ThothCompiler revamped

ThothCompiler has been revamped very near completely. Get it by executing:

Gofer it
    squeaksource: 'ASTBridge';
    addPackage: 'ThothCompiler';
    load

Then go to the Preference Browser (System->Preferences in the world menu) and choose ThothCompiler for the option "whichCompiler".

ThothCompiler allows you to use a modern AST in Pharo, rather than the 20 year old default one. The code is parsed with Lukas' really fast RBParser and then transformed to the 20 year old nodes, from there compiled. What's the advantage?

Well, you can transform the modern AST nodes before compilation! It has a great visitor API, that lets you do all kinds of transformations. You can use ThothCompiler as is just to feel fancy, or better: subclass it and overwrite the transform: method, in which you can transform the AST to your liking.

ThothCompiler is now used in Helvetica (albeit under the name of RBCompiler, because things can never have enough names!).

Changes since the last blog post:

• Now uses the RBParser, which is much faster than SmaCC
  
• No more dependency on the NewCompiler or AST package
  
• Adds a preference to the system (in the system menu), where you can choose the compiler, even when you can't compile anymore :)
  

Introducing ThothCompiler

ThothCompiler combines the strengths of the two most popular smalltalk compilers. It takes the extensibility and wealth of the AST implementation from the NewCompiler and combines it with the most important asset of the old Compiler that per default ships with Squeak: it actually works.

Installation

The installation is fantastically easy. Go to Thoth on Squeaksource and get ASTBridgeLoader.

In a workspace, then execute:

ASTBridgeLoader load


Add the method compilerClass to the CLASS side of your class to set the compiler for the class. Thoth installs itself as the default compiler of the image. If you're unhappy with that, for example because you don't like the lack of error messages when you accept uncompilable code, you can choose for each class which compiler is to be used. Behavior>compilerClasss sets the default.

How do I hack into it?

Subclass ThothCompiler and override #compile:in:classified:notifying:ifFail: and #evaluate:in:to:notifying:ifFail:logged: Transform the AST before generate is called. Perhaps I should provide some infrastructure here …

How it works

It is a really simple thing: It uses the parser of the NewCompiler, then transforms the AST into the old model, and then uses the backend of the old compiler to compile.