Workspace_Registration.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.CompilerServices;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis
{
    /* This is the static API on Workspace that lets you associate text containers with workspace instances */
    public abstract partial class Workspace
    {
        private static readonly ConditionalWeakTable<SourceTextContainer, WorkspaceRegistration> s_bufferToWorkspaceRegistrationMap =
            new();

        /// <summary>
        /// Gets the workspace associated with the specific text container.
        /// </summary>
        public static bool TryGetWorkspace(SourceTextContainer textContainer, [NotNullWhen(true)] out Workspace? workspace)
        {
            if (textContainer == null)
            {
                throw new ArgumentNullException(nameof(textContainer));
            }

            var registration = GetWorkspaceRegistration(textContainer);
            workspace = registration.Workspace;

            return workspace != null;
        }

        /// <summary>
        /// Register a correspondence between a text container and a workspace.
        /// </summary>
        protected void RegisterText(SourceTextContainer textContainer)
        {
            if (textContainer == null)
            {
                throw new ArgumentNullException(nameof(textContainer));
            }

            var registration = GetWorkspaceRegistration(textContainer);
            registration.SetWorkspace(this);
            this.ScheduleTask(() =>
            {
                registration.RaiseEvents();
            }, "Workspace.RegisterText");
        }

        /// <summary>
        /// Unregister a correspondence between a text container and a workspace.
        /// </summary>
        protected void UnregisterText(SourceTextContainer textContainer)
        {
            if (textContainer == null)
            {
                throw new ArgumentNullException(nameof(textContainer));
            }

            var registration = GetWorkspaceRegistration(textContainer);

            if (registration.Workspace == this)
            {
                registration.SetWorkspaceAndRaiseEvents(null);
            }
        }

        private static WorkspaceRegistration CreateRegistration(SourceTextContainer container)
            => new();

        private static readonly ConditionalWeakTable<SourceTextContainer, WorkspaceRegistration>.CreateValueCallback s_createRegistration = CreateRegistration;

        /// <summary>
        /// Returns a <see cref="WorkspaceRegistration" /> for a given text container.
        /// </summary>
        public static WorkspaceRegistration GetWorkspaceRegistration(SourceTextContainer? textContainer)
        {
            if (textContainer == null)
            {
                throw new ArgumentNullException(nameof(textContainer));
            }

            return s_bufferToWorkspaceRegistrationMap.GetValue(textContainer, s_createRegistration);
        }
    }
}