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allwpilib/wpiutil/src/main/native/include/wpi/struct/Struct.h

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// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
#pragma once
#include <stdint.h>
#include <concepts>
#include <memory>
#include <span>
#include <string>
#include <string_view>
#include <type_traits>
#include <utility>
#include <vector>
#include <fmt/format.h>
#include "wpi/Endian.h"
#include "wpi/array.h"
#include "wpi/bit.h"
#include "wpi/ct_string.h"
#include "wpi/function_ref.h"
#include "wpi/mutex.h"
#include "wpi/type_traits.h"
namespace wpi {
/**
* Struct serialization template. Unspecialized class has no members; only
* specializations of this class are useful, and only if they meet the
* StructSerializable concept.
*
* @tparam T type to serialize/deserialize
* @tparam I optional struct type info
*/
template <typename T, typename... I>
struct Struct {};
/**
* Specifies that a type is capable of raw struct serialization and
* deserialization.
*
* This is designed for serializing small fixed-size data structures in the
* fastest and most compact means possible. Serialization consists of writing
* values into a mutable std::span and deserialization consists of reading
* values from an immutable std::span.
*
* Implementations must define a template specialization for wpi::Struct with
* T being the type that is being serialized/deserialized, with the following
* static members (as enforced by this concept):
* - std::string_view GetTypeName(): function that returns the type name
* - size_t GetSize(): function that returns the structure size in bytes
* - std::string_view GetSchema(): function that returns the struct schema
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* - T Unpack(std::span<const uint8_t>): function for deserialization
* - void Pack(std::span<uint8_t>, T&& value): function for
* serialization
*
* If possible, the GetTypeName(), GetSize(), and GetSchema() functions should
* be marked constexpr. GetTypeName() and GetSchema() may return types other
* than std::string_view, as long as the return value is convertible to
* std::string_view.
*
* If the struct has nested structs, implementations should also meet the
* requirements of HasNestedStruct<T>.
*/
template <typename T, typename... I>
concept StructSerializable = requires(std::span<const uint8_t> in,
std::span<uint8_t> out, T&& value,
const I&... info) {
typename Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>;
{
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::GetTypeName(info...)
} -> std::convertible_to<std::string_view>;
{
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::GetSize(info...)
} -> std::convertible_to<size_t>;
{
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::GetSchema(info...)
} -> std::convertible_to<std::string_view>;
{
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::Unpack(in, info...)
} -> std::same_as<typename std::remove_cvref_t<T>>;
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::Pack(out, std::forward<T>(value),
info...);
};
/**
* Specifies that a type is capable of in-place raw struct deserialization.
*
* In addition to meeting StructSerializable, implementations must define a
* wpi::Struct<T> static member `void UnpackInto(T*, std::span<const uint8_t>)`
* to update the pointed-to T with the contents of the span.
*/
template <typename T, typename... I>
concept MutableStructSerializable =
StructSerializable<T, I...> &&
requires(T* out, std::span<const uint8_t> in, const I&... info) {
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::UnpackInto(out, in, info...);
};
/**
* Specifies that a struct type has nested struct declarations.
*
* In addition to meeting StructSerializable, implementations must define a
* wpi::Struct<T> static member
* `void ForEachNested(std::invocable<std::string_view, std::string_view) auto
* fn)` (or equivalent) and call ForEachNestedStruct<Type> on each nested struct
* type.
*/
template <typename T, typename... I>
concept HasNestedStruct =
StructSerializable<T, I...> &&
requires(function_ref<void(std::string_view, std::string_view)> fn,
const I&... info) {
Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>::ForEachNested(fn, info...);
};
/**
* Unpack a serialized struct.
*
* @tparam T object type
* @param data raw struct data
* @param info optional struct type info
* @return Deserialized object
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
inline T UnpackStruct(std::span<const uint8_t> data, const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
return S::Unpack(data, info...);
}
/**
* Unpack a serialized struct starting at a given offset within the data.
* This is primarily useful in unpack implementations to unpack nested structs.
*
* @tparam T object type
* @tparam Offset starting offset
* @param data raw struct data
* @param info optional struct type info
* @return Deserialized object
*/
template <typename T, size_t Offset, typename... I>
requires StructSerializable<T, I...>
inline T UnpackStruct(std::span<const uint8_t> data, const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
return S::Unpack(data.subspan(Offset), info...);
}
/**
* Unpack a serialized struct array starting at a given offset within the data.
