105 lines
3.9 KiB
C#
105 lines
3.9 KiB
C#
// MonoGame - Copyright (C) The MonoGame Team
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// This file is subject to the terms and conditions defined in
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// file 'LICENSE.txt', which is part of this source code package.
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using System;
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using System.Collections.ObjectModel;
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namespace Microsoft.Xna.Framework.Content.Pipeline
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{
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/// <summary>
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/// Provides a collection of child objects for a content item.
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///
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/// Links from a child object to its parent are maintained as the collection contents are modified.
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/// </summary>
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/// <typeparam name="TParent"></typeparam>
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/// <typeparam name="TChild"></typeparam>
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public abstract class ChildCollection<TParent, TChild> : Collection<TChild>
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where TParent : class
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where TChild : class
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{
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TParent parent;
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/// <summary>
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/// Creates an instance of ChildCollection.
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/// </summary>
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/// <param name="parent">Parent object of the child objects returned in the collection.</param>
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protected ChildCollection(TParent parent)
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: base()
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{
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if (parent == null)
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throw new ArgumentNullException("parent");
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this.parent = parent;
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}
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/// <summary>
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/// Removes all children from the collection.
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/// </summary>
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protected override void ClearItems()
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{
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// Remove parent reference from each child before clearing
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foreach (TChild child in this)
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SetParent(child, default(TParent));
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base.ClearItems();
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}
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/// <summary>
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/// Gets the parent of a child object.
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/// </summary>
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/// <param name="child">The child of the parent being retrieved.</param>
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/// <returns>The parent of the child object.</returns>
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protected abstract TParent GetParent(TChild child);
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/// <summary>
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/// Inserts a child object into the collection at the specified location.
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/// </summary>
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/// <param name="index">The position in the collection.</param>
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/// <param name="item">The child object being inserted.</param>
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protected override void InsertItem(int index, TChild item)
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{
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// Make sure we have a
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if (item == null)
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throw new ArgumentNullException("child");
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if (GetParent(item) != null)
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throw new InvalidOperationException("Child already has a parent");
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SetParent(item, parent);
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base.InsertItem(index, item);
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}
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/// <summary>
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/// Removes a child object from the collection.
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/// </summary>
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/// <param name="index">The index of the item being removed.</param>
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protected override void RemoveItem(int index)
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{
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TChild child = this[index];
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SetParent(child, default(TParent));
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base.RemoveItem(index);
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}
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/// <summary>
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/// Modifies the value of the child object at the specified location.
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/// </summary>
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/// <param name="index">The index of the child object being modified.</param>
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/// <param name="item">The new value for the child object.</param>
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protected override void SetItem(int index, TChild item)
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{
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if (item == null)
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throw new ArgumentNullException("child");
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if (GetParent(item) != null)
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throw new InvalidOperationException("Child already has a parent");
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TChild child = this[index];
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SetParent(child, default(TParent));
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SetParent(item, parent);
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base.SetItem(index, item);
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}
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/// <summary>
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/// Modifies the value of the parent object of the specified child object.
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/// </summary>
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/// <param name="child">The child of the parent being modified.</param>
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/// <param name="parent">The new value for the parent object.</param>
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protected abstract void SetParent(TChild child, TParent parent);
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}
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}
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