[GitHub] [iceberg] chenjunjiedada commented on a change in pull request #2651: Core: add checkShouldKeep for DeleteFilter

[GitBox <gi...@apache.org>]

chenjunjiedada commented on a change in pull request #2651:
URL: https://github.com/apache/iceberg/pull/2651#discussion_r642351720



##########
File path: api/src/main/java/org/apache/iceberg/io/CheckIterator.java
##########
@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.iceberg.io;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+
+/**
+ * An Iterator of {@link Optional} that checks a predicate for each item based on another Iterator.
+ * If predicate is true, the optional item has content, otherwise the optional is empty.
+ *
+ * @param <T> the type of objects of the dependent Iterator
+ */
+public abstract class CheckIterator<T> implements CloseableIterator<Optional<T>> {
+  private final Iterator<T> items;
+  private boolean closed;
+
+  protected CheckIterator(Iterator<T> items) {
+    this.items = items;
+    this.closed = false;
+  }
+
+  protected abstract boolean check(T item);
+
+  @Override
+  public boolean hasNext() {
+    boolean itemsHasNext = items.hasNext();
+    if (!itemsHasNext) {
+      close();
+    }
+
+    return !closed && itemsHasNext;
+  }
+
+  @Override
+  public Optional<T> next() {
+    if (!hasNext()) {
+      throw new NoSuchElementException();
+    }
+
+    T item = items.next();
+    return check(item) ? Optional.ofNullable(item) : Optional.empty();
+  }
+
+  @Override
+  public void close() {
+    if (!closed) {
+      try {
+        ((Closeable) items).close();

Review comment:
       Why not use CloseableIterable in ctor?




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