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// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once
#include "pw_bytes/span.h"
#include "pw_rpc/internal/method_union.h"
#include "pw_rpc/internal/raw_method.h"
namespace pw::rpc::internal {
// MethodUnion which stores only a raw method. For use in fully raw RPC
// services, without any additional memory overhead.
class RawMethodUnion : public MethodUnion {
public:
constexpr RawMethodUnion(RawMethod&& method)
: impl_({.raw = std::move(method)}) {}
constexpr const Method& method() const { return impl_.method; }
constexpr const RawMethod& raw_method() const { return impl_.raw; }
private:
union {
Method method;
RawMethod raw;
} impl_;
};
// MethodTraits specialization for a unary method.
template <typename T>
struct MethodTraits<StatusWithSize (T::*)(
ServerContext&, ConstByteSpan, ByteSpan)> {
static constexpr MethodType kType = MethodType::kUnary;
using Service = T;
using Implementation = RawMethod;
};
// MethodTraits specialization for a raw server streaming method.
template <typename T>
struct MethodTraits<void (T::*)(
ServerContext&, ConstByteSpan, RawServerWriter&)> {
static constexpr MethodType kType = MethodType::kServerStreaming;
using Service = T;
using Implementation = RawMethod;
};
template <auto method>
constexpr bool kIsRaw = std::is_same_v<MethodImplementation<method>, RawMethod>;
// Deduces the type of an implemented service method from its signature, and
// returns the appropriate MethodUnion object to invoke it.
template <auto method>
constexpr RawMethod GetRawMethodFor(uint32_t id) {
static_assert(kIsRaw<method>,
"GetRawMethodFor should only be called on raw RPC methods");
using Traits = MethodTraits<decltype(method)>;
using ServiceImpl = typename Traits::Service;
if constexpr (Traits::kType == MethodType::kUnary) {
constexpr auto invoker =
+[](ServerCall& call, ConstByteSpan request, ByteSpan response) {
return (static_cast<ServiceImpl&>(call.service()).*method)(
call.context(), request, response);
};
return RawMethod::Unary<invoker>(id);
}
if constexpr (Traits::kType == MethodType::kServerStreaming) {
constexpr auto invoker =
+[](ServerCall& call, ConstByteSpan request, RawServerWriter& writer) {
(static_cast<ServiceImpl&>(call.service()).*method)(
call.context(), request, writer);
};
return RawMethod::ServerStreaming<invoker>(id);
}
constexpr auto fake_invoker =
+[](ServerCall&, ConstByteSpan, RawServerWriter&) {};
return RawMethod::ServerStreaming<fake_invoker>(0);
};
} // namespace pw::rpc::internal
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