Add a new API which can be used to store metadata for persistence

One current challenge of our option persistence story is the
determination of the name of an option being serialized is mixed in
with the core logic for how to serialize things to a store. This results
in some very hard-to-maintain code since the logic for an option
is spread across many different areas.

src/Workspaces/Core/Portable/Options/IOption.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.Options
 {
@@ -11,5 +12,7 @@ public interface IOption
         Type Type { get; }
         object DefaultValue { get; }
         bool IsPerLanguage { get; }
+
+        ImmutableArray<OptionPersistence> Persistences { get; }
     }
 }

src/Workspaces/Core/Portable/Options/LocalUserProfilePersistence.cs

+namespace Microsoft.CodeAnalysis.Options
+{
+    /// <summary>
+    /// Specifies that the option should be persisted into the user's local registry hive.
+    /// </summary>
+    internal sealed class LocalUserProfilePersistence : OptionPersistence
+    {
+        public string KeyName { get; }
+
+        public LocalUserProfilePersistence(string keyName)
+        {
+            KeyName = keyName;
+        }
+    }
+}

src/Workspaces/Core/Portable/Options/OptionPersistence.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.Options
+{
+    /// <summary>
+    /// The base type of all persistence information for different options.
+    /// </summary>
+    public abstract class OptionPersistence
+    {
+    }
+}

src/Workspaces/Core/Portable/Options/Option`1.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.Options
 {
@@ -29,7 +30,15 @@ public class Option<T> : IOption
         /// </summary>
         public Type Type => typeof(T);
 
-        public Option(string feature, string name, T defaultValue = default(T))
+        public ImmutableArray<OptionPersistence> Persistences { get; }
+
+        public Option(string feature, string name)
+            : this(feature, name, default(T))
+        {
+            // This constructor forwards to the next one; it exists to maintain source-level compatibility with older callers.
+        }
+
+        public Option(string feature, string name, T defaultValue)
         {
             if (string.IsNullOrWhiteSpace(feature))
             {
@@ -46,6 +55,12 @@ public Option(string feature, string name, T defaultValue = default(T))
             this.DefaultValue = defaultValue;
         }
 
+        public Option(string feature, string name, T defaultValue, params OptionPersistence[] persistences)
+            : this(feature, name, defaultValue)
+        {
+            Persistences = persistences.ToImmutableArray();
+        }
+
         object IOption.DefaultValue => this.DefaultValue;
 
         bool IOption.IsPerLanguage => false;
@@ -60,4 +75,4 @@ public override string ToString()
             return new OptionKey(option);
         }
     }
-}
\ No newline at end of file
+}

src/Workspaces/Core/Portable/Options/PerLanguageOption.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Immutable;
 
 namespace Microsoft.CodeAnalysis.Options
 {
@@ -30,6 +31,8 @@ public class PerLanguageOption<T> : IOption
         /// </summary>
         public T DefaultValue { get; }
 
+        public ImmutableArray<OptionPersistence> Persistences { get; }
+
         public PerLanguageOption(string feature, string name, T defaultValue)
         {
             if (string.IsNullOrWhiteSpace(feature))
@@ -47,6 +50,12 @@ public PerLanguageOption(string feature, string name, T defaultValue)
             this.DefaultValue = defaultValue;
         }
 
+        public PerLanguageOption(string feature, string name, T defaultValue, params OptionPersistence[] persistences)
+            : this(feature, name, defaultValue)
+        {
+            Persistences = persistences.ToImmutableArray();
+        }
+
         object IOption.DefaultValue => this.DefaultValue;
 
         bool IOption.IsPerLanguage => true;
@@ -56,4 +65,4 @@ public override string ToString()
             return string.Format("{0} - {1}", this.Feature, this.Name);
         }
     }
-}
\ No newline at end of file
+}

src/Workspaces/Core/Portable/Options/RoamingProfilePersistence.cs

+using System;
+
+namespace Microsoft.CodeAnalysis.Options
+{
+    /// <summary>
+    /// Specifies that the option should be persisted into a roamed profile across machines.
+    /// </summary>
+    internal sealed class RoamingProfilePersistence : OptionPersistence
+    {
+        private readonly Func<string, string> _keyNameFromLanguageName;
+
+        public string GetKeyNameForLanguage(string languageName)
+        {
+            string unsubstitutedKeyName = _keyNameFromLanguageName(languageName);
+
+            if (languageName == null)
+            {
+                return unsubstitutedKeyName;
+            }
+            else
+            {
+                string substituteLanguageName = languageName == LanguageNames.CSharp ? "CSharp" :
+                                                languageName == LanguageNames.VisualBasic ? "VisualBasic" :
+                                                languageName;
+
+                return unsubstitutedKeyName.Replace("%LANGUAGE%", substituteLanguageName);
+            }
+        }
+
+        public RoamingProfilePersistence(string keyName)
+        {
+            _keyNameFromLanguageName = _ => keyName;
+        }
+
+        /// <summary>
+        /// Creates a <see cref="RoamingProfilePersistence"/> that has different key names for different languages.
+        /// </summary>
+        /// <param name="keyNameFromLanguageName">A function that maps from a <see cref="LanguageNames"/> value to the key name.</param>
+        public RoamingProfilePersistence(Func<string, string> keyNameFromLanguageName)
+        {
+            _keyNameFromLanguageName = keyNameFromLanguageName;
+        }
+    }
+}

