logical/src/main/java/org/apache/drill/common/expression/FunctionCallFactory.java

/*
 * 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.drill.common.expression;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.drill.common.exceptions.DrillRuntimeException;
import org.apache.drill.common.types.TypeProtos.MajorType;

import org.apache.drill.shaded.guava.com.google.common.collect.ImmutableMap;
import org.apache.drill.shaded.guava.com.google.common.collect.Lists;

public class FunctionCallFactory {

  private static final Map<String, String> OP_TO_FUNC_NAME = ImmutableMap.<String, String>builder()
      .put("+", "add")
      .put("-", "subtract")
      .put("/", "divide")
      .put("*", "multiply")
      .put("%", "modulo")
      .put("^", "xor")
      .put("||", "concatOperator")
      .put("or", "booleanOr")
      .put("and", "booleanAnd")
      .put(">", "greater_than")
      .put("<", "less_than")
      .put("==", "equal")
      .put("=", "equal")
      .put("!=", "not_equal")
      .put("<>", "not_equal")
      .put(">=", "greater_than_or_equal_to")
      .put("<=", "less_than_or_equal_to")
      .put("is null", "isnull")
      .put("is not null", "isnotnull")
      .put("is true", "istrue")
      .put("is not true", "isnottrue")
      .put("is false", "isfalse")
      .put("is not false", "isnotfalse")
      .put("similar to", "similar_to")
      .put("!", "not")
      .put("u-", "negative")
      .build();

  public static String convertToDrillFunctionName(String op) {
    return OP_TO_FUNC_NAME.getOrDefault(op, op);
  }

  public static boolean isBooleanOperator(String funcName) {
    String drillFuncName  = convertToDrillFunctionName(funcName);
    return drillFuncName.equals("booleanAnd") || drillFuncName.equals("booleanOr");
  }

  /*
   * create a cast function.
   * arguments : type -- targetType
   *             ep   -- input expression position
   *             expr -- input expression
   */
  public static LogicalExpression createCast(MajorType type, ExpressionPosition ep, LogicalExpression expr){
    return new CastExpression(expr, type, ep);
  }

  public static LogicalExpression createConvert(String function, String conversionType, LogicalExpression expr, ExpressionPosition ep) {
    return new ConvertExpression(function, conversionType, expr, ep);
  }

  public static LogicalExpression createAnyValue(ExpressionPosition ep, LogicalExpression expr) {
    return new AnyValueExpression(expr, ep);
  }

  public static LogicalExpression createAnyValue(String functionName, List<LogicalExpression> args) {
    return createExpression(functionName, args);
  }

  public static LogicalExpression createExpression(String functionName, List<LogicalExpression> args){
    return createExpression(functionName, ExpressionPosition.UNKNOWN, args);
  }

  public static LogicalExpression createExpression(String functionName, ExpressionPosition ep, List<LogicalExpression> args){
    String name = convertToDrillFunctionName(functionName);
    if (isBooleanOperator(name)) {
      return new BooleanOperator(name, args, ep);
    } else {
      return new FunctionCall(name, args, ep);
    }
  }

  public static LogicalExpression createExpression(String functionName, ExpressionPosition ep, LogicalExpression... e){
    return createExpression(functionName, ep, Lists.newArrayList(e));
  }

  public static LogicalExpression createBooleanOperator(String functionName, List<LogicalExpression> args){
    return createBooleanOperator(functionName, ExpressionPosition.UNKNOWN, args);
  }

  public static LogicalExpression createBooleanOperator(String functionName, ExpressionPosition ep, List<LogicalExpression> args){
    return new BooleanOperator(convertToDrillFunctionName(functionName), args, ep);
  }

  public static LogicalExpression createByOp(List<LogicalExpression> args, ExpressionPosition ep, List<String> opTypes) {
    if (args.size() == 1) {
      return args.get(0);
    }

    if (args.size() - 1 != opTypes.size()) {
      throw new DrillRuntimeException("Must receive one more expression then the provided number of operators.");
    }

    LogicalExpression first = args.get(0);
    for (int i = 0; i < opTypes.size(); i++) {
      List<LogicalExpression> l2 = new ArrayList<LogicalExpression>();
      l2.add(first);
      l2.add(args.get(i + 1));
      first = createExpression(opTypes.get(i), ep, l2);
    }
    return first;
  }

}