unit Scanner;
interface
resourcestring
ERR_SCANNER_UNEXPECTED_CHAR = '
Error: 0: Scnner: Unexpected char found in stream.';
ERR_PARSER_EXPECTED = '
Error 1: Parser: %s expected, %s found instead';
ERR_PARSER_UNALLOWED_STATEMENT = '
Error 2: Parser: unallowed Statement';
ERR_PARSER_WRONG_PROCEDURE_ENDED = '
Error 3: Parser: Procedure end %s expected, but %s found';
ERR_PARSER_UNKNOWN_IDENT = '
Error 4: Parser: Unknown Identifier';
ERR_PARSER_VAR_CONSTANT_EXPECTED = '
Error 5: Parser: Variable or Constant expected';
ERR_PARSER_VAR_EXPECTED = '
Error 6: Parser: Variable expected';
ERR_PARSER_PROCEDURE_EXPECTED = '
Error 7: Parser: Procedure expected';
ERR_PARSER_NO_CONST_ALLOWED = '
Error 8: Parser: No Constant allowed here';
procedure LexScanner(filename:
String);
implementation
uses
Vcl.Forms,
Vcl.Dialogs, System.SysUtils, Unit2;
type
TSymbol = (
sUnknown, sIdent, sInteger, sPlus, sMinus, sStar, sSlash, sEqual,
sSmaller, sBigger, sBiggerEqual, sSmallerEqual, sUnEqual,
sOpenBracket, sCloseBracket, sComma, sDot, sSemiColon, sBecomes,
sVar, sConst, sProcedure, sBegin, sEnd, sIf, sThen,
sElseIf, sElse, sWhile, sDo, sUnit, sWrite,
sNone
);
const
cSymbols :
Array[TSymbol]
of String = (
'
','
','
','
+','
-','
*','
/','
=',
'
<','
>','
>=','
<=','
#',
'
(','
)','
,','
.','
;','
:=',
'
VAR','
CONST','
PROCEDURE','
BEGIN','
END','
IF','
THEN',
'
ELSEIF','
ELSE','
WHILE','
DO','
UNIT','
WRITE',
'
'
);
type
TIdentType = (itConstant, itVariable, itProcedure);
TIdent =
record
name:
String;
case kind: TIdentType
of
itConstant: (val: Integer);
itVariable,
itProcedure: (level,adr,size: Integer);
end;
TIdentList =
Array of TIdent;
TOpCode = (lit,opr,lod,sto,cal,int,jmp,jpc,wri);
PInstruction = ^TInstruction;
TInstruction =
record
f: TOpCode;
// command
l: Byte;
// level
a: Integer;
// address
end;
var
Table: TIdentList;
Instructions:
Array of TInstruction;
cx: Integer;
// code position
ID:
String;
num: Integer;
var
ch: Char;
str:
String;
Symbol: TSymbol;
var
inFile:
File;
bcFile:
File of Byte;
Line: Integer;
procedure Error(ErrorText:
String);
var
s:
String;
begin
s := Format('
%d: ' + ErrorText, [Line]);
raise Exception.Create(s);
end;
procedure ErrorExpected(Expected:
Array of TSymbol; Found: TSymbol);
const
eSymbols :
Array[TSymbol]
of String = (
'
Unknown','
Identifier','
Integer','
+','
-','
*','
/','
=',
'
<','
>','
>=','
<=','
#',
'
(','
)','
,','
.','
;','
:=',
'
VAR','
CONST','
PROCEDURE','
BEGIN','
END','
IF','
THEN',
'
ELSEIF','
ELSE','
WHILE','
DO','
UNIT','
WRITE',
'
!none!'
