ui/src/common/selection_observer.ts

// Copyright (C) 2022 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {Selection} from './state';

export type SelectionChangedObserver =
    (newSelection?: Selection, oldSelection?: Selection) => void;

const selectionObservers: SelectionChangedObserver[] = [];

export function onSelectionChanged(
    newSelection?: Selection, oldSelection?: Selection) {
  for (const observer of selectionObservers) {
    observer(newSelection, oldSelection);
  }
}

export function addSelectionChangeObserver(observer: SelectionChangedObserver):
    void {
  selectionObservers.push(observer);
}