From 25153001c0d7f02a7b126a965d0574e1ec7268ba Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sun, 4 Jul 2021 23:17:33 +0300
Subject: [PATCH] Proper move, reset & null-construct for gfx::program

---
 libs/gfx/include/psemek/gfx/program.hpp | 15 +++++++++++++
 libs/gfx/source/program.cpp             | 29 ++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/libs/gfx/include/psemek/gfx/program.hpp b/libs/gfx/include/psemek/gfx/program.hpp
index b1066b9a..1167c097 100644
--- a/libs/gfx/include/psemek/gfx/program.hpp
+++ b/libs/gfx/include/psemek/gfx/program.hpp
@@ -19,12 +19,23 @@ namespace psemek::gfx
 		program(std::string_view vertex_source, std::string_view fragment_source);
 		program(std::string_view vertex_source, std::string_view geometry_source, std::string_view fragment_source);
 
+		program(program && other);
+
+		program & operator = (program && other);
+
 		~program();
 
+		static program null()
+		{
+			return program(nullptr);
+		}
+
 		GLuint id() const;
 
 		void bind() const;
 
+		void reset();
+
 		GLint location(char const * name) const;
 
 		struct uniform_proxy
@@ -104,6 +115,10 @@ namespace psemek::gfx
 	private:
 		GLuint program_;
 		mutable std::unordered_map<std::string, GLint> uniforms_;
+
+		program(std::nullptr_t)
+			: program_{0}
+		{}
 	};
 
 	template <typename T, std::size_t D>
diff --git a/libs/gfx/source/program.cpp b/libs/gfx/source/program.cpp
index 8c88187f..b4358e48 100644
--- a/libs/gfx/source/program.cpp
+++ b/libs/gfx/source/program.cpp
@@ -322,9 +322,30 @@ namespace psemek::gfx
 		program_ = create_program({{gl::VERTEX_SHADER, vertex_source}, {gl::GEOMETRY_SHADER, geometry_source}, {gl::FRAGMENT_SHADER, fragment_source}});
 	}
 
+	program::program(program && other)
+		: program_(other.program_)
+		, uniforms_(std::move(other.uniforms_))
+	{
+		other.program_ = 0;
+	}
+
+	program & program::operator = (program && other)
+	{
+		if (this == &other)
+			return *this;
+
+		reset();
+
+		program_ = other.program_;
+		uniforms_ = std::move(other.uniforms_);
+		other.program_ = 0;
+
+		return *this;
+	}
+
 	program::~program()
 	{
-		gl::DeleteProgram(program_);
+		reset();
 	}
 
 	GLuint program::id() const
@@ -337,6 +358,12 @@ namespace psemek::gfx
 		gl::UseProgram(program_);
 	}
 
+	void program::reset()
+	{
+		gl::DeleteProgram(program_);
+		program_ = 0;
+	}
+
 	GLint program::location(char const * name) const
 	{
 		auto it = uniforms_.find(name);