Grammar loader

The following program reads a grammar from the file named c.def and print it on console. The grammar of grammar are used implicitly, Formally, rules may be written in the same language, but how to use it? Nonetheless here are the rules:

name ; string ; numb ; colon ":" ; or "|" ; semi ";" ; period "." . Grammar : 0 Tokens period Rules period ; Tokens : 0 Tokens semi Token | 0 Token ; Token : 0 name | 0 name numb numb | 0 name string numb numb ; Rules : 0 Rules semi Rule | 0 Rule ; Rule : 0 Symbol colon Variants ; Variants : 0 Variants or Variant | 0 Variant ; Variant : 0 numb Symbols ; Symbols : 0 Symbols Symbol | 0 Symbol ; Symbol : 0 name ;

And the grammar loader program that read c.def file:

char Text [16384]; word pText; word nText; word nLine; byte Code [16384]; word nCode; word hFile; char Heap [ 2048]; word nHeap; word nData; word Name [ 256]; word Cls [ 256]; word Sub [ 256]; word Type [ 256]; word Size [ 256]; word Ofs [ 256]; word nName; word Sym [ 96]; word nSym; word Left [ 128]; word Id [ 128]; word pRight [ 128]; word nLeft; word Right [ 384]; word pLeft [ 384]; word nRight; word Stk [ 32]; word nStk; char Buff [ 32]; word open() is inline 0xB4, 0x3D; // mov AH, 3DH inline 0xB0, 0x00; // mov AL, 0 inline 0xBA, 0x4A, 0xC1; // mov DX, @@DATA+Ofs(Heap[64]) inline 0xCD, 0x21; // int 21H end word create() is inline 0xB4, 0x3C; // mov AH, 3CH inline 0xB9, 0x00, 0x00; // mov CX, 0 inline 0xBA, 0x4A, 0xC1; // mov DX, @@DATA+Ofs(Heap[64]) inline 0xCD, 0x21; // int 21H end word read() is inline 0xB4, 0x3F; // mov AH, 3FH inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)] inline 0xB9, 0x00, 0x40; // mov CX, 16384 inline 0xBA, 0x00, 0x41; // mov DX, @@DATA+Ofs(Text) inline 0xCD, 0x21; // int 21H end word write() is inline 0xB4, 0x40; // mov AH, 40H inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)] inline 0x8B, 0x0E, 0x06, 0xC1; // mov CX, word [@@DATA+Ofs(nCode)] inline 0xBA, 0x06, 0x81; // mov DX, @@DATA+Ofs(Code) inline 0xCD, 0x21; // int 21H end word close() is inline 0xB4, 0x3E; // mov AH, 3EH inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)] inline 0xCD, 0x21; // int 21H end char putc(char C) is char C1:=C; inline 0x92; // xchg DX, AX inline 0xB4, 0x02; // mov AH, 2 inline 0xCD, 0x21; // int 21H end word halt() is inline 0xB8, 0x00, 0x4C; // mov AX, 4C00H inline 0xCD, 0x21; // int 21H end word Init() is Heap [ 0]:='0'; Heap [ 1]:='1'; Heap [ 2]:='2'; Heap [ 3]:='3'; Heap [ 4]:='4'; Heap [ 5]:='5'; Heap [ 6]:='6'; Heap [ 7]:='7'; Heap [ 8]:='8'; Heap [ 9]:='9'; Heap [ 10]:='A'; Heap [ 11]:='B'; Heap [ 12]:='C'; Heap [ 13]:='D'; Heap [ 14]:='E'; Heap [ 15]:='F'; Heap [ 16]:='#'; Heap [ 17]:= char(0); Heap [ 64]:='c'; Heap [ 65]:='.'; Heap [ 66]:='d'; // p Heap [ 67]:='e'; // r Heap [ 68]:='f'; // g Heap [ 69]:= char(0); nHeap := 70; Sym [ 1]:= 16; // # nSym := 2; end word Stop() is nStk:=0; while nLine!=0 do Stk[nStk]:=nLine%10; nStk :=nStk+1; nLine :=nLine/10; end while nStk !=0 do nStk :=nStk-1; putc(char(Stk[nStk]+48)); end close(); halt (); end word val () is word E:=10; word J:= 0; if Buff[0]='0' then if Buff[1]='x' then E:=16; J:= 2; end end word N:=0; while Buff[J]!=char(0) do word K:=0; while Heap[K]!=Buff[J] do if K=E then Stop(); end K:=K+1; end N:=E*N; N:=N+K; J:=J+1; end return N; end word Copy() is word pHeap:=nHeap; word pBuff:=0; while Buff[pBuff]!