* This is primarily useful in unpack implementations to unpack nested struct
* arrays.
*
* @tparam T object type
* @tparam Offset starting offset
* @tparam N number of objects
* @param data raw struct data
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* @return Deserialized array
*/
template <StructSerializable T, size_t Offset, size_t N>
inline wpi::array<T, N> UnpackStructArray(std::span<const uint8_t> data) {
if (is_constexpr([] { Struct<std::remove_cvref_t<T>>::GetSize(); })) {
constexpr auto StructSize = Struct<std::remove_cvref_t<T>>::GetSize();
wpi::array<T, N> arr(wpi::empty_array);
[&]<size_t... Is>(std::index_sequence<Is...>) {
((arr[Is] = UnpackStruct<T, Offset + Is * StructSize>(data)), ...);
}(std::make_index_sequence<N>{});
return arr;
} else {
auto size = Struct<std::remove_cvref_t<T>>::GetSize();
wpi::array<T, N> arr(wpi::empty_array);
for (size_t i = 0; i < N; i++) {
arr[i] = UnpackStruct<T>(data);
data = data.subspan(size);
}
return arr;
}
}
/**
* Pack a serialized struct.
*
* @param data struct storage (mutable, output)
* @param value object
* @param info optional struct type info
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
inline void PackStruct(std::span<uint8_t> data, T&& value, const I&... info) {
using S = Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>;
S::Pack(data, std::forward<T>(value), info...);
}
/**
* Pack a serialized struct starting at a given offset within the data. This is
* primarily useful in pack implementations to pack nested structs.
*
* @tparam Offset starting offset
* @param data struct storage (mutable, output)
* @param value object
* @param info optional struct type info
*/
template <size_t Offset, typename T, typename... I>
requires StructSerializable<T, I...>
inline void PackStruct(std::span<uint8_t> data, T&& value, const I&... info) {
using S = Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>;
S::Pack(data.subspan(Offset), std::forward<T>(value), info...);
}
/**
* Pack a serialized struct array starting at a given offset within the data.
* This is primarily useful in pack implementations to pack nested struct
* arrays.
*
* @tparam Offset starting offset
* @tparam N number of objects
* @param data struct storage (mutable, output)
* @param arr array of object
*/
template <size_t Offset, size_t N, StructSerializable T>
inline void PackStructArray(std::span<uint8_t> data,
const wpi::array<T, N>& arr) {
if (is_constexpr([] { Struct<std::remove_cvref_t<T>>::GetSize(); })) {
constexpr auto StructSize = Struct<std::remove_cvref_t<T>>::GetSize();
[&]<size_t... Is>(std::index_sequence<Is...>) {
(PackStruct<Offset + Is * StructSize>(data, arr[Is]), ...);
}(std::make_index_sequence<N>{});
} else {
auto size = Struct<std::remove_cvref_t<T>>::GetSize();
for (auto&& val : arr) {
PackStruct(data, val);
data = data.subspan(size);
}
}
}
/**
* Unpack a serialized struct into an existing object, overwriting its contents.
*
* @param out object (output)
* @param data raw struct data
* @param info optional struct type info
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
inline void UnpackStructInto(T* out, std::span<const uint8_t> data,
const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (MutableStructSerializable<T, I...>) {
S::UnpackInto(out, data, info...);
} else {
*out = UnpackStruct<T>(data, info...);
}
}
/**
* Unpack a serialized struct into an existing object, overwriting its contents,
* and starting at a given offset within the data.
* This is primarily useful in unpack implementations to unpack nested structs.
