implement ProxySongList for handling general operations on lists

src/Makefile.am

@@ -72,6 +72,7 @@ noinst_HEADERS = \
 	mutable_song.h \
 	outputs.h \
 	playlist_editor.h \
+	proxy_song_list.h \
 	regex_filter.h \
 	regexes.h \
 	screen.h \

src/actions.cpp

@@ -508,84 +508,96 @@ void ScrollDown::Run()
 	ListsChangeFinisher();
 }
 
+bool ScrollUpArtist::canBeRun() const
+{
+	return proxySongList(myScreen).get();
+}
+
 void ScrollUpArtist::Run()
 {
-	// FIXME
+	auto pl = proxySongList(myScreen);
-	/*List *mList = myScreen->GetList();
+	assert(pl);
-	if (!mList || mList->Empty())
+	size_t pos = pl->choice();
-		return;
+	if (MPD::Song *s = pl->getSong(pos))
-	size_t pos = mList->Choice();
-	if (MPD::Song *s = myScreen->GetSong(pos))
 	{
 		std::string artist = s->getArtist();
 		while (pos > 0)
 		{
-			s = myScreen->GetSong(--pos);
+			s = pl->getSong(--pos);
-			myScreen->Scroll(wUp);
 			if (!s || s->getArtist() != artist)
 				break;
 		}
-	}*/
+		pl->highlight(pos);
+	}
+}
+
+bool ScrollUpAlbum::canBeRun() const
+{
+	return proxySongList(myScreen).get();
 }
 
 void ScrollUpAlbum::Run()
 {
-	// FIXME
+	auto pl = proxySongList(myScreen);
-	/*List *mList = myScreen->GetList();
+	assert(pl);
-	if (!mList || mList->Empty())
+	size_t pos = pl->choice();
-		return;
+	if (MPD::Song *s = pl->getSong(pos))
-	size_t pos = mList->Choice();
-	if (MPD::Song *s = myScreen->GetSong(pos))
 	{
 		std::string album = s->getAlbum();
 		while (pos > 0)
 		{
-			s = myScreen->GetSong(--pos);
+			s = pl->getSong(--pos);
-			myScreen->Scroll(wUp);
 			if (!s || s->getAlbum() != album)
 				break;
 		}
-	}*/
+		pl->highlight(pos);
+	}
+}
+
+bool ScrollDownArtist::canBeRun() const
+{
+	return proxySongList(myScreen).get();
 }
 
 void ScrollDownArtist::Run()
 {
-	// FIXME
+	auto pl = proxySongList(myScreen);
-	/*List *mList = myScreen->GetList();
+	assert(pl);
-	if (!mList || mList->Empty())
+	size_t pos = pl->choice();
-		return;
+	if (MPD::Song *s = pl->getSong(pos))
-	size_t pos = mList->Choice();
-	if (MPD::Song *s = myScreen->GetSong(pos))
 	{
 		std::string artist = s->getArtist();
-		while (pos < mList->Size() - 1)
+		while (pos < pl->size() - 1)
 		{
-			s = myScreen->GetSong(++pos);
+			s = pl->getSong(++pos);
-			myScreen->Scroll(wDown);
 			if (!s || s->getArtist() != artist)
 				break;
 		}
-	}*/
+		pl->highlight(pos);
+	}
+}
+
+bool ScrollDownAlbum::canBeRun() const
+{
+	return proxySongList(myScreen).get();
 }
 
 void ScrollDownAlbum::Run()
 {
-	// FIXME
+	auto pl = proxySongList(myScreen);
-	/*List *mList = myScreen->GetList();
+	assert(pl);
-	if (!mList || mList->Empty())
+	size_t pos = pl->choice();
-		return;
+	if (MPD::Song *s = pl->getSong(pos))
-	size_t pos = mList->Choice();
-	if (MPD::Song *s = myScreen->GetSong(pos))
 	{
 		std::string album = s->getAlbum();
-		while (pos < mList->Size() - 1)
+		while (pos < pl->size() - 1)
 		{
-			s = myScreen->GetSong(++pos);
+			s = pl->getSong(++pos);
-			myScreen->Scroll(wDown);
 			if (!s || s->getAlbum() != album)
 				break;
 		}
-	}*/
+		pl->highlight(pos);
+	}
 }
 
