parse-test.r

REBOL []
Red []

do {
src: [
	#switch OS [
		Windows  [#define LIBREDRT-file "libRedRT.dll"]
		macOS	 [#define LIBREDRT-file "libRedRT.dylib"]
		#default [#define LIBREDRT-file "libRedRT.so"]
	]
	print LIBREDRT-file
]

defs:  make block! 100
insert defs <no-match>

stack: append/only clear [] make block! 100
append stack/1 1							;-- insert root header starting size
header: none

check-condition: func [type [word!] payload [block!]][
	case [
		type = 'switch [
			any [
				select payload/2 'Windows
				select payload/2 #default
			]
		]
		payload/2 = 'contains [
			do bind/copy 
				compose/deep [all [(payload/1) find (payload/1) (payload/3)]]
				job
		]
		'else [do bind/copy payload job]
	]
]

rule-blk: [
	some [
		defs
		| s: #define set name word! (args: none) [
			set args paren! set value [block! | paren!]
			| set value skip
		  ] e: (
			print [mold name #":" mold value]
			if word? value [value: to lit-word! value]
			rule: copy/deep [s: _ e: (e: change/part s _ e) :s]
			rule/4/4: :value
			rule/2: to lit-word! name
			either tag? defs/1 [remove defs][append defs '|]
			append defs rule
			remove/part s e
		) :s
		| s: #switch set name word! set cases block! e: (
			either body: check-condition 'switch reduce [name cases][
				change/part s body e
			][
				remove/part s e
			]
		) :s
		| s: (if any [block? s/1 paren? s/1][append/only stack copy [1]])
		  p: [block! | paren!] :p into blk
		  s: (
			if any [block? s/-1 paren? s/-1][
				header: last stack
				change header length? header	;-- update header size
				s/-1: insert copy s/-1 header	;-- insert hidden header
				remove back tail stack
			]
		  )
		| skip
	]
]
}
either Rebol [
	parse/all/case src rule-blk
][
	parse/case src rule-blk
]
?? src

halt