// -----------------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
// -----------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using Microsoft.Internal;
using Microsoft.Internal.Collections;
using System.ComponentModel.Composition.Primitives;
namespace System.ComponentModel.Composition.Hosting{
/// <summary>
/// Provides data for the <see cref="ExportProvider.ExportsChanged"/> and
/// <see cref="ExportProvider.ExportsChanging"/> events.
/// </summary>
public class ExportsChangeEventArgs : EventArgs
{
private IEnumerable<string> _changedContractNames = null;
/// <summary>
/// Initializes a new instance of the <see cref="ExportsChangeEventArgs"/> class with
/// the specified changed export definitions.
/// </summary>
/// <param name="addedExports">
/// An <see cref="IEnumerable{T}"/> of <see cref="ExportDefinition"/>s of the exports
/// that have been added.
/// </param>
/// <param name="removedExports">
/// An <see cref="IEnumerable{T}"/> of <see cref="ExportDefinition"/>s of the exports
/// that have been removed.
/// </param>
/// <param name="atomicComposition">
/// A <see cref="AtomicComposition"/> representing all tentative changes that will
/// be completed if the change is successful, or discarded if it is not.
/// <see langword="null"/> if being applied outside a <see cref="AtomicComposition"/>
/// or during a <see cref="ExportProvider.ExportsChanged"/> event.
/// </param>
/// <exception cref="ArgumentNullException">
/// <paramref name="addedExports"/> or <paramref name="removedExports"/> is <see langword="null"/>.
/// </exception>
public ExportsChangeEventArgs(IEnumerable<ExportDefinition> addedExports,
IEnumerable<ExportDefinition> removedExports, AtomicComposition atomicComposition)
{
Requires.NotNull(addedExports, "addedExports");
Requires.NotNull(removedExports, "removedExports");
this.AddedExports = addedExports.AsArray();
this.RemovedExports = removedExports.AsArray();
this.AtomicComposition = atomicComposition;
}
/// <summary>
/// Gets the export definitions for the exports that have been added.
/// </summary>
/// <value>
/// A <see cref="IEnumerable{T}"/> of ExportDefinitions representing
/// the exports that have been added to the <see cref="CompositionContainer"/>.
/// </value>
public IEnumerable<ExportDefinition> AddedExports { get; private set; }
/// <summary>
/// Gets the export definitions for the exports that have been removed.
/// </summary>
/// <value>
/// A <see cref="IEnumerable{T}"/> of ExportDefinitions representing
/// the exports that have been added to the <see cref="CompositionContainer"/>.
/// </value>
public IEnumerable<ExportDefinition> RemovedExports { get; private set; }
/// <summary>
/// Gets the contract names of the exports that have changed.
/// </summary>
/// <value>
/// A <see cref="IEnumerable{T}"/> of strings representing the contract names of
/// the exports that have changed in the <see cref="CompositionContainer"/>.
/// </value>
public IEnumerable<string> ChangedContractNames
{
get
{
if (this._changedContractNames == null)
{
this._changedContractNames = this.AddedExports
.Concat(this.RemovedExports)
.Select(export => export.ContractName)
.Distinct()
.ToArray();
}
return this._changedContractNames;
}
}
/// <summary>
/// Gets the atomicComposition, if any, that this change applies to.
/// </summary>
/// <value>
/// A <see cref="AtomicComposition"/> that this set of changes applies too.
///
/// It can be <see langword="null"/> if the changes are being applied outside a
/// <see cref="AtomicComposition"/> or during a
/// <see cref="ExportProvider.ExportsChanged"/> event.
///
/// When the value is non-null it should be used to record temporary changed state
/// and actions that will be executed when the atomicComposition is completeed.
/// </value>
public AtomicComposition AtomicComposition { get; private set; }
}
}
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