 void PageUp::Run()
@@ -1384,8 +1396,7 @@ void SetCrossfade::Run()
 bool EditSong::canBeRun() const
 {
 #	ifdef HAVE_TAGLIB_H
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	return currentSong(myScreen);
-	return w && w->currentSong();
 #	else
 	return false;
 #	endif // HAVE_TAGLIB_H
@@ -1396,9 +1407,7 @@ void EditSong::Run()
 #	ifdef HAVE_TAGLIB_H
 	if (!isMPDMusicDirSet())
 		return;
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto s = currentSong(myScreen);
-	assert(w);
-	auto s = w->currentSong();
 	assert(s);
 	myTinyTagEditor->SetEdited(*s);
 	myTinyTagEditor->SwitchTo();
@@ -1641,29 +1650,24 @@ void EditLyrics::Run()
 
 bool JumpToBrowser::canBeRun() const
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	return currentSong(myScreen);
-	return w && w->currentSong();
 }
 
 void JumpToBrowser::Run()
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto s = currentSong(myScreen);
-	auto s = w->currentSong();
 	assert(s);
 	myBrowser->LocateSong(*s);
 }
 
 bool JumpToMediaLibrary::canBeRun() const
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	return currentSong(myScreen);
-	return w && w->currentSong();
 }
 
 void JumpToMediaLibrary::Run()
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto s = currentSong(myScreen);
-	assert(w);
-	auto s = w->currentSong();
 	assert(s);
 	myLibrary->LocateSong(*s);
 }
@@ -1719,8 +1723,7 @@ void ToggleScreenLock::Run()
 bool JumpToTagEditor::canBeRun() const
 {
 #	ifdef HAVE_TAGLIB_H
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	return currentSong(myScreen);
-	return w && w->currentSong();
 #	else
 	return false;
 #	endif // HAVE_TAGLIB_H
@@ -1731,9 +1734,7 @@ void JumpToTagEditor::Run()
 #	ifdef HAVE_TAGLIB_H
 	if (!isMPDMusicDirSet())
 		return;
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto s = currentSong(myScreen);
-	assert(w);
-	auto s = w->currentSong();
 	assert(s);
 	myTagEditor->LocateSong(*s);
 #	endif // HAVE_TAGLIB_H
@@ -1794,13 +1795,13 @@ void JumpToPositionInSong::Run()
 
 bool ReverseSelection::canBeRun() const
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto w = hasSongs(myScreen);
 	return w && w->allowsSelection();
 }
 
 void ReverseSelection::Run()
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto w = hasSongs(myScreen);
 	assert(w);
 	w->reverseSelection();
 	ShowMessage("Selection reversed");
@@ -1808,58 +1809,54 @@ void ReverseSelection::Run()
 
 bool DeselectItems::canBeRun() const
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	return proxySongList(myScreen).get();
-	return w && w->allowsSelection();
 }
 
 void DeselectItems::Run()
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto pl = proxySongList(myScreen);
-	assert(w);
+	assert(pl);
-	w->removeSelection();
+	for (size_t i = 0; i < pl->size(); ++i)
+		pl->setSelected(i, false);
 }
 
 bool SelectAlbum::canBeRun() const
 {
-	auto w = dynamic_cast<HasSongs *>(myScreen);
+	auto w = hasSongs(myScreen);
-	return w && w->allowsSelection()
+	return w && w->allowsSelection() && w->getProxySongList().get();
-	    && myScreen->GetList();
 }
 
