From 387f3b78d6f13bc80c980f517c38e7b4f268ba03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Mon, 8 Jun 2015 10:37:49 +0200
Subject: [PATCH] Ability to move-construct Context.

Useful in this case:

    std::optional<Platform::Context> context;
    context = Platform::Context{};

This was currently possible only with calling context.emplace(), which
in my opinion is confusing and looks like a no-op. Move assignment is
still not allowed, because having two separate state trackers (and
deleting one of them) currently makes no sense.
---
 src/Magnum/Context.cpp | 18 ++++++++++++++++--
 src/Magnum/Context.h   |  6 +++---
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/src/Magnum/Context.cpp b/src/Magnum/Context.cpp
index 296a8f6e8..458bea2d9 100644
--- a/src/Magnum/Context.cpp
+++ b/src/Magnum/Context.cpp
@@ -543,10 +543,24 @@ Context::Context(void functionLoader()) {
     Renderer::initializeContextBasedFunctionality();
 }
 
+Context::Context(Context&& other): _version{std::move(other._version)},
+    #ifndef MAGNUM_TARGET_WEBGL
+    _flags{std::move(other._flags)},
+    #endif
+    _extensionRequiredVersion{std::move(other._extensionRequiredVersion)},
+    _extensionStatus{std::move(other._extensionStatus)},
+    _supportedExtensions{std::move(other._supportedExtensions)},
+    _state{std::move(other._state)},
+    _detectedDrivers{std::move(other._detectedDrivers)}
+{
+    other._state = nullptr;
+    if(_current == &other) _current = this;
+}
+
 Context::~Context() {
-    CORRADE_ASSERT(_current == this, "Context: Cannot destroy context which is not currently active", );
     delete _state;
-    _current = nullptr;
+
+    if(_current == this) _current = nullptr;
 }
 
 std::vector<std::string> Context::shadingLanguageVersionStrings() const {
diff --git a/src/Magnum/Context.h b/src/Magnum/Context.h
index 41dc783d8..c4bdfd876 100644
--- a/src/Magnum/Context.h
+++ b/src/Magnum/Context.h
@@ -210,15 +210,15 @@ class MAGNUM_EXPORT Context {
         /** @brief Copying is not allowed */
         Context(const Context&) = delete;
 
-        /** @brief Moving is not allowed */
-        Context(Context&&) = delete;
+        /** @brief Move constructor */
+        Context(Context&& other);
 
         ~Context();
 
         /** @brief Copying is not allowed */
         Context& operator=(const Context&) = delete;
 
-        /** @brief Moving is not allowed */
+        /** @brief Move assignment is not allowed */
         Context& operator=(Context&&) = delete;
 
         /** @brief Current context */