commit object caching, getParents

src/de/uni_passau/fim/seibt/gitwrapper/repo/Commit.java

 package de.uni_passau.fim.seibt.gitwrapper.repo;
 
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
+import java.util.function.Function;
 import java.util.logging.Logger;
+import java.util.stream.Collectors;
+
+import de.uni_passau.fim.seibt.gitwrapper.repo.GitWrapper.ExecRes;
 
 public class Commit {
 
     private static final Logger LOG = Logger.getLogger(Commit.class.getCanonicalName());
 
-    private Repository repo;
     private GitWrapper git;
+    private Repository repo;
 
     private String id;
 
-    public Commit(Repository repo, String id) {
-        this.repo = repo;
+    Commit(Repository repo, String id) {
         this.git = repo.getGit();
+        this.repo = repo;
         this.id = id;
     }
 
+    public List<Commit> getParents() {
+        Optional<ExecRes> revList = git.exec(repo.getDir(), "rev-list", "--parents", "-n", "1", id);
+        Function<ExecRes, List<Commit>> toParentsList = res -> {
+            String[] ids = res.output.split("\\s+");
+
+            LOG.fine(() -> String.format("Found %d parents for %s.", ids.length - 1, this));
+
+            return Arrays.stream(ids).skip(1).map(repo::getCommit).collect(Collectors.toList());
+        };
+
+        return revList.map(toParentsList).orElse(Collections.emptyList());
+    }
+
     public String getId() {
         return id;
     }

src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java

@@ -4,7 +4,9 @@ import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.function.Function;
@@ -26,6 +28,8 @@ public class Repository {
     private String url;
     private File dir;
 
+    private Map<String, Commit> commits;
+
     /**
      * Constructs a new {@link Repository}.
      *
@@ -46,6 +50,8 @@ public class Repository {
             LOG.log(Level.WARNING, e, () -> "Exception computing the canonical file for " + dir + ". Using the absolute file instead.");
             this.dir = dir.getAbsoluteFile();
         }
+
+        this.commits = new HashMap<>();
     }
 
     /**
@@ -60,12 +66,23 @@ public class Repository {
 
             LOG.fine(() -> String.format("Found %d merge commits in %s.", lines.length, this));
 
-            return Arrays.stream(lines).map(id -> new Commit(this, id)).collect(Collectors.toList());
+            return Arrays.stream(lines).map(this::getCommit).collect(Collectors.toList());
         };
 
         return revList.map(toCommitList).orElse(Collections.emptyList());
     }
 
+    /**
+     * Returns a {@link Commit} for the given id. The <code>id</code> is not checked for validity, this method
+     * only ensures that only one {@link Commit} object is created for every <code>id</code>.
+     *
+     * @param id the ID of the commit
+     * @return the {@link Commit}
+     */
+    public Commit getCommit(String id) {
+        return commits.computeIfAbsent(id, theID -> new Commit(this, theID));
+    }
+
     public GitWrapper getGit() {
         return git;
     }