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.util.mapping;
  
  import java.util.Iterator;
  
  /**
   * Simple implementation of
   * {@link org.apache.calcite.util.mapping.Mappings.TargetMapping} where the
   * number of sources and targets are specified as constructor parameters, and you
   * just need to implement one method.
   */
  public abstract class AbstractTargetMapping
      extends Mappings.AbstractMapping
      implements Mapping {
    private final int sourceCount;
    private final int targetCount;
  
    protected AbstractTargetMapping(int sourceCount, int targetCount) {
      this.sourceCount = sourceCount;
      this.targetCount = targetCount;
    }
  
    @Override public int getSourceCount() {
      return sourceCount;
    }
  
    @Override public int getTargetCount() {
      return targetCount;
    }
  
    @Override public Mapping inverse() {
      return Mappings.invert(this);
    }
  
    @Override public int size() {
      return sourceCount;
    }
  
    @Override public void clear() {
      throw new UnsupportedOperationException();
    }
  
    @Override public MappingType getMappingType() {
      return MappingType.PARTIAL_FUNCTION;
    }
  
    @SuppressWarnings("method.invocation.invalid")
    @Override public Iterator<IntPair> iterator() {
      return new Iterator<IntPair>() {
        int source = -1;
        int target;
  
        {
          moveToNext();
        }
  
        private void moveToNext() {
          while (++source < sourceCount) {
            target = getTargetOpt(source);
            if (target >= 0) {
              break;
            }
          }
        }
  
        @Override public boolean hasNext() {
          return source < sourceCount;
        }
  
        @Override public IntPair next() {
          IntPair p = new IntPair(source, target);
          moveToNext();
          return p;
        }
  
        @Override public void remove() {
          throw new UnsupportedOperationException("remove");
        }
      };
    }
  
    @Override public abstract int getTargetOpt(int source);
  }
  