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Objective-C target

Author

Kay Röpke
kroepke(at)classdump(dot)org

Status

As of mid September '06 it can build ASTs and tree parsers are not far off anymore working. (smile)

Features (partially) missing are:

  • Scopes
    • multiple return values - need testing/enhancements
    • arbitrary scopes
  • Labels
    • other labels
  • Tests - well, most of them
  • Template support (this will be a lot of work (sad))
  • Semantic predicates - need more testing

Features completed:

  • Single rule return values
  • FOLLOW sets (bitsets)
  • cyclic DFAs
  • Scopes
    • dynamic scopes
    • rule parameters
  • Labels
    • token reference labels
  • Syntactic Predicates
  • Tree support (buildAST=true)
  • Tree parsers

Roadmap

Building ASTs and tree parsers is working now. ANTLR.framework is known to be Universal.
I will use v3 to write a number of different small applications in order to find out about all the small bugs that are hiding in the corners. Thus development will probably not be milestone based, but rather fix-as-they-come-up.
Regarding the template output support of v3, this will require an Objective-C implementation of ST, which will take a lot of time. So don't expect that for 3.0.
Soon I will add debugging support to the code generation and add a bit to ANTLRWorks to make it support debugging Objective-C based grammars in their natural environment (=your application) or as simple standalone recognizers.

Platforms

I will only concern myself with the Mac. There will be no GNUStep support.
As for Mac OS X versions, I aim to be compatible with at least 10.3 as a target platform, though the Xcode project will require the latest version available, since it really doesn't make a lot of sense to use it in an earlier version.
Currently ANTLR requires 10.4. Unless there are very good reasons to support versions prior to that, it will not get priority.

Runtime

The runtime will be built in terms of the NS* level of classes, and is probably not very optimized in the first versions. I'll identify hotspots later and maybe add a CF-based runtime for speed if it turns out to be a problem.
The layout of the runtime is essentially the same as the Java version, though subtle differences will be visible where it makes it more natural to the Objective-C programmer. Naming of classes and methods may be slightly different and sometimes inner workings are too.
Initial tests don't show serious performance problems, though I'm sure there will be opportunities for optimization.

Examples

The goal is to provide the complete set of Java-based examples in Objective-C for comparison. There may be additional examples contained in the Xcode project. These exist mainly for development purposes as testcases, or to try out features.
I am currently working on an editor for StringTemplates as a big "example"/testcase for v3.

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