query_optimizer/expressions/ExpressionUtil.cpp

/**
 *   Copyright 2011-2015 Quickstep Technologies LLC.
 *   Copyright 2015 Pivotal Software, Inc.
 *   Copyright 2016, Quickstep Research Group, Computer Sciences Department,
 *     University of Wisconsin—Madison.
 *
 *   Licensed 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.
 **/

#include "query_optimizer/expressions/ExpressionUtil.hpp"

#include <vector>

#include "query_optimizer/expressions/AttributeReference.hpp"
#include "query_optimizer/expressions/NamedExpression.hpp"

namespace quickstep {
namespace optimizer {
namespace expressions {

AttributeReferencePtr ToRef(const NamedExpressionPtr &expression) {
  return AttributeReference::Create(expression->id(),
                                    expression->attribute_name(),
                                    expression->attribute_alias(),
                                    expression->relation_name(),
                                    expression->getValueType(),
                                    AttributeReferenceScope::kLocal);
}

std::vector<AttributeReferencePtr> GetNullableAttributeVector(
    const std::vector<AttributeReferencePtr> &attributes) {
  std::vector<AttributeReferencePtr> nullable_attributes;
  for (const auto &attr : attributes) {
    if (!attr->getValueType().isNullable()) {
      nullable_attributes.emplace_back(
          AttributeReference::Create(attr->id(),
                                     attr->attribute_name(),
                                     attr->attribute_alias(),
                                     attr->relation_name(),
                                     attr->getValueType().getNullableVersion(),
                                     attr->scope()));
    } else {
      nullable_attributes.emplace_back(attr);
    }
  }
  return nullable_attributes;
}

std::vector<AttributeReferencePtr> GetAttributeReferencesWithinScope(
    const std::vector<AttributeReferencePtr> &attributes,
    const AttributeReferenceScope scope) {
  std::vector<AttributeReferencePtr> filtered_attributes;
  for (const auto &attr_it : attributes) {
    if (attr_it->scope() == scope) {
      filtered_attributes.emplace_back(attr_it);
    }
  }
  return filtered_attributes;
}

}  // namespace expressions
}  // namespace optimizer
}  // namespace quickstep