Basic multi-line calculator language in Jison

calc.jison

/* description: Basic multi-line calculator */

%lex
%%

[^\n\S]+        /* ignore whitespace */
[0-9]+          { return 'INT' }
(\n|\;)         { return 'TERMINATOR' }
"-"             { return '-' }
"+"             { return '+' }
'('             { return '(' }
')'             { return ')' }
<<EOF>>         { return 'EOF' }

/lex

%left "+" "-"

%start root
%%

root
    : 'EOF'
        {  }
    | calc 'EOF'
        { return $1 }
    ;

calc
    : expr
        { $$ = new yy.Calc($1) }
    | calc TERMINATOR expr
        { $1.push($3); $$ = $1 }
    | calc TERMINATOR
        { $$ = $1 }
    ;

expr
    : expr '+' expr
        { $$ = new yy.Addition($1, $3); }
    | expr '-' expr
        { $$ = new yy.Subtraction($1, $3); }
    | 'INT'
        { console.log(yy); $$ = new yy.Integer($1) }
    ;

output.txt

{ lexer: 
   { EOF: 1,
     parseError: [Function: parseError],
     setInput: [Function],
     input: [Function],
     unput: [Function],
     more: [Function],
     less: [Function],
     pastInput: [Function],
     upcomingInput: [Function],
     showPosition: [Function],
     next: [Function],
     lex: [Function: lex],
     begin: [Function: begin],
     popState: [Function: popState],
     _currentRules: [Function: _currentRules],
     topState: [Function],
     pushState: [Function: begin],
     options: {},
     performAction: [Function: anonymous],
     rules: [ /^[^\n\S]+/, /^[0-9]+/, /^(\n|;)/, /^-/, /^\+/, /^\(/, /^\)/, /^$/ ],
     conditions: { INITIAL: [Object] },
     _input: '4\n9-5',
     done: false,
     _less: false,
     _more: false,
     yyleng: 1,
     yylineno: 0,
     match: '+',
     matched: '4+',
     yytext: '+',
     conditionStack: [ 'INITIAL' ],
     yylloc: { first_line: 1, last_line: 1, first_column: 1, last_column: 2 },
     yy: [Circular] } }

/Users/andrewcobby/Documents/projects/calc/calc.js:26
case 8: console.log(yy); this.$ = new yy.Integer($$[$0]) 
                                  ^
TypeError: undefined is not a function
    at Object.anonymous (/Users/andrewcobby/Documents/projects/calc/calc.js:26:35)
    at Object.parse (/Users/andrewcobby/Documents/projects/calc/calc.js:194:40)
    at Object.parse (/Users/andrewcobby/Documents/projects/calc/calc.js:383:49)
    at /Users/andrewcobby/Documents/projects/calc/runtime.js:58:22
    at [object Object].<anonymous> (fs.js:115:5)
    at [object Object].emit (events.js:64:17)
    at afterRead (fs.js:1111:12)
    at Object.wrapper [as oncomplete] (fs.js:254:17)

run.js

var parser = require('./calc'),
    fs     = require('fs');

parser.yy = {
    Calc: function(body) {
        this.body = body;
    },

    Addition: function(left, right)
    {
        this.left  = left;
        this.right = right;
    },

    Subtraction: function(left, right)
    {
        this.left  = left;
        this.right = right;
    },

    Integer: function(value)
    {
        this.value = parseInt(value, 10);
    }
};

fs.readFile('./test.calc', 'utf8', function(err, data) {
    if (err) {
        console.log("ERROR: ", err);
        return false;
    }

    var ast = parser.parse(data);
    console.log(ast);
});