scan_type.hxx

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/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 *   Copyright 2024. Couchbase, Inc.
 *
 *   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.
 */
 
#pragma once
 
#include <cstdint>
#include <optional>
#include <string>
#include <utility>
 
namespace couchbase
{
struct scan_term {
public:
  explicit scan_term(std::string term)
    : term_{ std::move(term) }
  {
  }
 
  auto exclusive(bool exclusive) -> scan_term&
  {
    exclusive_ = exclusive;
    return *this;
  }
 
  struct built {
    std::string term;
    bool exclusive;
  };
 
  [[nodiscard]] auto build() const -> built
  {
    return { term_, exclusive_ };
  }
 
private:
  std::string term_{};
  bool exclusive_{ false };
};
 
struct scan_type {
  virtual ~scan_type() = default;
 
  struct built {
    enum type {
      prefix_scan,
      range_scan,
      sampling_scan
    };
    type type;
 
    std::string prefix{};
 
    std::optional<scan_term::built> from{};
    std::optional<scan_term::built> to{};
 
    std::size_t limit{};
    std::optional<std::uint64_t> seed{};
  };
 
  [[nodiscard]] virtual auto build() const -> built = 0;
};
 
struct prefix_scan : scan_type {
public:
  explicit prefix_scan(std::string prefix)
    : prefix_{ std::move(prefix) }
  {
  }
 
  [[nodiscard]] auto build() const -> built override
  {
    return {
      scan_type::built::prefix_scan,
      prefix_,
    };
  }
 
private:
  std::string prefix_{};
};
 
struct range_scan : scan_type {
public:
  range_scan() = default;
 
  range_scan(std::optional<scan_term> from, std::optional<scan_term> to)
    : from_{ std::move(from) }
    , to_{ std::move(to) }
  {
  }
 
  auto from(scan_term from) -> range_scan&
  {
    from_ = std::move(from);
    return *this;
  }
 
  auto to(scan_term to) -> range_scan&
  {
    to_ = std::move(to);
    return *this;
  }
 
  [[nodiscard]] auto build() const -> built override
  {
    return {
      scan_type::built::type::range_scan,
      {},
      (from_) ? std::make_optional(from_->build()) : std::nullopt,
      (to_) ? std::make_optional(to_->build()) : std::nullopt,
    };
  }
 
private:
  std::optional<scan_term> from_{};
  std::optional<scan_term> to_{};
};
 
struct sampling_scan : scan_type {
public:
  explicit sampling_scan(std::size_t limit)
    : limit_{ limit }
  {
  }
 
  sampling_scan(std::size_t limit, std::uint64_t seed)
    : limit_{ limit }
    , seed_{ seed }
  {
  }
 
  auto seed(std::uint64_t seed) -> sampling_scan&
  {
    seed_ = seed;
    return *this;
  }
 
  [[nodiscard]] auto build() const -> built override
  {
    return {
      scan_type::built::type::sampling_scan, {}, {}, {}, limit_, seed_,
    };
  }
 
private:
  std::size_t limit_{};
  std::optional<std::uint64_t> seed_{};
};
} // namespace couchbase