Introduce ObjectType

7 files changed, 146 insertions, 23 deletions

diff --git a/LibGit2Sharp/Core/GitObjectTypeMap.cs b/LibGit2Sharp/Core/GitObjectTypeMap.cs
deleted file mode 100644
index df33787e..00000000
--- a/LibGit2Sharp/Core/GitObjectTypeMap.cs
+++ /dev/null
@@ -1,13 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace LibGit2Sharp.Core
-{
-    internal class GitObjectTypeMap : Dictionary<Type, GitObjectType>
-    {
-        public new GitObjectType this[Type type]
-        {
-            get { return !ContainsKey(type) ? GitObjectType.Any : base[type]; }
-        }
-    }
-}
diff --git a/LibGit2Sharp/GitObject.cs b/LibGit2Sharp/GitObject.cs
index f42ecd88..e8420926 100644
--- a/LibGit2Sharp/GitObject.cs
+++ b/LibGit2Sharp/GitObject.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.Globalization;
 using LibGit2Sharp.Core;
@@ -12,14 +13,13 @@ namespace LibGit2Sharp
     [DebuggerDisplay("{DebuggerDisplay,nq}")]
     public abstract class GitObject : IEquatable<GitObject>
     {
-        internal static GitObjectTypeMap TypeToTypeMap =
-            new GitObjectTypeMap
+        internal static IDictionary<Type, ObjectType> TypeToKindMap =
+            new Dictionary<Type, ObjectType>
                 {
-                    { typeof(Commit), GitObjectType.Commit },
-                    { typeof(Tree), GitObjectType.Tree },
-                    { typeof(Blob), GitObjectType.Blob },
-                    { typeof(TagAnnotation), GitObjectType.Tag },
-                    { typeof(GitObject), GitObjectType.Any },
+                    { typeof(Commit), ObjectType.Commit },
+                    { typeof(Tree), ObjectType.Tree },
+                    { typeof(Blob), ObjectType.Blob },
+                    { typeof(TagAnnotation), ObjectType.Tag },
                 };
 
         private static readonly LambdaEqualityHelper<GitObject> equalityHelper =
diff --git a/LibGit2Sharp/IRepository.cs b/LibGit2Sharp/IRepository.cs
index fcc45b7f..24f41031 100644
--- a/LibGit2Sharp/IRepository.cs
+++ b/LibGit2Sharp/IRepository.cs
@@ -106,6 +106,36 @@ namespace LibGit2Sharp
         GitObject Lookup(string objectish, GitObjectType type = GitObjectType.Any);
 
         /// <summary>
+        ///   Try to lookup an object by its <see cref = "ObjectId" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "id">The id to lookup.</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        GitObject Lookup(ObjectId id);
+
+        /// <summary>
+        ///   Try to lookup an object by its sha or a reference canonical name. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "objectish">A revparse spec for the object to lookup.</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        GitObject Lookup(string objectish);
+
+        /// <summary>
+        ///   Try to lookup an object by its <see cref = "ObjectId" /> and <see cref = "GitObjectType" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "id">The id to lookup.</param>
+        /// <param name = "type">The kind of GitObject being looked up</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        GitObject Lookup(ObjectId id, ObjectType type);
+
+        /// <summary>
+        ///   Try to lookup an object by its sha or a reference canonical name and <see cref = "GitObjectType" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "objectish">A revparse spec for the object to lookup.</param>
+        /// <param name = "type">The kind of <see cref = "GitObject" /> being looked up</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        GitObject Lookup(string objectish, ObjectType type);
+
+        /// <summary>
         ///   Stores the content of the <see cref = "Repository.Index" /> as a new <see cref = "Commit" /> into the repository.
         ///   The tip of the <see cref = "Repository.Head"/> will be used as the parent of this new Commit.
         ///   Once the commit is created, the <see cref = "Repository.Head"/> will move forward to point at it.
diff --git a/LibGit2Sharp/LibGit2Sharp.csproj b/LibGit2Sharp/LibGit2Sharp.csproj
index ff377b8d..cf4fc0a3 100644
--- a/LibGit2Sharp/LibGit2Sharp.csproj
+++ b/LibGit2Sharp/LibGit2Sharp.csproj
@@ -67,6 +67,7 @@
     <Compile Include="Changes.cs" />
     <Compile Include="CheckoutCallbacks.cs" />
     <Compile Include="CheckoutOptions.cs" />
+    <Compile Include="ObjectType.cs" />
     <Compile Include="ReferenceExtensions.cs" />
     <Compile Include="Conflict.cs" />
     <Compile Include="ConflictCollection.cs" />
@@ -185,7 +186,6 @@
     <Compile Include="Core\Ensure.cs" />
     <Compile Include="Core\Epoch.cs" />
     <Compile Include="Core\GitErrorCode.cs" />
-    <Compile Include="Core\GitObjectTypeMap.cs" />
     <Compile Include="Core\GitOid.cs" />
     <Compile Include="Core\GitReferenceType.cs" />
     <Compile Include="Core\GitSignature.cs" />
diff --git a/LibGit2Sharp/ObjectType.cs b/LibGit2Sharp/ObjectType.cs
new file mode 100644
index 00000000..efe4e251
--- /dev/null
+++ b/LibGit2Sharp/ObjectType.cs
@@ -0,0 +1,54 @@
+using System;
+
+namespace LibGit2Sharp
+{
+    /// <summary>
+    ///   Underlying type of a <see cref = "GitObject" />
+    /// </summary>
+    public enum ObjectType
+    {
+        /// <summary>
+        ///   A commit object.
+        /// </summary>
+        Commit = 1,
+
+        /// <summary>
+        ///   A tree (directory listing) object.
+        /// </summary>
+        Tree = 2,
+
+        /// <summary>
+        ///   A file revision object.
+        /// </summary>
+        Blob = 3,
+
+        /// <summary>
+        ///   An annotated tag object.
+        /// </summary>
+        Tag = 4,
+    }
+
+    internal static class ObjectTypeExtensions
+    {
+        public static GitObjectType ToGitObjectType(this ObjectType type)
+        {
+            switch (type)
+            {
+                case ObjectType.Commit:
+                    return GitObjectType.Commit;
+
+                case ObjectType.Tree:
+                    return GitObjectType.Tree;
+
+                case ObjectType.Blob:
+                    return GitObjectType.Blob;
+
+                case ObjectType.Tag:
+                    return GitObjectType.Tag;
+
+                default:
+                    throw new InvalidOperationException(string.Format("Cannot map {0} to a GitObjectType.", type));
+            }
+        }
+    }
+}
diff --git a/LibGit2Sharp/Repository.cs b/LibGit2Sharp/Repository.cs
index 4e06ea6f..54707803 100644
--- a/LibGit2Sharp/Repository.cs
+++ b/LibGit2Sharp/Repository.cs
@@ -386,6 +386,48 @@ namespace LibGit2Sharp
         }
 
