::SHE+ILA::'s Parser Grows [$77]

More about ::SHE+ILA::'s Parser Grows [$77]

The ::SHE+ILA:: Front End and Parser has now expanded and generalised to about 40 states, each having about 40 exits. These transitions between states are selected by character class, with each special or punctuation character having its own slot in every state. The first 9 cover A to F, then the remaining alphabetics, the numerics 0 to 9, control characters (the keyboard and VDU drivers are built into the Parser), an error exit (to show syntax errors in black-on-red), and then a separate exit for each operator (+,-,*,!,#,£,$,%,^,&,@) and each flavour of bracket ( (,),[,],{,}) and the comparisons (<,=,>). This comes to about 40 transitions for each state. All the syntactically incorrect exits go to the ER (error) state, and the operator transitions distinguish monadic and dyadic usages by context, and implement the PEMDAS hierarchy. All this in about 2000 lines of Assembler code :)