Add base::optional as a wrapper of base::variant.

Telegram/SourceFiles/base/flat_map.h

@@ -20,6 +20,8 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 */
 #pragma once
 
+#include "base/optional.h"
+
 namespace base {
 
 template <typename Key, typename Type>
@@ -378,7 +380,6 @@ public:
 	using iterator = typename parent::iterator;
 	using const_iterator = typename parent::const_iterator;
 	using value_type = typename parent::value_type;
-	using reference = typename parent::reference;
 
 	iterator insert(const value_type &value) {
 		if (this->empty() || (value.first < this->front().first)) {
@@ -424,19 +425,29 @@ public:
 		return this->findFirst(key);
 	}
 
-	reference operator[](const Key &key) {
+	Type &operator[](const Key &key) {
 		if (this->empty() || (key < this->front().first)) {
-			this->_impl.push_front(Type());
+			this->_impl.push_front({ key, Type() });
-			return this->front();
+			return this->front().second;
 		} else if (this->back().first < key) {
-			this->_impl.push_back(Type());
+			this->_impl.push_back({ key, Type() });
-			return this->back();
+			return this->back().second;
 		}
 		auto where = this->getLowerBound(key);
 		if (key < where->first) {
-			return *this->_impl.insert(where, { key, Type() });
+			return this->_impl.insert(where, { key, Type() })->second;
 		}
-		return *where;
+		return where->second;
+	}
+
+	optional<Type> take(const Key &key) {
+		auto it = find(key);
+		if (it == this->end()) {
+			return base::none;
+		}
+		auto result = std::move(it->second);
+		this->erase(it);
+		return std::move(result);
 	}
 
 };

Telegram/SourceFiles/base/functors.h

@@ -0,0 +1,42 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop version of Telegram messaging app, see https://telegram.org
+
+Telegram Desktop is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+It is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+In addition, as a special exception, the copyright holders give permission
+to link the code of portions of this program with the OpenSSL library.
+
+Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
+Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
+*/
+#pragma once
+
+namespace base {
+namespace functors {
+
+struct abs_helper {
+	template <typename Type,
+		typename = decltype(0 < std::declval<Type>()),
+		typename = decltype(-std::declval<Type>())>
+		constexpr Type operator()(Type value) const {
+		return (0 < value) ? value : (-value);
+	}
+};
+constexpr auto abs = abs_helper {};
+
+template <typename Type>
+inline auto add(Type a) {
+	return [a](auto b) { return a + b; };
+};
+
+} // namespace functors
+} // namespace base