);
var
ExpectedSymbol:
String;
i: Integer;
s:
String;
begin
ExpectedSymbol := eSymbols[Expected[Low(Expected)]];
for I := Low(Expected)+1
to High(Expected)
do
ExpectedSymbol := ExpectedSymbol + '
, ' + eSymbols[Expected[i]];
s := System.SysUtils.Format('
%d: '
+ ERR_PARSER_EXPECTED,[Line,ExpectedSymbol,eSymbols[Found]]);
raise Exception.Create(s);
end;
procedure Emulate;
const
StackSize = 1024;
var
p,b,t: Integer;
s:
Array[1..StackSize]
of Integer;
function Base(a: Integer): Integer;
var
b1: Integer;
begin
b1 := b;
while a > 9
do
begin
b1 := s[b1];
dec(a);
end;
base := b1;
end;
begin
Form2.FEditorFrame.Memo2.Lines.Add('
Interpreting Code');
showmessage('
size: ' + inttostr(sizeof(instructions)));
t := 0;
b := 1;
p := -1;
s[1] := 0;
s[2] := 0;
s[3] := 0;
repeat
inc(p);
ShowMessage('
len: ' + inttostr(sizeof(Instructions)));
ShowMessage('
mem 1: ' + inttostr(sizeof(Instructions[p])));
ShowMessage('
mem 2: ' + inttostr(sizeof(Instructions[p+1])));
ShowMessage('
opr: ' + inttostr(Instructions[p].a));
with Instructions[p]
do
begin
showmessage('
huhu');
case f
of
lit:
begin
showmessage('
11111');
inc(t);
s[t] := a;
end;
lod:
begin
showmessage('
2222');
inc(t);
s[t] := s[base(l)+a];
end;
sto:
begin
showmessage('
3333');
s[base(l)+a] := s[t];
dec(t);
end;
cal:
begin
showmessage('
444');
s[t + 1] := base(l);
s[t + 2] := b;
s[t + 3] := p;
b := t + 1;
p := a;
end;
int: t := t + a;
jmp: p := a;
jpc:
begin
if s[t] = 0
then p := a;
dec(t);
end;
wri:
begin
showmessage('
6666');
Form2.FEditorFrame.Memo2.Lines.Add(
'
wri: ' + IntToStr(s[t]));
dec(t);
end;
opr:
begin
case a
of
0:
begin
t := b - 1;
p := s[ t + 3];
b := s[ t + 2];
end;
1:
begin
s[t] := -s[t];
// negation
end;
2:
begin
// addition
dec(t);
s[t] := s[t] + s[t + 1];
end;
3:
begin
// subtraction
dec(t);
s[t] := s[t] - s[t + 1];
end;
4:
begin
// multiplication
dec(t);
s[t] := s[t] * s[t + 1];
end;
5:
begin
// division
dec(t);
s[t] := s[t]
div s[t + 1];
end;
8:
begin
// Equal
dec(t);
s[t] := Ord(s[t] = s[t + 1]);
end;
9:
begin
// unequal
dec(t);
s[t] := Ord(s[t] <> s[t + 1]);
end;
10:
begin
// smaller
dec(t);
s[t] := Ord(s[t] < s[t + 1]);
end;
11:
begin
// bigger
dec(t);
s[t] := Ord(s[t] > s[t + 1]);
end;
12:
begin
// biggerequal
dec(t);
s[t] := Ord(s[t] >= s[t + 1]);
end;
13:
begin
// smallerequal
dec(t);
s[t] := Ord(s[t] <= s[t + 1]);
end;
else
begin
raise Exception.Create('
Unknown Operand');
end;
end;
end;
else
begin
raise Exception.Create('
Unknown opcode');
end;
end;
end;
until p = 4;
end;
procedure Expect(Expected: TSymbol);
begin
if Symbol <> Expected
then
ErrorExpected([Expected], Symbol);
end;
procedure GenCode(f: TOpCode; l,a: Integer);
begin
if cx > Length(Instructions) - 1
then
SetLength(Instructions, Length(Instructions) + 64);
Instructions[cx].f := f;
Instructions[cx].a := a;
Instructions[cx].l := l;
inc (cx);
end;
procedure GetSym;
procedure GetCh;
begin
if not Eof(inFile)
then
BlockRead(inFile, ch, 1)
else
ch := '
';
ch := UpCase(ch);
// case in-sensitive
if ch = #13
then inc(Line);
if Ord(ch) < Ord('
')
then ch := '
';
end;
var i: TSymbol;
begin
while true
do
begin
str := '
';
Symbol := sNone;
while (ch = '
')
and not Eof(inFile)
do
GetCh;
if Eof(inFile)
then
exit;
case ch
of
// ident/reserved word
'
A'..'
