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.dataflow.data.common;
  
  import org.apache.asterix.common.exceptions.CompilationException;
  import org.apache.asterix.common.exceptions.ErrorCode;
  import org.apache.asterix.om.constants.AsterixConstantValue;
  import org.apache.asterix.om.functions.FunctionInfo;
  import org.apache.asterix.om.typecomputer.base.IResultTypeComputer;
  import org.apache.asterix.om.types.BuiltinType;
  import org.apache.asterix.om.types.IAType;
  import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
  import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IAlgebricksConstantValue;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
  import org.apache.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
  import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
  import org.apache.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
  
  public class ExpressionTypeComputer implements IExpressionTypeComputer {
  
      public static final ExpressionTypeComputer INSTANCE = new ExpressionTypeComputer();
  
      private ExpressionTypeComputer() {
      }
  
      @Override
      public Object getType(ILogicalExpression expr, IMetadataProvider<?, ?> metadataProvider,
              IVariableTypeEnvironment env) throws AlgebricksException {
          switch (expr.getExpressionTag()) {
              case CONSTANT:
                  return getTypeForConstant((ConstantExpression) expr, env);
              case FUNCTION_CALL:
                  return getTypeForFunction((AbstractFunctionCallExpression) expr, env, metadataProvider);
              case VARIABLE:
                  try {
                      return env.getVarType(((VariableReferenceExpression) expr).getVariableReference());
                  } catch (Exception e) {
                      throw new CompilationException(ErrorCode.COMPILATION_ERROR, e, expr.getSourceLocation(),
                              "Could not resolve type for " + expr + ","
                                      + "please check whether the used variable has been defined!");
                  }
              default:
                  throw new IllegalStateException();
          }
      }
  
      private IAType getTypeForFunction(AbstractFunctionCallExpression expr, IVariableTypeEnvironment env,
              IMetadataProvider<?, ?> mp) throws AlgebricksException {
          IResultTypeComputer rtc = ((FunctionInfo) expr.getFunctionInfo()).getResultTypeComputer();
          return rtc.computeType(expr, env, mp);
      }
  
      private IAType getTypeForConstant(ConstantExpression expr, IVariableTypeEnvironment env) {
          IAlgebricksConstantValue acv = expr.getValue();
          if (acv.isFalse() || acv.isTrue()) {
              return BuiltinType.ABOOLEAN;
          } else if (acv.isMissing()) {
              return BuiltinType.AMISSING;
          } else if (acv.isNull()) {
              return BuiltinType.ANULL;
          } else {
              AsterixConstantValue value = (AsterixConstantValue) acv;
              return value.getObject().getType();
          }
      }
  
  }
  