From 4dce8e6aeb770fee1a7190526b04d03f3da69cb0 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Thu, 27 Oct 2022 18:28:42 +0200
Subject: wip binary serializer

---
 serialize/binary-serializer.cpp | 86 +++++++++++++++++++++++++++++++++++++++++
 serialize/binary-serializer.hpp | 82 +++++++++++++++++++++++++++++++++++++++
 serialize/binary-serializer.inl | 54 ++++++++++++++++++++++++++
 3 files changed, 222 insertions(+)
 create mode 100644 serialize/binary-serializer.cpp
 create mode 100644 serialize/binary-serializer.hpp
 create mode 100644 serialize/binary-serializer.inl

diff --git a/serialize/binary-serializer.cpp b/serialize/binary-serializer.cpp
new file mode 100644
index 00000000..08606768
--- /dev/null
+++ b/serialize/binary-serializer.cpp
@@ -0,0 +1,86 @@
+#include "binary-serializer.inl"
+#include <array>
+
+namespace floormat::Serialize {
+
+#if 0
+template<std::size_t N>
+struct byte_array_iterator final
+{
+    using iterator_category = std::forward_iterator_tag;
+    using difference_type   = std::ptrdiff_t;
+    using value_type        = char;
+    using pointer           = char*;
+    using reference         = char&;
+
+    constexpr byte_array_iterator(char (&buf)[N]) : buf{&buf}, i{0} {}
+    constexpr byte_array_iterator(char (&buf)[N], std::size_t i) : buf{&buf}, i{i} {}
+
+    constexpr reference operator*() const { fm_assert(i < N); return (*buf)[i]; }
+    constexpr pointer operator->() { fm_assert(i < N); return &(*buf)[i]; }
+    constexpr byte_array_iterator<N>& operator++() noexcept { i++; return *this; }
+    constexpr byte_array_iterator<N> operator++(int) noexcept { byte_array_iterator<N> tmp = *this; ++(*this); return tmp; }
+    friend constexpr bool operator==(const byte_array_iterator<N>&& a, const byte_array_iterator<N>&& b) noexcept = default;
+
+private:
+    char (*buf)[N];
+    std::size_t i;
+};
+
+template struct byte_array_iterator<sizeof(double)>;
+#endif
+
+struct value_buf final {
+    value_u value;
+    std::int8_t len;
+
+    explicit constexpr value_buf(value_u value, std::int8_t len) : value{value}, len{len} {}
+    constexpr bool operator==(const value_buf& o) const noexcept;
+
+    fm_DECLARE_DEFAULT_MOVE_ASSIGNMENT_(value_buf);
+    fm_DECLARE_DEFAULT_COPY_ASSIGNMENT(value_buf);
+};
+
+constexpr bool value_buf::operator==(const value_buf& o) const noexcept
+{
+    const auto N = len;
+    if (N != o.len)
+        return false;
+    for (std::int8_t i = 0; i < N; i++)
+        if (value.bytes[i] != o.value.bytes[i])
+            return false;
+    return true;
+}
+
+[[maybe_unused]]
+static constexpr bool test1()
+{
+    constexpr std::array<char, 4> bytes = { 1, 0, 1, 0 };
+    auto x = binary_reader(bytes.cbegin(), bytes.cend());
+    return x.read_u<unsigned char>().bytes[0] == 1 &&
+           x.read_u<unsigned char>().bytes[0] == 0 &&
+           x.read_u<unsigned char>().bytes[0] == 1 &&
+           x.read_u<unsigned char>().bytes[0] == 0;
+}
+static_assert(test1());
+
+[[maybe_unused]]
+static constexpr bool test2()
+{
+    constexpr std::array<char, 4> bytes = { 1, 0, 1, 0 };
+    auto r = binary_reader(bytes.cbegin(), bytes.cend());
+    const auto x = r.read_u<int>();
+    return x.bytes[0] == 1 && x.bytes[1] == 0 && x.bytes[2] == 1 && x.bytes[3] == 0;
+}
+static_assert(test2());
+
+template<typename T>
+[[maybe_unused]] static constexpr T maybe_byteswap(T x)
+{
+    if constexpr(std::endian::native == std::endian::big)
+        return std::byteswap(x);
+    else
+        return x;
+}
+
+} // namespace floormat::Serialize
diff --git a/serialize/binary-serializer.hpp b/serialize/binary-serializer.hpp
new file mode 100644
index 00000000..19aa5548
--- /dev/null
+++ b/serialize/binary-serializer.hpp
@@ -0,0 +1,82 @@
+#pragma once
+#include "compat/integer-types.hpp"
+#include "compat/defs.hpp"
+
+#include <bit>
+#include <iterator>
+#include <concepts>
+#include <type_traits>
+
+namespace floormat::Serialize {
+
+static_assert(std::endian::native == std::endian::big || std::endian::native == std::endian::little);
+
+enum class value_type : std::uint8_t {
