Proposal: Javac Abstract Syntax Tree Viewer

Chris Newland cnewland at
Fri May 2 12:55:35 UTC 2014

Hi Jan,

Do you mean something like this:

I'm also working on a tool as part of the Adoption Group
( that may be suitable
for code-tools.

I don't mean to hijack the thread but there may be some crossover.

I've built a tool called JITWatch[1] for visualising the result of
HotSpot's LogCompilation output but it can also be used for more general
bytecode analysis and I think an AST viewer would be a great addition.

Happy to work together on this if you like?

Kind regards,

Chris Newland


> Hi Volker,
> I was not considering that so far. I might have been confusing saying
> "graphical". What I meant so far was a GUI, not painting the AST as a
> graph. My current prototype is simply a text pane showing the source
> code and a tree view showing the AST for the source code.
> Thanks,
>      Jan
> On 05/02/2014 07:48 AM, Volker Simonis wrote:
>> Hi Jan,
>> will this new tool integrate with and/or reuse parts of the Ideal Graph
>> Visualizer [1], [2] already used in HotSpot and Graal?
>> Thanks,
>> Volker
>> [1]
>> [2]
>> On Monday, April 28, 2014, Jan Lahoda <jan.lahoda at
>> <mailto:jan.lahoda at>> wrote:
>>     Hi,
>>     I would like to propose a tool for inclusion to the Code Tools
>> project:
>>     ---
>>     Tool Name: Javac Abstract Syntax Tree Viewer
>>     Summary: Graphical viewer for inspection of AST, and other data,
>>     produced by the standard Java compiler, javac.
>>     Proposed By: Jan Lahoda
>>     Rationale:
>>     The way javac models source code is not always easy to grasp,
>>     despite all attempts to make it as convenient as possible. Being
>>     able to actually see and inspect the AST and related information
>>     using a convenient UI is therefore very useful.
>>     Hereby, a GUI tool to visualize javac ASTs and related information
>>     is proposed for the Code Tools project. The primary target audience
>>     of the tool are clients using the javac source code modeling APIs.
>>     Secondary target audience are javac developers themselves. The tool
>>     should therefore also support inspection of javac internal aspects
>>     of the model.
>>     ---
>>     Thanks,
>>          Jan

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