*
* @tparam Offset starting offset
* @param out object (output)
* @param data raw struct data
* @param info optional struct type info
*/
template <size_t Offset, typename T, typename... I>
requires StructSerializable<T, I...>
inline void UnpackStructInto(T* out, std::span<const uint8_t> data,
const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (MutableStructSerializable<T, I...>) {
S::UnpackInto(out, data.subspan(Offset), info...);
} else {
*out = UnpackStruct<T, Offset>(data, info...);
}
}
/**
* Get the type name for a raw struct serializable type
*
* @tparam T serializable type
* @param info optional struct type info
* @return type name
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
constexpr auto GetStructTypeName(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
return S::GetTypeName(info...);
}
/**
* Get the type string for a raw struct serializable type
*
* @tparam T serializable type
* @param info optional struct type info
* @return type string (struct: followed by type name)
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
constexpr auto GetStructTypeString(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (sizeof...(I) == 0 &&
is_constexpr([&] { S::GetTypeName(info...); })) {
constexpr auto typeName = S::GetTypeName(info...);
using namespace literals;
return Concat(
"struct:"_ct_string,
ct_string<char, std::char_traits<char>, typeName.size()>{typeName});
} else {
return fmt::format("struct:{}", S::GetTypeName(info...));
}
}
/**
* Get the size for a raw struct serializable type
*
* @tparam T serializable type
* @param info optional struct type info
* @return size
*/
template <typename T, typename... I>
requires StructSerializable<T, I...>
constexpr size_t GetStructSize(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
return S::GetSize(info...);
}
template <typename T, size_t N, typename... I>
requires StructSerializable<T, I...>
constexpr auto MakeStructArrayTypeName(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (sizeof...(I) == 0 &&
is_constexpr([&] { S::GetTypeName(info...); })) {
constexpr auto typeName = S::GetTypeName(info...);
using namespace literals;
if constexpr (N == std::dynamic_extent) {
return Concat(
ct_string<char, std::char_traits<char>, typeName.size()>{typeName},
"[]"_ct_string);
} else {
return Concat(
ct_string<char, std::char_traits<char>, typeName.size()>{typeName},
"["_ct_string, NumToCtString<N>(), "]"_ct_string);
}
} else {
if constexpr (N == std::dynamic_extent) {
return fmt::format("{}[]", S::GetTypeName(info...));
} else {
return fmt::format("{}[{}]", S::GetTypeName(info...), N);
}
}
}
template <typename T, size_t N, typename... I>
requires StructSerializable<T, I...>
constexpr auto MakeStructArrayTypeString(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (sizeof...(I) == 0 &&
is_constexpr([&] { S::GetTypeName(info...); })) {
using namespace literals;
return Concat("struct:"_ct_string, MakeStructArrayTypeName<T, N>(info...));
} else {
return fmt::format("struct:{}", MakeStructArrayTypeName<T, N>(info...));
}
}
template <typename T, size_t N, typename... I>
requires StructSerializable<T, I...>
constexpr auto MakeStructArraySchema(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
if constexpr (sizeof...(I) == 0 &&
is_constexpr([&] { S::GetSchema(info...); })) {
constexpr auto schema = S::GetSchema(info...);
using namespace literals;
if constexpr (N == std::dynamic_extent) {
return Concat(
ct_string<char, std::char_traits<char>, schema.size()>{schema},
"[]"_ct_string);
} else {
return Concat(
ct_string<char, std::char_traits<char>, schema.size()>{schema},
"["_ct_string, NumToCtString<N>(), "]"_ct_string);
}
} else {
if constexpr (N == std::dynamic_extent) {
return fmt::format("{}[]", S::GetSchema(info...));
} else {
return fmt::format("{}[{}]", S::GetSchema(info...), N);
}
}
}
template <typename T, typename... I>
requires StructSerializable<T, I...>
constexpr std::string_view GetStructSchema(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
return S::GetSchema(info...);
}
template <typename T, typename... I>
requires StructSerializable<T, I...>
constexpr std::span<const uint8_t> GetStructSchemaBytes(const I&... info) {
using S = Struct<T, typename std::remove_cvref_t<I>...>;
auto schema = S::GetSchema(info...);
return {reinterpret_cast<const uint8_t*>(schema.data()), schema.size()};
}
template <typename T, typename... I>
requires StructSerializable<T, I...>
