content: /*
   * 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.arrow.vector.util;
  
  import org.apache.arrow.vector.VectorSchemaRoot;
  import org.apache.arrow.vector.compare.TypeEqualsVisitor;
  
  /** Utility to append {@link org.apache.arrow.vector.VectorSchemaRoot}s with the same schema. */
  public class VectorSchemaRootAppender {
  
    /**
     * Appends a number of {@link VectorSchemaRoot}s.
     *
     * @param checkSchema if we need to check schema for the vector schema roots.
     * @param targetRoot the vector schema root to be appended.
     * @param rootsToAppend the vector schema roots to append.
     * @throws IllegalArgumentException throws if we need to check schema, and checking schema fails.
     */
    public static void append(
        boolean checkSchema, VectorSchemaRoot targetRoot, VectorSchemaRoot... rootsToAppend) {
      // create appenders
      VectorAppender[] appenders = new VectorAppender[targetRoot.getFieldVectors().size()];
      for (int i = 0; i < appenders.length; i++) {
        appenders[i] = new VectorAppender(targetRoot.getVector(i));
      }
  
      // create type checkers, if necessary
      TypeEqualsVisitor[] typeCheckers = null;
      if (checkSchema) {
        typeCheckers = new TypeEqualsVisitor[targetRoot.getFieldVectors().size()];
        for (int i = 0; i < typeCheckers.length; i++) {
          typeCheckers[i] =
              new TypeEqualsVisitor(
                  targetRoot.getVector(i), /* check name */ false, /* check meta data */ false);
        }
      }
  
      for (VectorSchemaRoot delta : rootsToAppend) {
        // check schema, if necessary
        if (checkSchema) {
          if (delta.getFieldVectors().size() != targetRoot.getFieldVectors().size()) {
            throw new IllegalArgumentException(
                "Vector schema roots have different numbers of child vectors.");
          }
          for (int i = 0; i < typeCheckers.length; i++) {
            if (!typeCheckers[i].equals(delta.getVector(i))) {
              throw new IllegalArgumentException("Vector schema roots have different schemas.");
            }
          }
        }
  
        // append child vectors.
        for (int i = 0; i < appenders.length; i++) {
          delta.getVector(i).accept(appenders[i], null);
        }
        targetRoot.setRowCount(targetRoot.getRowCount() + delta.getRowCount());
      }
    }
  
    /**
     * Appends a number of {@link VectorSchemaRoot}s. This method performs schema checking before
     * appending data.
     *
     * @param targetRoot the vector schema root to be appended.
     * @param rootsToAppend the vector schema roots to append.
     * @throws IllegalArgumentException throws if we need to check schema, and checking schema fails.
     */
    public static void append(VectorSchemaRoot targetRoot, VectorSchemaRoot... rootsToAppend) {
      append(true, targetRoot, rootsToAppend);
    }
  }
  