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#pragma once
/**
* @file Reusable serialisers for serialization container types in a
* length-prefixed manner.
*
* Used by both the Worker and Serve protocols.
*/
#include "types.hh"
namespace nix {
class Store;
/**
* Reusable serialisers for serialization container types in a
* length-prefixed manner.
*
* @param T The type of the collection being serialised
*
* @param Inner This the most important parameter; this is the "inner"
* protocol. The user of this will substitute `MyProtocol` or similar
* when making a `MyProtocol::Serialiser<Collection<T>>`. Note that the
* inside is allowed to call to call `Inner::Serialiser` on different
* types. This is especially important for `std::map` which doesn't have
* a single `T` but one `K` and one `V`.
*/
template<class Inner, typename T>
struct LengthPrefixedProtoHelper;
/*!
* \typedef LengthPrefixedProtoHelper::S
*
* Read this as simply `using S = Inner::Serialise;`.
*
* It would be nice to use that directly, but C++ doesn't seem to allow
* it. The `typename` keyword needed to refer to `Inner` seems to greedy
* (low precedence), and then C++ complains that `Serialise` is not a
* type parameter but a real type.
*
* Making this `S` alias seems to be the only way to avoid these issues.
*/
#define LENGTH_PREFIXED_PROTO_HELPER(Inner, T) \
struct LengthPrefixedProtoHelper< Inner, T > \
{ \
static T read(const Store & store, typename Inner::ReadConn conn); \
static void write(const Store & store, typename Inner::WriteConn conn, const T & str); \
private: \
template<typename U> using S = typename Inner::template Serialise<U>; \
}
template<class Inner, typename T>
LENGTH_PREFIXED_PROTO_HELPER(Inner, std::vector<T>);
template<class Inner, typename T>
LENGTH_PREFIXED_PROTO_HELPER(Inner, std::set<T>);
template<class Inner, typename... Ts>
LENGTH_PREFIXED_PROTO_HELPER(Inner, std::tuple<Ts...>);
template<class Inner, typename K, typename V>
#define _X std::map<K, V>
LENGTH_PREFIXED_PROTO_HELPER(Inner, _X);
#undef _X
template<class Inner, typename T>
std::vector<T>
LengthPrefixedProtoHelper<Inner, std::vector<T>>::read(
const Store & store, typename Inner::ReadConn conn)
{
std::vector<T> resSet;
auto size = readNum<size_t>(conn.from);
while (size--) {
resSet.push_back(S<T>::read(store, conn));
}
return resSet;
}
template<class Inner, typename T>
void
LengthPrefixedProtoHelper<Inner, std::vector<T>>::write(
const Store & store, typename Inner::WriteConn conn, const std::vector<T> & resSet)
{
conn.to << resSet.size();
for (auto & key : resSet) {
S<T>::write(store, conn, key);
}
}
template<class Inner, typename T>
std::set<T>
LengthPrefixedProtoHelper<Inner, std::set<T>>::read(
const Store & store, typename Inner::ReadConn conn)
{
std::set<T> resSet;
auto size = readNum<size_t>(conn.from);
while (size--) {
resSet.insert(S<T>::read(store, conn));
}
return resSet;
}
template<class Inner, typename T>
void
LengthPrefixedProtoHelper<Inner, std::set<T>>::write(
const Store & store, typename Inner::WriteConn conn, const std::set<T> & resSet)
{
conn.to << resSet.size();
for (auto & key : resSet) {
S<T>::write(store, conn, key);
}
}
template<class Inner, typename K, typename V>
std::map<K, V>
LengthPrefixedProtoHelper<Inner, std::map<K, V>>::read(
const Store & store, typename Inner::ReadConn conn)
{
std::map<K, V> resMap;
auto size = readNum<size_t>(conn.from);
while (size--) {
auto k = S<K>::read(store, conn);
auto v = S<V>::read(store, conn);
resMap.insert_or_assign(std::move(k), std::move(v));
}
return resMap;
}
template<class Inner, typename K, typename V>
void
LengthPrefixedProtoHelper<Inner, std::map<K, V>>::write(
const Store & store, typename Inner::WriteConn conn, const std::map<K, V> & resMap)
{
conn.to << resMap.size();
for (auto & i : resMap) {
S<K>::write(store, conn, i.first);
S<V>::write(store, conn, i.second);
}
}
template<class Inner, typename... Ts>
std::tuple<Ts...>
LengthPrefixedProtoHelper<Inner, std::tuple<Ts...>>::read(
const Store & store, typename Inner::ReadConn conn)
{
return std::tuple<Ts...> {
S<Ts>::read(store, conn)...,
};
}
template<class Inner, typename... Ts>
void
LengthPrefixedProtoHelper<Inner, std::tuple<Ts...>>::write(
const Store & store, typename Inner::WriteConn conn, const std::tuple<Ts...> & res)
{
std::apply([&]<typename... Us>(const Us &... args) {
(S<Us>::write(store, conn, args), ...);
}, res);
}
}
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