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.lang.common.util;
  
  import java.util.ArrayList;
  import java.util.LinkedList;
  import java.util.List;
  
  import org.apache.asterix.common.exceptions.CompilationException;
  import org.apache.asterix.lang.common.base.Expression;
  import org.apache.asterix.lang.common.base.ILangExpression;
  import org.apache.asterix.lang.common.expression.GbyVariableExpressionPair;
  import org.apache.asterix.lang.common.expression.VariableExpr;
  import org.apache.asterix.lang.common.rewrites.LangRewritingContext;
  import org.apache.asterix.lang.common.rewrites.VariableSubstitutionEnvironment;
  import org.apache.asterix.lang.common.struct.Identifier;
  import org.apache.asterix.lang.common.visitor.CloneAndSubstituteVariablesVisitor;
  import org.apache.hyracks.algebricks.common.utils.Pair;
  
  public class VariableCloneAndSubstitutionUtil {
  
      private VariableCloneAndSubstitutionUtil() {
      }
  
      public static List<GbyVariableExpressionPair> substInVarExprPair(LangRewritingContext context,
              List<GbyVariableExpressionPair> gbyVeList, VariableSubstitutionEnvironment newSubs,
              CloneAndSubstituteVariablesVisitor visitor) throws CompilationException {
          VariableSubstitutionEnvironment subs = newSubs;
          List<GbyVariableExpressionPair> veList = new LinkedList<>();
          for (GbyVariableExpressionPair vep : gbyVeList) {
              VariableExpr oldGbyVar = vep.getVar();
              VariableExpr newGbyVar = null;
              if (oldGbyVar != null) {
                  newGbyVar = visitor.generateNewVariable(context, oldGbyVar);
                  subs = eliminateSubstFromList(newGbyVar, subs);
              }
              Pair<ILangExpression, VariableSubstitutionEnvironment> p1 = vep.getExpr().accept(visitor, subs);
              GbyVariableExpressionPair ve2 = new GbyVariableExpressionPair(newGbyVar, (Expression) p1.first);
              veList.add(ve2);
          }
          return veList;
      }
  
      public static List<Pair<Expression, Identifier>> substInFieldList(List<Pair<Expression, Identifier>> fieldList,
              VariableSubstitutionEnvironment newSubs, CloneAndSubstituteVariablesVisitor visitor)
              throws CompilationException {
          List<Pair<Expression, Identifier>> newFieldList = new ArrayList<>(fieldList.size());
          for (Pair<Expression, Identifier> p : fieldList) {
              Expression newExpr = (Expression) p.first.accept(visitor, newSubs).first;
              newFieldList.add(new Pair<>(newExpr, p.second));
          }
          return newFieldList;
      }
  
      public static VariableSubstitutionEnvironment eliminateSubstFromList(VariableExpr variableExpr,
              VariableSubstitutionEnvironment arg) {
          VariableSubstitutionEnvironment newArg = new VariableSubstitutionEnvironment(arg);
          newArg.removeSubstitution(variableExpr);
          return newArg;
      }
  
      public static List<Expression> visitAndCloneExprList(List<Expression> oldExprList,
              VariableSubstitutionEnvironment arg, CloneAndSubstituteVariablesVisitor visitor)
              throws CompilationException {
          List<Expression> exprs = new ArrayList<>(oldExprList.size());
          for (Expression e : oldExprList) {
              Pair<ILangExpression, VariableSubstitutionEnvironment> p1 = e.accept(visitor, arg);
              exprs.add((Expression) p1.first);
          }
          return exprs;
      }
  }
  