20 January 2011

Tags: asm ast groovy intellij java transform

I’m releasing a new version of my ASM plugin for IntelliJ IDEA tonight, as well as a new version of the Groovy @Bytecode AST Transformation. Both are worth an upgrade as they greatly improve your experience :

ASM plugin for IntelliJ IDEA

The new version of the plugin provides several improvements :

  • Ability to show the differences between two versions of the bytecode

  • Configuration of output verbosity : skip frames, skip code, skip debug and expand frames

  • Support for showing bytecode of test classes

  • A new Groovy tab which displays Groovified code for the @Bytecode AST Transformation

  • Support for two types of Groovy code : legacy and Groovified

The last two items are directly related to the upgrade of the Groovy AST bytecode transformation, and will make integration of ASM bytecode into Groovy even easier !

Improved syntax for the @Bytecode AST Transformation

The new release of the transformation adds support for a Groovier syntax, mostly contributed by Guillaume Laforge. Basically, the AST Transformation now supports different syntaxes that you can mix :

  • a legacy syntax which is as close as possible of the output of tools like javap or the ASM plugin for Eclipse/IntelliJ

  • a Groovified syntax which makes it really easy to embed bytecode into Groovy : just copy and paste !

if you use the IntelliJ IDEA ASM plugin, you wont need to modify the generated bytecode to make it work with the @Bytecode transformation :

First, on the class you want to show the bytecode for, right click on the editor and choose “Show bytecode outline” : image

The new plugin includes a third tab which shows generated Groovy code. Select the 3rd tab :

You’ll notice that the syntax here is the legacy syntax, as close as possible to the javap output. Now, click on the settings tab and choose Groovified code style :
image  http://www.jroller.com/melix/resource/asm/asm-groovified-new.png[image]

Right click on the editor to show bytecode again. The Groovified tab will now use the brand new syntax. You can click on the “Show differences” button to highlight the differences :

I definitely wanted to keep the two syntaxes as both have great interest. Here are the differences :

  • Labels

    • Legacy syntax : l0

    • Groovified syntax : anyLabel:

    • The Groovified syntax uses regular Groovy labels, allowing you to use any label, not only the l[0-9]+ syntax

  • Goto jumps

    • Legacy syntax : _goto l15

    • Groovified syntax : go to: myLabel

    • The underscore is replaced with a Groovier go to: syntax

  • instanceof checks

    • Legacy syntax : _instanceof 'java/lang/String'

    • Groovified syntax : instance of: String

    • Just like the goto variation, but allows class literals to be specified directly, not only string literals

  • Fields access

    • Legacy syntax : putfield 'com/lingway/test/MaClasse.valeur','I'

    • Groovified syntax : putfield MaClasse.valeur >> int

    • get/put (static) field instructions support direct class literals. Field type is specified by the right hand side of the expression, after the right shift operator

  • Methods

    • Legacy syntax : invokevirtual 'java/lang/StringBuilder.append','(Ljava/lang/String;)Ljava/lang/StringBuilder;'

    • Groovified syntax : invokevirtual StringBuilder.append(String) >> StringBuilder

    • method instructions support direct class literals. Field type is specified by the right hand side of the expression, after the right shift operator

  • ‘New’ operator

    • Legacy syntax : _new 'java/lang/String'

    • Groovified syntax : newobject String

    • A newobject keyword, supporting the class directly, not as a string literal

  • Arrays

    • Legacy syntax : newarray T_INT

    • Groovified syntax : newarray int

    • Supports class literals as well as primitive types

  • Multidimensional arrays

    • Legacy syntax : multianewarray '[[Ljava/lang/Object;',2

    • Groovified syntax : multianewarray Object[][],2

    • Supports classes directly, as well as primitive types

  • Type casting

    • Legacy syntax : checkcast 'java/lang/String'

    • Groovified syntax : checkcast String

    • Supports class literals

  • Exceptions

    • Legacy syntax : trycatchblock l0,l1,l2,'java/lang/Throwable'

    • Groovified syntax : trycatchblock l0,l1,l2,Throwable

    • Supports class literals


Plugin for IDEA

The plugin for IntelliJ IDEA can be downloaded directly from the plugin manager or from this link.

Groovy @Bytecode AST Transformation

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