JD2022-TU1/main/tools/framework/JD.Pickers/PickerControls/ViewModelCollection.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using JetBrains.Annotations;

namespace JD.Pickers.PickerControls
{
    public class ViewModelCollection<TModel, TViewModel> : IEnumerable<TViewModel>
    {
        private readonly Dictionary<TViewModel, TModel> _viewToModel;
        private readonly Dictionary<TModel, TViewModel> _modelToView;

        public ViewModelCollection(IEnumerable<TModel> items, Func<TModel, TViewModel> createViewModel)
        {
            _viewToModel = items.ToDictionary(createViewModel);
            _modelToView = _viewToModel.ToDictionary(pair => pair.Value, pair => pair.Key);
        }

        [CanBeNull]
        public TViewModel GetViewModel(TModel model)
        {
            TViewModel viewModel;
            if (_modelToView.TryGetValue(model, out viewModel))
            {
                return viewModel;
            }

            return default(TViewModel);
        }

        [CanBeNull]
        public TModel GetModel(TViewModel viewModel)
        {
            TModel model;
            if (_viewToModel.TryGetValue(viewModel, out model))
            {
                return model;
            }

            return default(TModel);
        }

        public IEnumerator<TViewModel> GetEnumerator()
        {
            return _modelToView.Values.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}