+    none, uc, u8, u16, u32, u64,
+    f32, f64,
+    COUNT
+};
+
+template<std::size_t N> struct make_integer;
+template<std::size_t N> using make_integer_t = typename make_integer<N>::type;
+
+#define FM_SERIALIZE_MAKE_INTEGER(T) template<> struct make_integer<sizeof(T)> { using type = T; }
+FM_SERIALIZE_MAKE_INTEGER(std::uint8_t);
+FM_SERIALIZE_MAKE_INTEGER(std::uint16_t);
+FM_SERIALIZE_MAKE_INTEGER(std::uint32_t);
+FM_SERIALIZE_MAKE_INTEGER(std::uint64_t);
+#undef FN_SERIALIZE_MAKE_INTEGER
+
+template<typename T>
+concept integer = requires(T x) {
+    requires std::integral<T>;
+    requires sizeof(T) == sizeof(make_integer_t<sizeof(T)>);
+};
+
+union value_u {
+    alignas(alignof(double)) char bytes[8];
+    unsigned char uc;
+    std::uint8_t u8;
+    std::uint16_t u16;
+    std::uint32_t u32;
+    std::uint64_t u64;
+    float f32;
+    double f64;
+};
+
+static_assert(sizeof(value_u) == 8);
+
+template<typename T>
+concept char_sequence = requires(T& x, const T& cx) {
+    requires std::same_as<decltype(std::begin(x)), decltype(std::end(x))>;
+    requires std::same_as<decltype(std::cbegin(cx)), decltype(std::cend(cx))>;
+    requires std::forward_iterator<decltype(std::begin(x))>;
+    requires std::forward_iterator<decltype(std::cbegin(cx))>;
+    requires std::same_as<char, std::decay_t<decltype(*std::begin(x))>>;
+    requires std::same_as<char, std::decay_t<decltype(*std::cbegin(x))>>;
+};
+
+template<std::forward_iterator It>
+struct binary_reader final {
+    fm_DECLARE_DEFAULT_MOVE_COPY_ASSIGNMENTS(binary_reader<It>);
+    constexpr binary_reader(It begin, It end) noexcept : it{begin}, end{end} {}
+    template<char_sequence Seq>
+    explicit constexpr binary_reader(const Seq& seq) noexcept : it{std::begin(seq)}, end{std::end(seq)} {}
+    constexpr ~binary_reader() noexcept;
+
+    template<integer T> constexpr value_u read_u() noexcept;
+    template<std::floating_point T> constexpr value_u read_u() noexcept;
+    template<typename T> T read() noexcept;
+
+    static_assert(std::is_same_v<char, std::decay_t<decltype(*std::declval<It>())>>);
+
+private:
+    It it, end;
+};
+
+template<std::forward_iterator It> binary_reader(It&& begin, It&& end) -> binary_reader<std::decay_t<It>>;
+
+template<typename Array>
+binary_reader(Array&& array) -> binary_reader<std::decay_t<decltype(std::begin(array))>>;
+
+} // namespace floormat::Serialize
diff --git a/serialize/binary-serializer.inl b/serialize/binary-serializer.inl
new file mode 100644
index 00000000..9e7e58fa
--- /dev/null
+++ b/serialize/binary-serializer.inl
@@ -0,0 +1,54 @@
+#pragma once
+
+#include "binary-serializer.hpp"
+
+namespace floormat::Serialize {
+
+template<std::forward_iterator It>
+template<std::floating_point T>
+constexpr value_u binary_reader<It>::read_u() noexcept
+{
+    value_u buf;
+    static_assert(sizeof(T) <= sizeof(buf));
+    fm_assert(std::distance(it, end) >= sizeof(T));
+    for (int i = 0; i < sizeof(T); i++)
+        buf.bytes[i] = *it++;
+    return buf;
+}
+
+template<std::forward_iterator It>
+template<typename T>
+T binary_reader<It>::read() noexcept
+{
+    value_u buf = read_u<T>();
+    return *reinterpret_cast<T>(buf.bytes);
+}
+
+template<std::forward_iterator It>
+constexpr binary_reader<It>::~binary_reader() noexcept
+{
+    fm_assert(it == end);
+}
+
+template<std::forward_iterator It>
+template<integer T>
+constexpr value_u binary_reader<It>::read_u() noexcept
+{
+    value_u buf;
+    if (std::is_constant_evaluated())
+        for (std::size_t i = 0; i < std::size(buf.bytes); i++)
+            buf.bytes[i] = 0;
+    static_assert(sizeof(T) <= sizeof(buf));
+    fm_assert(std::distance(it, end) >= (std::ptrdiff_t) sizeof(T));
+    if constexpr(std::endian::native == std::endian::big)
+        for (int i = sizeof(T) - 1; i >= 0; i--)
+            buf.bytes[i] = *it++;
+    else
+        for (std::size_t i = 0; i < sizeof(T); i++)
+            buf.bytes[i] = *it++;
+    return buf;
+}
+
+} // namespace floormat::Serialize
+
+
-- 
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