 void SelectAlbum::Run()
 {
-	// FIXME
+	auto pl = proxySongList(myScreen);
-	/*List *mList = myScreen->GetList();
+	assert(pl);
-	assert(mList);
+	size_t pos = pl->choice();
-	size_t pos = mList->Choice();
+	if (MPD::Song *s = pl->getSong(pos))
-	if (MPD::Song *s = myScreen->GetSong(pos))
 	{
 		std::string album = s->getAlbum();
-		
 		// select song under cursor
-		mList->Select(pos, 1);
+		pl->setSelected(pos, true);
 		// go up
 		while (pos > 0)
 		{
-			s = myScreen->GetSong(--pos);
+			s = pl->getSong(--pos);
 			if (!s || s->getAlbum() != album)
 				break;
 			else
-				mList->Select(pos, 1);
+				pl->setSelected(pos, true);
 		}
 		// go down
-		pos = mList->Choice();
+		pos = pl->choice();
-		while (pos < mList->Size() - 1)
+		while (pos < pl->size() - 1)
 		{
-			s = myScreen->GetSong(++pos);
+			s = pl->getSong(++pos);
 			if (!s || s->getAlbum() != album)
 				break;
 			else
-				mList->Select(pos, 1);
+				pl->setSelected(pos, true);
 		}
 		ShowMessage("Album around cursor position selected");
 	}
-	*/
 }
 
 void AddSelectedItems::Run()
@@ -2354,7 +2351,11 @@ void ShowSongInfo::Run()
 bool ShowArtistInfo::canBeRun() const
 {
 	#ifdef HAVE_CURL_CURL_H
-	return myScreen == myLastfm || dynamic_cast<HasSongs *>(myScreen);
+	return myScreen == myLastfm
+	  ||   (myScreen->ActiveWindow() == myLibrary->Tags
+	    && !myLibrary->Tags->Empty()
+	    && Config.media_lib_primary_tag == MPD_TAG_ARTIST)
+	  ||   currentSong(myScreen);
 #	else
 	return false;
 #	endif // NOT HAVE_CURL_CURL_H
@@ -2370,14 +2371,18 @@ void ShowArtistInfo::Run()
 	}
 	
 	std::string artist;
-	auto hs = dynamic_cast<HasSongs *>(myScreen);
+	if (myScreen->ActiveWindow() == myLibrary->Tags)
-	assert(hs);
+	{
-	auto s = hs->currentSong();
+		assert(!myLibrary->Tags->Empty());
-	
+		assert(Config.media_lib_primary_tag == MPD_TAG_ARTIST);
-	if (s)
-		artist = s->getArtist();
-	else if (myScreen == myLibrary && myLibrary->Main() == myLibrary->Tags && !myLibrary->Tags->Empty())
 		artist = myLibrary->Tags->Current().value();
+	}
+	else
+	{
+		auto s = currentSong(myScreen);
+		assert(s);
+		artist = s->getArtist();
+	}
 	
 	if (!artist.empty() && myLastfm->SetArtistInfoArgs(artist, Config.lastfm_preferred_language))
 		myLastfm->SwitchTo();

src/actions.h

@@ -168,24 +168,28 @@ struct ScrollDown : public Action
 struct ScrollUpArtist : public Action
 {
 	ScrollUpArtist() : Action(aScrollUpArtist, "scroll_up_artist") { }
+	virtual bool canBeRun() const;
 	virtual void Run();
 };
 
 struct ScrollUpAlbum : public Action
 {
 	ScrollUpAlbum() : Action(aScrollUpAlbum, "scroll_up_album") { }
+	virtual bool canBeRun() const;
 	virtual void Run();
 };
 
 struct ScrollDownArtist : public Action
 {
 	ScrollDownArtist() : Action(aScrollDownArtist, "scroll_down_artist") { }
+	virtual bool canBeRun() const;
 	virtual void Run();
 };
 
 struct ScrollDownAlbum : public Action
 {
 	ScrollDownAlbum() : Action(aScrollDownAlbum, "scroll_down_album") { }
+	virtual bool canBeRun() const;
 	virtual void Run();
 };
 

src/browser.cpp

@@ -301,6 +301,16 @@ void Browser::prevFound(bool wrap)
 
