Commit-level translator interface and command composition

src/main/java/jp/ac/titech/c/se/stein/Application.java

@@ -9,7 +9,6 @@
 import java.util.concurrent.Callable;
 import java.util.stream.Collectors;
 
-import jp.ac.titech.c.se.stein.rewriter.BlobTranslator;
 import jp.ac.titech.c.se.stein.app.Identity;
 import jp.ac.titech.c.se.stein.rewriter.RewriterCommand;
 import jp.ac.titech.c.se.stein.util.SettableHelpCommand;
@@ -292,7 +291,7 @@ public int execute(final ParseResult parseResult) throws ExecutionException, Par
                 .collect(Collectors.toList());
         if (conf.useComposite) {
             log.debug("Optimizing rewriters...");
-            commands = optimizeRewriters(commands);
+            commands = RewriterCommand.optimize(commands);
         }
         this.rewriters.addAll(prepareRewriters(commands));
 
@@ -307,35 +306,6 @@ public List<RepositoryRewriter> prepareRewriters(final List<RewriterCommand> com
         return commands.stream().map(RewriterCommand::toRewriter).collect(Collectors.toList());
     }
 
-    public List<RewriterCommand> optimizeRewriters(final List<RewriterCommand> commands) {
-        final List<RewriterCommand> result = new ArrayList<>();
-        final List<BlobTranslator> pending = new ArrayList<>();
-
-        for (final RewriterCommand cmd : commands) {
-            if (cmd instanceof BlobTranslator t) {
-                pending.add(t);
-            } else {
-                flushPendingTranslators(pending, result);
-                result.add(cmd);
-            }
-        }
-        flushPendingTranslators(pending, result);
-        return result;
-    }
-
-    private void flushPendingTranslators(final List<BlobTranslator> pending, final List<RewriterCommand> result) {
-        if (pending.isEmpty()) {
-            return;
-        }
-        if (pending.size() >= 2) {
-            log.info("Compose {} blob translators: {}", pending.size(), pending);
-            result.add(new BlobTranslator.Composite(pending));
-        } else {
-            result.add(new BlobTranslator.Single(pending.get(0)));
-        }
-        pending.clear();
-    }
-
     /**
      * Add all the command classes found in the given package as subcommands to the given commandline.
      */

src/main/java/jp/ac/titech/c/se/stein/app/Anonymize.java

@@ -14,6 +14,7 @@
 import org.eclipse.jgit.lib.PersonIdent;
 
 import jp.ac.titech.c.se.stein.core.Context;
+import jp.ac.titech.c.se.stein.rewriter.EntryResolver;
 import jp.ac.titech.c.se.stein.rewriter.RepositoryRewriter;
 import picocli.CommandLine.Command;
 import picocli.CommandLine.Option;
@@ -124,8 +125,8 @@ public AnyHotEntry rewriteBlobEntry(BlobEntry entry, final Context c) {
     }
 
     @Override
-    protected AnyColdEntry rewriteTreeEntry(TreeEntry entry, Context c) {
-        final AnyColdEntry result = super.rewriteTreeEntry(entry, c);
+    protected AnyColdEntry rewriteTreeEntry(TreeEntry entry, EntryResolver resolver, Context c) {
+        final AnyColdEntry result = super.rewriteTreeEntry(entry, resolver, c);
         if (isTreeNameEnabled && result instanceof Entry e) {
             return Entry.of(e.mode, treeNameMap.convert(e.name), e.id, e.directory);
         }

src/main/java/jp/ac/titech/c/se/stein/app/commit/NoteCommit.java

@@ -1,6 +1,8 @@
 package jp.ac.titech.c.se.stein.app.commit;
 
 import jp.ac.titech.c.se.stein.core.Context;
+import jp.ac.titech.c.se.stein.core.RepositoryAccess;
+import jp.ac.titech.c.se.stein.rewriter.CommitTranslator;
 import jp.ac.titech.c.se.stein.rewriter.RepositoryRewriter;
 import lombok.ToString;
 import lombok.extern.slf4j.Slf4j;
@@ -11,25 +13,31 @@
 import java.nio.charset.StandardCharsets;
 
 /**
- * Prepends the original commit ID (from Git notes) to each commit message.
- * If no note exists, the zero ID is used instead.
+ * Prepends the original commit ID to each commit message.
+ * If the source has notes (chained transformation), the original ID is read from the note.
+ * Otherwise, the current commit ID itself is used as the original.
  */
 @Slf4j
 @ToString
 @Command(name = "@note-commit", description = "Note original commit id on each commit message")
-public class NoteCommit extends RepositoryRewriter {
+public class NoteCommit implements CommitTranslator {
     @Option(names = "--length", paramLabel = "<num>", description = "length of SHA1 hash (default: ${DEFAULT-VALUE})")
     protected int length = 40;
 
