ReflectiveCallNotNullImplementor.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.calcite.adapter.enumerable;

import org.apache.calcite.linq4j.tree.Expression;
import org.apache.calcite.linq4j.tree.Expressions;
import org.apache.calcite.rex.RexCall;

import java.lang.reflect.Method;
import java.util.List;

import static org.apache.calcite.util.ReflectUtil.isStatic;

/**
 * Implementation of
 * {@link org.apache.calcite.adapter.enumerable.NotNullImplementor}
 * that calls a given {@link java.lang.reflect.Method}.
 *
 * <p>When method is not static, a new instance of the required class is
 * created.
 */
public class ReflectiveCallNotNullImplementor implements NotNullImplementor {
  protected final Method method;

  /**
   * Constructor of {@link ReflectiveCallNotNullImplementor}.
   *
   * @param method Method that is used to implement the call
   */
  public ReflectiveCallNotNullImplementor(Method method) {
    this.method = method;
  }

  @Override public Expression implement(RexToLixTranslator translator,
      RexCall call, List<Expression> translatedOperands) {
    translatedOperands =
        EnumUtils.fromInternal(method.getParameterTypes(), translatedOperands);
    translatedOperands =
        EnumUtils.convertAssignableTypes(method.getParameterTypes(), translatedOperands);
    final Expression callExpr;
    if (isStatic(method)) {
      callExpr = Expressions.call(method, translatedOperands);
    } else {
      final Expression target =
          translator.functionInstance(call, method);
      callExpr = Expressions.call(target, method, translatedOperands);
    }
    if (!containsCheckedException(method)) {
      return callExpr;
    }
    return translator.handleMethodCheckedExceptions(callExpr);
  }

  private static boolean containsCheckedException(Method method) {
    Class[] exceptions = method.getExceptionTypes();
    if (exceptions == null || exceptions.length == 0) {
      return false;
    }
    for (Class clazz : exceptions) {
      if (!RuntimeException.class.isAssignableFrom(clazz)) {
        return true;
      }
    }
    return false;
  }
}