 /***********************************************************************/
 
+std::shared_ptr<ProxySongList> Browser::getProxySongList()
+{
+	return mkProxySongList(*w, [](NC::Menu<MPD::Item>::Item &item) {
+		MPD::Song *ptr = 0;
+		if (item.value().type == itSong)
+			ptr = item.value().song.get();
+		return ptr;
+	});
+}
+
 MPD::Song *Browser::getSong(size_t pos)
 {
 	MPD::Song *ptr = 0;
@@ -322,11 +332,6 @@ bool Browser::allowsSelection()
 	return true;
 }
 
-void Browser::removeSelection()
-{
-	removeSelectionHelper(w->Begin(), w->End());
-}
-
 void Browser::reverseSelection()
 {
 	reverseSelectionHelper(w->Begin()+(itsBrowsedDir == "/" ? 0 : 1), w->End());

src/browser.h

@@ -22,6 +22,7 @@
 #define _BROWSER_H
 
 #include "interfaces.h"
+#include "mpdpp.h"
 #include "screen.h"
 
 class Browser : public Screen< NC::Menu<MPD::Item> >, public Filterable, public HasSongs, public Searchable
@@ -51,10 +52,10 @@ class Browser : public Screen< NC::Menu<MPD::Item> >, public Filterable, public
 		/// HasSongs implementation
 		virtual MPD::Song *getSong(size_t pos);
 		virtual MPD::Song *currentSong();
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual NC::List *GetList() { return w; }

src/display.cpp

@@ -79,7 +79,9 @@ void setProperties(NC::Menu<T> &menu, const MPD::Song &s, HasSongs &screen, bool
 	separate_albums = false;
 	if (Config.playlist_separate_albums)
 	{
-		auto next = screen.getSong(menu.DrawnPosition()+1);
+		auto pl = screen.getProxySongList();
+		assert(pl);
+		auto next = pl->getSong(menu.DrawnPosition()+1);
 		if (next && next->getAlbum() != s.getAlbum())
 			separate_albums = true;
 	}

src/helpers.h

@@ -32,10 +32,22 @@ inline HasSongs *hasSongs(BasicScreen *screen)
 	return dynamic_cast<HasSongs *>(screen);
 }
 
-template <typename Iterator> void removeSelectionHelper(Iterator first, Iterator last)
+inline std::shared_ptr<ProxySongList> proxySongList(BasicScreen *screen)
 {
-	for (; first != last; ++first)
+	auto ptr = nullProxySongList();
-		first->setSelected(false);
+	auto hs = hasSongs(screen);
+	if (hs)
+		ptr = hs->getProxySongList();
+	return ptr;
+}
+
+inline MPD::Song *currentSong(BasicScreen *screen)
+{
+	MPD::Song *ptr = 0;
+	auto pl = proxySongList(screen);
+	if (pl)
+		ptr = pl->currentSong();
+	return ptr;
 }
 
 template <typename Iterator> void reverseSelectionHelper(Iterator first, Iterator last)

src/interfaces.h

@@ -22,8 +22,9 @@
 #define _INTERFACES_H
 
 #include <string>
-#include "mpdpp.h"
 #include "gcc.h"
+#include "song.h"
+#include "proxy_song_list.h"
 
 struct Filterable
 {
@@ -40,12 +41,10 @@ struct Searchable
 
 struct HasSongs
 {
-	virtual MPD::Song *getSong(size_t pos) = 0;
+	virtual std::shared_ptr<ProxySongList> getProxySongList() = 0;
-	virtual MPD::Song *currentSong() = 0;
 	
