Module CodeGenerator (s$){
	Function code$(op$) {
		=format$("{0::-6} {1}", pc, op$)
		pc++
	}
	Function code2$(op$, n$) {
		=format$("{0::-6} {1} {2}", pc, op$, n$)
		pc+=5
	}
	Function code3$(op$,pc, st, ed) {
		=format$("{0::-6} {1} ({2}) {3}", pc, op$, ed-st-1, ed)
	}
	
	Enum tok {
		gneg, gnot, gmul, gdiv, gmod, gadd, gle, gsub, glt
		gle, ggt, gge, geq, gne, gand, gor, gprtc, gprti, gprts,
		gif, gwhile, gAssign, gSeq, gstring, gidentifier, gint, gnone
	}

	\\ Inventories are lists with keys, or keys/data (key must be unique)
	\\ there is one type more the Invetory Queue which get same keys.
	\\ But here not used.
	Inventory symb="Multiply":=gmul, "Divide":=gdiv, "Mod":=gmod, "Add":=gadd
	Append  symb, "Negate":=gneg, "Not":=gnot,"Less":=glt,"Subtract":=gsub
	Append  symb, "LessEqual":=gle, "Greater":=ggt, "GreaterEqual":=gge, "Sequence":=gSeq
	Append  symb, "Equal":=geq, "NotEqual":=gne,  "And":=gand, "Or":=gor, "While":=gwhile
	Append  symb, "Prtc":=gprtc,"Prti":=gprti,"Prts":=gprts, "Assign":=gAssign, "If":=gif
	Append  symb, "String":=gstring, "Identifier":=gidentifier, "Integer":=gint, ";", gnone

	Inventory DataSet
	\\ We set string as key. key maybe an empty string, a string or a number.
	\\ so we want eash string to saved one time only.
	Inventory Strings
	
	Const nl$=chr$(13)+chr$(10), Ansi=3
	Def z$, lim, line$, newvar_ok, i=0
	Document message$=nl$
	Global pc     \\ functions have own scope, so we make it global, for this module, and childs.

	Dim lines$()
	s$=filter$(s$,chr$(9))   \\ exclude tabs
	Lines$()=piece$(s$,nl$) \\ break to lines
	lim=len(Lines$())
	Flush ' empty stack (there is a current stack of values which we use here)
	
	Load_Ast()
	If not stack.size=1 Then Flush : Error "Ast not loaded"
	AST=array   \\ pop the array from stack
	Document Assembly$, Header$

	\\ all lines of assembly goes to stack. Maybe not in right order.
	\\ Push statement push to top, Data statement push to bottom of stack
	
	CodeGenerator(Ast)
	Data  code$("halt") ' append to end of stack
	\\ So now we get all data (letters) from stack
	While not empty
		Assembly$=letter$+nl$
	end while
	\\ So now we have to place them in order
	Sort Assembly$
	
	\\ Let's make the header
	Header$=format$("Datasize: {0} Strings: {1}", Len(Dataset),Len(strings))
	\\ we use an iterator object, str^ is the counter, readonly, but Eval$() use it from object.
	str=each(strings)
	While str
		Header$=nl$+Eval$(str)
	End while
	Assembly$=nl$
	\\ insert to line 1 the Header
	Insert 1 Assembly$=Header$
	\\ Also we check for warnings
	If len(message$)>2 then Assembly$="Warnings: "+nl$+message$
	\\ So now we get a report
	\\ (at each 3/4 of window's lines, the printing stop and wait for user response, any key)
	Report Assembly$
	Clipboard Assembly$
	Save.Doc Assembly$, "code.t", Ansi
	End
	\\ subs have 10000 limit for recursion but can be extended to 1000000 or more.
	Sub CodeGenerator(t)
	
		If len(t)=3 then
			select case  t#val(0)
			Case gSeq
				CodeGenerator(t#val(1)) : CodeGenerator(t#val(2))
			Case gwhile
			{
				local spc=pc
				CodeGenerator(t#val(1))
				local pc1=pc
				pc+=5 ' room for jz
				CodeGenerator(t#val(2))
				data code3$("jz",pc1, pc1, pc+5)
				data code3$("jmp",pc,  pc, spc)
				pc+=5  ' room for jmp
			}
			Case gif
			{
				CodeGenerator(t#val(1))
				local pc1=pc, pc2
				pc+=5
				CodeGenerator(t#val(2)#val(1))
				If len(t#val(2)#val(2))>0 then
					pc2=pc
					pc+=5
					data code3$("jz",pc1, pc1, pc)
					CodeGenerator(t#val(2)#val(2))
					data code3$("jmp",pc2, pc2, pc)
				else
					data code3$("jz",pc1, pc1, pc)
				end If		
			}
			Case gAssign
			{
				CodeGenerator(t#val(2))
				local newvar_ok=true
				CodeGenerator(t#val(1))
			}
			case gneg to gnot, gprtc to gprts
				CodeGenerator(t#val(1)) : data code$(mid$(eval$(t#val(0)),2))
			case gmul to gor
			{
				CodeGenerator(t#val(1))
				CodeGenerator(t#val(2))
				data code$(mid$(eval$(t#val(0)),2))
			}
			End select
		Else.if len(t)=2 then
			select case  t#val(0)
			Case gString
			{
				local spos
				If exist(strings,t#val$(1)) then
					spos=eval(strings!)
				else
					append strings, t#val$(1)		
					spos=len(strings)-1
				end If
				Push code2$("push",str$(spos,0))
			}
			Case gInt
				Push code2$("push",t#val$(1), pc)
			Case gIdentifier
			{
				local ipos
				If exist(dataset,t#val$(1)) then
					ipos=Eval(dataset!)  ' return position
				else.if newvar_ok then
					Append dataset, t#val$(1)
					ipos=len(dataset)-1
				else
					message$="Variable "+t#val$(1)+" not initialized"+nl$
					
				end If
				If newvar_ok then
					Push code2$("store","["+str$(ipos, 0)+"]")
				else
					Push code2$("fetch","["+str$(ipos, 0)+"]")
				end If
			}
			end select
		End If
	End Sub
	Sub Load_Ast()
			If i>=lim then Push (,) : exit sub
			do
			line$=Trim$(lines$(i))
			I++
			tok$=piece$(line$," ")(0)
			until line$<>"" or i>=lim
			If tok$="Identifier" then
				Push (gidentifier,trim$(Mid$(line$,11)))
			else.if tok$="Integer" then
				long n=Val(Mid$(line$,8))  ' check overflow
				Push (gint, Trim$(Mid$(line$,8)))
			else.if tok$="String" then
				Push (gstring,Trim$(Mid$(line$,7)))
			else.if tok$=";" then
				Push (,)
			Else
				local otok=symb(tok$)
				Load_Ast()
				Load_Ast()
				Shift 2
				Push (otok,array, array)
			End If
	End Sub
}

CodeGenerator {
	Sequence
	Sequence
	;
	Assign
	Identifier    count
	Integer       1
	While
	Less
	Identifier    count
	Integer       10
	Sequence
	Sequence
	;
	Sequence
	Sequence
	Sequence
	;
	Prts
	String        "count is: "
	;
	Prti
	Identifier    count
	;
	Prts
	String        "\n"
	;
	Assign
	Identifier    count
	Add
	Identifier    count
	Integer       1
}