Toy/.notes/control-flow-opcodes.txt

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

if-then:
	cond-branch
	if false jump end
	{
		then-branch
	}
	end

if-then-else: (also ternary)
	cond-branch
	if false jump else
	{
		then-branch
	}
	jump end
	{
		else-branch
	}
	end

while:
	begin
	cond-branch
	if false jump end
	{
		then-branch
	}
	jump begin
	end

do-while:
	begin
	{
		then-branch
	}
	cond-branch
	if true jump begin
	end

for:
	{
		pre-branch
		begin
		cond-branch
		if false jump end
		{
			then-branch
		}
		post-branch
		jump begin
		end
	}

foreach:
	...needs more planning

switch-case-default:
	...needs more planning

continue:
	jump begin
	unwind scopes

break:
	jump end
	unwind scopes

---

Notes:
	The additional scope in 'for' is to safely encapsulate pre-branch, as variables can be declared here.
	do-while's 'end' is only there for the break/continue keywords.
	break and continue will also unwind scopes, up to the innermost control-flow level.

break/continue within nested scopes:
	Because control flows can be nested, a stack of scope depths may be needed for break/continue...
	However, this would get more complicated with closures.
	To fix this, scopes may need to remember their own depth, and the depth of the innermost control-flow level.
	If a scope's depth is 10 and the inner control-flow-level is 7, then calling break/continue will jump AND unwind to the inner control-flow level.

---

JUMP word:
	opcode
	type (absolute, relative)
	conditional (always, if_true, if_false)
	-

	value

absolute:
	"value" is relative to the code sections starting position

relative:
	"value" is relative to the program counter, after this opcode has been read from the bytecode

always:
	Always jump

if_true:
	pop the stack top
	if the popped value is true, then jump
	else ignore

if_false:
	pop the stack top
	if the popped value is true, then ignore
	else jump