iterator.ts

/**
 * itérateur sur un tableau dans le sens inverse (depuis la fin)
 * 
 * utilisation :
     let arr = [1,2,3];
     const it = new ArrayReverseIterator<Result>(arr);
     for (let r of it)
       console.log( r );   // 3 2 1
 */
export class ArrayReverseIterator<T> implements IterableIterator<T> {
    private _index: number;

    constructor(private _arr: any[]) {
        this._index = this._arr == undefined ? 0 : this._arr.length - 1;
    }

    public next(): IteratorResult<T> {
        if (this._arr != undefined && this._index >= 0) {
            return {
                done: false,
                value: this._arr[this._index--]
            }
        } else {
            return {
                done: true,
                value: null
            }
        }
    }

    [Symbol.iterator](): IterableIterator<T> {
        return this;
    }
}

/**
 * itérateur sur un map string<->any
   
   utilisation :

   class MaClasseAIterer implements Iterable<Machin> {
       private _machinMap: { [key: string]: Machin } = {};

       [Symbol.iterator](): Iterator<Machin> {
          return new MapIterator(this._machinMap);
       }
   }

   const mc = new MaClasseAIterer();
   for ( const m of mc ) {
     ...
   }
 */
export class MapIterator<T> implements Iterator<T> {
    private _map: { [key: string]: T } = {};

    private _keys: string[];

    private _lastIndex: number = -1; // index of last element returned; -1 if no such

    private _index: number = 0;

    private _currentKey: string;

    constructor(m: { [key: string]: T }) {
        this._map = m;
        if (this._map != undefined)
            this._keys = Object.keys(this._map);
        else
            this._keys = [];