Javascript - Parse Polynomials From String

I Just Asked this question for objective-c here, but need the answer quick and am able to do the parsing in either objective-c or javascript, so I will ask for js here. In my app t

Solution 1:

you cantry writing jison grammer with online also http://zaach.github.io/jison/try/

calculator grammer is like this I am also learning this it is little bit difficult to understand

From http://zaach.github.io/jison/try/ :

/* description: Parses end executes mathematical expressions. *//* lexical grammar */
%lex
%%

\s+                   /* skip whitespace */
[0-9]+("."[0-9]+)?\b  return'NUMBER'"*"return'*'"/"return'/'"-"return'-'"+"return'+'"^"return'^'"!"return'!'"%"return'%'"("return'('")"return')'"PI"return'PI'"E"return'E'
<<EOF>>               return'EOF'
.                     return'INVALID'

/lex

/* operator associations and precedence */

%left '+''-'
%left '*''/'
%left '^'
%right '!'
%right '%'
%left UMINUS

%start expressions

%% /* language grammar */

expressions
    : e EOF
        { typeof console !== 'undefined' ? console.log($1) : print($1);
          return $1; }
    ;

e
    : e '+' e
        {$$ = $1+$3;}
    | e '-' e
        {$$ = $1-$3;}
    | e '*' e
        {$$ = $1*$3;}
    | e '/' e
        {$$ = $1/$3;}
    | e '^' e
        {$$ = Math.pow($1, $3);}
    | e '!'
        {{
          $$ = (function fact (n) { return n==0 ? 1 : fact(n-1) * n })($1);
        }}
    | e '%'
        {$$ = $1/100;}
    | '-' e %prec UMINUS
        {$$ = -$2;}
    | '(' e ')'
        {$$ = $2;}
    | NUMBER
        {$$ = Number(yytext);}
    | E
        {$$ = Math.E;}
    | PI
        {$$ = Math.PI;}
    ;