97 lines
2.8 KiB
C#
97 lines
2.8 KiB
C#
/*
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Copyright (C) 2014-2019 de4dot@gmail.com
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This file is part of dnSpy
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dnSpy is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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dnSpy is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with dnSpy. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections;
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using System.Diagnostics;
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namespace dnSpy.AsmEditor.Hex.PE {
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interface IVirtualizedListItem {
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int Index { get; }
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}
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// The key to make this work is to implement IList, yes, IList, not IList<T>.
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sealed class VirtualizedList<T> : IList where T : class, IVirtualizedListItem {
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readonly WeakReference[] list;
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readonly Func<int, T> createItem;
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public VirtualizedList(int count, Func<int, T> createItem) {
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list = new WeakReference[count];
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this.createItem = createItem;
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}
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public T? TryGet(int index) {
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Debug.Assert(0 <= index && index < list.Length);
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if ((uint)index >= (uint)list.Length)
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return null;
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return (T?)list[index]?.Target;
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}
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public T this[int index] {
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get {
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T? obj;
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var weakRef = list[index];
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if (weakRef is null) {
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list[index] = new WeakReference(obj = createItem(index));
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return obj;
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}
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obj = (T?)weakRef.Target;
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if (obj is null)
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weakRef.Target = obj = createItem(index);
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return obj;
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}
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}
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object? IList.this[int index] {
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get => this[index];
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set => Debug.Fail("Method shouldn't be called");
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}
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public int Count => list.Length;
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bool IList.IsFixedSize => true;
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bool IList.IsReadOnly => true;
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bool ICollection.IsSynchronized => false;
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object ICollection.SyncRoot => this;
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int IList.Add(object? value) {
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Debug.Fail("Method shouldn't be called");
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return -1;
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}
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void IList.Clear() => Debug.Fail("Method shouldn't be called");
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bool IList.Contains(object? value) => value is IVirtualizedListItem;
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void ICollection.CopyTo(Array array, int index) {
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Debug.Fail("Method shouldn't be called");
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throw new NotImplementedException("ICollection.CopyTo shouldn't be called");
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}
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IEnumerator IEnumerable.GetEnumerator() {
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for (int i = 0; i < list.Length; i++)
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yield return this[i];
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}
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int IList.IndexOf(object? value) => (value as IVirtualizedListItem)?.Index ?? -1;
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void IList.Insert(int index, object? value) => Debug.Fail("Method shouldn't be called");
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void IList.Remove(object? value) => Debug.Fail("Method shouldn't be called");
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void IList.RemoveAt(int index) => Debug.Fail("Method shouldn't be called");
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}
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}
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