M2000 Compiler Task

From Rosetta Code

One module compile, including lexical analyzer, syntax analyzer, code generator and virtual machine interpreter. The VM running using lambda functions, which include in an inventory (a kind of map), so each byte code is a key to this inventory, and the vm loop is just three lines. Normally functions (including lambda functions) and modules have own name space, but we can call functions with a L Call Local statement, which place the same name space of the caller (subroutines get always name space from the caller). Each module get a string (the (a$) is a syntactic sugar, interpreter insert a Read a$ when module added to modules/function list), and place a string to the stack of values. So we have to put one module after the other to do all the process.

The stack of values internal is a collection, which we can add to top (using Push) or to bottom (using Data) and we can pop values using Read, or peak values using ItemStack() and ItemStack$() for strings. A module get the parent stack of value, a function in an expression has own stack of value. We can switch temporary to a new stack using a Stack New { } statement, and at the end of this the previous object attach to "process object". (modules and functions run on separate process objects, subs are implemented in execution code, they are not objects).

Enum variables can return the name of value using a Eval$(enum_name_or_variable), So we can store values as Enum types, and handle them as numbers and as strings (using Eval$()). Functions Eval() and Eval$() do many things, depends of the first argument.

Generator save the byte code to a byte buffer. In a buffer bytes, integer, long are unsigned numbers. We have to use Uint(a) to place a signed value, and Sint() to get the signed from buffer. Also we can read from bytes offsets using casting to integer or to long, which we done here to get the long value after the operand (like in jmp or in fetch).

lambda functions can get closures as copies. In lexical analyzer the Scanner variable is a pointer to a buffer, so the copy is a reference. Lambda functions are not reference type, but a value type. We can pass a lambda as a closure too.

Select Case is a mystery in M2000. We can have one line after Case or a Block but no blank lines. This happen because interpreter execute code every time from source; Only look ahead to find if an expression is a string or number which is very fast because, strings functions and variables have $ at the end of name. Maybe some day interpreter find a lexical/syntax analyzer, but for this time works as one function which consume source code.


M2000 Interpreter[edit]