 	virtual bool allowsSelection() = 0;
 	virtual void reverseSelection() = 0;
-	virtual void removeSelection() = 0;
 	virtual MPD::SongList getSelectedSongs() = 0;
 };
 

src/lyrics.cpp

@@ -117,28 +117,26 @@ void Lyrics::SwitchTo()
 	}
 #	endif // HAVE_CURL_CURL_H
 	
-	auto hs = dynamic_cast<HasSongs *>(myScreen);
+	const MPD::Song *s = currentSong(myScreen);
-	if (!hs)
+	if (!s)
 		return;
 	
-	if (const MPD::Song *s = hs->currentSong())
+	if (!s->getArtist().empty() && !s->getTitle().empty())
 	{
-		if (!s->getArtist().empty() && !s->getTitle().empty())
+		myOldScreen = myScreen;
-		{
+		myScreen = this;
-			myOldScreen = myScreen;
+		
-			myScreen = this;
+		itsSong = *s;
-			
+		Load();
-			itsSong = *s;
+		
-			Load();
+		Global::RedrawHeader = true;
-			
-			Global::RedrawHeader = true;
-		}
-		else
-		{
-			ShowMessage("Song must have both artist and title tag set");
-			return;
-		}
 	}
+	else
+	{
+		ShowMessage("Song must have both artist and title tag set");
+		return;
+	}
+	
 	// if we resize for locked screen, we have to do that in the end since
 	// fetching lyrics may fail (eg. if tags are missing) and we don't want
 	// to adjust screen size then.

src/media_library.cpp

@@ -531,37 +531,21 @@ void MediaLibrary::prevFound(bool wrap)
 
 /***********************************************************************/
 
-MPD::Song *MediaLibrary::getSong(size_t pos)
+std::shared_ptr<ProxySongList> MediaLibrary::getProxySongList()
 {
-	MPD::Song *ptr = 0;
+	auto ptr = nullProxySongList();
 	if (w == Songs)
-		ptr = &(*Songs)[pos].value();
+		ptr = mkProxySongList(*Songs, [](NC::Menu<MPD::Song>::Item &item) {
+			return &item.value();
+		});
 	return ptr;
 }
 
-MPD::Song *MediaLibrary::currentSong()
-{
-	if (w == Songs && !Songs->Empty())
-		return getSong(Songs->Choice());
-	else
-		return 0;
-}
-
 bool MediaLibrary::allowsSelection()
 {
 	return true;
 }
 
-void MediaLibrary::removeSelection()
-{
-	if (w == Tags)
-		removeSelectionHelper(Tags->Begin(), Tags->End());
-	else if (w == Albums)
-		removeSelectionHelper(Albums->Begin(), Albums->End());
-	else if (w == Songs)
-		removeSelectionHelper(Songs->Begin(), Songs->End());
-}
-
 void MediaLibrary::reverseSelection()
 {
 	if (w == Tags)

src/media_library.h

@@ -50,12 +50,10 @@ class MediaLibrary : public Screen<NC::Window>, public Filterable, public HasSon
 		virtual void prevFound(bool wrap);
 		
 		/// HasSongs implementation
-		virtual MPD::Song *getSong(size_t pos);
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
-		virtual MPD::Song *currentSong();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual NC::List *GetList();

src/mpdpp.cpp

@@ -1193,7 +1193,7 @@ MPD::ItemList MPD::Connection::GetDirectory(const std::string &path)
 				it.type = itDirectory;
 				break;
 			case MPD_ENTITY_TYPE_SONG:
-				it.song = std::shared_ptr<Song>(new Song(mpd_song_dup(mpd_entity_get_song(item))));
+				it.song = std::make_shared<Song>(Song(mpd_song_dup(mpd_entity_get_song(item))));
 				it.type = itSong;
 				break;
 			case MPD_ENTITY_TYPE_PLAYLIST:

src/playlist.cpp

@@ -318,6 +318,16 @@ void Playlist::prevFound(bool wrap)
 
