term.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 <concepts>
#include <memory>
#include <string>
#include <string_view>
 
#include "iceberg/expression/expression.h"
#include "iceberg/expression/literal.h"
#include "iceberg/type_fwd.h"
#include "iceberg/util/formattable.h"
 
namespace iceberg {
 
class ICEBERG_EXPORT Term : public util::Formattable {
 public:
  enum class Kind : uint8_t { kReference, kTransform, kExtract };
 
  virtual Kind kind() const = 0;
 
  virtual bool is_unbound() const = 0;
};
 
template <typename T>
concept TermType = std::derived_from<T, Term>;
 
template <typename B>
class ICEBERG_EXPORT UnboundTerm : public Unbound<B>, public Term {
 public:
  using BoundType = B;
 
  bool is_unbound() const override { return true; }
};
 
class ICEBERG_EXPORT BoundTerm : public Bound, public Term {
 public:
  ~BoundTerm() override;
 
  virtual std::shared_ptr<Type> type() const = 0;
 
  virtual bool MayProduceNull() const = 0;
 
  virtual bool Equals(const BoundTerm& other) const = 0;
 
  friend bool operator==(const BoundTerm& lhs, const BoundTerm& rhs) {
    return lhs.Equals(rhs);
  }
 
  bool is_unbound() const override { return false; }
};
 
class ICEBERG_EXPORT Reference {
 public:
  virtual ~Reference();
 
  virtual std::string_view name() const = 0;
};
 
class ICEBERG_EXPORT NamedReference
    : public Reference,
      public UnboundTerm<BoundReference>,
      public std::enable_shared_from_this<NamedReference> {
 public:
  static Result<std::unique_ptr<NamedReference>> Make(std::string field_name);
 
  ~NamedReference() override;
 
  std::string_view name() const override { return field_name_; }
 
  Result<std::shared_ptr<BoundReference>> Bind(const Schema& schema,
                                               bool case_sensitive) const override;
 
  std::shared_ptr<NamedReference> reference() override { return shared_from_this(); }
 
  std::string ToString() const override;
 
  Kind kind() const override { return Kind::kReference; }
 
 private:
  explicit NamedReference(std::string field_name);
 
  std::string field_name_;
};
 
class ICEBERG_EXPORT BoundReference
    : public Reference,
      public BoundTerm,
      public std::enable_shared_from_this<BoundReference> {
 public:
  static Result<std::unique_ptr<BoundReference>> Make(
      SchemaField field, std::unique_ptr<StructLikeAccessor> accessor);
 
  ~BoundReference() override;
 
  const SchemaField& field() const { return field_; }
 
  std::string_view name() const override { return field_.name(); }
 
  std::string ToString() const override;
 
  Result<Literal> Evaluate(const StructLike& data) const override;
 
  std::shared_ptr<BoundReference> reference() override { return shared_from_this(); }
 
  std::shared_ptr<Type> type() const override { return field_.type(); }
 
  int32_t field_id() const { return field_.field_id(); }
 
  bool MayProduceNull() const override { return field_.optional(); }
 
  bool Equals(const BoundTerm& other) const override;
 
  Kind kind() const override { return Kind::kReference; }
 
  const StructLikeAccessor& accessor() const { return *accessor_; }
 
 private:
  BoundReference(SchemaField field, std::unique_ptr<StructLikeAccessor> accessor);
 
  SchemaField field_;
  std::unique_ptr<StructLikeAccessor> accessor_;
};
 
class ICEBERG_EXPORT UnboundTransform : public UnboundTerm<class BoundTransform> {
 public:
  static Result<std::unique_ptr<UnboundTransform>> Make(
      std::shared_ptr<NamedReference> ref, std::shared_ptr<Transform> transform);
 
  ~UnboundTransform() override;
 
  std::string ToString() const override;
 
  Result<std::shared_ptr<BoundTransform>> Bind(const Schema& schema,
                                               bool case_sensitive) const override;
 
  std::shared_ptr<NamedReference> reference() override { return ref_; }
 
  const std::shared_ptr<Transform>& transform() const { return transform_; }
 
  Kind kind() const override { return Kind::kTransform; }
 
 private:
  UnboundTransform(std::shared_ptr<NamedReference> ref,
                   std::shared_ptr<Transform> transform);
 
  std::shared_ptr<NamedReference> ref_;
  std::shared_ptr<Transform> transform_;
};
 
class ICEBERG_EXPORT BoundTransform : public BoundTerm {
 public:
  static Result<std::unique_ptr<BoundTransform>> Make(
      std::shared_ptr<BoundReference> ref, std::shared_ptr<Transform> transform,
      std::shared_ptr<TransformFunction> transform_func);
 
  ~BoundTransform() override;
 
  std::string ToString() const override;
 
  Result<Literal> Evaluate(const StructLike& data) const override;
 
  std::shared_ptr<BoundReference> reference() override { return ref_; }
 
  std::shared_ptr<Type> type() const override;
 
  bool MayProduceNull() const override;
 
  bool Equals(const BoundTerm& other) const override;
 
  const std::shared_ptr<Transform>& transform() const { return transform_; }
 
  Kind kind() const override { return Kind::kTransform; }
 
 private:
  BoundTransform(std::shared_ptr<BoundReference> ref,
                 std::shared_ptr<Transform> transform,
                 std::shared_ptr<TransformFunction> transform_func);
 
  std::shared_ptr<BoundReference> ref_;
  std::shared_ptr<Transform> transform_;
  std::shared_ptr<TransformFunction> transform_func_;
};
 
}  // namespace iceberg