Telegram/SourceFiles/base/optional.h

@@ -0,0 +1,214 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop version of Telegram messaging app, see https://telegram.org
+
+Telegram Desktop is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+It is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+In addition, as a special exception, the copyright holders give permission
+to link the code of portions of this program with the OpenSSL library.
+
+Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
+Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
+*/
+#pragma once
+
+#include "base/variant.h"
+
+namespace base {
+
+struct none_type {
+	bool operator==(none_type other) const {
+		return true;
+	}
+	bool operator!=(none_type other) const {
+		return false;
+	}
+	bool operator<(none_type other) const {
+		return false;
+	}
+	bool operator<=(none_type other) const {
+		return true;
+	}
+	bool operator>(none_type other) const {
+		return false;
+	}
+	bool operator>=(none_type other) const {
+		return true;
+	}
+
+};
+
+constexpr none_type none = {};
+
+template <typename... Types>
+class optional_variant {
+public:
+	optional_variant() : _impl(none) {
+	}
+	optional_variant(const optional_variant &other) : _impl(other._impl) {
+	}
+	optional_variant(optional_variant &&other) : _impl(std::move(other._impl)) {
+	}
+	template <typename T, typename = std::enable_if_t<!std::is_base_of<optional_variant, std::decay_t<T>>::value>>
+	optional_variant(T &&value) : _impl(std::forward<T>(value)) {
+	}
+	optional_variant &operator=(const optional_variant &other) {
+		_impl = other._impl;
+		return *this;
+	}
+	optional_variant &operator=(optional_variant &&other) {
+		_impl = std::move(other._impl);
+		return *this;
+	}
+	template <typename T, typename = std::enable_if_t<!std::is_base_of<optional_variant, std::decay_t<T>>::value>>
+	optional_variant &operator=(T &&value) {
+		_impl = std::forward<T>(value);
+		return *this;
+	}
+
+	explicit operator bool() const {
+		return (get_if<none_type>(&_impl) == nullptr);
+	}
+	bool operator==(const optional_variant &other) const {
+		return _impl == other._impl;
+	}
+	bool operator!=(const optional_variant &other) const {
+		return _impl != other._impl;
+	}
+	bool operator<(const optional_variant &other) const {
+		return _impl < other._impl;
+	}
+	bool operator<=(const optional_variant &other) const {
+		return _impl <= other._impl;
+	}
+	bool operator>(const optional_variant &other) const {
+		return _impl > other._impl;
+	}
+	bool operator>=(const optional_variant &other) const {
+		return _impl >= other._impl;
+	}
+
+	template <typename T>
+	decltype(auto) is() const {
+		return _impl.template is<T>();
+	}
+	template <typename T>
+	decltype(auto) get_unchecked() {
+		return _impl.template get_unchecked<T>();
+	}
+	template <typename T>
+	decltype(auto) get_unchecked() const {
+		return _impl.template get_unchecked<T>();
+	}
+
+private:
+	variant<none_type, Types...> _impl;
+
+};
+
+template <typename T, typename... Types>
+inline T *get_if(optional_variant<Types...> *v) {
+	return (v && v->template is<T>()) ? &v->template get_unchecked<T>() : nullptr;
+}
+
+template <typename T, typename... Types>
+inline const T *get_if(const optional_variant<Types...> *v) {
+	return (v && v->template is<T>()) ? &v->template get_unchecked<T>() : nullptr;
+}
+
+template <typename Type>
+class optional;
+
+template <typename Type>
+struct optional_wrap_once {
+	using type = optional<Type>;
+};
+
+template <typename Type>
+struct optional_wrap_once<optional<Type>> {
+	using type = optional<Type>;
+};
+
+template <typename Type>
+using optional_wrap_once_t = typename optional_wrap_once<std::decay_t<Type>>::type;
+
+template <typename Type>
+struct optional_chain_result {
+	using type = optional_wrap_once_t<Type>;
+};
+
+template <>
+struct optional_chain_result<void> {
+	using type = bool;
+};
+
+template <typename Type>
+using optional_chain_result_t = typename optional_chain_result<Type>::type;
+
+template <typename Type>
+class optional : public optional_variant<Type> {
+public:
+	using optional_variant<Type>::optional_variant;
+
+	Type &operator*() {
+		auto result = get_if<Type>(this);
+		Expects(result != nullptr);
+		return *result;
+	}
+	const Type &operator*() const {
+		auto result = get_if<Type>(this);
+		Expects(result != nullptr);
+		return *result;
+	}
+	Type *operator->() {
+		auto result = get_if<Type>(this);
+		Expects(result != nullptr);
+		return result;
+	}
+	const Type *operator->() const {
+		auto result = get_if<Type>(this);
+		Expects(result != nullptr);
+		return result;
+	}
+
+};
+
+template <typename Type>
+optional_wrap_once_t<Type> make_optional(Type &&value) {
+	return optional_wrap_once_t<Type> { std::forward<Type>(value) };
+}
+
+template <typename Type, typename Method>
+inline auto optional_chain(
+	const optional<Type> &value,
+	Method &method,
+	std::false_type)
+-> optional_chain_result_t<decltype(method(*value))> {
+	return value ? make_optional(method(*value)) : none;
+}
+
+template <typename Type, typename Method>
+inline auto optional_chain(
+	const optional<Type> &value,
+	Method &method,
+	std::true_type)
+-> optional_chain_result_t<decltype(method(*value))> {
+	return value ? (method(*value), true) : false;
+}
+
+template <typename Type, typename Method>
+inline auto operator|(const optional<Type> &value, Method method)
+-> optional_chain_result_t<decltype(method(*value))> {
+	using is_void_return = std::is_same<decltype(method(*value)), void>;
+	return optional_chain(value, method, is_void_return {});
+}
+
+} // namespace base

Telegram/SourceFiles/base/variant.h

@@ -25,21 +25,6 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 // We use base::variant<> alias and base::get_if() helper while we don't have std::variant<>.
 namespace base {
 
