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Add CommitCollection.FindCommonAncestor()
Fix issue #149
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‎LibGit2Sharp.Tests/CommitAncestorFixture.cs

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using System;
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using System.Linq;
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using LibGit2Sharp.Tests.TestHelpers;
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using Xunit;
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namespace LibGit2Sharp.Tests
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{
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public class CommitAncestorFixture : BaseFixture
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{
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/*
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* BareTestRepoPath structure
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*
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* * commit 4c062a6361ae6959e06292c1fa5e2822d9c96345
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* |
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* * commit be3563ae3f795b2b4353bcce3a527ad0a4f7f644
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* |\
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* | |
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* | * commit c47800c7266a2be04c571c04d5a6614691ea99bd
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* | |
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* * | commit 9fd738e8f7967c078dceed8190330fc8648ee56a
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* | |
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* * | commit 4a202b346bb0fb0db7eff3cffeb3c70babbd2045
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* |/
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* |
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* * commit 5b5b025afb0b4c913b4c338a42934a3863bf3644
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* |
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* * commit 8496071c1b46c854b31185ea97743be6a877447
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*
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*/
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[Fact]
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public void CanFindCommonAncestorForTwoCommits()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
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var second = repo.Lookup<Commit>("9fd738e8f7967c078dceed8190330fc8648ee56a");
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Commit ancestor = repo.Commits.FindCommonAncestor(first, second);
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Assert.NotNull(ancestor);
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ancestor.Id.Sha.ShouldEqual("5b5b025afb0b4c913b4c338a42934a3863bf3644");
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}
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}
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[Fact]
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public void CanFindCommonAncestorForTwoCommitsAsEnumerable()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
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var second = repo.Lookup<Commit>("9fd738e8f7967c078dceed8190330fc8648ee56a");
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Commit ancestor = repo.Commits.FindCommonAncestor(new[] { first, second });
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Assert.NotNull(ancestor);
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ancestor.Id.Sha.ShouldEqual("5b5b025afb0b4c913b4c338a42934a3863bf3644");
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}
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}
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[Fact]
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public void CanFindCommonAncestorForSeveralCommits()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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var second = repo.Lookup<Commit>("be3563ae3f795b2b4353bcce3a527ad0a4f7f644");
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var third = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
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var fourth = repo.Lookup<Commit>("5b5b025afb0b4c913b4c338a42934a3863bf3644");
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Commit ancestor = repo.Commits.FindCommonAncestor(new[] { first, second, third, fourth });
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Assert.NotNull(ancestor);
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ancestor.Id.Sha.ShouldEqual("5b5b025afb0b4c913b4c338a42934a3863bf3644");
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}
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}
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[Fact]
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public void CannotFindAncestorForTwoCommmitsWithoutCommonAncestor()
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{
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var scd = BuildTemporaryCloneOfTestRepo();
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using (var repo = new Repository(scd.RepositoryPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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var second = repo.Lookup<Commit>("be3563ae3f795b2b4353bcce3a527ad0a4f7f644");
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var third = repo.Lookup<Commit>("c47800c7266a2be04c571c04d5a6614691ea99bd");
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var fourth = repo.Lookup<Commit>("5b5b025afb0b4c913b4c338a42934a3863bf3644");
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Commit orphanedCommit = CreateOrphanedCommit(repo);
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Commit ancestor = repo.Commits.FindCommonAncestor(new[] { first, second, orphanedCommit, third, fourth });
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Assert.Null(ancestor);
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}
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}
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[Fact]
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public void CannotFindCommonAncestorForSeveralCommmitsWithoutCommonAncestor()
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{
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var scd = BuildTemporaryCloneOfTestRepo();
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using (var repo = new Repository(scd.RepositoryPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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var orphanedCommit = CreateOrphanedCommit(repo);
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Commit ancestor = repo.Commits.FindCommonAncestor(first, orphanedCommit);
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Assert.Null(ancestor);
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}
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}
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private static Commit CreateOrphanedCommit(Repository repo)
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{
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Commit random = repo.Head.Tip;
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Commit orphanedCommit = repo.ObjectDatabase.CreateCommit(
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"This is a test commit created by 'CommitFixture.CannotFindCommonAncestorForCommmitsWithoutCommonAncestor'",
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random.Author,
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random.Committer,
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random.Tree,
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Enumerable.Empty<Commit>());
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return orphanedCommit;
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}
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[Fact]
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public void FindCommonAncestorForSingleCommitThrows()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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Assert.Throws<ArgumentException>(() => repo.Commits.FindCommonAncestor(new[] { first }));
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}
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}
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[Fact]
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public void FindCommonAncestorForEnumerableWithNullCommitThrows()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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var second = repo.Lookup<Commit>("be3563ae3f795b2b4353bcce3a527ad0a4f7f644");
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Assert.Throws<ArgumentException>(() => repo.Commits.FindCommonAncestor(new[] { first, second, null }));
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}
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}
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[Fact]
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public void FindCommonAncestorForWithNullCommitThrows()
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{
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using (var repo = new Repository(BareTestRepoPath))
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{
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var first = repo.Lookup<Commit>("4c062a6361ae6959e06292c1fa5e2822d9c96345");
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Assert.Throws<ArgumentNullException>(() => repo.Commits.FindCommonAncestor(first, null));
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Assert.Throws<ArgumentNullException>(() => repo.Commits.FindCommonAncestor(null, first));
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}
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}
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}
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}

