[Backport 2.19-dev] Return comparable LinkedHashMap in valueForCalcite() of ExprTupleValue

core/src/main/java/org/opensearch/sql/data/model/ExprTupleValue.java

@@ -14,6 +14,7 @@
 import lombok.RequiredArgsConstructor;
 import org.opensearch.sql.data.type.ExprCoreType;
 import org.opensearch.sql.data.type.ExprType;
+import org.opensearch.sql.data.utils.ComparableLinkedHashMap;
 import org.opensearch.sql.storage.bindingtuple.BindingTuple;
 import org.opensearch.sql.storage.bindingtuple.LazyBindingTuple;
 
@@ -44,7 +45,7 @@ public Object value() {
 
   @Override
   public Object valueForCalcite() {
-    LinkedHashMap<String, Object> resultMap = new LinkedHashMap<>();
+    ComparableLinkedHashMap<String, Object> resultMap = new ComparableLinkedHashMap<>();
     for (Entry<String, ExprValue> entry : valueMap.entrySet()) {
       resultMap.put(entry.getKey(), entry.getValue().valueForCalcite());
     }

core/src/main/java/org/opensearch/sql/data/utils/ComparableLinkedHashMap.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.data.utils;
+
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+public class ComparableLinkedHashMap<K, V> extends LinkedHashMap<K, V>
+    implements Comparable<ComparableLinkedHashMap<K, V>> {
+
+  public ComparableLinkedHashMap() {
+    super();
+  }
+
+  public ComparableLinkedHashMap(int initialCapacity) {
+    super(initialCapacity);
+  }
+
+  public ComparableLinkedHashMap(int initialCapacity, float loadFactor) {
+    super(initialCapacity, loadFactor);
+  }
+
+  @Override
+  public int compareTo(ComparableLinkedHashMap<K, V> other) {
+    if (this.isEmpty() && other.isEmpty()) return 0;
+    if (this.isEmpty()) return -1;
+    if (other.isEmpty()) return 1;
+    Iterator<Map.Entry<K, V>> thisIterator = this.entrySet().iterator();
+    Iterator<Map.Entry<K, V>> otherIterator = other.entrySet().iterator();
+    return compareRecursive(thisIterator, otherIterator);
+  }
+
+  private int compareRecursive(
+      Iterator<Map.Entry<K, V>> thisIterator, Iterator<Map.Entry<K, V>> otherIterator) {
+    boolean thisHasNext = thisIterator.hasNext();
+    boolean otherHasNext = otherIterator.hasNext();
+    if (!thisHasNext && !otherHasNext) return 0;
+    if (!thisHasNext) return -1;
+    if (!otherHasNext) return 1;
+
+    V thisValue = thisIterator.next().getValue();
+    V otherValue = otherIterator.next().getValue();
+    int comparison = compareValues(thisValue, otherValue);
+    if (comparison != 0) return comparison;
+    return compareRecursive(thisIterator, otherIterator);
+  }
+
+  @SuppressWarnings("unchecked")
+  private int compareValues(V value1, V value2) {
+    if (value1 == null && value2 == null) return 0;
+    if (value1 == null) return -1;
+    if (value2 == null) return 1;
+    if (value1 instanceof Comparable) {
+      return ((Comparable<V>) value1).compareTo(value2);
+    }
+    return value1.toString().compareTo(value2.toString());
+  }
+}

