www.pudn.com > 12cocorc.zip > CALC.ATG

$C   /* Generate Main Module */ 
COMPILER Calc 
 
#define upcase(c)       ((c >= 'a' && c <= 'z')? c-32:c) 
int VARS[10000]; 
 
int GetSpix() 
{ 
  char VarName[20]; 
  S_GetString(S_Pos, S_Len, VarName, sizeof(VarName) - 1); 
  if (strlen(VarName) >= 2) 
    return 26*(upcase(VarName[1])-'A')+(upcase(VarName[0])-'A'); 
  else return (upcase(VarName[0])-'A'); 
} 
 
int GetNumber() 
{ 
  char VarName[20]; 
  S_GetString(S_Pos, S_Len, VarName, sizeof(VarName) - 1); 
  return atoi(VarName); 
} 
 
int NewVar(int spix) 
{ 
  VARS[spix] = 0; 
} 
 
int GetVar(int spix) 
{ 
  return VARS[spix]; 
} 
 
int WriteVal(int val) 
{ 
  printf("%d\n", val); 
} 
 
int ReadVal(int spix) 
{ 
  printf("READ ?"); 
  scanf("%d", &VARS[spix]); 
} 
 
int SetVar(int spix, int val) 
{ 
  VARS[spix] = val; 
} 
 
IGNORE CASE     
 
CHARACTERS 
  letter = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz". 
  digit  = "0123456789". 
  eol    = CHR(13) . 
  lf     = CHR(10) . 
 
COMMENTS 
  FROM '--' TO eol 
 
IGNORE eol + lf 
 
TOKENS 
  ident  = letter {letter | digit} . 
  number = digit {digit} . 
 
PRODUCTIONS 
  Calc = 
    [Declarations] StatSeq . 
 
  Declarations 
    =                                     (. int spix; .) 
       'VAR' 
       Ident <&spix>                      (. NewVar(spix); .) 
       { ',' Ident <&spix>                (. NewVar(spix); .) 
       } ';'. 
 
  StatSeq = 
    Stat {';' Stat}. 
 
  Stat 
    =                                     (. int spix, val; .) 
        "READ"  Ident <&spix>             (. ReadVal(spix); .) 
      | "WRITE" Expr <&val>               (. WriteVal(val); .) 
      | Ident <&spix> ":=" Expr <&val>    (. SetVar(spix, val); .) . 
 
  Expr  
    =                                     (. int termVal; .) 
      Term  
      {  '+' Term <&termVal>              (. *exprVal += termVal; .) 
      |  '-' Term <&termVal>              (. *exprVal -= termVal; .) 
      } . 
 
  Term  
    =                                     (. int factVal; .) 
      Fact  
      {  '*' Fact <&factVal>              (. *termVal *= factVal; .) 
      |  '/' Fact <&factVal>              (. *termVal /= factVal; .) 
      } . 
 
  Fact  
    =                                     (. int spix; .) 
         Ident <&spix>                    (. *factVal = GetVar(spix); .) 
      |  number                           (. *factVal = GetNumber(); .) 
      | '(' Expr  ')' . 
 
  Ident  
    = ident                               (. *spix = GetSpix(); .) . 
 
END Calc.