src/Workspaces/Core/Portable/PublicAPI.Shipped.txt

@@ -506,7 +506,8 @@ Microsoft.CodeAnalysis.Options.Option<T>
 Microsoft.CodeAnalysis.Options.Option<T>.DefaultValue.get -> T
 Microsoft.CodeAnalysis.Options.Option<T>.Feature.get -> string
 Microsoft.CodeAnalysis.Options.Option<T>.Name.get -> string
-Microsoft.CodeAnalysis.Options.Option<T>.Option(string feature, string name, T defaultValue = default(T)) -> void
+Microsoft.CodeAnalysis.Options.Option<T>.Option(string feature, string name) -> void
+Microsoft.CodeAnalysis.Options.Option<T>.Option(string feature, string name, T defaultValue) -> void
 Microsoft.CodeAnalysis.Options.Option<T>.Type.get -> System.Type
 Microsoft.CodeAnalysis.Options.OptionKey
 Microsoft.CodeAnalysis.Options.OptionKey.Equals(Microsoft.CodeAnalysis.Options.OptionKey other) -> bool

src/Workspaces/Core/Portable/PublicAPI.Unshipped.txt

@@ -23,7 +23,14 @@ Microsoft.CodeAnalysis.DocumentActiveContextChangedEventArgs.SourceTextContainer
 Microsoft.CodeAnalysis.Editing.SyntaxGenerator.AddSwitchSections(Microsoft.CodeAnalysis.SyntaxNode switchStatement, System.Collections.Generic.IEnumerable<Microsoft.CodeAnalysis.SyntaxNode> switchSections) -> Microsoft.CodeAnalysis.SyntaxNode
 Microsoft.CodeAnalysis.Options.DocumentOptionSet
 Microsoft.CodeAnalysis.Options.DocumentOptionSet.GetOption<T>(Microsoft.CodeAnalysis.Options.PerLanguageOption<T> option) -> T
+Microsoft.CodeAnalysis.Options.IOption.Persistences.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Options.OptionPersistence>
+Microsoft.CodeAnalysis.Options.Option<T>.Option(string feature, string name, T defaultValue, params Microsoft.CodeAnalysis.Options.OptionPersistence[] persistences) -> void
+Microsoft.CodeAnalysis.Options.Option<T>.Persistences.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Options.OptionPersistence>
+Microsoft.CodeAnalysis.Options.OptionPersistence
+Microsoft.CodeAnalysis.Options.OptionPersistence.OptionPersistence() -> void
 Microsoft.CodeAnalysis.Options.OptionSet.OptionSet() -> void
+Microsoft.CodeAnalysis.Options.PerLanguageOption<T>.PerLanguageOption(string feature, string name, T defaultValue, params Microsoft.CodeAnalysis.Options.OptionPersistence[] persistences) -> void
+Microsoft.CodeAnalysis.Options.PerLanguageOption<T>.Persistences.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.Options.OptionPersistence>
 Microsoft.CodeAnalysis.Solution.Options.get -> Microsoft.CodeAnalysis.Options.OptionSet
 Microsoft.CodeAnalysis.Workspace.DocumentActiveContextChanged -> System.EventHandler<Microsoft.CodeAnalysis.DocumentActiveContextChangedEventArgs>
 Microsoft.CodeAnalysis.Workspace.RaiseDocumentActiveContextChangedEventAsync(Microsoft.CodeAnalysis.Text.SourceTextContainer sourceTextContainer, Microsoft.CodeAnalysis.DocumentId oldActiveContextDocumentId, Microsoft.CodeAnalysis.DocumentId newActiveContextDocumentId) -> System.Threading.Tasks.Task

src/Workspaces/Core/Portable/Workspaces.csproj

@@ -395,6 +395,9 @@
     <Compile Include="Options\IWorkspaceOptionService.cs" />
     <Compile Include="Shared\RuntimeOptions.cs" />
     <Compile Include="Shared\RuntimeOptionsProvider.cs" />
+    <Compile Include="Options\OptionPersistence.cs" />
+    <Compile Include="Options\LocalUserProfilePersistence.cs" />
+    <Compile Include="Options\RoamingProfilePersistence.cs" />
     <Compile Include="SolutionCrawler\ExportIncrementalAnalyzerProviderAttribute.cs" />
     <Compile Include="SolutionCrawler\IIncrementalAnalyzer.cs" />
     <Compile Include="SolutionCrawler\IIncrementalAnalyzerProvider.cs" />