<lang M2000 Interpreter> Module CompilerExample { Set Fast ! Module lexical_analyzer (a$){ lim=Len(a$) LineNo=1 ColumnNo=1 Document Output$ Buffer Scanner as Integer*lim Return Scanner, 0:=a$ offset=0 buffer1$="" flag_rem=true Ahead=lambda Scanner (a$, offset)->{ =false Try { \\ second parameter is the offset in buffer units \\ third parameter is length in bytes =Eval$(Scanner, offset,2*len(a$))=a$ } } Ahead2=lambda Scanner (a$, offset)->{ =false Try { =Eval$(Scanner, offset,2) ~ a$ } } const nl$=chr$(13)+chr$(10), quo$="""", er$="@", Ansi=3 Try { Do If Ahead("/*", offset) Then { offset+=2 : ColumnNo+=2 While not Ahead("*/", offset) If Ahead(nl$, offset) Then lineNo++: ColumnNo=1 : offset+=2 Else offset++ : ColumnNo++ End If if offset>lim then Error "End-of-file in comment. Closing comment characters not found"+er$ End if End While offset+=2 : ColumnNo+=2 } Else.if Ahead(nl$, offset) Then{ LineNo++: ColumnNo=1 offset+=2 } Else.if Ahead(quo$, offset) Then { Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo) offset++ : ColumnNo++ strin=offset While not Ahead(quo$, offset) If Ahead("/", offset) Then offset+=2 : ColumnNo+=2 else offset++ : ColumnNo++ End if checkerror() End While Output$="String "+quote$(Eval$(Scanner, strin, (offset-strin)*2))+nl$ offset++ : ColumnNo++ } Else.if Ahead("'", offset) Then { Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo) offset++ : ColumnNo++ strin=offset While not Ahead("'", offset) If Ahead("/", offset) Then offset+=2 : ColumnNo+=2 else offset++ : ColumnNo++ End if checkerror() End While lit$=format$(Eval$(Scanner, strin, (offset-strin)*2)) select case len(lit$) case 1 Output$="Integer "+str$(asc(lit$),0)+nl$ case >1 {Error "Multi-character constant."+er$} case 0 {Error "Empty character constant."+er$} end select offset++ : ColumnNo++ } Else.if Ahead2("[a-z]", offset) Then { strin=offset Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo) offset++ : ColumnNo++ While Ahead2("[a-zA-Z0-9_]", offset) offset++ : ColumnNo++ End While Keywords(Eval$(Scanner, strin, (offset-strin)*2)) } Else.if Ahead2("[0-9]", offset) Then { strin=offset Output$=format$("{0::-10}{1::-10} Integer ", LineNo, ColumnNo) offset++ : ColumnNo++ While Ahead2("[0-9]", offset) offset++ : ColumnNo++ End While if Ahead2("[a-zA-Z_]", offset) then {Error " Invalid number. Starts like a number, but ends in non-numeric characters."+er$} else Output$=Eval$(Scanner, strin, (offset-strin)*2)+nl$ end if } Else { Symbols(Eval$(Scanner, Offset, 2)) offset++ : ColumnNo++ } Until offset>=lim } er1$=leftpart$(error$,er$) if er1$<>"" then Print Report "Error:"+er1$ Output$="(Error)"+nl$+"Error:"+er1$ else Output$=format$("{0::-10}{1::-10}", LineNo, ColumnNo)+" End_of_Input"+nl$ end if Push Output$ Exit Clipboard Output$ Save.Doc Output$, "lex.t", Ansi document lex$ Load.Doc lex$,"lex.t", Ansi Report lex$ Sub Keywords(a$) select case a$ case "if" a$="Keyword_if" case "else" a$="Keyword_else" case "while" a$="Keyword_while" case "print" a$="Keyword_print" case "putc" a$="Keyword_putc" else case a$="Identifier "+a$ end select Output$=a$+nl$ End sub Sub Symbols(a$) select case a$ case " ", chr$(9) a$="" case "(" a$="LeftParen" case ")" a$="RightParen" case "{" a$="LeftBrace" case "}" a$="RightBrace" case ";" a$="Semicolon" case "," a$="Comma" case "*" a$="Op_multiply" case "/" a$="Op_divide" case "+" a$="Op_add" case "-" a$="Op_subtract" case "%" a$="Op_mod" case "<" { if Ahead("=", offset+1) Then offset++ a$="Op_lessequal" ColumnNo++ else a$="Op_less" end if } case ">" { if Ahead("=", offset+1) Then offset++ ColumnNo++ a$="Op_greaterequal" else a$="Op_greater" end if } case "=" { if Ahead("=", offset+1) Then offset++ ColumnNo++ a$="Op_equal" else a$="Op_assign" end if } case "!" { if Ahead("=", offset+1) Then offset++ ColumnNo++ a$="Op_notequal" else a$="Op_not" end if } case "&" { if Ahead("&", offset+1) Then offset++ ColumnNo++ a$="Op_and" else a$="" end if } case "|" { if Ahead("|", offset+1) Then offset++ ColumnNo++ a$="Op_or" else a$="" end if } else case {Error "Unrecognized character."+er$} end select if a$<>"" then Output$=format$("{0::-10}{1::-10} ", LineNo, ColumnNo)+a$+nl$ end if End Sub Sub checkerror() if offset>lim then { Error "End-of-line while scanning string literal. Closing string character not found before end-of-line."+er$ } else.if Ahead(nl$,offset) then { Error "End-of-file while scanning string literal. Closing string character not found."+er$ } End Sub } Module syntax_analyzer (b$){ enum tokens { Op_add, Op_subtract, Op_not=5, Op_multiply=10, Op_divide, Op_mod, Op_negate, Op_less, Op_lessequal, Op_greater, Op_greaterequal, Op_equal, Op_notequal, Op_and, Op_or, Op_assign=100, Keyword_if=110, Keyword_else, Keyword_while, Keyword_print, Keyword_putc, LeftParen, RightParen, LeftBrace, RightBrace, Semicolon, Comma, Identifier, Integer, String, End_of_input } Inventory precedence=Op_multiply:=13, Op_divide:=13, Op_mod:=13, Op_add:=12, Op_subtract:=12 Append precedence, Op_negate:=14, Op_not:=14, Op_less:=10, Op_lessequal:=10, Op_greater:=10 Append precedence, Op_greaterequal:=10, Op_equal:=9, Op_notequal:=9, Op_assign:=-1, Op_and:=5 Append precedence, Op_or:=4 Inventory symbols=Op_multiply:="Multiply", Op_divide:="Divide", Op_mod:="Mod", Op_add:="Add" Append symbols, Op_negate:="Negate", Op_not:="Not", Op_less:="Less", Op_subtract:="Subtract" Append symbols, Op_lessequal:="LessEqual", Op_greater:="Greater", Op_greaterequal:="GreaterEqual" Append symbols, Op_equal:="Equal", Op_notequal:="NotEqual", Op_and:="And", Op_or:="Or" def lineNo, ColumnNo, m, line$, a, lim, cur=-1 const nl$=chr$(13)+chr$(10), Ansi=3 Dim lex$() lex$()=piece$(b$,chr$(13)+chr$(10)) lim=dimension(lex$(),1)-1 op=End_of_input flush k=0 Try { push (,) ' Null getone(&op) repeat stmt(&op) shift 2 ' swap two top items push ("Sequence", array, array) k++ until op=End_of_Input } er$=error$ if er$<>"" then print er$ : flush: break Print "Ast" Document Output$ prt_ast() Push Output$ exit clipboard Output$ Save.Doc Output$, "parse.t", Ansi document