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.calcite.avatica.util;
  
  import java.lang.reflect.Field;
  import java.sql.SQLException;
  import java.util.List;
  import java.util.Map;
  
  /**
   * Abstract implementation of {@link org.apache.calcite.avatica.util.Cursor}
   * that caches its current row.
   *
   * @param <T> Element type
   */
  public abstract class PositionedCursor<T> extends AbstractCursor {
    /**
     * Returns the current row.
     *
     * @return current row
     *
     * @throws java.util.NoSuchElementException if the iteration has no more
     * elements
     */
    protected abstract T current();
  
    /** Implementation of
     * {@link org.apache.calcite.avatica.util.AbstractCursor.Getter}
     * that reads from records that are arrays. */
    protected class ArrayGetter extends AbstractGetter {
      protected final int field;
  
      public ArrayGetter(int field) {
        this.field = field;
      }
  
      public Object getObject() throws SQLException {
        Object collection;
        Object o;
        try {
          collection = current();
  
          if (collection instanceof List) {
            o = ((List) collection).get(field);
          } else if (collection instanceof StructImpl) {
            o = ((StructImpl) collection).getAttributes()[field];
          } else {
            o = ((Object[]) collection)[field];
          }
        } catch (RuntimeException e) {
          throw new SQLException(e);
        }
        wasNull[0] = o == null;
        return o;
      }
    }
  
    /** Implementation of
     * {@link org.apache.calcite.avatica.util.AbstractCursor.Getter}
     * that reads items from a list. */
    protected class ListGetter extends AbstractGetter {
      protected final int index;
  
      public ListGetter(int index) {
        this.index = index;
      }
  
      public Object getObject() throws SQLException {
        Object o;
        try {
          o = ((List) current()).get(index);
        } catch (RuntimeException e) {
          throw new SQLException(e);
        }
        wasNull[0] = o == null;
        return o;
      }
    }
  
    /** Implementation of
     * {@link org.apache.calcite.avatica.util.AbstractCursor.Getter}
     * for records that consist of a single field.
     *
     * <p>Each record is represented as an object, and the value of the sole
     * field is that object. */
    protected class ObjectGetter extends AbstractGetter {
      public ObjectGetter(int field) {
        assert field == 0;
      }
  
      public Object getObject() throws SQLException {
        Object o;
        try {
          o = current();
        } catch (RuntimeException e) {
          throw new SQLException(e);
        }
        wasNull[0] = o == null;
        return o;
      }
    }
  
    /** Implementation of
     * {@link org.apache.calcite.avatica.util.AbstractCursor.Getter}
     * that reads fields via reflection. */
    protected class FieldGetter extends AbstractGetter {
      protected final Field field;
  
      public FieldGetter(Field field) {
        this.field = field;
      }
  
      public Object getObject() throws SQLException {
        Object o;
        try {
          o = field.get(current());
        } catch (IllegalAccessException | RuntimeException e) {
          throw new SQLException(e);
        }
        wasNull[0] = o == null;
        return o;
      }
    }
  
    /** Implementation of
     * {@link org.apache.calcite.avatica.util.AbstractCursor.Getter}
     * that reads entries from a {@link java.util.Map}.
     * @param <K> the key type */
    protected class MapGetter<K> extends AbstractGetter {
      protected final K key;
  
      public MapGetter(K key) {
        this.key = key;
      }
  
      public Object getObject() throws SQLException {
        Object o;
        try {
          @SuppressWarnings("unchecked") final Map<K, Object> map =
              (Map<K, Object>) current();
          o = map.get(key);
        } catch (RuntimeException e) {
          throw new SQLException(e);
        }
        wasNull[0] = o == null;
        return o;
      }
    }
  }
  
  // End PositionedCursor.java
  