     @Override
     public String rewriteCommitMessage(final String message, final Context c) {
+        final ObjectId originalId = resolveOriginalId(c);
+        return originalId.name().substring(0, length) + " " + message;
+    }
+
+    private ObjectId resolveOriginalId(final Context c) {
         final ObjectId current = c.getRev().getId();
-        final byte[] note = source.readNote(source.getDefaultNotes(), current);
+        final RepositoryAccess source = c.getRewriter().getSource();
+        final byte[] note = source.readNote(source.getNotes(RepositoryRewriter.R_NOTES_ORIG), current);
         if (note != null && note.length == 40) {
-            // use the commit note for the original commit id
-            return new String(note, StandardCharsets.UTF_8).substring(0, length) + " " + message;
-        }
-        // no note or no valid note: use the zero id
-        return RepositoryRewriter.ZERO.name().substring(0, length) + " " + message;
+            return ObjectId.fromString(new String(note, StandardCharsets.UTF_8));
+        } else {
+            return current;
+            }
     }
 }

src/main/java/jp/ac/titech/c/se/stein/app/commit/SvnMetadata.java

@@ -16,7 +16,7 @@
 import org.eclipse.jgit.revwalk.RevCommit;
 
 import jp.ac.titech.c.se.stein.core.Context;
-import jp.ac.titech.c.se.stein.rewriter.RepositoryRewriter;
+import jp.ac.titech.c.se.stein.rewriter.CommitTranslator;
 import jp.ac.titech.c.se.stein.core.Try;
 import picocli.CommandLine.Command;
 import picocli.CommandLine.Option;
@@ -29,7 +29,7 @@
 @Slf4j
 @ToString
 @Command(name = "@svn-metadata", description = "Attach metadata obtained from svn2git")
-public class SvnMetadata extends RepositoryRewriter {
+public class SvnMetadata implements CommitTranslator {
     @Option(names = "--svn-mapping", paramLabel = "<log-git-repository>", description = "svn mapping",
             required = true)
     protected Path svnMappingFile;
@@ -41,12 +41,12 @@ public class SvnMetadata extends RepositoryRewriter {
     protected Map<ObjectId, Integer> mapping;
 
     @Override
-    protected void setUp(final Context c) {
+    public void setUp(final Context c) {
         mapping = Try.io(() -> collectCommitMapping(svnMappingFile, objectMappingFile));
     }
 
     @Override
-    protected String rewriteCommitMessage(final String message, final Context c) {
+    public String rewriteCommitMessage(final String message, final Context c) {
         final RevCommit commit = c.getCommit();
         final Integer svnId = mapping.get(commit.getId());
         if (svnId != null) {

src/main/java/jp/ac/titech/c/se/stein/core/Context.java

@@ -10,6 +10,7 @@
 import java.util.stream.Stream;
 
 import jp.ac.titech.c.se.stein.Application;
+import jp.ac.titech.c.se.stein.rewriter.RepositoryRewriter;
 import org.eclipse.jgit.lib.ObjectInserter;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.revwalk.RevCommit;
@@ -31,7 +32,7 @@ public class Context implements Map<Context.Key, Object> {
      * The keys that can be stored in a context.
      */
     public enum Key {
-        commit, path, entry, rev, tag, ref, conf, inserter;
+        commit, path, entry, rev, tag, ref, conf, inserter, rewriter;
 
         public static final Key[] ALL = Key.values();
         public static final int SIZE = ALL.length;
@@ -230,4 +231,11 @@ public Application.Config getConfig() {
     public ObjectInserter getInserter() {
         return (ObjectInserter) get(Key.inserter);
     }
+
+    /**
+     * Returns the rewriter, or {@code null} if not set.
+     */
+    public RepositoryRewriter getRewriter() {
+        return (RepositoryRewriter) get(Key.rewriter);
+    }
 }

src/main/java/jp/ac/titech/c/se/stein/core/RepositoryAccess.java

@@ -35,8 +35,7 @@ public class RepositoryAccess implements AutoCloseable {
 
     public final Repository repo;
 
-    @Getter
-    protected final NoteMap defaultNotes;
+    private final Map<String, NoteMap> notesCache = new HashMap<>();
 
     protected boolean isDryRunning = false;
 
@@ -51,7 +50,6 @@ public void setDryRunning(final boolean isDryRunning) {
 
     public RepositoryAccess(final Repository repo) {
         this.repo = repo;
-        this.defaultNotes = readNotes();
     }
 
     @Override
@@ -388,7 +386,6 @@ public void writeNotes(final NoteMap notes, final String ref, final Context writ
         final ObjectId commit = writeCommit(NO_PARENTS, treeId, ident, ident, message, writingContext);
 
         applyRefUpdate(new RefEntry(ref, commit));
-
     }
 
     /**
@@ -403,10 +400,17 @@ public void forEachNote(final NoteMap notes, final BiConsumer<ObjectId, byte[]>
     }
 
     /**
-     * Reads notes from the default notes ref ({@code refs/notes/commits}).
+     * Returns the notes for the default ref ({@code refs/notes/commits}), reading lazily.
+     */
+    public NoteMap getDefaultNotes() {
+        return getNotes(Constants.R_NOTES_COMMITS);
+    }
+
+    /**
+     * Returns the notes for the specified ref, reading lazily and caching the result.
      */
-    public NoteMap readNotes() {
-        return readNotes(Constants.R_NOTES_COMMITS);
+    public NoteMap getNotes(final String noteRef) {
+        return notesCache.computeIfAbsent(noteRef, this::readNotes);
     }
 
     /**

src/main/java/jp/ac/titech/c/se/stein/rewriter/BlobTranslator.java

@@ -24,6 +24,14 @@ static BlobTranslator of(Function<String, String> f) {
         return (entry, c) -> entry.update(f.apply(entry.getContent()));
     }
 
+    static BlobTranslator composite(BlobTranslator... translators) {
+        return new Composite(translators);
+    }
+
+    static BlobTranslator composite(List<BlobTranslator> translators) {
+        return new Composite(translators);
+    }
+
     default RepositoryRewriter toRewriter() {
         return new Single(this);
     }
@@ -44,7 +52,7 @@ public AnyHotEntry rewriteBlobEntry(final BlobEntry entry, final Context c) {
     }
 
     @ToString
-    class Composite extends RepositoryRewriter {
+    class Composite implements BlobTranslator {
         BlobTranslator[] translators;
 
         public Composite(BlobTranslator... translators) {