refactor(dqe): remove deprecated ExpressionEvaluator and old FilterOperator BiFunction path

Author: penghuo

dqe/src/main/java/org/opensearch/sql/dqe/operator/FilterOperator.java

@@ -8,43 +8,27 @@
 import io.trino.spi.Page;
 import io.trino.spi.block.Block;
 import io.trino.spi.type.BooleanType;
-import java.util.function.BiFunction;
 import org.opensearch.sql.dqe.function.expression.BlockExpression;
 
 /**
- * Physical operator that filters rows based on a predicate. Supports two modes: a row-at-a-time
- * BiFunction predicate (legacy) and a vectorized BlockExpression predicate (new).
+ * Physical operator that filters rows based on a vectorized {@link BlockExpression} predicate.
  *
  * <p>Uses Trino's {@link Page#copyPositions(int[], int, int)} for efficient row selection.
  */
 public class FilterOperator implements Operator {
 
   private final Operator source;
-  private final BiFunction<Page, Integer, Boolean> predicate;
-  private final BlockExpression blockPredicate;
-
-  /**
-   * Create a FilterOperator with a row-at-a-time predicate.
-   *
-   * @param source child operator providing input pages
-   * @param predicate function that receives (page, position) and returns true to keep the row
-   */
-  public FilterOperator(Operator source, BiFunction<Page, Integer, Boolean> predicate) {
-    this.source = source;
-    this.predicate = predicate;
-    this.blockPredicate = null;
-  }
+  private final BlockExpression predicate;
 
   /**
    * Create a FilterOperator with a vectorized BlockExpression predicate.
    *
    * @param source child operator providing input pages
-   * @param blockPredicate expression that produces a BOOLEAN Block for filtering
+   * @param predicate expression that produces a BOOLEAN Block for filtering
    */
-  public FilterOperator(Operator source, BlockExpression blockPredicate) {
+  public FilterOperator(Operator source, BlockExpression predicate) {
     this.source = source;
-    this.predicate = null;
-    this.blockPredicate = blockPredicate;
+    this.predicate = predicate;
   }
 
   @Override
@@ -59,18 +43,10 @@ public Page processNextBatch() {
       int[] selectedPositions = new int[positionCount];
       int selectedCount = 0;
 
-      if (blockPredicate != null) {
-        Block filterResult = blockPredicate.evaluate(page);
-        for (int pos = 0; pos < positionCount; pos++) {
-          if (!filterResult.isNull(pos) && BooleanType.BOOLEAN.getBoolean(filterResult, pos)) {
-            selectedPositions[selectedCount++] = pos;
-          }
-        }
-      } else {
-        for (int pos = 0; pos < positionCount; pos++) {
-          if (predicate.apply(page, pos)) {
-            selectedPositions[selectedCount++] = pos;
-          }
+      Block filterResult = predicate.evaluate(page);
+      for (int pos = 0; pos < positionCount; pos++) {
+        if (!filterResult.isNull(pos) && BooleanType.BOOLEAN.getBoolean(filterResult, pos)) {
+          selectedPositions[selectedCount++] = pos;
         }
       }