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      1 grammar t015calc;
      2 options {
      3   language = JavaScript;
      4 }
      5 
      6 @parser::members {
      7 this.emitErrorMessage = function(msg) {
      8     if (!this.reportedErrors) {
      9         this.reportedErrors = [msg];
     10     } else {
     11         this.reportedErrors.push(msg)
     12     }
     13 };
     14 }
     15 
     16 evaluate returns [result]: r=expression {result = r;};
     17 
     18 expression returns [result]: r=mult (
     19     '+' r2=mult {r += r2;}
     20   | '-' r2=mult {r -= r2;}
     21   )* {result = r};
     22 
     23 mult returns [result]: r=log (
     24     '*' r2=log {r *= r2;}
     25   | '/' r2=log {r /= r2;}
     26   )* {result = r};
     27 
     28 log returns [result]: 'ln' r=exp {result = Math.log(r);}
     29     | r=exp {result = r;}
     30     ;
     31 
     32 exp returns [result]: r=atom ('^' r2=atom {r = Math.pow(r,r2);} )? {result = r;}
     33     ;
     34 
     35 atom returns [result]:
     36     n=INTEGER {result = parseInt($n.text, 10);}
     37   | n=DECIMAL {result = parseFloat($n.text);} 
     38   | '(' r=expression {result = r;} ')'
     39   | 'PI' {result = Math.PI;}
     40   | 'E' {result = Math.E;}
     41   ;
     42 
     43 INTEGER: DIGIT+;
     44 
     45 DECIMAL: DIGIT+ '.' DIGIT+;
     46 
     47 fragment
     48 DIGIT: '0'..'9';
     49 
     50 WS: (' ' | '\n' | '\t')+ {$channel = HIDDEN;};
     51