void ForEachStructSchema(
std::invocable<std::string_view, std::string_view> auto fn,
const I&... info) {
using S = Struct<typename std::remove_cvref_t<T>,
typename std::remove_cvref_t<I>...>;
if constexpr (HasNestedStruct<T, I...>) {
S::ForEachNested(fn, info...);
}
fn(GetStructTypeString<T>(info...), S::GetSchema(info...));
}
template <typename T, typename... I>
requires StructSerializable<T, I...>
class StructArrayBuffer {
using S = Struct<T, I...>;
public:
StructArrayBuffer() = default;
StructArrayBuffer(const StructArrayBuffer&) = delete;
StructArrayBuffer& operator=(const StructArrayBuffer&) = delete;
StructArrayBuffer(StructArrayBuffer&& rhs) : m_buf{std::move(rhs.m_buf)} {}
StructArrayBuffer& operator=(StructArrayBuffer&& rhs) {
m_buf = std::move(rhs.m_buf);
return *this;
}
template <typename U, typename F>
requires
#if __cpp_lib_ranges >= 201911L
std::ranges::range<U> &&
std::convertible_to<std::ranges::range_value_t<U>, T> &&
#endif
std::invocable<F, std::span<const uint8_t>>
void Write(U&& data, F&& func, const I&... info) {
auto size = S::GetSize(info...);
if ((std::size(data) * size) < 256) {
// use the stack
uint8_t buf[256];
auto out = buf;
for (auto&& val : data) {
S::Pack(std::span<uint8_t>{std::to_address(out), size},
std::forward<decltype(val)>(val), info...);
out += size;
}
func(std::span<uint8_t>{buf, out});
} else {
std::scoped_lock lock{m_mutex};
m_buf.resize(std::size(data) * size);
auto out = m_buf.begin();
for (auto&& val : data) {
S::Pack(std::span<uint8_t>{std::to_address(out), size},
std::forward<decltype(val)>(val), info...);
out += size;
}
func(m_buf);
}
}
private:
wpi::mutex m_mutex;
std::vector<uint8_t> m_buf;
};
/**
* Raw struct support for fixed-size arrays of other structs.
*/
template <typename T, size_t N, typename... I>
requires StructSerializable<T, I...>
struct Struct<std::array<T, N>, I...> {
static constexpr auto GetTypeName(const I&... info) {
return MakeStructArrayTypeName<T, N>(info...);
}
static constexpr size_t GetSize(const I&... info) {
return N * GetStructSize<T>(info...);
}
static constexpr auto GetSchema(const I&... info) {
return MakeStructArraySchema<T, N>(info...);
}
static std::array<T, N> Unpack(std::span<const uint8_t> data,
const I&... info) {
auto size = GetStructSize<T>(info...);
std::array<T, N> result;
for (size_t i = 0; i < N; ++i) {
result[i] = UnpackStruct<T, 0>(data, info...);
data = data.subspan(size);
}
return result;
}
static void Pack(std::span<uint8_t> data, std::span<const T, N> values,
const I&... info) {
auto size = GetStructSize<T>(info...);
std::span<uint8_t> unsizedData = data;
for (auto&& val : values) {
PackStruct(unsizedData, val, info...);
unsizedData = unsizedData.subspan(size);
}
}
static void UnpackInto(std::array<T, N>* out, std::span<const uint8_t> data,
const I&... info) {
UnpackInto(std::span{*out}, data, info...);
}
// alternate span-based function
static void UnpackInto(std::span<T, N> out, std::span<const uint8_t> data,
const I&... info) {
auto size = GetStructSize<T>(info...);
std::span<const uint8_t> unsizedData = data;
for (size_t i = 0; i < N; ++i) {
UnpackStructInto(&out[i], unsizedData, info...);
unsizedData = unsizedData.subspan(size);
}
}
};
/**
* Raw struct support for boolean values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<bool> {
static constexpr std::string_view GetTypeName() { return "bool"; }
static constexpr size_t GetSize() { return 1; }
static constexpr std::string_view GetSchema() { return "bool value"; }
static bool Unpack(std::span<const uint8_t> data) { return data[0]; }
static void Pack(std::span<uint8_t> data, bool value) {
data[0] = static_cast<char>(value ? 1 : 0);
}
};
/**
* Raw struct support for uint8_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<uint8_t> {
static constexpr std::string_view GetTypeName() { return "uint8"; }
static constexpr size_t GetSize() { return 1; }
static constexpr std::string_view GetSchema() { return "uint8 value"; }
static uint8_t Unpack(std::span<const uint8_t> data) { return data[0]; }
static void Pack(std::span<uint8_t> data, uint8_t value) { data[0] = value; }
};
/**
* Raw struct support for int8_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<int8_t> {
static constexpr std::string_view GetTypeName() { return "int8"; }
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static constexpr size_t GetSize() { return 1; }
