hudi-common/src/main/java/org/apache/hudi/internal/schema/visitor/NameToPositionVisitor.java

/*
 * 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.hudi.internal.schema.visitor;

import org.apache.hudi.internal.schema.InternalSchema;
import org.apache.hudi.internal.schema.Type;
import org.apache.hudi.internal.schema.Types;

import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

import static org.apache.hudi.internal.schema.utils.InternalSchemaUtils.createFullName;

/**
 * Schema visitor to produce name -> position map for internalSchema. Positions are assigned in a depth-first manner.
 */
public class NameToPositionVisitor extends InternalSchemaVisitor<Map<String, Integer>> {
  private final Deque<String> fieldNames = new LinkedList<>();
  private final Map<String, Integer> nameToId = new HashMap<>();
  private final AtomicInteger position = new AtomicInteger(0);

  @Override
  public void beforeField(Types.Field field) {
    nameToId.put(createFullName(field.name(), fieldNames), position.getAndIncrement());
    fieldNames.push(field.name());
  }

  @Override
  public void afterField(Types.Field field) {
    fieldNames.pop();
  }

  @Override
  public void beforeArrayElement(Types.Field elementField) {
    nameToId.put(createFullName(InternalSchema.ARRAY_ELEMENT, fieldNames), position.getAndIncrement());
    fieldNames.push(elementField.name());
  }

  @Override
  public void afterArrayElement(Types.Field elementField) {
    fieldNames.pop();
  }

  @Override
  public void beforeMapKey(Types.Field keyField) {
    nameToId.put(createFullName(InternalSchema.MAP_KEY, fieldNames), position.getAndIncrement());
    fieldNames.push(keyField.name());
  }

  @Override
  public void afterMapKey(Types.Field keyField) {
    fieldNames.pop();
  }

  @Override
  public void beforeMapValue(Types.Field valueField) {
    nameToId.put(createFullName(InternalSchema.MAP_VALUE, fieldNames), position.getAndIncrement());
    fieldNames.push(valueField.name());
  }

  @Override
  public void afterMapValue(Types.Field valueField) {
    fieldNames.pop();
  }

  @Override
  public Map<String, Integer> schema(InternalSchema schema, Map<String, Integer> recordResult) {
    return nameToId;
  }

  @Override
  public Map<String, Integer> record(Types.RecordType record, List<Map<String, Integer>> fieldResults) {
    return nameToId;
  }

  @Override
  public Map<String, Integer> field(Types.Field field, Map<String, Integer> fieldResult) {
    return nameToId;
  }

  @Override
  public Map<String, Integer> array(Types.ArrayType array, Map<String, Integer> elementResult) {
    return nameToId;
  }

  @Override
  public Map<String, Integer> map(Types.MapType map, Map<String, Integer> keyResult, Map<String, Integer> valueResult) {
    return nameToId;
  }

  @Override
  public Map<String, Integer> primitive(Type.PrimitiveType primitive) {
    return nameToId;
  }
}