name_mapping.h

/*
 * 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 <functional>
#include <map>
#include <memory>
#include <optional>
#include <span>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
 
#include "iceberg/iceberg_export.h"
#include "iceberg/result.h"
#include "iceberg/schema.h"
 
namespace iceberg {
 
struct ICEBERG_EXPORT MappedField {
  std::unordered_set<std::string> names;
  std::optional<int32_t> field_id;
  std::shared_ptr<class MappedFields> nested_mapping;
 
  friend bool operator==(const MappedField& lhs, const MappedField& rhs);
};
 
using MappedFieldConstRef = std::reference_wrapper<const MappedField>;
 
class ICEBERG_EXPORT MappedFields {
 public:
  static std::unique_ptr<MappedFields> Make(std::vector<MappedField> fields);
 
  std::optional<MappedFieldConstRef> Field(int32_t id) const;
 
  std::optional<int32_t> Id(std::string_view name) const;
 
  size_t Size() const;
 
  std::span<const MappedField> fields() const;
 
  ICEBERG_EXPORT friend bool operator==(const MappedFields& lhs, const MappedFields& rhs);
 
 private:
  explicit MappedFields(std::vector<MappedField> fields);
 
  const std::unordered_map<std::string_view, int32_t>& LazyNameToId() const;
  const std::unordered_map<int32_t, MappedFieldConstRef>& LazyIdToField() const;
 
 private:
  std::vector<MappedField> fields_;
 
  // Lazy-initialized mappings
  mutable std::unordered_map<std::string_view, int32_t> name_to_id_;
  mutable std::unordered_map<int32_t, MappedFieldConstRef> id_to_field_;
};
 
class ICEBERG_EXPORT NameMapping {
 public:
  static std::unique_ptr<NameMapping> Make(std::unique_ptr<MappedFields> fields);
 
  static std::unique_ptr<NameMapping> Make(std::vector<MappedField> fields);
 
  static std::unique_ptr<NameMapping> MakeEmpty();
 
  std::optional<MappedFieldConstRef> Find(int32_t id) const;
 
  std::optional<MappedFieldConstRef> Find(std::span<const std::string> names) const;
 
  std::optional<MappedFieldConstRef> Find(const std::string& name) const;
 
  const MappedFields& AsMappedFields() const;
 
  ICEBERG_EXPORT friend bool operator==(const NameMapping& lhs, const NameMapping& rhs);
 
 private:
  explicit NameMapping(std::unique_ptr<MappedFields> mapping);
 
  const std::unordered_map<int32_t, MappedFieldConstRef>& LazyFieldsById() const;
  const std::unordered_map<std::string, MappedFieldConstRef>& LazyFieldsByName() const;
 
 private:
  std::unique_ptr<MappedFields> mapping_;
 
  // Lazy-initialized mappings
  mutable std::unordered_map<int32_t, MappedFieldConstRef> fields_by_id_;
  mutable std::unordered_map<std::string, MappedFieldConstRef> fields_by_name_;
};
 
ICEBERG_EXPORT std::string ToString(const MappedField& field);
ICEBERG_EXPORT std::string ToString(const MappedFields& fields);
ICEBERG_EXPORT std::string ToString(const NameMapping& mapping);
 
ICEBERG_EXPORT Result<std::unique_ptr<NameMapping>> CreateMapping(const Schema& schema);
 
ICEBERG_EXPORT Result<std::unique_ptr<NameMapping>> UpdateMapping(
    const NameMapping& mapping,
    const std::unordered_map<int32_t, std::shared_ptr<SchemaField>>& updates,
    const std::multimap<int32_t, int32_t>& adds);
 
}  // namespace iceberg