-struct null_variant_type {
-};
-
-inline constexpr null_variant_type null_variant() {
-	return null_variant_type {};
-}
-
-inline bool operator<(null_variant_type a, null_variant_type b) {
-	return false;
-}
-
-inline bool operator==(null_variant_type a, null_variant_type b) {
-	return true;
-}
-
 template <typename... Types>
 using variant = mapbox::util::variant<Types...>;
 
@@ -53,36 +38,4 @@ inline const T *get_if(const variant<Types...> *v) {
 	return (v && v->template is<T>()) ? &v->template get_unchecked<T>() : nullptr;
 }
 
-template <typename... Types>
-using optional_variant = variant<null_variant_type, Types...>;
-
-template <typename... Types>
-inline bool is_null_variant(const optional_variant<Types...> &variant) {
-	return get_if<null_variant_type>(&variant) != nullptr;
-}
-
-template <typename Type>
-using optional = optional_variant<Type>;
-
-using null_optional_type = null_variant_type;
-
-template <typename Type>
-inline Type *get_if(optional<Type> *v) {
-	return (v && v->template is<Type>()) ? &v->template get_unchecked<Type>() : nullptr;
-}
-
-template <typename Type>
-inline const Type *get_if(const optional<Type> *v) {
-	return (v && v->template is<Type>()) ? &v->template get_unchecked<Type>() : nullptr;
-}
-
-template <typename Type>
-inline bool is_null_optional(const optional<Type> &optional) {
-	return is_null_variant(optional);
-}
-
-inline constexpr null_optional_type null_optional() {
-	return null_optional_type {};
-}
-
 } // namespace base

Telegram/SourceFiles/chat_helpers/stickers_list_widget.cpp

@@ -635,7 +635,7 @@ void StickersListWidget::paintFeaturedStickers(Painter &p, QRect clip) {
 
 	auto &sets = shownSets();
 	auto selectedSticker = base::get_if<OverSticker>(&_selected);
-	auto selectedButton = base::get_if<OverButton>(base::is_null_variant(_pressed) ? &_selected : &_pressed);
+	auto selectedButton = base::get_if<OverButton>(_pressed ? &_pressed : &_selected);
 
 	auto tilly = st::stickerPanPadding;
 	auto ms = getms();
@@ -727,7 +727,7 @@ void StickersListWidget::paintStickers(Painter &p, QRect clip) {
 	auto ms = getms();
 	auto &sets = shownSets();
 	auto selectedSticker = base::get_if<OverSticker>(&_selected);
-	auto selectedButton = base::get_if<OverButton>(base::is_null_variant(_pressed) ? &_selected : &_pressed);
+	auto selectedButton = base::get_if<OverButton>(_pressed ? &_pressed : &_selected);
 	enumerateSections([this, &p, clip, fromColumn, toColumn, selectedSticker, selectedButton, ms](const SectionInfo &info) {
 		if (clip.top() >= info.rowsBottom) {
 			return true;
@@ -979,7 +979,7 @@ void StickersListWidget::mouseReleaseEvent(QMouseEvent *e) {
 	_previewTimer.stop();
 
 	auto pressed = _pressed;
-	setPressed(base::null_variant());
+	setPressed(base::none);
 	if (pressed != _selected) {
 		update();
 	}
@@ -994,7 +994,7 @@ void StickersListWidget::mouseReleaseEvent(QMouseEvent *e) {
 	updateSelected();
 
 	auto &sets = shownSets();
-	if (!base::is_null_variant(pressed) && pressed == _selected) {
+	if (pressed && pressed == _selected) {
 		if (auto sticker = base::get_if<OverSticker>(&pressed)) {
 			t_assert(sticker->section >= 0 && sticker->section < sets.size());
 			auto &set = sets[sticker->section];
@@ -1104,8 +1104,8 @@ void StickersListWidget::enterFromChildEvent(QEvent *e, QWidget *child) {
 }
 
 void StickersListWidget::clearSelection() {
-	setPressed(base::null_variant());
+	setPressed(base::none);
-	setSelected(base::null_variant());
+	setSelected(base::none);
 	update();
 }
 
@@ -1394,11 +1394,11 @@ bool StickersListWidget::preventAutoHide() {
 }
 
 void StickersListWidget::updateSelected() {
-	if (!base::is_null_variant(_pressed) && !_previewShown) {
+	if (_pressed && !_previewShown) {
 		return;
 	}
 