 /***********************************************************************/
 
+std::shared_ptr<ProxySongList> Playlist::getProxySongList()
+{
+	auto ptr = nullProxySongList();
+	if (w == Items)
+		ptr = mkProxySongList(*Items, [](NC::Menu<MPD::Song>::Item &item) {
+			return &item.value();
+		});
+	return ptr;
+}
+
 MPD::Song *Playlist::getSong(size_t pos)
 {
 	MPD::Song *ptr = 0;
@@ -339,11 +349,6 @@ bool Playlist::allowsSelection()
 	return w == Items;
 }
 
-void Playlist::removeSelection()
-{
-	removeSelectionHelper(Items->Begin(), Items->End());
-}
-
 void Playlist::reverseSelection()
 {
 	reverseSelectionHelper(Items->Begin(), Items->End());

src/playlist.h

@@ -55,10 +55,10 @@ class Playlist : public Screen<NC::Window>, public Filterable, public HasSongs,
 		/// HasSongs implementation
 		virtual MPD::Song *getSong(size_t pos);
 		virtual MPD::Song *currentSong();
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual NC::List *GetList() { return w == Items ? Items : 0; }

src/playlist_editor.cpp

@@ -486,35 +486,21 @@ void PlaylistEditor::prevFound(bool wrap)
 
 /***********************************************************************/
 
-MPD::Song *PlaylistEditor::getSong(size_t pos)
+std::shared_ptr<ProxySongList> PlaylistEditor::getProxySongList()
 {
-	MPD::Song *ptr = 0;
+	auto ptr = nullProxySongList();
 	if (w == Content)
-		ptr = &(*Content)[pos].value();
+		ptr = mkProxySongList(*Content, [](NC::Menu<MPD::Song>::Item &item) {
+			return &item.value();
+		});
 	return ptr;
 }
 
-MPD::Song *PlaylistEditor::currentSong()
-{
-	if (w == Content && !Content->Empty())
-		return getSong(Content->Choice());
-	else
-		return 0;
-}
-
 bool PlaylistEditor::allowsSelection()
 {
 	return true;
 }
 
-void PlaylistEditor::removeSelection()
-{
-	if (w == Playlists)
-		removeSelectionHelper(Playlists->Begin(), Playlists->End());
-	else if (w == Content)
-		removeSelectionHelper(Content->Begin(), Content->End());
-}
-
 void PlaylistEditor::reverseSelection()
 {
 	if (w == Playlists)

src/playlist_editor.h

@@ -49,12 +49,10 @@ class PlaylistEditor : public Screen<NC::Window>, public Filterable, public HasS
 		virtual void prevFound(bool wrap);
 		
 		/// HasSongs implementation
-		virtual MPD::Song *getSong(size_t pos);
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
-		virtual MPD::Song *currentSong();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual void Locate(const std::string &);

