feat: Abstract Git log calls

Author: ibbem

src/main/java/org/variantsync/diffdetective/datasets/Repository.java

@@ -15,6 +15,7 @@
 import java.nio.file.Path;
 import java.util.Iterator;
 import java.util.Optional;
+import java.util.function.Function;
 
 /**
  * Representation of git repositories used as datasets for DiffDetective.
@@ -44,6 +45,11 @@ public class Repository {
 	 */
 	private final String repositoryName;
 
+	/**
+	 * A function that extracts the list of commits that are represented by this repository instance.
+	 */
+	private Function<Repository, Iterator<RevCommit>> listCommits;
+
 	/**
 	 * Filter determining which files and commits to consider for diffs.
 	 */
@@ -55,14 +61,45 @@ public class Repository {
 	private PatchDiffParseOptions parseOptions;
 
 	private final Lazy<Git> git = Lazy.of(this::load);
-	
+
+	/**
+	 * List all commits reachable by the current {@code HEAD} of the repository.
+	 * This is intended to be used as an argument for the {@code listCommits} argument of
+	 * {@link #Repository(RepositoryLocationType, Path, URI, String, Function<Repository, Iterator<RevCommit>>, PatchDiffParseOptions, DiffFilter)}.
+	 */
+	public static final Function<Repository, Iterator<RevCommit>> TraverseHEAD =
+		(Repository repository) -> {
+			try {
+				return repository.getGitRepo().log().call().iterator();
+			} catch (GitAPIException e) {
+				Logger.warn("Could not get log for git repository {}", repository.getRepositoryName());
+				throw new RuntimeException(e);
+			}
+		};
+
+	/**
+	 * List all commits reachable from a branch of the repository.
+	 * This is intended to be used as an argument for the {@code listCommits} argument of
+	 * {@link #Repository(RepositoryLocationType, Path, URI, String, Function<Repository, Iterator<RevCommit>>, PatchDiffParseOptions, DiffFilter)}.
+	 */
+	public static final Function<Repository, Iterator<RevCommit>> AllCommits =
+		(Repository repository) -> {
+			try {
+				return repository.getGitRepo().log().all().call().iterator();
+			} catch (GitAPIException | IOException e) {
+				Logger.warn("Could not get log for git repository {}", repository.getRepositoryName());
+				throw new RuntimeException(e);
+			}
+		};
+
 	/**
 	 * Creates a repository.
 	 * 
 	 * @param repoLocation {@link RepositoryLocationType} From which location the repository is read from
 	 * @param localPath The local path where the repository can be found or should be cloned to.
 	 * @param remote The remote url of the repository. May be <code>null</code> if local.
 	 * @param repositoryName Name of the cloned repository (<code>null</code> if local)
+	 * @param listCommits extracts the commits from {@link #getGitRepo()} that should be represented.
 	 * @param parseOptions Omit some debug data to save RAM.
 	 * @param diffFilter Filter determining which files and commits to consider for diffs.
 	 */
@@ -71,27 +108,38 @@ public Repository(
 			final Path localPath,
 			final URI remote,
 			final String repositoryName,
+			final Function<Repository, Iterator<RevCommit>> listCommits,
 			final PatchDiffParseOptions parseOptions,
 			final DiffFilter diffFilter) {
 		this.repoLocation = repoLocation;
 		this.localPath = localPath;
 		this.remote = remote;
 		this.repositoryName = repositoryName;
+		this.listCommits = listCommits;
 		this.parseOptions = parseOptions;
 		this.diffFilter = diffFilter;
 	}
 
 	/**
 	 * Creates repository of the given source and with all other settings set to default values.
 	 * @see Repository
+	 * <p>
+	 * Defaults to {@link #TraverseHEAD}, {@link PatchDiffParseOptions#Default} and {@link DiffFilter#ALLOW_ALL}.
 	 */
 	public Repository(
 			final RepositoryLocationType repoLocation,
 			final Path localPath,
 			final URI remote,
 			final String repositoryName) {
-		this(repoLocation, localPath, remote, repositoryName,
-                PatchDiffParseOptions.Default, DiffFilter.ALLOW_ALL);
+		this(
+			repoLocation,
+			localPath,
+			remote,
+			repositoryName,
+			TraverseHEAD,
+			PatchDiffParseOptions.Default,
+			DiffFilter.ALLOW_ALL
+		);
 	}
 
 	/**
@@ -251,12 +299,7 @@ public RevCommit getCommit(String commitHash) throws IOException {
 	 * Returns all commits in the repository's history.
 	 */
 	public Iterator<RevCommit> getCommits() {
-		try {
-			return getGitRepo().log().call().iterator();
-		} catch (GitAPIException e) {
-			Logger.warn("Could not get log for git repository {}", getRepositoryName());
-			throw new RuntimeException(e);
-		}
+		return listCommits.apply(this);
 	}
 
 	/**