int.js

// A 0+ integer of unlimited size
function Int(p) { // Takes a number like 5, a string of numerals like "789", a bignumber.js BigNumber, or another Int
	if (isType(p, "Int")) return p; // Return the given Int instead of making a new one, the value inside an Int can't change
	var o = {};
	o.v = _3type(p); // Parse the given parameter, keeping together v.s() numerals, and v.n() number and v.b() BigNumber once we have them or they are necessary
	o.inside = o.v.inside; // Point to function, see which types v has built up with text like "bns" or "--s" for testing

	o.add                  = function(q) { return _add(o.v, q); } // Math
	o.subtract             = function(q) { return _sub(o.v, q); }
	o.multiply             = function(q) { return _mul(o.v, q); }
	o.divide               = function(q) { return _div(o.v, q); }
	o.modulo               = function(q) { return _mod(o.v, q); }

	o.equals               = function(q) { return _equ(o.v, q); }
	o.greaterThan          = function(q) { return _gth(o.v, q); }
	o.greaterThanOrEqualTo = function(q) { return _gte(o.v, q); }
	o.lessThan             = function(q) { return _lth(o.v, q); }
	o.lessThanOrEqualTo    = function(q) { return _lte(o.v, q); }

	o.increment            = function()  { return _inc(o.v); }
	o.decrement            = function()  { return _dec(o.v); }
	o.is                   = function()  { return _isp(o.v); }

	o._ = function(c, q) { return _calculate(o.v, c, q); }
	o.text = o.v.s();
	o.hasNumber = function() { return o.v.fit; } // True if our value is small enough to fit in a number as an integer, not a floating point number
	o.toNumber = o.v.n; // Point to function, throws if too big
	o.type = "Int";
	return freeze(o);
}
function _3type(p) { // Parse the parameter given to Int or a method on Int, keeping the same integer value in up to 3 different types
	var type = getType(p);
	if (type == "Int") return p.v; // We got an Int, return the value inside instead of making a new one

	// Hold the same integer value 1, 2 or 3 different ways, keeping the type we were given, only converting when necessary, and checking everything we can with the types we have
	var b = "none"; // Our integer value in a BigNumber object, or "none" before we have one
	var n = "none"; // Our integer value in a number type variable, or "none" before we have one, or if our value won't fit
	var s = "none"; // Our integer value as a string of numerals, we always have this type

	if (hasMethod(p, "dividedToIntegerBy")) { b = p;                     s = b.toFixed(0); checkNumerals(s);                      } // Given a BigNumber, make and check numerals
	else if (type == "number")              { n = p; checkNumberMath(n); s = n+"";         checkNumerals(s); checkNumeralsFit(s); } // Given a number, check it, make numerals, and check them
	else if (type == "string")              {                            s = p;            checkNumerals(s);                      } // Given numerals, check them
	else { toss("type"); } // Int(p).method(p) only accepts p as an Int, BigNumber, number, or string

	var o = {}; // Return, or make, check, keep, and return, our value in a BigNumber, number, or string ♫ There's three ways of saying, the very same thing
	o.b = function() { if (b !== "none") return b; b = new platformBigNumber(s); checkSame(s, b.toFixed(0)); return b; } // Make from numerals rather than number to avoid 15 digit limit
	o.n = function() { if (n !== "none") return n; n = numeralsToNumber(s);                                  return n; }
	o.s = function() {                   return s;                                                                     }

	o.fit = numeralsFit(s); // Small enough to fit
	o.bs = function() { return b !== "none" ? b : s; } // Our value in a BigNumber if we have one, numerals otherwise
	o.inside = function() { return "###".fill(b === "none" ? "-" : "b", n === "none" ? "-" : "n", s === "none" ? "-" : "s"); } // Show which types we've built up
	return o;
}
//                                                                    Small values            use number for speed             Potentially large values use BigNumber instead
function _add(v, q) { var w = _3type(q);                       return _bothFitProduct(v, w) ? Int(v.n() + w.n())             : Int(v.b().plus(              w.bs())); }
function _sub(v, q) { var w = _3type(q); _checkSubtract(v, w); return _bothFit(v, w)        ? Int(v.n() - w.n())             : Int(v.b().minus(             w.bs())); }
function _mul(v, q) { var w = _3type(q);                       return _bothFitProduct(v, w) ? Int(v.n() * w.n())             : Int(v.b().times(             w.bs())); }
function _div(v, q) { var w = _3type(q); _checkDivide(v, w);   return _bothFit(v, w)        ? Int(Math.floor(v.n() / w.n())) : Int(v.b().dividedToIntegerBy(w.bs())); }
function _mod(v, q) { var w = _3type(q); _checkDivide(v, w);   return _bothFit(v, w)        ? Int(v.n() % w.n())             : Int(v.b().mod(               w.bs())); }

function _equ(v, q) { var w = _3type(q);                       return _bothFit(v, w)        ? v.n() == w.n()                 : v.b().equals(                w.bs());  }
function _gth(v, q) { var w = _3type(q);                       return _bothFit(v, w)        ? v.n() >  w.n()                 : v.b().greaterThan(           w.bs());  }
function _gte(v, q) { var w = _3type(q);                       return _bothFit(v, w)        ? v.n() >= w.n()                 : v.b().greaterThanOrEqualTo(  w.bs());  }
function _lth(v, q) { var w = _3type(q);                       return _bothFit(v, w)        ? v.n() <  w.n()                 : v.b().lessThan(              w.bs());  }
function _lte(v, q) { var w = _3type(q);                       return _bothFit(v, w)        ? v.n() <= w.n()                 : v.b().lessThanOrEqualTo(     w.bs());  }

function _inc(v) { return _add(v, 1); }
function _dec(v) { return _sub(v, 1); }
function _isp(v) { return _gth(v, 0); }

function _checkSubtract(v, w)  { if (compareCheckedNumerals(v.s(), w.s()) < 0) toss("bounds"); } // Make sure v - w will be 0+, as negative values aren't allowed
function _checkDivide(v, w)    { if (w.s() == "0") toss("math"); }                               // Who says you can't divide by zero? OH SHI-
function _bothFit(v, w)        { return v.fit && w.fit; }                                        // True if both values will fit in numbers, so we can use minus, divide, and modulo
function _bothFitProduct(v, w) {                                                                 // True if adding or multipling the given two numbers can't produce an answer that's too big
	return _bothFit(v, w) && v.s().length + w.s().length < (Number.MAX_SAFE_INTEGER+"").length;    // Even if v and w are all 9s, a*b will still be a digit shorter than max safe integer
}
function _calculate(v, c, q) { // Who says JavaScript can't do operator overloading?
	if      (c == "+")  { return _add(v, q); }
	else if (c == "-")  { return _sub(v, q); }
	else if (c == "*")  { return _mul(v, q); }
	else if (c == "/")  { return _div(v, q); }
	else if (c == "%")  { return _mod(v, q); }

	else if (c == "==") { return _equ(v, q); }
	else if (c == ">")  { return _gth(v, q); }
	else if (c == ">=") { return _gte(v, q); }
	else if (c == "<")  { return _lth(v, q); }
	else if (c == "<=") { return _lte(v, q); }

	else if (c == "++") { return _inc(v); }
	else if (c == "--") { return _dec(v); }
	else if (c == ">0") { return _isp(v); }
	else { toss("code"); }
}

exports.Int = Int;