         /// <summary>
+        ///   Try to lookup an object by its <see cref = "ObjectId" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "id">The id to lookup.</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        public GitObject Lookup(ObjectId id)
+        {
+            return LookupInternal(id, GitObjectType.Any, null);
+        }
+
+        /// <summary>
+        ///   Try to lookup an object by its sha or a reference canonical name. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "objectish">A revparse spec for the object to lookup.</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        public GitObject Lookup(string objectish)
+        {
+            return Lookup(objectish, GitObjectType.Any, LookUpOptions.None);
+        }
+
+        /// <summary>
+        ///   Try to lookup an object by its <see cref = "ObjectId" /> and <see cref = "GitObjectType" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "id">The id to lookup.</param>
+        /// <param name = "type">The kind of GitObject being looked up</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        public GitObject Lookup(ObjectId id, ObjectType type)
+        {
+            return LookupInternal(id, type.ToGitObjectType(), null);
+        }
+
+        /// <summary>
+        ///   Try to lookup an object by its sha or a reference canonical name and <see cref = "GitObjectType" />. If no matching object is found, null will be returned.
+        /// </summary>
+        /// <param name = "objectish">A revparse spec for the object to lookup.</param>
+        /// <param name = "type">The kind of <see cref = "GitObject" /> being looked up</param>
+        /// <returns>The <see cref = "GitObject" /> or null if it was not found.</returns>
+        public GitObject Lookup(string objectish, ObjectType type)
+        {
+            return Lookup(objectish, type.ToGitObjectType(), LookUpOptions.None);
+        }
+
+        /// <summary>
         ///   Try to lookup an object by its <see cref = "ObjectId" /> and <see cref = "GitObjectType" />. If no matching object is found, null will be returned.
         /// </summary>
         /// <param name = "id">The id to lookup.</param>
diff --git a/LibGit2Sharp/RepositoryExtensions.cs b/LibGit2Sharp/RepositoryExtensions.cs
index ae62fab2..1cc638b8 100644
--- a/LibGit2Sharp/RepositoryExtensions.cs
+++ b/LibGit2Sharp/RepositoryExtensions.cs
@@ -23,7 +23,12 @@ namespace LibGit2Sharp
         {
             EnsureNoGitLink<T>();
 
-            return (T)repository.Lookup(objectish, GitObject.TypeToTypeMap[typeof (T)]);
+            if (typeof (T) == typeof (GitObject))
+            {
+                return (T)repository.Lookup(objectish);
+            }
+
+            return (T)repository.Lookup(objectish, GitObject.TypeToKindMap[typeof(T)]);
         }
 
         /// <summary>
@@ -37,7 +42,12 @@ namespace LibGit2Sharp
         {
             EnsureNoGitLink<T>();
 
-            return (T)repository.Lookup(id, GitObject.TypeToTypeMap[typeof(T)]);
+            if (typeof(T) == typeof(GitObject))
+            {
+                return (T)repository.Lookup(id);
+            }
+
+            return (T)repository.Lookup(id, GitObject.TypeToKindMap[typeof(T)]);
         }
 
         private static void EnsureNoGitLink<T>() where T : GitObject