Z', '
_':
begin
while ch
in ['
A'..'
Z','
_','
0'..'
9']
do
begin
str := str + ch;
GetCh;
end;
Symbol := sIdent;
for i := sUnknown
to sNone
do
begin
if str = cSymbols[I]
then
begin
Symbol := i;
break;
end;
end;
if Symbol = sIdent
then
ID := str;
exit;
end;
// symbols that consists only of one char
'
;','
+','
-','
=','
#','
,','
.','
*','
/':
begin
str := ch;
Symbol := sUnknown;
for i := sUnknown
to sNone
do
begin
if str = cSymbols[i]
then
begin
Symbol := i;
break;
end;
end;
GetCh;
exit;
end;
// chars, that can contain forward chars (=)
'
:','
<','
>':
begin
str := ch;
GetCh;
if ch = '
='
then str := str + ch;
GetCh;
Symbol := sUnknown;
for i := sUnknown
to sNone
do
begin
if str = cSymbols[i]
then
begin
Symbol := i;
break;
end;
end;
exit;
end;
// parens, and comas
'
(','
)':
begin
str := ch;
GetCh;
if (str = '
(')
and (ch = '
*')
then
begin
// skip comment
GetCh;
while true
do
begin
GetCh;
if ch = '
*'
then
begin
GetCh;
if ch = '
)'
then
begin
Getch;
break;
end;
end else
begin
if Eof(inFile)
then
break;
end;
end;
end else
begin
if str = '
('
then
begin
Symbol := sOpenBracket;
exit;
end else
if str = '
)'
then
begin
Symbol := sCloseBracket;
exit;
end;
end;
end;
// digits
'
0'..'
9','
$':
begin
Symbol := sInteger;
str := ch;
GetCh;
if str = '
$'
then // hex value
begin
while ch
in ['
0'..'
9','
A'..'
F']
do
begin
str := str + ch;
GetCh;
end;
exit;
end else
begin
while ch
in ['
0'..'
9']
do
begin
str := str + ch;
GetCh;
end;
exit;
end;
end;
else Error(ERR_SCANNER_UNEXPECTED_CHAR);
end;
Assert(Symbol <> sUnknown);
end;
end;
procedure Module;
function Position(ID:
String; TablePosition: Integer): Integer;
var
i: Integer;
begin
Table[0].
name := ID;
I := TablePosition;
while Table[I].
name <> ID
do
dec(i);
result := I;
end;
procedure StatementSequence(TablePosition, lev: Integer);
procedure Statement;
procedure Expression;
procedure Term;
procedure Factor;
var
identPos: Integer;
begin
if (Symbol
in [sIdent])
then
begin
identPos := Position(ID,TablePosition);
if identPos = 0
then
Error(ERR_PARSER_UNKNOWN_IDENT);
if Table[identPos].kind = itProcedure
then
Error(ERR_PARSER_VAR_CONSTANT_EXPECTED);
case Table[identPos].kind
of
itConstant: GenCode(lit, 0, Table[identPos].val);
itVariable: GenCode(lod, lev-Table[identPos].level,Table[identPos].val);
end;
GetSym;
end else
if (Symbol = sInteger)
then
begin
GenCode(lit,0,num);
GetSym;
end else
if (Symbol = sOpenBracket)
then
begin
GetSym;
Expression;
Expect(sCloseBracket);
GetSym;
end else
ErrorExpected([sIdent, sInteger, sOpenBracket],Symbol);
end;
var
operation: TSymbol;
begin
Factor;
while Symbol
in [sStar, sSlash]
do
begin
Operation := Symbol;
GetSym;
Factor;
case Operation
of
sStar: GenCode(opr,0,4);
sSlash: GenCode(opr,0,5);
end;
end;
end;
var
Operation: TSymbol;
begin
if Symbol
in [sPlus, sMinus]
then
begin
Operation := Symbol;
GetSym;
Term;
if Operation = sMinus
then
GenCode(opr,0,1);
end else
Term;
while Symbol
in [sPlus, sMinus]
do
begin
Operation := Symbol;
GetSym;
Term;
case Operation
