antlr4
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antlr
Why can't we compress the ATN?
Depending on how simply its implemented, it could be incredibly beneficial. Personally, since I'm already using zstd in my compiler project, I wouldn't mind zstd, but a super simple compression implementation could work.
Should not be a 3rd party lib, to avoid forcing all targets to have that in their specific environment. Instead a simple RLE might make more sense, but it's unclear if compressing the serialized ATN has any significant impact (on code size or runtime speed).
Instead maybe a new serialization format might be the better choice? However, I don't think that will ever be considered in ANTLR4. Instead follow the ANTLRng project, where this might become a reality.
Should not be a 3rd party lib, to avoid forcing all targets to have that in their specific environment. Instead a simple RLE might make more sense, but it's unclear if compressing the serialized ATN has any significant impact (on code size or runtime speed).
Instead maybe a new serialization format might be the better choice? However, I don't think that will ever be considered in ANTLR4. Instead follow the ANTLRng project, where this might become a reality.
I'm not sure whether every ATN actually needs to be fully unpacked, and whether it should even be done in the parser constructor. For our largest grammar sql/plsql, unpacking takes 0.2s in C#, but most of the grammar isn't even used for the parse. For the entire test suite of 379 files, it's only 66% of the rules that are used. You would think that for small tests the %-used is even less.
But is there a problem? Is this too much time or space required?