=char(0) do Heap[nHeap]:= Buff[pBuff]; nHeap :=nHeap+1; pBuff :=pBuff+1; end Heap[nHeap]:=char(0); nHeap :=nHeap+1; return pHeap; end word Comp(word pHeap) is word pBuff:=0; while Buff[pBuff]=Heap[pHeap] do if Buff[pBuff]=char(0) then return 0; end pHeap:=pHeap+1; pBuff:=pBuff+1; end return 1; end char Look() is if pText>=nText then pText:=0; nText:=read(); if pText>=nText then return char(0); end end return Text[pText]; end char Read() is char C:=Look(); pText :=pText+1; return C; end word isalpha (char C) is if 'A'<=C then if C<='Z' then return 0; end end if 'a'<=C then if C<='z' then return 0; end end return 1; end word isnumber(char C) is if '0'<=C then if C<='9' then return 0; end end return 1; end word isalnum (char C) is if isalpha (C)=0 then return 0; end if isnumber(C)=0 then return 0; end return 1; end word Digraph(char C1, char C2) is if Buff[0]=C1 then if Look()=C2 then Buff[1]:=Read(); Buff[2]:=char(0); end end end char Scan() is word pBuff:=0; while pBuff =0 do word sFlag:=0; while sFlag =0 do if Look()!=char( 9) then if Look()!=char(10) then if Look()!=char(13) then if Look()!=char(32) then sFlag:=1; end end end end if sFlag=0 then if Read()=char(10) then nLine:=nLine+1; end end end //if pBuff=0 then while isalnum(Look())=0 do Buff[pBuff]:= Read(); pBuff :=pBuff+1; end //end if pBuff=0 then Buff[pBuff]:= Read(); pBuff :=pBuff+1; end if Buff[0]=''' then Buff[pBuff]:=Read(); // char pBuff :=pBuff+1; Buff[pBuff]:=Read(); // ' pBuff :=pBuff+1; end Buff[pBuff] :=char(0); Digraph('<', '='); Digraph('!', '='); Digraph('>', '='); Digraph(':', '='); if Buff[0]='/' then if Look()='/' then while Look()!=char(10) do if Read()=char( 0) then Stop(); end end pBuff:=0; end end end end word pSymb; word pProg; word L; word V; word Alter() is L:=1; word pName:=0; while pName <nName do word pHeap:=Name[pName]; if Heap[pHeap]!=char(0) then if Comp(pHeap)=0 then L:=pSymb+2; //L:=L+Cls[pName]; V:=pName; if Cls [pName]=0 then L:=Ofs [pName]; V:=Size[pName]; end return L; end end pName:=pName+1; end if Buff[0]=''' then L:=pSymb; V:= word(Buff[1]); end if isnumber(Buff[0])=0 then L:=pSymb+1; V:= val (); end if isalpha (Buff[0])=0 then L:=pSymb+2; //V:= Copy(); end return L; end word Find() is word I:=1; while I<nSym do if Comp(Sym[I])=0 then return I; end I:=I+1; end Sym [nSym]:= Copy(); nSym :=nSym +1; return I; end word IsEnd() is Scan(); if Buff[0]!='|' then if Buff[0]!=';' then if Buff[0]!='.' then return 1; end end end return 0; end word AddSym(word pSym) is Right[nRight]:=pSym; pLeft[nRight]:=nLeft; nRight :=nRight+1; end word LoadGrammar() is hFile := open(); pText := 0; nText := 0; nLine := 1; pSymb :=nSym; nName := 0; Buff[0] := ';'; while Buff[0]= ';' do Scan(); word pSym:=Find(); Scan(); if Buff[0]!=';' then Name[nName]:= Sym [pSym]; if Buff[0]='"' then Scan(); Name[nName]:=Copy(); Scan(); // " Scan(); end Cls [nName]:= val (); Scan(); Size[nName]:= val (); Ofs [nName]:=pSym; nName :=nName+1; Scan(); // ; end end pProg :=nSym; nLeft := 0; nRight := 0; Buff[0] := ';'; while Buff[0]= ';' do Scan(); word pSym:=Find(); Scan(); Buff[0]:='|'; while Buff[0]='|' do Scan(); Left [nLeft]:=pSym; Id [nLeft]:= val(); pRight[nLeft]:=nRight; while IsEnd()!=0 do AddSym(Find()); end AddSym(0); nLeft :=nLeft+1; end end close(); end word PrintSym(word pSym) is word nChar:=0; word pHeap:=Sym[pSym]; while Heap[pHeap]!=char(0) do putc(Heap[pHeap]); nChar:=nChar+1; pHeap:=pHeap+1; end return nChar; end char ListGrammar() is word pL:=0; while pL<nLeft do word nChar:=PrintSym(Left[pL]); while nChar<13 do putc(' '); nChar:=nChar+1; end putc(' '); putc(':'); word pR:=pRight[pL]; while Right[pR]!=0 do while nChar<13 do putc(' '); nChar:=nChar+1; end putc(' '); nChar:=PrintSym(Right[pR]); pR :=pR+1; end putc(char(13)); putc(char(10)); pL:=pL+1; end end begin Init(); LoadGrammar(); ListGrammar(); end

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