of
sPlus: GenCode(opr,0,2);
sMinus: GenCode(opr,0,3);
end;
end;
end;
procedure Condition;
var
Operation: TSymbol;
begin
Expression;
Operation := Symbol;
GetSym;
Expression;
case Operation
of
sEqual: GenCode(opr,0,8);
sSmaller: GenCode(opr,0,10);
sBigger: GenCode(opr,0,11);
sBiggerEqual: GenCode(opr,0,12);
sSmallerEqual: GenCode(opr,0,13);
sUnEqual: GenCode(opr,0, 9);
else ErrorExpected(
[sEqual, sSmaller, sBigger, sBiggerEqual, sSmallerEqual, sUnequal],
Symbol)
end;
end;
var
identPos: Integer;
ident:
String;
CodePosition1, CodePosition2: Integer;
begin
case Symbol
of
sIdent:
begin
ident := id;
identPos := Position(ID, TablePosition);
if identPos = 0
then
Error(ERR_PARSER_UNKNOWN_IDENT);
if Table[identPos].kind = itProcedure
then
begin
// procedure call
GenCode(cal,lev-Table[identPos].level,Table[identPos].adr);
GetSym;
end else
if Table[identPos].kind = itVariable
then
begin
GetSym;
Expect(sBecomes);
GetSym;
Expression;
GenCode(sto,lev-Table[identPos].level,Table[identPos].adr);
end else
Error(ERR_PARSER_NO_CONST_ALLOWED);
end;
sWrite:
begin
GetSym;
Expression;
GenCode(wri,0,0);
end;
sIf:
begin
GetSym;
Condition;
Expect(sThen);
GetSym;
CodePosition1 := cx;
GenCode(jpc,0,0);
StatementSequence(TablePosition,lev);
Expect(sEnd);
GetSym;
CodePosition2 := cx;
GenCode(jmp,0,0);
Instructions[CodePosition1].a := cx;
while Symbol = sElseIf
do
begin
GetSym;
Condition;
Expect(sThen);
GetSym;
CodePosition1 := cx;
GenCode(jpc,0,0);
StatementSequence(TablePosition,lev);
Expect(sEnd);
GetSym;
Instructions[CodePosition2].a := cx;
CodePosition2 := cx;
GenCode(jmp,0,0);
Instructions[CodePosition1].a := cx;
end;
if Symbol = sElse
then
begin
GetSym;
StatementSequence(TablePosition,lev);
Expect(sEnd);
GetSym;
Instructions[CodePosition2].a := cx;
end;
end;
sWhile:
begin
GetSym;
CodePosition2 := cx;
Condition;
Expect(sDo);
GetSym;
CodePosition1 := cx;
GenCode(jpc,0,0);
StatementSequence(TablePosition,lev);
Expect(sEnd);
GenCode(jmp,0,0);
GetSym;
Instructions[CodePosition1].a := cx;
end;
sBegin:
begin
GetSym;
StatementSequence(TablePosition,lev);
Expect(sEnd);
GetSym;
end;
else begin
//dummy error
end;
end;
end;
begin
Statement;
while Symbol = SSemiColon
do
begin
GetSym;
Statement;
end;
end;
function Declarations(TablePosition: Integer; lev: Integer): Integer;
var
DataPos: Integer;
InitTablePos: Integer;
InitCodePos: Integer;
procedure Enter(Typ: TIdentType);
begin
inc(TablePosition);
if TablePosition > Length(Table) - 1
then
SetLength(Table, Length(Table) + 16);
with Table[TablePosition]
do
begin
name := ID;
kind := Typ;
case kind
of
itVariable:
begin
level := lev;
adr := DataPos;
inc(DataPos);
end;
itConstant : val := num;
itProcedure: level := lev;
end;
end;
end;
procedure ProcedureDecl;
var
ProcedureName:
String;
ProcTablePos: Integer;
begin
Expect(sProcedure);
GetSym;
Expect(sIdent);
Enter(itProcedure);
ProcedureName := ID;
GetSym;
Expect(sSemiColon);
GetSym;
ProcTablePos := Declarations(TablePosition,lev+1);
Expect(sBegin);
GetSym;
