code: /*
   * 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.skywalking.oap.query.graphql.mqe.rt.operation;
  
  import java.math.BigDecimal;
  import java.math.RoundingMode;
  import java.util.function.Function;
  import org.apache.skywalking.mqe.rt.grammar.MQEParser;
  import org.apache.skywalking.oap.query.graphql.mqe.rt.exception.IllegalExpressionException;
  import org.apache.skywalking.oap.query.graphql.type.mql.ExpressionResult;
  
  public class FunctionOp {
      public static ExpressionResult doFunction0Op(ExpressionResult expResult,
                                                   int opType) throws IllegalExpressionException {
          switch (opType) {
              case MQEParser.ABS:
                  return FunctionOp.transResult(expResult, Math::abs);
              case MQEParser.CEIL:
                  return FunctionOp.transResult(expResult, Math::ceil);
              case MQEParser.FLOOR:
                  return FunctionOp.transResult(expResult, Math::floor);
          }
  
          throw new IllegalExpressionException("Unsupported function.");
      }
  
      public static ExpressionResult doFunction1Op(ExpressionResult expResult,
                                                   int opType,
                                                   int scale) throws IllegalExpressionException {
          switch (opType) {
              case MQEParser.ROUND:
                  return FunctionOp.transResult(expResult, aDouble -> {
                      BigDecimal bd = BigDecimal.valueOf(aDouble);
                      return bd.setScale(scale, RoundingMode.HALF_UP).doubleValue();
                  });
          }
  
          throw new IllegalExpressionException("Unsupported function.");
      }
  
      private static ExpressionResult transResult(ExpressionResult expResult, Function<Double, Double> calculator) {
          expResult.getResults().forEach(resultValues -> {
              resultValues.getValues().forEach(mqeValue -> {
                  if (!mqeValue.isEmptyValue()) {
                      double newValue = calculator.apply(mqeValue.getDoubleValue());
                      mqeValue.setDoubleValue(newValue);
                  }
              });
          });
          return expResult;
      }
  }
  