parse$ Load.Doc parse$,"parse.t", Ansi Report parse$ sub prt_ast(t) if len(t)<1 then Output$=";"+nl$ else.if len(t)=3 then Output$=t#val$(0) +nl$ prt_ast(t#val(1)) : prt_ast(t#val(2)) else Output$=t#val$(0) +nl$ end if end sub sub expr(p) ' only a number local x=(,), prev=op if op>=Identifier then x=(line$,) getone(&op) else.if op=LeftParen then paren_exp() x=array else.if op<10 then getone(&op) expr(precedence(int(Op_negate))) read local y if prev=Op_add then x=y else if prev=Op_subtract then prev=Op_negate x=(symbols(prev), y,(,)) End if else {error "??? "+eval$(op)} end if local prec while exist(precedence, int(op)) prev=op : prec=eval(precedence) if prec<14 and prec>=p else exit getone(&op) expr(prec+1) ' all operators are left associative (use prec for right a.) x=(symbols(int(prev)), x, array) End While Push x end sub sub paren_exp() expected(LeftParen) getone(&op) expr(0) expected(RightParen) getone(&op) end sub sub stmt(&op) local t=(,) if op=Identifier then t=(line$) getone(&op) expected(Op_assign) getone(&op) expr(0) read local rightnode Push ("Assign",t,rightnode) expected(Semicolon) getone(&op) else.if op=Semicolon then getone(&op) Push (";",) else.if op=Keyword_print then getone(&op) expected(LeftParen) repeat getone(&op) if op=String then Push ("Prts",(line$,),(,)) getone(&op) else expr(0) Push ("Prti", array,(,)) end if t=("Sequence", t, array) until op<>Comma expected(RightParen) getone(&op) expected(Semicolon) getone(&op) push t else.if op=Keyword_while then getone(&op) paren_exp() stmt(&op) shift 2 Push ("While",array, array) else.if op=Keyword_if then getone(&op) paren_exp() stmt(&op) local s2=(,) if op=Keyword_else then getone(&op) stmt(&op) read s2 end if shift 2 Push ("If",array ,("If",array,s2)) else.if op=Keyword_putc then getone(&op) paren_exp() Push ("Prtc",array,t) expected(Semicolon) getone(&op) else.if op=LeftBrace then Brace() else error "Unkown Op" end if end sub Sub Brace() getone(&op) while op<>RightBrace and op<>End_of_input stmt(&op) t=("Sequence", t, array) end while expected(RightBrace) getone(&op) push t End Sub Sub expected(what) if not op=what then {Error "Expected "+eval$(what)+str$(LineNo)+","+Str$(ColumnNo)} End Sub sub getone(&op) op=End_of_input while cur<lim cur++ line$=trim$(lex$(cur)) if line$<>"" then exit end while if cur=lim then exit sub LineNo=Val(line$,"int",m) line$=mid$(line$, m) ColumnNo=Val(line$,"int",m) line$=trim$(mid$(line$, m)) Rem : Print LineNo, ColumnNo m=instr(line$," ") if m>0 then op=Eval("."+leftpart$(line$, " ")) else op=Eval("."+line$) end sub } 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) Push Assembly$ Exit 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$) Load_Ast() Load_Ast() Shift 2 Push (otok,array, array) End If End Sub } Module Virtual_Machine_Interpreter (a$){ \\ function to extract string, replacing escape codes. Function GetString$(a$) { s=instr(a$, chr$(34)) m=rinstr(a$,chr$(34))-s if m>1 then \\ process escape codes =format$(mid$(a$, s+1, m-1)) else ="" end if }

