refactor and unify outputs of Store.list

Author: brokkoli71

src/main/java/dev/zarr/zarrjava/core/Group.java

@@ -64,7 +64,12 @@ public static Group open(String path) throws IOException, ZarrException {
     }
 
     @Nullable
-    public abstract Node get(String key) throws ZarrException, IOException;
+    public abstract Node get(String[] key) throws ZarrException, IOException;
+
+    @Nullable
+    public Node get(String key) throws ZarrException, IOException {
+        return get(new String[]{key});
+    }
 
     public Stream<Node> list() {
         return storeHandle.list()

src/main/java/dev/zarr/zarrjava/store/FilesystemStore.java

@@ -120,10 +120,16 @@ public void delete(String[] keys) {
       throw new RuntimeException(e);
     }
   }
-
-  public Stream<String> list(String[] keys) {
+  public Stream<String[]> list(String[] keys) {
     try {
-      return Files.list(resolveKeys(keys)).map(p -> p.toFile().getName());
+      return Files.list(resolveKeys(keys)).map(path -> {
+        Path relativePath = resolveKeys(keys).relativize(path);
+        String[] parts = new String[relativePath.getNameCount()];
+        for (int i = 0; i < relativePath.getNameCount(); i++) {
+          parts[i] = relativePath.getName(i).toString();
+        }
+        return parts;
+      });
     } catch (IOException e) {
       throw new RuntimeException(e);
     }

src/main/java/dev/zarr/zarrjava/store/MemoryStore.java

@@ -59,19 +59,18 @@ public void delete(String[] keys) {
     map.remove(resolveKeys(keys));
   }
 
-  public Stream<String> list(String[] keys) {
-    List<String> prefix = resolveKeys(keys);
-    Set<String> allKeys = new HashSet<>();
+  public Stream<String[]> list(String[] keys) {
+      List<String> prefix = resolveKeys(keys);
+      Set<List<String>> allKeys = new HashSet<>();
 
-    for (List<String> k : map.keySet()) {
-      if (k.size() <= prefix.size() || ! k.subList(0, prefix.size()).equals(prefix))
-        continue;
-      for (int i = 0; i < k.size(); i++) {
-        List<String> subKey = k.subList(0, i+1);
-        allKeys.add(String.join("/", subKey));
+      for (List<String> k : map.keySet()) {
+          if (k.size() <= prefix.size() || ! k.subList(0, prefix.size()).equals(prefix))
+              continue;
+          for (int i = prefix.size(); i < k.size(); i++) {
+              allKeys.add(k.subList(0, i+1));
+          }
       }
-    }
-    return allKeys.stream();
+      return allKeys.stream().map(k -> k.toArray(new String[0]));
   }
 
   @Nonnull

src/main/java/dev/zarr/zarrjava/store/S3Store.java

@@ -104,15 +104,15 @@ public void delete(String[] keys) {
   }
 
   @Override
-  public Stream<String> list(String[] keys) {
+  public Stream<String[]> list(String[] keys) {
     final String fullKey = resolveKeys(keys);
     ListObjectsRequest req = ListObjectsRequest.builder()
     .bucket(bucketName).prefix(fullKey)
     .build();
     ListObjectsResponse res = s3client.listObjects(req);
     return res.contents()
         .stream()
-        .map(p -> p.key().substring(fullKey.length() + 1));
+        .map(p -> p.key().substring(fullKey.length() + 1).split("/"));
   }
 
   @Nonnull

src/main/java/dev/zarr/zarrjava/store/Store.java

@@ -27,6 +27,19 @@ public interface Store {
 
   interface ListableStore extends Store {
 
-    Stream<String> list(String[] keys);
+  /**
+   * Lists all keys in the store that match the given prefix keys. Keys are represented as arrays of strings,
+   * where each string is a segment of the key path.
+   * Keys that are exactly equal to the prefix are not included in the results.
+   * Keys that do not contain data (i.e. "directories") are included in the results.
+   *
+   * @param keys The prefix keys to match.
+   * @return A stream of key arrays that match the given prefix. Prefixed keys are not included in the results.
+   */
+    Stream<String[]> list(String[] keys);
+
+    default Stream<String[]> list() {
+        return list(new String[]{});
+    }
   }
 }

src/main/java/dev/zarr/zarrjava/store/StoreHandle.java

@@ -56,7 +56,7 @@ public boolean exists() {
     return store.exists(keys);
   }
 
-  public Stream<String> list() {
+  public Stream<String[]> list() {
     if (!(store instanceof Store.ListableStore)) {
       throw new UnsupportedOperationException("The underlying store does not support listing.");
     }

src/main/java/dev/zarr/zarrjava/v2/Group.java

@@ -169,7 +169,7 @@ public static Group create(String path, Attributes attributes) throws IOExceptio
    * @throws IOException if there is an error accessing the storage
    */
   @Nullable
-  public Node get(String key) throws ZarrException, IOException {
+  public Node get(String[] key) throws ZarrException, IOException {
     StoreHandle keyHandle = storeHandle.resolve(key);
     try {
       return Node.open(keyHandle);

src/main/java/dev/zarr/zarrjava/v3/Group.java

@@ -182,7 +182,7 @@ public static Group create(String path) throws IOException, ZarrException {
    * @throws IOException if there is an error accessing the storage
    */
   @Nullable
-  public Node get(String key) throws ZarrException, IOException{
+  public Node get(String[] key) throws ZarrException, IOException{
     StoreHandle keyHandle = storeHandle.resolve(key);
     try {
       return Node.open(keyHandle);

src/test/java/dev/zarr/zarrjava/ZarrStoreTest.java

@@ -123,7 +123,7 @@ public void testMemoryStoreV2(boolean useParallel) throws ZarrException, IOExcep
         dev.zarr.zarrjava.v2.Array array = group.createArray("array", b -> b
                 .withShape(1024, 1024)
                 .withDataType(dev.zarr.zarrjava.v2.DataType.UINT32)
-                .withChunks(5, 5)
+                .withChunks(512, 512)
         );
         array.write(ucar.ma2.Array.factory(ucar.ma2.DataType.UINT, new int[]{1024, 1024}, testData), useParallel);
         group.createGroup("subgroup");
@@ -195,7 +195,7 @@ Group writeTestGroupV3(Store store, boolean useParallel) throws ZarrException, I
         return group;
     }
 
-    void assertIsTestGroupV3(Group group, boolean useParallel) throws ZarrException {
+    void assertIsTestGroupV3(Group group, boolean useParallel) throws ZarrException, IOException {
         Stream<dev.zarr.zarrjava.core.Node> nodes = group.list();
         Assertions.assertEquals(2, nodes.count());
         Array array = (Array) group.get("array");