slc/examples/if.slc

// Implementing if statement if its not a built-in in SLC!
// Not compiler writing in SLC language, but SLCs builtin itself...

::builtin if @cmp @then @else
	"" parseblock() // (*)
	if@cmp(.)
	"" parseblock{}
	if@then(_)
	// returns 0 if there was no [] block!
	// Calling 0 means just calling the
	// intstruction pointer ("avoiding call")
	"" parseblock[]
	if@else(_)

	// (*) cmp result at top of stack
	gen(!) gen(skipif) if@then
	gen(skipif) if@else
;

// Alternatively - by adding "branchcall" to the builtins
::builtin if
	"" parseblock()
	genpush(_)
	"" parseblock{}
	genpush(_)
	"" parseblock[] // returns 0 if there was no block (its SKIP to 'call' 0)
	genpush(_)
	gen(branchcall)
;

// Rem.: "branchcall" can be used in "real" code to split which word to call...

: smaller
	"smaller"
;

: bigger
	"bigger-or-eq"
;

// Gets a b
// returns "smaller" or "bigger-or-eq"
: smaller_or_bigger
	<
	gen(smaller)
	gen(bigger)
	branchcall
;

// Better example

: one 1 ;
: zero 0 ;

// Gets a b
// returns 1 if a < b, 0 otherwise
: smaller_or_bigger
	<
	gen(one)
	gen(zero)
	branchcall
;