Membuat Program Pascal untuk melakukan Analisis Leksikal
Contoh program menggunakan turbo pascal untuk melakukan
analisis leksikal :
program scanner; {judul program}
uses crt;
var
prg_sumber,f_hasil:text;
karakter:Char;
kata,Nm_token:string;
procedure bacafile; { prosedur membaca file
sumber }
begin
read(prg_sumber,karakter);
end;
procedure hasil; {prosedur utk menulis
hasil setiap token}
begin
append(f_hasil); {menambah hasil scan ke
file hasil}
writeln(f_hasil, kata : 15, ' : ',
Nm_token);
writeln(kata : 15, ' : ', Nm_token);
{mencetak hasil scan ke layar}
end;
function cekkeyword(s:string):string;
{fungsi mengecek keyword atau bukan}
var
x : byte;
panjang : integer;
ftext : text;
data : string;
begin
panjang:= length(s); {konversi kata ke
huruf kecil}
for x:=1 to panjang do
begin
if s[x] > upcase (s[x]) then
s[x] := s[x]
else
s[x]:= chr(ord(s[x])+32);
end;
assign(ftext,'keyword.txt');
reset(ftext);
while not eof(ftext) do {mencocokkan dgn
tabel keyword}
begin
readln(ftext,data);
if s=data then Nm_token:='Keyword';
end;
close(ftext);
end;
procedure periksa; {prosedur memeriksa
setiap karakter file sumber}
begin
while not eof(prg_sumber) do {kerjakan
sampai akhir file}
begin
bacafile;
if karakter = ''{‘ then
{mengabaikan/membuang komentar}
then
begin
repeat
begin
bacafile;
end;
until karakter = '}';
kata:='';
end;
if karakter = chr(39) then {mengecek tanda
petik (‘)}
begin
repeat
begin
kata := kata + karakter;
bacafile;
end;
until karakter = chr(39) ;
kata := kata + karakter;
Nm_token := 'Literals';
hasil;
kata :='';
end;
if (karakter in['A'..'Z','a'..'z','_'])
then {mengecek karakter/kata}
begin
repeat
begin
kata := kata + karakter;
bacafile;
end;
until (not(karakter
in['A'..'Z','a'..'z','_']));
Nm_token:='Identifier';
cekkeyword(kata);
hasil;
kata :='';
end;
if (karakter in['0'..'9']) then {mengecek
angka}
begin
repeat
begin
kata := kata + karakter;
bacafile;
end;
until (not(karakter in['0'..'9']));
Nm_token := 'Literal';
hasil;
kata :='';
end;
if (karakter in['+','-','*','/','^']) then
begin
repeat
begin
kata := kata+karakter;
bacafile;
end;
until (not(karakter
in['+','-','*','/','^']));
Nm_token :='Operator';
hasil;
kata:='';
end;
if (karakter
in['(',')','[',']','^',':',';',',',',']) then
begin
kata:=karakter;
Nm_token :='Punctuation';
hasil;
kata:='';
end;
end;
end;
begin {=program utama=}
clrscr;
assign(prg_sumber,'luas.pas'); {menetapkan
file sumber}
reset(prg_sumber); {membaca file sumber}
assign(f_hasil,'hasil.txt'); {menetapkan
file hasil}
rewrite(f_hasil); {menghapus isi file
hasil}
periksa; {menjalankan prosedur scan}
close(prg_sumber); {menutup file}
close(f_hasil);
readln;
end.
Output
programnya :
program : Identifier
coba : Identifier
; : Punctuation
uses : Identifier
crt : Keyword
; : Punctuation
var : Keyword
jari : Identifier
: : Punctuation
integer : Identifier
; : Punctuation
begin : Keyword
clrscr : Keyword
; : Punctuation
write : Identifier
( : Punctuation
'jari jari = ' : Literals
) : Punctuation
; : Punctuation
readln : Identifier
( : Punctuation
jari : Identifier
) : Punctuation
; : Punctuation
write : Identifier
( : Punctuation
' luas =' : Literals
, : Punctuation
jari : Identifier
* : Operator
ari : Identifier
* : Operator
2 : Literal
/ : Operator
: : Punctuation
2 : Literal
: : Punctuation
3 : Literal
) : Punctuation
; : Punctuation
writeln : Identifier
; : Punctuation
write : Identifier
( : Punctuation
' keliling lingkaran =' : Literals
, : Punctuation
2 : Literal
* : Operator
ari : Identifier
* : Operator
2 : Literal
/ : Operator
: : Punctuation
2 : Literal
: : Punctuation
3 : Literal
) : Punctuation
; : Punctuation
end : Keyword