‎LibGit2Sharp.Tests/LibGit2Sharp.Tests.csproj

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<ItemGroup>
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<Compile Include="ConfigurationFixture.cs" />
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<Compile Include="AttributesFixture.cs" />
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<Compile Include="CommitAncestorFixture.cs" />
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<Compile Include="DiffBlobToBlobFixture.cs" />
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<Compile Include="ObjectDatabaseFixture.cs" />
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<Compile Include="DiffTreeToTreeFixture.cs" />

‎LibGit2Sharp/CommitCollection.cs

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@@ -124,6 +124,75 @@ private static bool PointsAtTheHead(string shaOrRefName)
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return ("HEAD".Equals(shaOrRefName, StringComparison.Ordinal) || "refs/heads/master".Equals(shaOrRefName, StringComparison.Ordinal));
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}
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/// <summary>
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/// Find the best possible common ancestor given two <see cref = "Commit"/>s.
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/// </summary>
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/// <param name = "first">The first <see cref = "Commit"/>.</param>
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/// <param name = "second">The second <see cref = "Commit"/>.</param>
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/// <returns>The common ancestor or null if none found.</returns>
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public Commit FindCommonAncestor(Commit first, Commit second)
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{
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Ensure.ArgumentNotNull(first, "first");
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Ensure.ArgumentNotNull(second, "second");
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using (var osw1 = new ObjectSafeWrapper(first.Id, repo))
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using (var osw2 = new ObjectSafeWrapper(second.Id, repo))
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{
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GitOid ret;
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int result = NativeMethods.git_merge_base(out ret, repo.Handle, osw1.ObjectPtr, osw2.ObjectPtr);
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if (result == (int)GitErrorCode.GIT_ENOTFOUND)
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{
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return null;
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}
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Ensure.Success(result);
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return repo.Lookup<Commit>(new ObjectId(ret));
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}
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}
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/// <summary>
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/// Find the best possible common ancestor given two or more <see cref="Commit"/>.
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/// </summary>
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/// <param name = "commits">The <see cref = "Commit"/>s for which to find the common ancestor.</param>
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/// <returns>The common ancestor or null if none found.</returns>
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public Commit FindCommonAncestor(IEnumerable<Commit> commits)
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{
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Ensure.ArgumentNotNull(commits, "commits");
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Commit ret = null;
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int count = 0;
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foreach (var commit in commits)
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{
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if (commit == null)
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{
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throw new ArgumentException("Enumerable contains null at position: " + count.ToString(CultureInfo.InvariantCulture), "commits");
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}
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count++;
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if (count == 1)
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{
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ret = commit;
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continue;
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}
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ret = FindCommonAncestor(ret, commit);
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if (ret == null)
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{
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break;
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}
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}
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if (count < 2)
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{
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throw new ArgumentException("The enumerable must contains at least two commits.", "commits");
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}
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return ret;
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}
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/// <summary>
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/// Stores the content of the <see cref = "Repository.Index" /> as a new <see cref = "Commit" /> into the repository.
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/// The tip of the <see cref = "Repository.Head"/> will be used as the parent of this new Commit.

‎LibGit2Sharp/Core/NativeMethods.cs

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[DllImport(libgit2)]
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public static extern int git_index_write(IndexSafeHandle index);
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[DllImport(libgit2)]
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public static extern int git_merge_base(
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out GitOid mergeBase,
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RepositorySafeHandle repo,
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GitObjectSafeHandle one,
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GitObjectSafeHandle two);
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[DllImport(libgit2)]
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public static extern int git_odb_exists(ObjectDatabaseSafeHandle odb, ref GitOid id);
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‎LibGit2Sharp/IQueryableCommitCollection.cs

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namespace LibGit2Sharp
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using System.Collections.Generic;
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namespace LibGit2Sharp
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{
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public interface IQueryableCommitCollection : ICommitCollection //TODO: Find a name that's more explicit than IQueryableCommitCollection
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{
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/// <param name = "amendPreviousCommit">True to amend the current <see cref = "Commit"/> pointed at by <see cref = "Repository.Head"/>, false otherwise.</param>
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/// <returns>The generated <see cref = "Commit" />.</returns>
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Commit Create(string message, Signature author, Signature committer, bool amendPreviousCommit);
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/// <summary>
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/// Find the best possible common ancestor given two <see cref = "Commit"/>s.
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/// </summary>
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/// <param name = "first">The first <see cref = "Commit"/>.</param>
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/// <param name = "second">The second <see cref = "Commit"/>.</param>
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/// <returns>The common ancestor or null if none found.</returns>
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Commit FindCommonAncestor(Commit first, Commit second);
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/// <summary>
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/// Find the best possible common ancestor given two or more <see cref = "Commit"/>s.
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/// </summary>
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/// <param name = "commits">The <see cref = "Commit"/> for which to find the common ancestor.</param>
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/// <returns>The common ancestor or null if none found.</returns>
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Commit FindCommonAncestor(IEnumerable<Commit> commits);
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}
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}

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