[GitHub] [iceberg] singhpk234 commented on a diff in pull request #4947: API: Add expression equivalence testing

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

singhpk234 commented on code in PR #4947:
URL: https://github.com/apache/iceberg/pull/4947#discussion_r888645022


##########
api/src/main/java/org/apache/iceberg/expressions/BoundLiteralPredicate.java:
##########
@@ -76,6 +86,53 @@ public boolean test(T value) {
     }
   }
 
+  @Override
+  @SuppressWarnings("unchecked")
+  public boolean isEquivalentTo(Expression expr) {
+    if (op() == expr.op()) {
+      BoundLiteralPredicate<?> other = (BoundLiteralPredicate<?>) expr;
+      if (term().isEquivalentTo(other.term())) {
+        // because the term is equivalent, the literal must have the same type, T
+        Literal<T> otherLiteral = (Literal<T>) other.literal();
+        Comparator<T> cmp = literal.comparator();
+        return cmp.compare(literal.value(), otherLiteral.value()) == 0;
+      }
+
+    } else if (expr instanceof BoundLiteralPredicate) {
+      BoundLiteralPredicate<?> other = (BoundLiteralPredicate<?>) expr;
+      if (INTEGRAL_TYPES.contains(term().type().typeId()) && term().isEquivalentTo(other.term())) {
+        switch (op()) {
+          case LT:
+            if (other.op() == Operation.LT_EQ) {
+              // < 6 is equivalent to <= 5
+              return toLong(literal()) == toLong(other.literal()) + 1L;
+            }
+            break;
+          case LT_EQ:
+            if (other.op() == Operation.LT) {
+              // <= 5 is equivalent to < 6
+              return toLong(literal()) == toLong(other.literal()) - 1L;
+            }
+            break;
+          case GT:
+            if (other.op() == Operation.GT_EQ) {
+              // > 5 is equivalent to >= 6
+              return toLong(literal()) == toLong(other.literal()) - 1L;
+            }
+            break;
+          case GT_EQ:
+            if (other.op() == Operation.GT) {
+              // >= 5 is equivalent to > 5

Review Comment:
   [minor] should this be > 4
   ```suggestion
                 // >= 5 is equivalent to > 4
   ```



##########
api/src/main/java/org/apache/iceberg/expressions/BoundTransform.java:
##########
@@ -57,6 +57,18 @@ public Type type() {
     return transform.getResultType(ref.type());
   }
 
+  @Override
+  public boolean isEquivalentTo(BoundTerm<?> other) {
+    if (other instanceof BoundTransform) {
+      BoundTransform<?, ?> bound = (BoundTransform<?, ?>) other;
+      return ref.isEquivalentTo(bound.ref()) && transform.equals(((BoundTransform<?, ?>) other).transform());

Review Comment:
   [minor] 
   ```suggestion
         return ref.isEquivalentTo(bound.ref()) && transform.equals(bound.transform());
   ```



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