@d3x0r/sack-gui
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SACK abstraction library exposed to JS to provide low level system services.
83 lines (80 loc) • 2.54 kB
JavaScript
module.exports = exports = class Fraction {
numerator = 0;
denominator = 1n;
constructor(a,b){
//console.log( "type:", typeof a, typeof b );
if( a instanceof Fraction ) {
this.numerator = a.numerator;
this.denominator = a.denominator;
} else if( "number" === typeof a ) {
if( b === undefined ) {
this.numerator = BigInt(a);
} else if( "number" === typeof b ) {
this.numerator = BigInt(a); this.denominator = BigInt(b);
} else if( "bigint" === typeof b ) {
this.numerator = BigInt(a); this.denominator = b;
}
} else if( "bigint" === typeof a ) {
if( b === undefined ) {
this.numerator = BigInt(a);
} else if( "number" === typeof b ) {
this.numerator = BigInt(a); this.denominator = BigInt(b);
} else if( "bigint" === typeof b ) {
this.numerator = BigInt(a); this.denominator = b;
}
} else {
// may convert string to a number? Doesn't make a lot of sense for a lot of types.
this.numerator = BigInt(a);
}
}
add(f) {
if( f instanceof Fraction ) {
return new Fraction( this.numerator*f.denominator + f.numerator*this.denominator, this.denominator*f.denominator ).reduce();
}
}
sub(f) {
if( f instanceof Fraction ) {
return new Fraction( this.numerator*f.denominator - f.numerator*this.denominator, this.denominator*f.denominator ).reduce();
}
}
mul(f) {
if( f instanceof Fraction ) {
return new Fraction( this.numerator * f.numerator, this.denominator*f.denominator ).reduce();
}
}
div(f) {
if( f instanceof Fraction ) {
return new Fraction( this.numerator*f.denominator, this.denominator*f.numerator ).reduce();
}
}
scale(n) {
return n * this.numerator / this.denominator;
}
reduce() {
// GCD from https://stackoverflow.com/questions/17445231/js-how-to-find-the-greatest-common-divisor
let a = this.numerator<0?-this.numerator:this.numerator;
let b = this.denominator<0?-this.denominator:this.denominator;
//if (b > a) {const temp = a; a = b; b = temp;}
let gcd = 1n;
while (true) {
if (!b) { gcd=a; break; }
a %= b;
if( !a ) { gcd=b; break; }
b %= a;
}
//console.log( "gcd:", gcd );
this.numerator = this.numerator/gcd;
this.denominator = this.denominator/gcd;
return this;
}
toString() {
if( this.numerator > this.denominator ) {
const r = this.numerator%this.denominator;
if( r )
return `${this.numerator/this.denominator} ${r}/${this.denominator}`
else
return `${this.numerator/this.denominator}`
} else
return `${this.numerator}/${this.denominator}`;
}
}