Echo Writes Code

bits.hpp

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#ifndef CRUCIBLE_PARSING_BITS_HPP
#define CRUCIBLE_PARSING_BITS_HPP

#include "crucible/core/constant_error.inl"
#include "crucible/core/error_chain.inl"
#include "crucible/core/none.hpp"
#include "crucible/parsing/result.inl"

#include <concepts>
#include <cstddef>
#include <cstdint>
#include <span>

namespace crucible::parsing::bits {
  template<typename T>
  concept FixedWidthUnsignedIntegerType =
    std::same_as<T, std::uint8_t> ||
    std::same_as<T, std::uint16_t> ||
    std::same_as<T, std::uint32_t> ||
    std::same_as<T, std::uint64_t>;

  struct ByteSequenceMismatch final : core::constant_error::ConstantError<ByteSequenceMismatch> {
    static constexpr char const message[] = "Byte sequence mismatch";
  };

  struct UnexpectedEndOfInput final : core::constant_error::ConstantError<UnexpectedEndOfInput> {
    static constexpr char const message[] = "Unexpected end of input";
  };

  struct BitsError final : core::error_chain::ErrorChain<BitsError, ByteSequenceMismatch, UnexpectedEndOfInput> {
    using ErrorChain::ErrorChain;

    static constexpr char const message[] = "Parse error in bits primitive";
  };

  class BitsState final {
  public:
    explicit BitsState(std::span<std::byte const> const &input);

    BitsState(std::span<std::byte const> const &input, std::size_t const byte_offset, std::size_t const bit_offset);

    [[nodiscard]]
    auto is_finished() const -> bool;

    [[nodiscard]]
    auto get_remaining_bytes_in_input() const -> std::span<std::byte const>;

    [[nodiscard]]
    auto get_remaining_bits_in_byte() const -> std::byte;

    [[nodiscard]]
    auto advance_by_bytes(std::size_t const byte_count) const -> BitsState;

    [[nodiscard]]
    auto advance_by_bits(std::size_t const bit_count) const -> BitsState;

    [[nodiscard]]
    auto format_location() const -> std::string;

  private:
    std::span<std::byte const> my_input;

    std::size_t my_byte_offset = 0;

    std::size_t my_bit_offset = 0;
  };

  class ByteSequence final {
  public:
    using StateType = BitsState;

    using ErrorType = BitsError;

    using ValueType = core::none::None;

    using RejectType = result::Reject<StateType, ErrorType>;

    using AcceptType = result::Accept<StateType, ValueType>;

    using ResultType = core::result::Result<RejectType, AcceptType>;

    explicit ByteSequence(std::span<std::byte const> byte_sequence);

    [[nodiscard]]
    auto operator()(StateType const &state) const -> ResultType;

  private:
    std::span<std::byte const> my_byte_sequence;
  };

  template<FixedWidthUnsignedIntegerType T>
  struct LittleEndianUnsignedInteger final {
    using StateType = BitsState;

    using ErrorType = BitsError;

    using ValueType = T;

    using RejectType = result::Reject<StateType, ErrorType>;

    using AcceptType = result::Accept<StateType, ValueType>;

    using ResultType = core::result::Result<RejectType, AcceptType>;

    [[nodiscard]]
    auto operator()(StateType const &state) const -> ResultType;
  };

  template<FixedWidthUnsignedIntegerType T>
  struct BigEndianUnsignedInteger final {
    using StateType = BitsState;

    using ErrorType = BitsError;

    using ValueType = T;

    using RejectType = result::Reject<StateType, ErrorType>;

    using AcceptType = result::Accept<StateType, ValueType>;

    using ResultType = core::result::Result<RejectType, AcceptType>;

    [[nodiscard]]
    auto operator()(StateType const &state) const -> ResultType;
  };
}

#endif // CRUCIBLE_PARSING_BITS_HPP