stream_traits.h

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#pragma once
 
#include "byte_buffer.h"
 
#include <cstddef>
#include <cstdint>
#include <limits>
#include <type_traits>
 
namespace bitstream
{
    struct fixed_policy
    {
        fixed_policy(void* buffer, uint32_t num_bits) noexcept :
            m_Buffer(static_cast<uint32_t*>(buffer)),
            m_NumBitsSerialized(0),
            m_TotalBits(num_bits) {}
 
        template<size_t Size>
        fixed_policy(byte_buffer<Size>& buffer, uint32_t num_bits) noexcept :
            m_Buffer(reinterpret_cast<uint32_t*>(buffer.Bytes)),
            m_NumBitsSerialized(0),
            m_TotalBits(num_bits) {}
 
        template<size_t Size>
        fixed_policy(byte_buffer<Size>& buffer) noexcept :
            m_Buffer(reinterpret_cast<uint32_t*>(buffer.Bytes)),
            m_NumBitsSerialized(0),
            m_TotalBits(Size * 8) {}
 
        uint32_t* get_buffer() const noexcept { return m_Buffer; }
 
        // TODO: Transition sizes to size_t
        uint32_t get_num_bits_serialized() const noexcept { return m_NumBitsSerialized; }
 
        bool can_serialize_bits(uint32_t num_bits) const noexcept { return m_NumBitsSerialized + num_bits <= m_TotalBits; }
 
        uint32_t get_total_bits() const noexcept { return m_TotalBits; }
 
        bool extend(uint32_t num_bits)
        {
            if (!can_serialize_bits(num_bits))
                return false;
 
            m_NumBitsSerialized += num_bits;
            return true;
        }
 
        uint32_t* m_Buffer;
        // TODO: Transition sizes to size_t
        uint32_t m_NumBitsSerialized;
        uint32_t m_TotalBits;
    };
 
    template<typename T>
    struct growing_policy
    {
        growing_policy(T& container) noexcept :
            m_Buffer(container),
            m_NumBitsSerialized(0) {}
 
        uint32_t* get_buffer() const noexcept { return m_Buffer.data(); }
 
        uint32_t get_num_bits_serialized() const noexcept { return m_NumBitsSerialized; }
 
        bool can_serialize_bits(uint32_t num_bits) const noexcept { return true; }
 
        uint32_t get_total_bits() const noexcept { return (std::numeric_limits<uint32_t>::max)(); }
 
        bool extend(uint32_t num_bits)
        {
            m_NumBitsSerialized += num_bits;
            uint32_t num_bytes = (m_NumBitsSerialized - 1) / 8U + 1;
            m_Buffer.resize(num_bytes);
            return true;
        }
 
        T& m_Buffer;
 
        uint32_t m_NumBitsSerialized;
    };
}