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.calcite.adapter.hive;
  
  import org.apache.calcite.DataContext;
  import org.apache.calcite.adapter.enumerable.RexToLixTranslator;
  import org.apache.calcite.adapter.java.JavaTypeFactory;
  import org.apache.calcite.jdbc.JavaTypeFactoryImpl;
  import org.apache.calcite.linq4j.tree.BlockBuilder;
  import org.apache.calcite.linq4j.tree.Expression;
  import org.apache.calcite.linq4j.tree.Expressions;
  import org.apache.calcite.linq4j.tree.IndexExpression;
  import org.apache.calcite.linq4j.tree.MethodCallExpression;
  import org.apache.calcite.linq4j.tree.MethodDeclaration;
  import org.apache.calcite.linq4j.tree.ParameterExpression;
  import org.apache.calcite.prepare.CalcitePrepareImpl;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.rex.RexBuilder;
  import org.apache.calcite.rex.RexExecutable;
  import org.apache.calcite.rex.RexExecutor;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexProgram;
  import org.apache.calcite.rex.RexProgramBuilder;
  import org.apache.calcite.sql.validate.SqlConformance;
  import org.apache.calcite.sql.validate.SqlConformanceEnum;
  import org.apache.calcite.util.BuiltInMethod;
  import org.apache.calcite.util.Util;
  
  import com.google.common.collect.ImmutableList;
  
  import java.lang.reflect.Modifier;
  import java.lang.reflect.Type;
  import java.util.List;
  
  /**
   *
   */
  public class HiveRexExecutorImpl implements RexExecutor {
  
    private final DataContext dataContext;
  
    public HiveRexExecutorImpl(DataContext dataContext) {
      this.dataContext = dataContext;
    }
  
    private String compile(RexBuilder rexBuilder, List<RexNode> constExps,
        RexToLixTranslator.InputGetter getter) {
      final RelDataTypeFactory typeFactory = rexBuilder.getTypeFactory();
      final RelDataType emptyRowType = typeFactory.builder().build();
      return compile(rexBuilder, constExps, getter, emptyRowType);
    }
  
    private String compile(RexBuilder rexBuilder, List<RexNode> constExps,
        RexToLixTranslator.InputGetter getter, RelDataType rowType) {
      final RexProgramBuilder programBuilder =
          new RexProgramBuilder(rowType, rexBuilder);
      for (RexNode node : constExps) {
        programBuilder.addProject(
            node, "c" + programBuilder.getProjectList().size());
      }
      final JavaTypeFactoryImpl javaTypeFactory =
          new JavaTypeFactoryImpl(rexBuilder.getTypeFactory().getTypeSystem());
      final BlockBuilder blockBuilder = new BlockBuilder();
      final ParameterExpression root0_ =
          Expressions.parameter(Object.class, "root0");
      final ParameterExpression root_ = DataContext.ROOT;
      blockBuilder.add(
          Expressions.declare(
              Modifier.FINAL, root_,
              Expressions.convert_(root0_, DataContext.class)));
      final SqlConformance conformance = SqlConformanceEnum.HIVE;
      final RexProgram program = programBuilder.getProgram();
      final List<Expression> expressions =
          RexToLixTranslator.translateProjects(program, javaTypeFactory,
              conformance, blockBuilder, null, root_, getter, null);
      blockBuilder.add(
          Expressions.return_(null,
              Expressions.newArrayInit(Object[].class, expressions)));
      final MethodDeclaration methodDecl =
          Expressions.methodDecl(Modifier.PUBLIC, Object[].class,
              BuiltInMethod.FUNCTION1_APPLY.method.getName(),
              ImmutableList.of(root0_), blockBuilder.toBlock());
      String code = Expressions.toString(methodDecl);
      if (CalcitePrepareImpl.DEBUG) {
        Util.debugCode(System.out, code);
      }
      return code;
    }
  
    /**
     * Creates an {@link RexExecutable} that allows to apply the
     * generated code during query processing (filter, projection).
     *
     * @param rexBuilder Rex builder
     * @param exps Expressions
     * @param rowType describes the structure of the input row.
     */
    public RexExecutable getExecutable(RexBuilder rexBuilder, List<RexNode> exps,
        RelDataType rowType) {
      final JavaTypeFactoryImpl typeFactory =
          new JavaTypeFactoryImpl(rexBuilder.getTypeFactory().getTypeSystem());
      final RexToLixTranslator.InputGetter getter = new DataContextInputGetter(rowType, typeFactory);
      final String code = compile(rexBuilder, exps, getter, rowType);
      return new RexExecutable(code, "generated Rex code");
    }
  
    /**
     * Do constant reduction using generated code.
     */
    public void reduce(RexBuilder rexBuilder, List<RexNode> constExps,
        List<RexNode> reducedValues) {
      final String code = compile(rexBuilder, constExps,
          (list, index, storageType) -> {
            throw new UnsupportedOperationException();
          });
  
      final RexExecutable executable = new RexExecutable(code, constExps);
      executable.setDataContext(dataContext);
      executable.reduce(rexBuilder, constExps, reducedValues);
    }
  
    /**
     * Implementation of
     * {@link org.apache.calcite.adapter.enumerable.RexToLixTranslator.InputGetter}
     * that reads the values of input fields by calling
     * <code>{@link org.apache.calcite.DataContext#get}("inputRecord")</code>.
     */
    private static class DataContextInputGetter implements RexToLixTranslator.InputGetter {
      private final RelDataTypeFactory typeFactory;
      private final RelDataType rowType;
  
      DataContextInputGetter(RelDataType rowType,
          RelDataTypeFactory typeFactory) {
        this.rowType = rowType;
        this.typeFactory = typeFactory;
      }
  
      public Expression field(BlockBuilder list, int index, Type storageType) {
        MethodCallExpression recFromCtx = Expressions.call(
            DataContext.ROOT,
            BuiltInMethod.DATA_CONTEXT_GET.method,
            Expressions.constant("inputRecord"));
        Expression recFromCtxCasted =
            RexToLixTranslator.convert(recFromCtx, Object[].class);
        IndexExpression recordAccess = Expressions.arrayIndex(recFromCtxCasted,
            Expressions.constant(index));
        if (storageType == null) {
          final RelDataType fieldType =
              rowType.getFieldList().get(index).getType();
          storageType = ((JavaTypeFactory) typeFactory).getJavaClass(fieldType);
        }
        return RexToLixTranslator.convert(recordAccess, storageType);
      }
    }
  
  }
  
  // End HiveRexExecutorImpl.java
  