StatementSequence(ProcTablePos, lev+1);
Expect(sEnd);
GetSym;
Expect(sIdent);
if ProcedureName <> ID
then
begin
Error(Format(ERR_PARSER_WRONG_PROCEDURE_ENDED,
[ProcedureName, ID]));
end;
GetSym;
Expect(sSemiColon);
GenCode(opr,0,0);
// return back to sub caller
GetSym;
end;
procedure ConstDecl;
begin
Expect(sIdent);
GetSym;
Expect(sEqual);
GetSym;
Expect(sInteger);
Enter(itConstant);
GetSym;
end;
procedure VarDecl;
begin
Expect(sIdent);
Enter(itVariable);
GetSym;
while Symbol = sComma
do
begin
GetSym;
Expect(sIdent);
Enter(itVariable);
GetSym;
end;
end;
begin
DataPos := 3;
InitTablePos := TablePosition;
InitCodePos := cx;
Table[TablePosition].adr := cx;
GenCode(jmp,0,0);
while Symbol
in [sVar, sConst, sProcedure]
do
case Symbol
of
sVar:
begin
GetSym;
VarDecl;
Expect(sSemiColon);
GetSym;
while Symbol = sIdent
do
begin
VarDecl;
Expect(sSemiColon);
GetSym;
end;
end;
sConst:
begin
GetSym;
ConstDecl;
Expect(sSemiColon);
GetSym;
while Symbol = sIdent
do
begin
ConstDecl;
Expect(sSemiColon);
GetSym;
end;
end;
sProcedure:
begin
ProcedureDecl;
end;
end;
Instructions[Table[InitTablePos].adr].a := cx;
with Table[InitTablePos]
do
begin
adr := cx;
size := DataPos;
end;
// allocate memory space
GenCode(int,0,DataPos);
result := TablePosition;
end;
var
TablePosition: Integer;
UnitName:
String;
begin
Expect(sUnit);
GetSym;
Expect(sIdent);
UnitName := id;
showmessage(unitname);
GetSym;
Expect(sSemiColon);
GetSym;
TablePosition := Declarations(0,0);
Expect(sBegin);
GetSym;
StatementSequence(TablePosition,0);
Expect(sEnd);
// the end
GenCode(jmp,0,0);
GetSym;
Expect(sIdent);
if UnitName <> ID
then
raise Exception.Create(Format(
'
%d: Warning: Module ID <> End ID. Code already generated.',
[Line]));
GetSym;
Expect(sSemiColon);
GetSym;
if Symbol <> sNone
then
raise Exception.Create(Format(
'
%d: Code after unit END is ignored!',
[Line]));
end;
procedure LexScanner(filename:
String);
var
F:
File of TInstruction;
i: Integer;
FSize: Integer;
s:
String;
begin
try
try
AssignFile(inFile, filename);
Reset(inFile,1);
ch := '
';
Line := 1;
cx := 0;
SetLength(Table,1);
GetSym;
Module;
s := ChangeFileExt(filename,'
.bin');
AssignFile(F,s);
ReWrite(F);
i := 0;
while i < cx
do
begin
Write(F,Instructions[i]);
inc(i);
end;
with Form2.FEditorFrame.Memo2.Lines
do
begin
Clear;
Add('
Done, no syntax errors detected... Code success');
Add(Format('
# Instructions: %d',[cx]));
Add(Format('
# Code size : %d',[(cx) * sizeof(Instructions)]));
end;
Close(F);
Close(inFile);
AssignFile(bcFile,s);
FileMode := 0;
// read only
Reset(bcFile);
FSize := FileSize(bcFile);
SetLength(Instructions,FSize);
BlockRead(bcFile,Instructions,FSize
div sizeof(TInstruction));
ShowMessage('
buf: ' + inttostr(FSize));
ShowMessage('
---> ' + IntToStr(FSize
div sizeof(TInstruction)));
Emulate;
// SetLength(Instructions,0);
except
on E:
Exception do
begin
ShowMessage('
Exception'
+ #13#10
+ '
Message: '
+ E.
Message);
end;
end;
finally
CloseFile(bcFile);
CloseFile(F);
CloseFile(inFile);
end;
end;
end.