Implement Control Flow

[Ratstail91]

• if-then-else
• ternary ?:
• while
• do-while
• for
• foreach (compounds)
• continue
• break
• switch-case-default (and continue?)

I'm not sure how a switch statement could be done efficiently, so it'll need research.

[Ratstail91]

I did some thinking about this yesterday.

https://github.com/Ratstail91/Toy/blob/v2/.notes/control-flow-opcodes.txt

[Ratstail91]

I started working on if-then-else a few days ago, but the tests aren't finished yet due to unrelated bug hunts.

34577ec

Edit: And finished: 0947430

[Ratstail91]

The control flow for break and continue requires arrays to keep track during compilation, so #155 needs to be finished first.

Addendum: Turns out that wasn't the case. A bespoke "escape" structure was all that was needed.

[Ratstail91]

For break/continue keywords:

instruction:
	ESCAPE opcode
	ADDR   target
	UNWIND number of scopes to unwind

continue data: (point each keyword to the innermost position)
	current depth
	list<(addr, depth)> continues

break data: (wait unto the addr is found, then go back and set the keywords' parameters)
	current depth
	list<(addr, depth)> breaks

Therefore, the following structure is needed:

struct Escape {
	unsigned int addr;
	unsigned int depth;
};

Could wrap this in a reallocate function too, similar to Toy_Array.

[Ratstail91]

foreach isn't needed yet, and will apply to arrays and tables directly. Will add later.

do-while is rarely used, and switch isn'5 even thought out.

for might be easy, but I might start on something else, like functions, instead.