export interface IPoint { x : number ; y : number ; next : Point ; prev : Point ; } export class Point implements IPoint { public x : number ; public y : number ; private _next : Point ; private _prev : Point ; constructor ( x = 0 , y = 0 ) { this . x = x ; this . y = y ; } public get next ( ) : Point { return this . _next ; } public set next ( p ) { this . _next = p ; } public get prev ( ) : Point { return this . _prev ; } public set prev ( p ) { this . _prev = p ; } }