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.beam.sdk.extensions.sql.impl.cep;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexCall;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexLiteral;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexNode;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rex.RexPatternFieldRef;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.sql.SqlOperator;
  
  /**
   * A {@code CEPCall} instance represents an operation (node) that contains an operator and a list of
   * operands. It has the similar functionality as Calcite's {@code RexCall}.
   */
  public class CEPCall extends CEPOperation {
  
    private final CEPOperator operator;
    private final List<CEPOperation> operands;
  
    private CEPCall(CEPOperator operator, List<CEPOperation> operands) {
      this.operator = operator;
      this.operands = operands;
    }
  
    public CEPOperator getOperator() {
      return operator;
    }
  
    public List<CEPOperation> getOperands() {
      return operands;
    }
  
    public static CEPCall of(RexCall operation) {
      SqlOperator call = operation.getOperator();
      CEPOperator myOp = CEPOperator.of(call);
  
      ArrayList<CEPOperation> operandsList = new ArrayList<>();
      for (RexNode i : operation.getOperands()) {
        if (i.getClass() == RexCall.class) {
          CEPCall callToAdd = CEPCall.of((RexCall) i);
          operandsList.add(callToAdd);
        } else if (i.getClass() == RexLiteral.class) {
          RexLiteral lit = (RexLiteral) i;
          CEPLiteral litToAdd = CEPLiteral.of(lit);
          operandsList.add(litToAdd);
        } else if (i.getClass() == RexPatternFieldRef.class) {
          RexPatternFieldRef fieldRef = (RexPatternFieldRef) i;
          CEPFieldRef fieldRefToAdd = CEPFieldRef.of(fieldRef);
          operandsList.add(fieldRefToAdd);
        } else {
          throw new UnsupportedOperationException("RexNode not supported: " + i.getClass().getName());
        }
      }
  
      return new CEPCall(myOp, operandsList);
    }
  
    @Override
    public String toString() {
      ArrayList<String> operandStrings = new ArrayList<>();
      for (CEPOperation i : operands) {
        operandStrings.add(i.toString());
      }
      return operator.toString() + "(" + String.join(", ", operandStrings) + ")";
    }
  }
  