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.cassandra.cql3.ast;
  
  import java.util.EnumSet;
  import java.util.stream.Stream;
  
  import org.apache.cassandra.db.marshal.AbstractType;
  import org.apache.cassandra.db.marshal.CollectionType;
  import org.apache.cassandra.db.marshal.ListType;
  import org.apache.cassandra.db.marshal.MapType;
  import org.apache.cassandra.db.marshal.SetType;
  
  //TODO this is hacky as Mutation takes Expression then figures out where to put it...
  // this can only be applied to UPDATE ... SET
  public class AssignmentOperator implements Expression
  {
      public enum Kind
      {
          ADD('+'),
          SUBTRACT('-');
  
          private final char value;
  
          Kind(char value)
          {
              this.value = value;
          }
      }
  
      public final Kind kind;
      public final Expression right;
  
      public AssignmentOperator(Kind kind, Expression right)
      {
          this.kind = kind;
          this.right = right;
      }
  
      public static EnumSet<Kind> supportsOperators(AbstractType<?> type, boolean isTransaction)
      {
          type = type.unwrap();
          EnumSet<Kind> result = EnumSet.noneOf(Kind.class);
          if (type instanceof CollectionType && type.isMultiCell())
          {
              if (type instanceof SetType)
                  return EnumSet.of(Kind.ADD, Kind.SUBTRACT);
              if (type instanceof ListType)
                  return isTransaction
                         ? EnumSet.of(Kind.ADD, Kind.SUBTRACT)
                         : EnumSet.of(Kind.ADD);
              if (type instanceof MapType)
              {
                  //TODO (coverage): include SUBTRACT support
                  // map supports subtract, but not map - map; only map - set!
                  // since this is annoying to support, for now dropping -
                  return EnumSet.of(Kind.ADD);
              }
              throw new AssertionError("Unexpected collection type: " + type);
          }
          if (!isTransaction)
              return result; // only multi-cell collections can be updated outside of transactions
          for (Operator.Kind supported : Operator.supportsOperators(type))
          {
              Kind kind = toKind(supported);
              if (kind != null)
                  result.add(kind);
          }
          return result;
      }
  
      private static Kind toKind(Operator.Kind kind)
      {
          switch (kind)
          {
              case ADD: return Kind.ADD;
              case SUBTRACT: return Kind.SUBTRACT;
              default: return null;
          }
      }
  
      @Override
      public void toCQL(StringBuilder sb, CQLFormatter formatter)
      {
          sb.append(' ').append(kind.value).append("= ");
          right.toCQL(sb, formatter);
      }
  
      @Override
      public Stream<? extends Element> stream()
      {
          return Stream.of(right);
      }
  
      @Override
      public AbstractType<?> type()
      {
          return right.type();
      }
  
      @Override
      public Expression visit(Visitor v)
      {
          var u = v.visit(this);
          if (u != this) return u;
          var r = right.visit(v);
          if (r == right) return this;
          return new AssignmentOperator(kind, r);
      }
  
      @Override
      public String toString()
      {
          return debugCQL();
      }
  }
  