Simple Generator - PEG.js

Simple Generator - examples

(2*3)+4+8
3*(12-6)
\frac{1}{2}*\abs{-10}

Simple Generator - grammar

start
    = any
 
additive
    = left:primary "+" right:any { return left + right; }
 
multiplicative
    = left:primary "*" right:any { return left * right; }
 
subtractive
    = left:primary "-" right:any { return left - right; }
 
divisive
    = left:primary "/" right:any { return left / right; }
 
power
    = left:primary "^" right:any { return Math.pow(left, right); }
 
frac
    = "\\frac{" nominator:any "}{" denominator:any "}"
    {
        if (denominator === 0) {
            if (nominator < 0) {
                return Number.POSITIVE_INFINITY;
            } else {
                return Number.NEGATIVE_INFINITY;
            }
        } else {
            return nominator / denominator;
        }
    }
 
abs
    = "\\abs{" argument:any "}"
    {
        return Math.abs(argument);
    }
 
any
    = multiplicative
    / divisive
    / power
    / additive
    / subtractive
    / primary
 
primary
    = frac
    / abs
    / float
    / integer
    / "(" any:any ")" { return any; }
    / "" { return 0; }
 
float "float"
    = left:[0-9]+ "." right:[0-9]+ { return parseFloat(left.join("") + "." + right.join("")); }
 
integer "integer"
    = digits:[0-9]+ { return parseInt(digits.join(""), 10); }