Abstract Syntax Tree

[Kroc]

At the moment OZ80 uses a very simple linear list of word tokens. This is efficient at walking, but it means that we are doing a lot of structural validation as we execute the user-program. Execution and assembling are already very fast compared to tokenisation, but to speed things up more (especially when we introduce loops and macros) I want to be able to do away with the validation during execution.

The solution to this is to build an Abstract Syntax Tree instead of a linear token list and do a large amount of structural validation during the tokenisation stage. This will also allow us to pre-allocate Label and Value names and link those to the tokens in question, sparing us from the painful Dictionary object lookups currently used throughout.