Class SelectionSet

src/cdk-experimental/selection/selection-set.ts:47–130

 * expected to be set when calling `isSelected`, `select` and `deselect`.
 */
export class SelectionSet<T> implements TrackBySelection<T> {
  private _selectionMap = new Map<T | ReturnType<TrackByFunction<T>>, SelectableWithIndex<T>>();
  changed = new Subject<SelectionChange<T>>();

  constructor(
    private _multiple = false,
    private _trackByFn?: TrackByFunction<T>,
  ) {}

  isSelected(value: SelectableWithIndex<T>): boolean {
    return this._selectionMap.has(this._getTrackedByValue(value));
  }

  select(...selects: SelectableWithIndex<T>[]) {
    if (!this._multiple && selects.length > 1 && (typeof ngDevMode === 'undefined' || ngDevMode)) {
      throw Error('SelectionSet: not multiple selection');
    }

    const before = this._getCurrentSelection();

    if (!this._multiple) {
      this._selectionMap.clear();
    }

    const toSelect: SelectableWithIndex<T>[] = [];
    for (const select of selects) {
      if (this.isSelected(select)) {
        continue;
      }

      toSelect.push(select);
      this._markSelected(this._getTrackedByValue(select), select);
    }

    const after = this._getCurrentSelection();

    this.changed.next({before, after});
  }

  deselect(...selects: SelectableWithIndex<T>[]) {
    if (!this._multiple && selects.length > 1 && (typeof ngDevMode === 'undefined' || ngDevMode)) {
      throw Error('SelectionSet: not multiple selection');
    }

    const before = this._getCurrentSelection();
    const toDeselect: SelectableWithIndex<T>[] = [];

    for (const select of selects) {
      if (!this.isSelected(select)) {
        continue;
      }

      toDeselect.push(select);
      this._markDeselected(this._getTrackedByValue(select));
    }

    const after = this._getCurrentSelection();
    this.changed.next({before, after});