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/*
 * 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 com.hazelcast.org.apache.calcite.runtime;

import com.hazelcast.org.apache.calcite.DataContext;
import com.hazelcast.org.apache.calcite.rel.metadata.NullSentinel;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeFactory;
import com.hazelcast.org.apache.calcite.schema.FunctionContext;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Runtime support for {@link com.hazelcast.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 com.hazelcast.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  @Nullable V getArgumentValueAs(int ordinal,
        Class 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);
    }
  }
}