streaming

Author: normanrz

TODO

@@ -6,7 +6,7 @@
 - Partial read
 + Write
 - Partial write
-- List iterator
++ List iterator
 + Codec Builder
 + Mutability (e.g. editing attributes, resizing)
 - Tests and docs

src/main/java/com/scalableminds/zarrjava/store/FilesystemStore.java

@@ -121,11 +121,9 @@ public void delete(String[] keys) {
     }
   }
 
-  public String[] list(String[] keys) {
-    try (Stream<Path> paths = Files.list(resolveKeys(keys))) {
-      return paths.map(p -> p.toFile()
-              .getName())
-          .toArray(String[]::new);
+  public Stream<String> list(String[] keys) {
+    try {
+      return Files.list(resolveKeys(keys)).map(p -> p.toFile().getName());
     } catch (IOException e) {
       throw new RuntimeException(e);
     }

src/main/java/com/scalableminds/zarrjava/store/S3Store.java

@@ -9,6 +9,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
+import java.util.stream.Stream;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -85,15 +86,12 @@ public void delete(String[] keys) {
   }
 
   @Override
-  public String[] list(String[] keys) {
+  public Stream<String> list(String[] keys) {
     final String fullKey = resolveKeys(keys);
     return s3client.listObjects(bucketName, fullKey)
         .getObjectSummaries()
         .stream()
-        .map(
-            p -> p.getKey()
-                .substring(fullKey.length() + 1))
-        .toArray(String[]::new);
+        .map(p -> p.getKey().substring(fullKey.length() + 1));
   }
 
   @Nonnull

src/main/java/com/scalableminds/zarrjava/store/Store.java

@@ -1,6 +1,8 @@
 package com.scalableminds.zarrjava.store;
 
+import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.util.stream.Stream;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -26,6 +28,6 @@ public interface Store {
 
   interface ListableStore extends Store {
 
-    String[] list(String[] keys);
+    Stream<String> list(String[] keys);
   }
 }

src/main/java/com/scalableminds/zarrjava/store/StoreHandle.java

@@ -3,6 +3,7 @@
 import com.scalableminds.zarrjava.utils.Utils;
 import java.nio.ByteBuffer;
 import java.nio.file.NoSuchFileException;
+import java.util.stream.Stream;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -54,7 +55,7 @@ public boolean exists() {
     return store.exists(keys);
   }
 
-  public String[] list() {
+  public Stream<String> list() {
     if (!(store instanceof Store.ListableStore)) {
       throw new UnsupportedOperationException("The underlying store does not support listing.");
     }

src/main/java/com/scalableminds/zarrjava/v3/Group.java

@@ -5,10 +5,10 @@
 import com.scalableminds.zarrjava.store.StoreHandle;
 import java.io.IOException;
 import java.nio.ByteBuffer;
-import java.util.Arrays;
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.Function;
+import java.util.stream.Stream;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
@@ -96,18 +96,23 @@ public Array createArray(String key, ArrayMetadata arrayMetadata)
       throws IOException, ZarrException {
     return Array.create(storeHandle.resolve(key), arrayMetadata);
   }
-
-  public Node[] list() {
-    return Arrays.stream(storeHandle.list())
+  
+  public Stream<Node> list() {
+    return storeHandle.list()
         .map(key -> {
           try {
             return get(key);
           } catch (ZarrException e) {
             throw new RuntimeException(e);
           }
         })
-        .filter(Objects::nonNull)
-        .toArray(Node[]::new);
+        .filter(Objects::nonNull);
+  }
+
+  public Node[] listAsArray() {
+    try (Stream<Node> nodeStream = list()) {
+      return nodeStream.toArray(Node[]::new);
+    }
   }
 
   private Group writeMetadata(GroupMetadata newGroupMetadata) throws IOException {

src/test/java/com/scalableminds/zarrjava/ZarrTest.java

@@ -142,7 +142,7 @@ public void testV3Group() throws IOException, ZarrException {
     );
     array.write(new long[]{2, 2}, ucar.ma2.Array.factory(ucar.ma2.DataType.UBYTE, new int[]{8, 8}));
 
-    assertArrayEquals(((Array) ((Group) group.list()[0]).list()[0]).metadata.chunkShape(),
+    assertArrayEquals(((Array) ((Group) group.listAsArray()[0]).listAsArray()[0]).metadata.chunkShape(),
         new int[]{5, 5});
   }