86 lines
3.2 KiB
C#
86 lines
3.2 KiB
C#
// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of this
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// software and associated documentation files (the "Software"), to deal in the Software
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// without restriction, including without limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
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// to whom the Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all copies or
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// substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System;
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using System.Collections.ObjectModel;
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namespace Unity.CodeEditor.Utils
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{
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/// <summary>
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/// A collection where adding and removing items causes a callback.
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/// It is valid for the onAdd callback to throw an exception - this will prevent the new item from
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/// being added to the collection.
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/// </summary>
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internal sealed class ObserveAddRemoveCollection<T> : Collection<T>
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{
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private readonly Action<T> _onAdd;
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private readonly Action<T> _onRemove;
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/// <summary>
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/// Creates a new ObserveAddRemoveCollection using the specified callbacks.
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/// </summary>
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internal ObserveAddRemoveCollection(Action<T> onAdd, Action<T> onRemove)
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{
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_onAdd = onAdd ?? throw new ArgumentNullException(nameof(onAdd));
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_onRemove = onRemove ?? throw new ArgumentNullException(nameof(onRemove));
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}
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/// <inheritdoc/>
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protected override void ClearItems()
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{
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if (_onRemove != null)
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{
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foreach (T val in this)
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_onRemove(val);
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}
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base.ClearItems();
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}
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/// <inheritdoc/>
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protected override void InsertItem(int index, T item)
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{
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_onAdd?.Invoke(item);
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base.InsertItem(index, item);
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}
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/// <inheritdoc/>
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protected override void RemoveItem(int index)
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{
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_onRemove?.Invoke(this[index]);
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base.RemoveItem(index);
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}
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/// <inheritdoc/>
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protected override void SetItem(int index, T item)
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{
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_onRemove?.Invoke(this[index]);
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try
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{
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_onAdd?.Invoke(item);
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}
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catch
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{
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// When adding the new item fails, just remove the old one
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// (we cannot keep the old item since we already successfully called onRemove for it)
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RemoveAt(index);
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throw;
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}
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base.SetItem(index, item);
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}
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}
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} |