-	auto newSelected = OverState { base::null_variant() };
+	auto newSelected = OverState { base::none };
 	auto p = mapFromGlobal(_lastMousePosition);
 	if (!rect().contains(p)
 		|| p.y() < getVisibleTop() || p.y() >= getVisibleBottom()
@@ -1487,7 +1487,7 @@ bool StickersListWidget::stickerHasDeleteButton(const Set &set, int index) const
 
 void StickersListWidget::setSelected(OverState newSelected) {
 	if (_selected != newSelected) {
-		setCursor(base::is_null_variant(newSelected) ? style::cur_default : style::cur_pointer);
+		setCursor(newSelected ? style::cur_pointer : style::cur_default);
 
 		auto &sets = shownSets();
 		auto updateSelected = [this, &sets]() {

Telegram/SourceFiles/chat_helpers/stickers_list_widget.h

@@ -226,8 +226,8 @@ private:
 
 	Footer *_footer = nullptr;
 
-	OverState _selected = base::null_variant();
+	OverState _selected;
-	OverState _pressed = base::null_variant();
+	OverState _pressed;
 	QPoint _lastMousePosition;
 
 	Text _megagroupSetAbout;

Telegram/SourceFiles/history/history.cpp

@@ -1174,11 +1174,10 @@ void History::setUnreadMentionsCount(int count) {
 }
 
 bool History::addToUnreadMentions(MsgId msgId, AddToOverviewMethod method) {
-	auto count = base::get_if(&_unreadMentionsCount);
+	auto allLoaded = _unreadMentionsCount ? (_unreadMentions.size() >= *_unreadMentionsCount) : false;
-	auto allLoaded = count ? (_unreadMentions.size() >= *count) : false;
 	if (allLoaded) {
 		if (method == AddToOverviewNew) {
-			++*count;
+			++*_unreadMentionsCount;
 			_unreadMentions.insert(msgId);
 			return true;
 		}
@@ -1191,9 +1190,9 @@ bool History::addToUnreadMentions(MsgId msgId, AddToOverviewMethod method) {
 
 void History::eraseFromUnreadMentions(MsgId msgId) {
 	_unreadMentions.remove(msgId);
-	if (auto count = base::get_if(&_unreadMentionsCount)) {
+	if (_unreadMentionsCount) {
-		if (*count > 0) {
+		if (*_unreadMentionsCount > 0) {
-			--*count;
+			--*_unreadMentionsCount;
 		}
 	}
 	Notify::peerUpdatedDelayed(peer, Notify::PeerUpdate::Flag::UnreadMentionsChanged);

Telegram/SourceFiles/history/history.h

@@ -361,7 +361,7 @@ public:
 		return _unreadMentions.empty() ? 0 : _unreadMentions.back();
 	}
 	int getUnreadMentionsCount(int notLoadedValue = -1) const {
-		return base::is_null_optional(_unreadMentionsCount) ? notLoadedValue : *base::get_if(&_unreadMentionsCount);
+		return _unreadMentionsCount ? *_unreadMentionsCount : notLoadedValue;
 	}
 	bool hasUnreadMentions() const {
 		return (getUnreadMentionsCount() > 0);
@@ -559,7 +559,7 @@ private:
 	bool _mute = false;
 	int _unreadCount = 0;
 
-	base::optional<int> _unreadMentionsCount = base::null_optional();
+	base::optional<int> _unreadMentionsCount;
 	base::flat_set<MsgId> _unreadMentions;
 
 	Dialogs::RowsByLetter _chatListLinks[2];

Telegram/SourceFiles/stdafx.h

@@ -65,6 +65,7 @@ Copyright (c) 2014-2017 John Preston, https://desktop.telegram.org
 #include <gsl/gsl>
 
 #include "base/variant.h"
+#include "base/optional.h"
 #include "base/algorithm.h"
 
 #include "core/basic_types.h"

Telegram/gyp/telegram_sources.txt

@@ -7,6 +7,7 @@
 <(src_loc)/base/observer.h
 <(src_loc)/base/ordered_set.h
 <(src_loc)/base/openssl_help.h
+<(src_loc)/base/optional.h
 <(src_loc)/base/parse_helper.cpp
 <(src_loc)/base/parse_helper.h
 <(src_loc)/base/qthelp_regex.h