Refactor Parse Algorithm to Use One Pass

[offlinemark]

Figured there might be feedback, best to submit for review

[nixpulvis]

@mossberg nice cleanup. I'm not sure why I made a hash table for this, this is clearly better.

[nixpulvis]

@mossberg I can add a few tests to this branch if it would help make clear the interface and expectations of the parse function. There are a few cases to consider with the matching brackets.

[offlinemark]

@nixpulvis i could give a shot at that

the parse cases I can think of:

• equal open/close brackets
• more open brackets than close brackets (stack is not empty at end of algo)
• more close brackets than open brackets (will attempt to pop empty stack)

if I add an Error:InvalidProgram, seems like parse should return a Result<Program, InvalidProgram>?

[nixpulvis]

Yea exactly.

[nixpulvis]

Actually Result<Program, Error> but the right idea, since Error::InvalidProgram itself isn't s type.

[offlinemark]

actually this will break in regards to comment blocks. it will count comment brackets as actual code

[nixpulvis]

There is no such thing as a comment bracket, they are just brackets that will always skip over. See #20 for more about skipping irrelevant code.

[offlinemark]

right, but as of now, the "syntax analysis" in parse treats everything as code, even if it doesn't matter during runtime.

i guess that's an implementation decision. does incidental brainfuck code in a "comment" block need to be syntactically accurate? i feel like the "spirit" of brainfuck would say that the interpreter should not care.

example

[this is my comment block. this single bracket -> ] will cause an imbalance in brackets and cause an invalid program error, even though during execution, it's fine
]
+++[-,.]

[nixpulvis]

I see what you are saying now. Well, I'd guess most brainfuck interpreters don't preproces. You could try to find one that died and see what it does. For now until we have work done for #20 I'd say it's fine to require matching brackets in comments.

[offlinemark]

@nixpulvis if there are no other comments, i'll go ahead and merge on your ok

[nixpulvis]

LGTM