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.runtime;
  
  import org.apache.calcite.DataContext;
  import org.apache.calcite.rel.metadata.NullSentinel;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.schema.FunctionContext;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * Runtime support for {@link org.apache.calcite.schema.FunctionContext}.
   */
  public class FunctionContexts {
    private FunctionContexts() {
    }
  
    /** Creates a FunctionContext. */
    public static FunctionContext of(DataContext root, Object[] argumentValues) {
      return new FunctionContextImpl(root, argumentValues);
    }
  
    /** Implementation of {@link org.apache.calcite.schema.FunctionContext}. */
    private static class FunctionContextImpl implements FunctionContext {
      private final DataContext root;
      private final @Nullable Object[] argumentValues;
  
      FunctionContextImpl(DataContext root, @Nullable Object[] argumentValues) {
        this.root = root;
        this.argumentValues = argumentValues;
      }
  
      @Override public RelDataTypeFactory getTypeFactory() {
        return root.getTypeFactory();
      }
  
      @Override public int getParameterCount() {
        return argumentValues.length;
      }
  
      @Override public boolean isArgumentConstant(int ordinal) {
        return argumentValue(ordinal) != null;
      }
  
      private @Nullable Object argumentValue(int ordinal) {
        if (ordinal < 0 || ordinal >= argumentValues.length) {
          throw new IndexOutOfBoundsException("argument ordinal " + ordinal
              + " is out of range");
        }
        return argumentValues[ordinal];
      }
  
      @Override public <V> @Nullable V getArgumentValueAs(int ordinal,
          Class<V> valueClass) {
        final Object v = argumentValue(ordinal);
        if (v == null) {
          throw new IllegalArgumentException("value of argument " + ordinal
              + " is not constant");
        }
        if (v == NullSentinel.INSTANCE) {
          return null; // value is constant NULL
        }
        if (valueClass == String.class
            && !(v instanceof String)) {
          return valueClass.cast(v.toString());
        }
        return valueClass.cast(v);
      }
    }
  }
  