transform.h

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/*
 * 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.
 */
 
#pragma once
 
 
#include <cstdint>
#include <memory>
#include <string_view>
#include <utility>
#include <variant>
 
#include "iceberg/expression/literal.h"
#include "iceberg/iceberg_export.h"
#include "iceberg/result.h"
#include "iceberg/type_fwd.h"
#include "iceberg/util/formattable.h"
 
namespace iceberg {
 
enum class TransformType {
  kUnknown,
  kIdentity,
  kBucket,
  kTruncate,
  kYear,
  kMonth,
  kDay,
  kHour,
  kVoid,
};
 
ICEBERG_EXPORT constexpr std::string_view TransformTypeToString(TransformType type) {
  switch (type) {
    case TransformType::kUnknown:
      return "unknown";
    case TransformType::kIdentity:
      return "identity";
    case TransformType::kBucket:
      return "bucket";
    case TransformType::kTruncate:
      return "truncate";
    case TransformType::kYear:
      return "year";
    case TransformType::kMonth:
      return "month";
    case TransformType::kDay:
      return "day";
    case TransformType::kHour:
      return "hour";
    case TransformType::kVoid:
      return "void";
  }
  std::unreachable();
}
 
class ICEBERG_EXPORT Transform : public util::Formattable {
 public:
  static std::shared_ptr<Transform> Identity();
 
  static std::shared_ptr<Transform> Bucket(int32_t num_buckets);
 
  static std::shared_ptr<Transform> Truncate(int32_t width);
 
  static std::shared_ptr<Transform> Year();
 
  static std::shared_ptr<Transform> Month();
 
  static std::shared_ptr<Transform> Day();
 
  static std::shared_ptr<Transform> Hour();
 
  static std::shared_ptr<Transform> Void();
 
  TransformType transform_type() const;
 
  Result<std::shared_ptr<TransformFunction>> Bind(
      const std::shared_ptr<Type>& source_type) const;
 
  std::shared_ptr<Type> ResultType(const std::shared_ptr<Type>& source_type) const;
 
  bool CanTransform(const Type& source_type) const;
 
  Status Validate(const std::shared_ptr<Type>& source_type) const;
 
  bool PreservesOrder() const;
 
  bool SatisfiesOrderOf(const Transform& other) const;
 
  Result<std::unique_ptr<UnboundPredicate>> Project(
      std::string_view name, const std::shared_ptr<BoundPredicate>& predicate);
 
  Result<std::unique_ptr<UnboundPredicate>> ProjectStrict(
      std::string_view name, const std::shared_ptr<BoundPredicate>& predicate);
 
  Result<std::string> ToHumanString(const Literal& value);
 
  std::string ToString() const override;
 
  std::string DedupName() const;
 
  Result<std::string> GeneratePartitionName(std::string_view source_name) const;
 
  friend bool operator==(const Transform& lhs, const Transform& rhs) {
    return lhs.Equals(rhs);
  }
 
 private:
  explicit Transform(TransformType transform_type);
 
  Transform(TransformType transform_type, int32_t param);
 
  [[nodiscard]] virtual bool Equals(const Transform& other) const;
 
  TransformType transform_type_;
  std::variant<std::monostate, int32_t> param_;
};
ICEBERG_EXPORT Result<std::shared_ptr<Transform>> TransformFromString(
    std::string_view transform_str);
 
class ICEBERG_EXPORT TransformFunction {
 public:
  virtual ~TransformFunction() = default;
  TransformFunction(TransformType transform_type, std::shared_ptr<Type> source_type);
  virtual Result<Literal> Transform(const Literal& literal) = 0;
  TransformType transform_type() const;
  const std::shared_ptr<Type>& source_type() const;
  virtual std::shared_ptr<Type> ResultType() const = 0;
 
  friend bool operator==(const TransformFunction& lhs, const TransformFunction& rhs) {
    return lhs.Equals(rhs);
  }
 
 protected:
  [[nodiscard]] virtual bool Equals(const TransformFunction& other) const;
 
 private:
  TransformType transform_type_;
  std::shared_ptr<Type> source_type_;
};
 
}  // namespace iceberg