invokespecial   Method jdk/dynalink/DynamicLinkerFactory."<init>":"()V";
    astore_0;
    aload_0;
    invokevirtual   Method jdk/dynalink/DynamicLinkerFactory.createLinker:"()Ljdk/dynalink/DynamicLinker;";
    putstatic       Field linker:"Ljdk/dynalink/DynamicLinker;";
    return;
}

/*
    // Bootstrap method used with invokedynamic methods

    public static CallSite bootstrap(MethodHandles.Lookup caller, String name, MethodType type) {
        // use dynalink linker to perform the actual linking
        return linker.link(
            new SimpleRelinkableCallSite(
                new CallSiteDescriptor(
                    MethodHandles.publicLookup(), 
                    new NamedOperation(StandardOperation.GET_PROPERTY, name), type)
            )
        );
    }

 */
public static Method bootstrap:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;"
        stack 10 locals 3
{
    getstatic       Field linker:"Ljdk/dynalink/DynamicLinker;";
    new     class jdk/dynalink/support/SimpleRelinkableCallSite;
    dup;
    new     class jdk/dynalink/CallSiteDescriptor;
    dup;
    invokestatic    Method java/lang/invoke/MethodHandles.publicLookup:"()Ljava/lang/invoke/MethodHandles$Lookup;";
    new     class jdk/dynalink/NamedOperation;
    dup;
    getstatic       Field jdk/dynalink/StandardOperation.GET_PROPERTY:"Ljdk/dynalink/StandardOperation;";
    aload_1;
    invokespecial   Method jdk/dynalink/NamedOperation."<init>":"(Ljdk/dynalink/Operation;Ljava/lang/Object;)V";
    aload_2;
    invokespecial   Method jdk/dynalink/CallSiteDescriptor."<init>":"(Ljava/lang/invoke/MethodHandles$Lookup;Ljdk/dynalink/Operation;Ljava/lang/invoke/MethodType;)V";
    invokespecial   Method jdk/dynalink/support/SimpleRelinkableCallSite."<init>":"(Ljdk/dynalink/CallSiteDescriptor;)V";
    invokevirtual   Method jdk/dynalink/DynamicLinker.link:"(Ljdk/dynalink/RelinkableCallSite;)Ljdk/dynalink/RelinkableCallSite;";
    checkcast       class java/lang/invoke/CallSite;
    areturn;
}

// default constructor that does nothing!
public Method "<init>":"()V"
	stack 1 locals 1
{
    aload_0;
    invokespecial	Method java/lang/Object."<init>":"()V";
    return;
}

public static Method main:"([Ljava/lang/String;)V"
	stack 2 locals 2
{
    // List l = new ArrayList();
    new	class java/util/ArrayList;
    dup;
    invokespecial	Method java/util/ArrayList."<init>":"()V";
    astore_1;
    aload_1;

    // l.add("hello");
    ldc	String "hello";
    invokeinterface	InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;
    pop;

    // l.add("world");
    aload_1;
    ldc	String "world";
    invokeinterface	InterfaceMethod java/util/List.add:"(Ljava/lang/Object;)Z",  2;
    pop;

    // printLength(l);
    aload_1;
    invokestatic	Method printLength:"(Ljava/lang/Object;)V";

    // printLength(args); // args is argument of main method
    aload_0;
    invokestatic	Method printLength:"(Ljava/lang/Object;)V";
    return;
}

private static Method printLength:"(Ljava/lang/Object;)V"
	stack 2 locals 1
{
    getstatic	Field java/lang/System.out:"Ljava/io/PrintStream;";
    aload_0;

    // Using bootstrap method in this class with the following invokedynamic
    // which uses dynalink linker. Dynalink's bean linker handles Java beans.
    // 'length' property on a bean - arrays, lists supported

    invokedynamic   InvokeDynamic REF_invokeStatic:Main.bootstrap:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;":"length":"(Ljava/lang/Object;)Ljava/lang/Object;";

    // print 'length' value
    invokevirtual	Method java/io/PrintStream.println:"(Ljava/lang/Object;)V";
    return;
}

} // end Class Main