From 9c86a405b72a9eddec57a63f4a4a5f3b70f3949a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barnab=C3=A1s=20P=C5=91cze?=
 <barnabas.pocze@ideasonboard.com>
Date: Wed, 5 Feb 2025 17:48:22 +0100
Subject: [PATCH] libcamera: base: bound_method: Forward arguments when
 possible
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Use `std::{forward,move}` to forward the arguments, this enables the
use of move constructors, likely leading to less code and better runtime.
For example, move constructing a libstdc++ `std::shared_ptr` is noticeably
less code than copy constructing one.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 include/libcamera/base/bound_method.h | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/include/libcamera/base/bound_method.h b/include/libcamera/base/bound_method.h
index e14614bc..91fe8b8c 100644
--- a/include/libcamera/base/bound_method.h
+++ b/include/libcamera/base/bound_method.h
@@ -33,8 +33,9 @@ template<typename R, typename... Args>
 class BoundMethodPack : public BoundMethodPackBase
 {
 public:
-	BoundMethodPack(const Args &... args)
-		: args_(args...)
+	template<typename... Ts>
+	BoundMethodPack(Ts &&...args)
+		: args_(std::forward<Ts>(args)...)
 	{
 	}
 
@@ -46,8 +47,9 @@ template<typename... Args>
 class BoundMethodPack<void, Args...> : public BoundMethodPackBase
 {
 public:
-	BoundMethodPack(const Args &... args)
-		: args_(args...)
+	template<typename... Ts>
+	BoundMethodPack(Ts &&...args)
+		: args_(std::forward<Ts>(args)...)
 	{
 	}
 
@@ -121,16 +123,16 @@ public:
 
 	BoundMethodFunctor(T *obj, Object *object, Func func,
 			   ConnectionType type = ConnectionTypeAuto)
-		: BoundMethodArgs<R, Args...>(obj, object, type), func_(func)
+		: BoundMethodArgs<R, Args...>(obj, object, type), func_(std::move(func))
 	{
 	}
 
 	R activate(Args... args, bool deleteMethod = false) override
 	{
 		if (!this->object_)
-			return func_(args...);
+			return func_(std::forward<Args>(args)...);
 
-		auto pack = std::make_shared<PackType>(args...);
+		auto pack = std::make_shared<PackType>(std::forward<Args>(args)...);
 		[[maybe_unused]] bool sync = BoundMethodBase::activatePack(pack, deleteMethod);
 
 		if constexpr (!std::is_void_v<R>)
@@ -139,7 +141,7 @@ public:
 
 	R invoke(Args... args) override
 	{
-		return func_(args...);
+		return func_(std::forward<Args>(args)...);
 	}
 
 private:
@@ -164,10 +166,10 @@ public:
 	{
 		if (!this->object_) {
 			T *obj = static_cast<T *>(this->obj_);
-			return (obj->*func_)(args...);
+			return (obj->*func_)(std::forward<Args>(args)...);
 		}
 
-		auto pack = std::make_shared<PackType>(args...);
+		auto pack = std::make_shared<PackType>(std::forward<Args>(args)...);
 		[[maybe_unused]] bool sync = BoundMethodBase::activatePack(pack, deleteMethod);
 
 		if constexpr (!std::is_void_v<R>)
@@ -177,7 +179,7 @@ public:
 	R invoke(Args... args) override
 	{
 		T *obj = static_cast<T *>(this->obj_);
-		return (obj->*func_)(args...);
+		return (obj->*func_)(std::forward<Args>(args)...);
 	}
 
 private:
@@ -198,7 +200,7 @@ public:
 
 	R activate(Args... args, [[maybe_unused]] bool deleteMethod = false) override
 	{
-		return (*func_)(args...);
+		return (*func_)(std::forward<Args>(args)...);
 	}
 
 	R invoke(Args...) override