Kotlin Bytecode DSL

A DSL that assists with writing bytecode in ASM

Note: This is NOT an abstraction layer, it simply reduces the amount of boilerplate you have to write

Usage

repositories {
    mavenCentral()
    maven("https://jitpack.io")
}

dependencies {
    implementation("org.ow2.asm:asm-tree:9.4")
    implementation("com.github.Nilsen84:kt-bytecode-dsl:v1.0")
}

Extensibility

This library does not come with any utility functions, though these can easily be added using extensions:

fun InsnBuilder.int(n: Int) = when (n) {
    in -1..5 -> +InsnNode(Opcodes.ICONST_0 + n)
    in Byte.MIN_VALUE..Byte.MAX_VALUE -> bipush(n)
    in Short.MIN_VALUE..Short.MAX_VALUE -> sipush(n)
    else -> ldc(n)
}

val InsnBuilder.iconst_6 get() = bipush(6)

Comparisons

Java	Kotlin	Kotlin + Bytecode DSL
var list = new InsnList() {{ var start = new LabelNode(); add(start); add(new FieldInsnNode( Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;" )); add(new LdcInsnNode("Hello, World!")); add(new MethodInsnNode( Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V" )); add(new JumpInsnNode(Opcodes.GOTO, start)); }};	val list = InsnList().apply { val start = LabelNode() add(start) add(FieldInsnNode( Opcodes.GETSTATIC, "java/lang/System", "out", "Ljava/io/PrintStream;" )) add(LdcInsnNode("Hello, World!")) add(MethodInsnNode( Opcodes.INVOKEVIRTUAL, "java/io/PrintStream", "println", "(Ljava/lang/String;)V" )) add(JumpInsnNode(Opcodes.GOTO, start)) }	val list = asm { val start = LabelNode() +start getstatic( "java/lang/System", "out", "Ljava/io/PrintStream;" ) ldc("Hello, World!") invokevirtual( "java/io/PrintStream", "println", "(Ljava/lang/String;)V" ) goto(start) }