core/src/test/java/org/opensearch/sql/utils/ComparableLinkedHashMapTest.java

@@ -0,0 +1,258 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.utils;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Comparator;
+import java.util.Iterator;
+import java.util.TreeSet;
+import org.junit.jupiter.api.Test;
+import org.opensearch.sql.data.utils.ComparableLinkedHashMap;
+
+public class ComparableLinkedHashMapTest {
+
+  @Test
+  public void testEmptyMaps() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+
+    assertEquals(0, map1.compareTo(map2));
+  }
+
+  @Test
+  public void testOneEmptyMap() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("a", 1);
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testEqualMaps() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 1);
+    map2.put("d", 2);
+
+    assertEquals(0, map1.compareTo(map2));
+  }
+
+  @Test
+  public void testDifferentFirstValue() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 3);
+    map2.put("d", 2);
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testDifferentLaterValue() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+    map1.put("c", 3);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("d", 1);
+    map2.put("e", 3);
+    map2.put("f", 3);
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testDifferentSizes() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 1);
+
+    assertTrue(map1.compareTo(map2) > 0);
+    assertTrue(map2.compareTo(map1) < 0);
+  }
+
+  @Test
+  public void testNullValues() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", null);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 1);
+    map2.put("d", 2);
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+
+    ComparableLinkedHashMap<String, Integer> map3 = new ComparableLinkedHashMap<>();
+    map3.put("e", null);
+    map3.put("f", 2);
+
+    assertEquals(0, map1.compareTo(map3));
+  }
+
+  @Test
+  public void testCustomObjects() {
+    class Person {
+      String name;
+
+      Person(String name) {
+        this.name = name;
+      }
+
+      @Override
+      public String toString() {
+        return name;
+      }
+    }
+
+    ComparableLinkedHashMap<String, Person> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", new Person("Alice"));
+    map1.put("b", new Person("Bob"));
+
+    ComparableLinkedHashMap<String, Person> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", new Person("Alice"));
+    map2.put("d", new Person("Charlie"));
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testMixedTypes() {
+    ComparableLinkedHashMap<String, Object> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", "test");
+
+    ComparableLinkedHashMap<String, Object> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 1);
+    map2.put("d", "test");
+
+    assertEquals(0, map1.compareTo(map2));
+
+    ComparableLinkedHashMap<String, Object> map3 = new ComparableLinkedHashMap<>();
+    map3.put("e", 1);
+    map3.put("f", "test2");
+
+    assertTrue(map1.compareTo(map3) < 0);
+    assertTrue(map3.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testWithTreeSet() {
+    TreeSet<ComparableLinkedHashMap<String, Integer>> set = new TreeSet<>();
+
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 1);
+    map2.put("d", 3);
+
+    ComparableLinkedHashMap<String, Integer> map3 = new ComparableLinkedHashMap<>();
+    map3.put("e", 0);
+    map3.put("f", 4);
+
+    set.add(map2);
+    set.add(map1);
+    set.add(map3);
+
+    Iterator<ComparableLinkedHashMap<String, Integer>> iterator = set.iterator();
+    ComparableLinkedHashMap<String, Integer> first = iterator.next();
+    ComparableLinkedHashMap<String, Integer> second = iterator.next();
+    ComparableLinkedHashMap<String, Integer> third = iterator.next();
+
+    assertEquals(Integer.valueOf(0), first.get("e"));
+    assertEquals(Integer.valueOf(4), first.get("f"));
+
+    assertEquals(Integer.valueOf(1), second.get("a"));
+    assertEquals(Integer.valueOf(2), second.get("b"));
+
+    assertEquals(Integer.valueOf(1), third.get("c"));
+    assertEquals(Integer.valueOf(3), third.get("d"));
+
+    assertEquals(3, set.size());
+  }
+
+  @Test
+  public void testWithComparator() {
+    Comparator<ComparableLinkedHashMap<String, Integer>> comparator =
+        ComparableLinkedHashMap::compareTo;
+
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 5);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("b", 3);
+
+    assertTrue(comparator.compare(map1, map2) > 0);
+    assertTrue(comparator.compare(map2, map1) < 0);
+  }
+
+  @Test
+  public void testEqualValuesDifferentKeys() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+    map1.put("c", 3);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("d", 1);
+    map2.put("e", 2);
+    map2.put("f", 3);
+
+    assertEquals(0, map1.compareTo(map2));
+  }
+
+  @Test
+  public void testDifferentOrder() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    map1.put("a", 1);
+    map1.put("b", 2);
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    map2.put("c", 2);
+    map2.put("d", 1);
+
+    assertTrue(map1.compareTo(map2) < 0);
+    assertTrue(map2.compareTo(map1) > 0);
+  }
+
+  @Test
+  public void testLargeMaps() {
+    ComparableLinkedHashMap<String, Integer> map1 = new ComparableLinkedHashMap<>();
+    for (int i = 0; i < 100; i++) {
+      map1.put("key" + i, i);
+    }
+
+    ComparableLinkedHashMap<String, Integer> map2 = new ComparableLinkedHashMap<>();
+    for (int i = 0; i < 100; i++) {
+      map2.put("differentKey" + i, i);
+    }
+
+    assertEquals(0, map1.compareTo(map2));
+
+    map2.put("differentKey99", 100);
+    assertTrue(map1.compareTo(map2) < 0);
+  }
+}