static constexpr std::string_view GetSchema() { return "int8 value"; }
static int8_t Unpack(std::span<const uint8_t> data) { return data[0]; }
static void Pack(std::span<uint8_t> data, int8_t value) { data[0] = value; }
};
/**
* Raw struct support for uint16_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<uint16_t> {
static constexpr std::string_view GetTypeName() { return "uint16"; }
static constexpr size_t GetSize() { return 2; }
static constexpr std::string_view GetSchema() { return "uint16 value"; }
static uint16_t Unpack(std::span<const uint8_t> data) {
return support::endian::read16le(data.data());
}
static void Pack(std::span<uint8_t> data, uint16_t value) {
support::endian::write16le(data.data(), value);
}
};
/**
* Raw struct support for int16_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<int16_t> {
static constexpr std::string_view GetTypeName() { return "int16"; }
static constexpr size_t GetSize() { return 2; }
static constexpr std::string_view GetSchema() { return "int16 value"; }
static int16_t Unpack(std::span<const uint8_t> data) {
return support::endian::read16le(data.data());
}
static void Pack(std::span<uint8_t> data, int16_t value) {
support::endian::write16le(data.data(), value);
}
};
/**
* Raw struct support for uint32_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<uint32_t> {
static constexpr std::string_view GetTypeName() { return "uint32"; }
static constexpr size_t GetSize() { return 4; }
static constexpr std::string_view GetSchema() { return "uint32 value"; }
static uint32_t Unpack(std::span<const uint8_t> data) {
return support::endian::read32le(data.data());
}
static void Pack(std::span<uint8_t> data, uint32_t value) {
support::endian::write32le(data.data(), value);
}
};
/**
* Raw struct support for int32_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<int32_t> {
static constexpr std::string_view GetTypeName() { return "int32"; }
static constexpr size_t GetSize() { return 4; }
static constexpr std::string_view GetSchema() { return "int32 value"; }
static int32_t Unpack(std::span<const uint8_t> data) {
return support::endian::read32le(data.data());
}
static void Pack(std::span<uint8_t> data, int32_t value) {
support::endian::write32le(data.data(), value);
}
};
/**
* Raw struct support for uint64_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<uint64_t> {
static constexpr std::string_view GetTypeName() { return "uint64"; }
static constexpr size_t GetSize() { return 8; }
static constexpr std::string_view GetSchema() { return "uint64 value"; }
static uint64_t Unpack(std::span<const uint8_t> data) {
return support::endian::read64le(data.data());
}
static void Pack(std::span<uint8_t> data, uint64_t value) {
support::endian::write64le(data.data(), value);
}
};
/**
* Raw struct support for int64_t values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<int64_t> {
static constexpr std::string_view GetTypeName() { return "int64"; }
static constexpr size_t GetSize() { return 8; }
static constexpr std::string_view GetSchema() { return "int64 value"; }
static int64_t Unpack(std::span<const uint8_t> data) {
return support::endian::read64le(data.data());
}
static void Pack(std::span<uint8_t> data, int64_t value) {
support::endian::write64le(data.data(), value);
}
};
/**
* Raw struct support for float values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<float> {
static constexpr std::string_view GetTypeName() { return "float"; }
static constexpr size_t GetSize() { return 4; }
static constexpr std::string_view GetSchema() { return "float value"; }
static float Unpack(std::span<const uint8_t> data) {
return bit_cast<float>(support::endian::read32le(data.data()));
}
static void Pack(std::span<uint8_t> data, float value) {
support::endian::write32le(data.data(), bit_cast<uint32_t>(value));
}
};
/**
* Raw struct support for double values.
* Primarily useful for higher level struct implementations.
*/
template <>
struct Struct<double> {
static constexpr std::string_view GetTypeName() { return "double"; }
static constexpr size_t GetSize() { return 8; }
static constexpr std::string_view GetSchema() { return "double value"; }
static double Unpack(std::span<const uint8_t> data) {
return bit_cast<double>(support::endian::read64le(data.data()));
}
static void Pack(std::span<uint8_t> data, double value) {
support::endian::write64le(data.data(), bit_cast<uint64_t>(value));
}
};
} // namespace wpi