chasm

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= Chasm - Java assembler and disassembler using S-expressions

Chasm can disassemble {asterisk}.class files and {asterisk}.jar files and output assembly in s-expression form. Furthermore the main use case is to read s-expression assembly files and output {asterisk}.class or {asterisk}.jar files. The s-expression syntax is both easy to parse and easy to generate. Chasm uses the de-facto standard library ow2 ASM for bytecode generation. Since Chasm is only a minimal syntax on top of ASM it is easy to keep it up to date with the current bytecode standard.

[source,scheme]

(class 53 (final public super) chasm/Main null java/lang/Object () (source "Main.java" null) (inner-class chasm/Server$Command chasm/Server Command (abstract interface public static)) (inner-class java/lang/invoke/MethodHandles$Lookup java/lang/invoke/MethodHandles Lookup (final public static)) (method (public static) main "([Ljava/lang/String;)V" null (java/io/IOException) (code (label L0) (line 13 L0) (invokedynamic run "()Lchasm/Server$Command;" (H invokestatic java/lang/invoke/LambdaMetafactory metafactory "(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;" false) ((T "(Ljava/nio/file/Path;[Ljava/lang/String;Ljava/io/PrintStream;)V") (H invokestatic chasm/Main run "(Ljava/nio/file/Path;[Ljava/lang/String;Ljava/io/PrintStream;)V" false) (T "(Ljava/nio/file/Path;[Ljava/lang/String;Ljava/io/PrintStream;)V"))) (aload 0) (invokestatic chasm/Server main "(Lchasm/Server$Command;[Ljava/lang/String;)V") (label L1) (line 14 L1) (return) (label L2) (local args "[Ljava/lang/String;" null L0 L2 0) (maxs 2 1))) ...

See link:example.chasm[] for the full example.

== Quick start

1. Build with gradle or use the precompiled binary in dist (reproducible build).
2. Disassemble class/jar file to chasm with chasm example.{class|jar} example.chasm
3. Assemble chasm to class/jar file with chasm example.chasm example.{class|jar}

== Binary version

The 'dist' directory contains a precompiled version which includes a copy of ASM.

== License

MIT (c) 2018 Daniel Mendler

ASM: a very small and fast Java bytecode manipulation framework Copyright (c) 2000-2011 INRIA, France Telecom All rights reserved.

== Related projects

• http://asm.ow2.io/[ObjectWeb ASM]
• https://wiki.openjdk.java.net/display/CodeTools/asmtools[jdk asmtools]
• https://github.com/achmelev/lilac[Lilac] ** Does perfect roundtrip like chasm ** Overall more complex and more complex syntax ** Not based on ObjectWeb ASM
• https://github.com/Storyyeller/Krakatau[Krakatau] ** Written in Python ** Includes a decompiler
• https://github.com/davidar/jasmin[Jasmin]
• https://github.com/Whiley/Jasm[Whiley Jasm]
• http://www.judoscript.org/articles/jamaica.html[Jamaica]
• https://commons.apache.org/proper/commons-bcel/[BCEL]