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.math.BigDecimal;
  import java.math.BigInteger;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import javax.annotation.Nullable;
  
  import org.apache.cassandra.db.marshal.AbstractType;
  
  public class ExpressionEvaluator
  {
      @Nullable
      public static Object eval(Expression e)
      {
          if (e instanceof Value)
              return ((Value) e).value();
          if (e instanceof TypeHint)
              return eval(((TypeHint) e).e);
          if (e instanceof Operator)
              return eval((Operator) e);
          throw new UnsupportedOperationException("Unexpected expression type " + e.getClass() + ": " + e.toCQL());
      }
  
      @Nullable
      public static Object eval(Operator e)
      {
          Object lhs = eval(e.left);
          if (lhs instanceof ByteBuffer)
              lhs = e.left.type().compose((ByteBuffer) lhs);
          Object rhs = eval(e.right);
          if (rhs instanceof ByteBuffer)
              rhs = e.right.type().compose((ByteBuffer) rhs);
          // null + 42 = null
          // 42 + null = null
          // if anything is null, everything is null!
          if (lhs == null || rhs == null)
              return null;
          switch (e.kind)
          {
              case ADD:
              {
                  if (lhs instanceof Byte)
                      return (byte) (((Byte) lhs) + ((Byte) rhs));
                  if (lhs instanceof Short)
                      return (short) (((Short) lhs) + ((Short) rhs));
                  if (lhs instanceof Integer)
                      return (int) (((Integer) lhs) + ((Integer) rhs));
                  if (lhs instanceof Long)
                      return (long) (((Long) lhs) + ((Long) rhs));
                  if (lhs instanceof Float)
                      return (float) (((Float) lhs) + ((Float) rhs));
                  if (lhs instanceof Double)
                      return (double) (((Double) lhs) + ((Double) rhs));
                  if (lhs instanceof BigInteger)
                      return ((BigInteger) lhs).add((BigInteger) rhs);
                  if (lhs instanceof BigDecimal)
                      return ((BigDecimal) lhs).add((BigDecimal) rhs);
                  if (lhs instanceof String)
                      return lhs.toString() + rhs.toString();
                  if (lhs instanceof Set)
                  {
                      Set<Object> accum = new HashSet<>((Set<Object>) lhs);
                      accum.addAll((Set<Object>) rhs);
                      return accum;
                  }
                  if (lhs instanceof List)
                  {
                      List<Object> accum = new ArrayList<>((List<Object>) lhs);
                      accum.addAll((List<Object>) rhs);
                      return accum;
                  }
                  if (lhs instanceof Map)
                  {
                      Map<Object, Object> accum = new HashMap<>((Map<Object, Object>) lhs);
                      accum.putAll((Map<Object, Object>) rhs);
                      return accum;
                  }
                  throw new UnsupportedOperationException("Unexpected type: " + lhs.getClass());
              }
              case SUBTRACT:
              {
                  if (lhs instanceof Byte)
                      return (byte) (((Byte) lhs) - ((Byte) rhs));
                  if (lhs instanceof Short)
                      return (short) (((Short) lhs) - ((Short) rhs));
                  if (lhs instanceof Integer)
                      return (int) (((Integer) lhs) - ((Integer) rhs));
                  if (lhs instanceof Long)
                      return (long) (((Long) lhs) - ((Long) rhs));
                  if (lhs instanceof Float)
                      return (float) (((Float) lhs) - ((Float) rhs));
                  if (lhs instanceof Double)
                      return (double) (((Double) lhs) - ((Double) rhs));
                  if (lhs instanceof BigInteger)
                      return ((BigInteger) lhs).subtract((BigInteger) rhs);
                  if (lhs instanceof BigDecimal)
                      return ((BigDecimal) lhs).subtract((BigDecimal) rhs);
                  if (lhs instanceof Set)
                  {
                      Set<Object> accum = new HashSet<>((Set<Object>) lhs);
                      accum.removeAll((Set<Object>) rhs);
                      return accum.isEmpty() ? null : accum;
                  }
                  if (lhs instanceof List)
                  {
                      List<Object> accum = new ArrayList<>((List<Object>) lhs);
                      accum.removeAll((List<Object>) rhs);
                      return accum.isEmpty() ? null : accum;
                  }
                  if (lhs instanceof Map)
                  {
                      // rhs is a Set<Object> as CQL doesn't allow removing if the key and value both match
                      Map<Object, Object> accum = new HashMap<>((Map<Object, Object>) lhs);
                      ((Set<Object>) rhs).forEach(accum::remove);
                      return accum.isEmpty() ? null : accum;
                  }
                  throw new UnsupportedOperationException("Unexpected type: " + lhs.getClass());
              }
              case MULTIPLY:
              {
                  if (lhs instanceof Byte)
                      return (byte) (((Byte) lhs) * ((Byte) rhs));
                  if (lhs instanceof Short)
                      return (short) (((Short) lhs) * ((Short) rhs));
                  if (lhs instanceof Integer)
                      return (int) (((Integer) lhs) * ((Integer) rhs));
                  if (lhs instanceof Long)
                      return (long) (((Long) lhs) * ((Long) rhs));
                  if (lhs instanceof Float)
                      return (float) (((Float) lhs) * ((Float) rhs));
                  if (lhs instanceof Double)
                      return (double) ((Double) lhs) * ((Double) rhs);
                  if (lhs instanceof BigInteger)
                      return ((BigInteger) lhs).multiply((BigInteger) rhs);
                  if (lhs instanceof BigDecimal)
                      return ((BigDecimal) lhs).multiply((BigDecimal) rhs);
                  throw new UnsupportedOperationException("Unexpected type: " + lhs.getClass());
              }
              default:
                  throw new UnsupportedOperationException(e.kind.name());
          }
      }
  
      @Nullable
      public static ByteBuffer evalEncoded(Expression e)
      {
          Object v = eval(e);
          if (v == null) return null;
          if (v instanceof ByteBuffer) return (ByteBuffer) v;
          return ((AbstractType) e.type()).decompose(v);
      }
  }
  