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.asterix.translator.util;
  
  import java.util.List;
  
  import org.apache.asterix.lang.common.util.FunctionUtil;
  import org.apache.asterix.om.base.AOrderedList;
  import org.apache.asterix.om.base.AString;
  import org.apache.asterix.om.base.IAObject;
  import org.apache.asterix.om.constants.AsterixConstantValue;
  import org.apache.asterix.om.functions.BuiltinFunctions;
  import org.apache.commons.lang3.mutable.Mutable;
  import org.apache.commons.lang3.mutable.MutableObject;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.base.IVariableContext;
  import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
  import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
  import org.apache.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
  import org.apache.hyracks.api.exceptions.SourceLocation;
  
  public class PlanTranslationUtil {
      private static final LogicalVariable DUMMY_VAR = new LogicalVariable(-1);
  
      public static void prepareMetaKeyAccessExpression(List<String> field, LogicalVariable resVar,
              List<Mutable<ILogicalExpression>> assignExpressions, List<LogicalVariable> vars,
              List<Mutable<ILogicalExpression>> varRefs, IVariableContext context, SourceLocation sourceLoc) {
          IAObject value = (field.size() > 1) ? new AOrderedList(field) : new AString(field.get(0));
          ScalarFunctionCallExpression metaKeyFunction =
                  new ScalarFunctionCallExpression(FunctionUtil.getFunctionInfo(BuiltinFunctions.META_KEY));
          metaKeyFunction.setSourceLocation(sourceLoc);
          VariableReferenceExpression resVarRef = new VariableReferenceExpression(resVar);
          resVarRef.setSourceLocation(sourceLoc);
          metaKeyFunction.getArguments().add(new MutableObject<ILogicalExpression>(resVarRef));
          metaKeyFunction.getArguments()
                  .add(new MutableObject<>(new ConstantExpression(new AsterixConstantValue(value))));
          assignExpressions.add(new MutableObject<ILogicalExpression>(metaKeyFunction));
          LogicalVariable v = context.newVar();
          vars.add(v);
          if (varRefs != null) {
              VariableReferenceExpression vRef = new VariableReferenceExpression(v);
              vRef.setSourceLocation(sourceLoc);
              varRefs.add(new MutableObject<ILogicalExpression>(vRef));
          }
      }
  
      public static void prepareVarAndExpression(List<String> field, LogicalVariable resVar, List<LogicalVariable> vars,
              List<Mutable<ILogicalExpression>> assignExpressions, List<Mutable<ILogicalExpression>> varRefs,
              IVariableContext context, SourceLocation sourceLoc) {
          VariableReferenceExpression dummyVarRef = new VariableReferenceExpression(DUMMY_VAR);
          dummyVarRef.setSourceLocation(sourceLoc);
          ScalarFunctionCallExpression f = createFieldAccessExpression(dummyVarRef, field, sourceLoc);
          f.substituteVar(DUMMY_VAR, resVar);
          assignExpressions.add(new MutableObject<ILogicalExpression>(f));
          LogicalVariable v = context.newVar();
          vars.add(v);
          if (varRefs != null) {
              VariableReferenceExpression vRef = new VariableReferenceExpression(v);
              vRef.setSourceLocation(sourceLoc);
              varRefs.add(new MutableObject<ILogicalExpression>(vRef));
          }
      }
  
      private static ScalarFunctionCallExpression createFieldAccessExpression(ILogicalExpression target,
              List<String> field, SourceLocation sourceLoc) {
          FunctionIdentifier functionIdentifier;
          IAObject value;
          if (field.size() > 1) {
              functionIdentifier = BuiltinFunctions.FIELD_ACCESS_NESTED;
              value = new AOrderedList(field);
          } else {
              functionIdentifier = BuiltinFunctions.FIELD_ACCESS_BY_NAME;
              value = new AString(field.get(0));
          }
          IFunctionInfo finfoAccess = FunctionUtil.getFunctionInfo(functionIdentifier);
          ScalarFunctionCallExpression faExpr = new ScalarFunctionCallExpression(finfoAccess, new MutableObject<>(target),
                  new MutableObject<>(new ConstantExpression(new AsterixConstantValue(value))));
          faExpr.setSourceLocation(sourceLoc);
          return faExpr;
      }
  }
  