src/calc.ypp

   1 %{
   2 #include <iostream>
   3 #include <cstdlib>
   4 #include "BinExpr.hpp"
   5 #include "Exception.hpp"
   6
   7 extern int yylex();
   8
   9 typedef Expr* pExpr;
  10
  11 // better error reporting
  12 #define YYERROR_VERBOSE
  13
  14 // bison requires that you supply this function
  15 void yyerror(const char *msg)
  16 {
  17         std::cerr << "ERROR(PARSER): " << msg << std::endl;
  18 }
  19
  20 %}
  21
  22 %union {
  23     Expr* expr;
  24     double dvalue;
  25     long ivalue;
  26 }
  27
  28 %token <dvalue> DOUBLE
  29 %token <ivalue> INTEGER
  30 %type  <expr> number
  31
  32 %type <expr> dexpression
  33 %type <expr> dterm
  34
  35 %type <expr> iexpression
  36 %type <expr> iterm
  37
  38 %%
  39
  40 statementlist : statement '\n'
  41               | statement '\n' statementlist
  42               ;
  43
  44 statement :     dexpression              { std::cout << "ANS" << $1->eval() << std::endl; }
  45               | iexpression              { std::cout << "ANS" << $1->eval() << std::endl; }
  46               ;
  47
  48 number : DOUBLE                          {$$ = new Number(double($1)); }
  49        | INTEGER                         {$$ = new Number(double($1)) ; }
  50
  51 dexpression: dexpression '+' number     { $$ = new AddExpr($1, $3); }
  52           | iexpression  '+' dterm      { $$ = new AddExpr($1, $3); }
  53           | dterm                    { $$ = $1; }
  54           ;
  55
  56 iexpression: iexpression '+' iterm     { $$ = new AddExpr($1, $3);}
  57           | iterm                    { $$ = $1; }
  58           ;
  59
  60 dterm : dterm '*' number            { $$ = new MulExpr($1, $3); }
  61       | iterm '*' DOUBLE             { $$ = new MulExpr($1, new Number($3)); }
  62
  63       | dterm '/' DOUBLE            { if ($3==0) {
  64                                           throw DivByZero("");
  65                                       }
  66                                       else {
  67                                           $$ = new DivExpr($1, new Number($3));
  68                                       }
  69                                     }
  70       | dterm '/' INTEGER            { if ($3==0) {
  71                                           throw DivByZero("");
  72                                       }
  73                                       else {
  74                                           $$ = new DivExpr($1, new Number(long($3)));
  75                                       }
  76                                     }
  77       | iterm '/' DOUBLE            { if ($3==0) {
  78                                           throw DivByZero("");
  79                                       }
  80                                       else {
  81                                           $$ = new DivExpr($1, new Number(double($3)));
  82                                       }
  83                                     }
  84        | DOUBLE                     { $$ = new Number(double($1)); }
  85      ;
  86
  87 iterm : iterm '*' INTEGER            { $$ = new MulExpr($1, new Number(long($3))); }
  88      | iterm '/' INTEGER            { if ($3==0) {
  89                                           throw DivByZero("");
  90                                       }
  91                                       else {
  92                                           $$ = new DivExpr($1, new Number(long($3)));
  93                                       }
  94                                     }
  95       | INTEGER                     { $$ = new Number(long($1)); }
  96      ;
  97
  98 %%
  99
 100 main()
 101 {
 102         yyparse();
 103 }
 104