		const nl$=chr$(13)+chr$(10)

\\ we can set starting value to any number n where 0<=n<=232 enum op { halt_=232, add_, sub_, mul_, div_, mod_, not_, neg_, and_, or_, lt_, gt_, le_, ge_, ne_, eq_, prts_, prti_, prtc_, store_, fetch_, push_, jmp_, jz_ } exit_now=false Inventory func=halt_:=lambda->{exit_now=true} Append func, push_:=lambda->{sp--:return stack_, sp:=eval(code_, pc as long):pc+=4} Append func, jz_:=lambda->{ sp++: if eval(stack_, sp-1)=0 then pc=eval(code_, pc as long) else pc+=4 } Append func, jmp_:=lambda->{pc=eval(code_, pc as long)} Append func, fetch_:=lambda->{sp--:Return stack_, sp:=eval(stack_, eval(code_, pc as long)):pc+=4} Append func, store_:=lambda->{Return stack_, eval(code_, pc as long):=eval(stack_, sp):sp++:pc+=4} Append func, add_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))+sint(eval(stack_, sp))):sp++} Append func, sub_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))-sint(eval(stack_, sp))):sp++} Append func, mul_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))*sint(eval(stack_, sp))):sp++} Append func, div_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) div sint(eval(stack_, sp))):sp++} Append func, mod_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) mod sint(eval(stack_, sp))) :sp++} Append func, not_:=lambda->{Return stack_, sp:=if(eval(stack_, sp)=0->uint(-1),0)} Append func, neg_:=lambda->{Return stack_, sp:=uint(-sint(eval(stack_, sp)))} Append func, and_:=lambda->{Return stack_, sp+1:=binary.and(eval(stack_, sp+1),eval(stack_, sp)):sp++ } Append func, or_:=lambda->{Return stack_, sp+1:=binary.or(eval(stack_, sp+1),eval(stack_, sp)):sp++ } Append func, lt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<sint(eval(stack_, sp))->-1, 0)):sp++} Append func, gt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>sint(eval(stack_, sp))->-1, 0)):sp++} Append func, le_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<=sint(eval(stack_, sp))->-1, 0)):sp++} Append func, ge_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>=sint(eval(stack_, sp))->-1, 0)):sp++} Append func, ne_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)<>eval(stack_, sp)->-1, 0)):sp++} Append func, eq_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)=eval(stack_, sp)->-1, 0)):sp++} Append func, prts_:=lambda->{Print #-2, strings$(eval(stack_,sp));: Refresh:sp++} Append func, prti_:=lambda->{Print #-2, str$(sint(eval(stack_,sp)),0);: Refresh:sp++} Append func, prtc_:=lambda->{Print #-2, chrcode$(eval(stack_,sp));: Refresh:sp++} Rem : Form 120, 60 ' change console width X height to run Ascii Mandlebrot example \\ change Report with Print #-2, (report stop when scrolling 3/4 of height of console, waiting key or mouse key to continue) Print #-2, "Virtual Assembly Code:"+{ }+a$ Print "Prepare Byte Code" \\ get datasize a$=rightpart$(a$, "Datasize:") m=0 data_size=val(a$, "int", m) a$=mid$(a$, m) \\ make stack if data_size>0 then Buffer Clear stack_ as long*data_size \\ dim or redim buffer append 1000 long as is. Buffer stack_ as long*(1000+data_size) \\ get strings a$=rightpart$(a$, "Strings:") m=0 strings=val(a$, "int", m) a$=rightpart$(a$, nl$) if strings>0 then Dim strings$(strings) for i=0 to strings-1 strings$(i)=GetString$(leftpart$(a$, nl$)) a$=rightpart$(a$, nl$) Next i End if buffer clear code_ as byte*1000 do m=0 offset=val(a$,"int", m) if m<0 then exit a$=mid$(a$,m) line$=trim$(leftpart$(a$,nl$)) if line$="" then line$=trim$(a$) else a$=trim$(rightpart$(a$, nl$)) op$=if$(instr(line$," ")>0->leftpart$(line$," "), line$) if not valid(eval(op$+"_")) then exit opc=eval(op$+"_") Return code_, offset:=opc if opc>=store_ then line$=rightpart$(line$," ") select case opc case store_, fetch_ Return code_, offset+1:=val(rightpart$(leftpart$(line$,"]"),"[")) as long : offset+=4 case push_ Return code_, offset+1:=uint(val(line$)) as long : offset+=4 case jz_, jmp_ Return code_, offset+1:=val(rightpart$(line$,")")) as long : offset+=4 end select end if Always Print "Press any key" : Push key$ : Drop \\ Prepare VM let pc=0, sp=len(stack_) div 4 do b=func(eval(code_, pc)) pc++ call local b() until exit_now Print "done" } Push {

           	        This is an integer ascii Mandelbrot generator
           	        left_edge= -420;
           	        bottom_edge = -300;
           	        y0 = top_edge;
           	        while (y0 > bottom_edge) {
           	                x0 = left_edge;
           	                while (x0 < right_edge) {
           	                        y = 0;
           	                        x = 0;
           	                        the_char = ' ';
           	                        i = 0;
           	                        while (i < max_iter) {
           	                                x_x = (x * x) / 200;
           	                                y_y = (y * y) / 200;
           	                                if (x_x + y_y > 800 ) {
           	                                        the_char = '0' + i;
           	                                        if (i > 9) {
           	                                                the_char = '@';
           	                                        i = max_iter;
           	                                y = x * y / 100 + y0;
           	                                x = x_x - y_y + x0;
           	                                i = i + 1;
           	                        x0 = x0 + x_step;
           	                y0 = y0 - y_step;


	Form ! 120, 60

Refresh Print "Lexical Analyzer" : Refresh lexical_analyzer Print "Syntaxl Analyzer" : Refresh syntax_analyzer Print "Code Generator" : Refresh CodeGenerator Virtual_Machine_Interpreter Set Fast 'restore speed setting } CompilerExample </lang>