src/proxy_song_list.h

@@ -0,0 +1,110 @@
+/***************************************************************************
+ *   Copyright (C) 2008-2012 by Andrzej Rybczak                            *
+ *   electricityispower@gmail.com                                          *
+ *                                                                         *
+ *   This program 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 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ *   This program 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.                          *
+ *                                                                         *
+ *   You should have received a copy of the GNU General Public License     *
+ *   along with this program; if not, write to the                         *
+ *   Free Software Foundation, Inc.,                                       *
+ *   51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.              *
+ ***************************************************************************/
+
+#ifndef _PROXY_SONG_LIST
+#define _PROXY_SONG_LIST
+
+#include "menu.h"
+#include "song.h"
+
+class ProxySongList
+{
+	struct Interface
+	{
+		virtual ~Interface() { }
+		
+		virtual bool empty() = 0;
+		virtual size_t size() = 0;
+		virtual size_t choice() = 0;
+		virtual void highlight(size_t pos) = 0;
+		
+		virtual bool isSelected(size_t pos) = 0;
+		virtual void setSelected(size_t pos, bool selected) = 0;
+		
+		virtual MPD::Song *getSong(size_t pos) = 0;
+		virtual MPD::Song *currentSong() = 0;
+	};
+	
+	template <typename T, typename F> struct Impl : Interface
+	{
+		typedef typename NC::Menu<T> Menu;
+		
+		Impl(Menu &menu, F f) : m_menu(menu), m_song_getter(f) { }
+		virtual ~Impl() { }
+		
+		virtual bool empty() { return m_menu.Empty(); }
+		virtual size_t size() { return m_menu.Size(); }
+		virtual size_t choice() { return m_menu.Choice(); }
+		virtual void highlight(size_t pos) { m_menu.Highlight(pos); }
+		
+		virtual bool isSelected(size_t pos) {
+			return m_menu[pos].isSelected();
+		}
+		
+		virtual void setSelected(size_t pos, bool selected) {
+			m_menu[pos].setSelected(selected);
+		}
+		
+		virtual MPD::Song *getSong(size_t pos) {
+			return m_song_getter(m_menu[pos]);
+		}
+		
+		virtual MPD::Song *currentSong() {
+			if (!m_menu.Empty())
+				return getSong(m_menu.Choice());
+			else
+				return 0;
+		}
+	
+	private:
+		Menu &m_menu;
+		F m_song_getter;
+	};
+	
+	std::shared_ptr<Interface> m_impl;
+	
+public:
+	template <typename T, typename F>
+	ProxySongList(typename NC::Menu<T> &menu, F f) : m_impl(new Impl<T, F>(menu, f)) { }
+	
+	bool empty() { return m_impl->empty(); }
+	size_t size() { return m_impl->size(); }
+	size_t choice() { return m_impl->choice(); }
+	void highlight(size_t pos) { m_impl->highlight(pos); }
+	
+	bool isSelected(size_t pos) { return m_impl->isSelected(pos); }
+	void setSelected(size_t pos, bool selected) { m_impl->setSelected(pos, selected); }
+	
+	MPD::Song *getSong(size_t pos) { return m_impl->getSong(pos); }
+	MPD::Song *currentSong() { return m_impl->currentSong(); }
+};
+
+template <typename T, typename F>
+std::shared_ptr<ProxySongList> mkProxySongList(typename NC::Menu<T> &menu, F f)
+{
+	return std::make_shared<ProxySongList>(ProxySongList(menu, f));
+}
+
+inline std::shared_ptr<ProxySongList> nullProxySongList()
+{
+	return std::shared_ptr<ProxySongList>();
+}
+
+#endif

src/search_engine.cpp

@@ -314,21 +314,14 @@ void SearchEngine::prevFound(bool wrap)
 
 /***********************************************************************/
 
-MPD::Song *SearchEngine::getSong(size_t pos)
+std::shared_ptr< ProxySongList > SearchEngine::getProxySongList()
 {
-	MPD::Song *ptr = 0;
+	return mkProxySongList(*w, [](NC::Menu<SEItem>::Item &item) {
-	auto &item = (*w)[pos];
+		MPD::Song *ptr = 0;
-	if (!item.isSeparator() && item.value().isSong())
+		if (!item.isSeparator() && item.value().isSong())
-		ptr = &item.value().song();
+			ptr = &item.value().song();
-	return ptr;
+		return ptr;
-}
+	});
-
-MPD::Song *SearchEngine::currentSong()
-{
-	if (w->Empty())
-		return 0;
-	else
-		return getSong(w->Choice());
 }
 
 bool SearchEngine::allowsSelection()
@@ -336,11 +329,6 @@ bool SearchEngine::allowsSelection()
 	return w->Current().value().isSong();
 }
 
-void SearchEngine::removeSelection()
-{
-	removeSelectionHelper(w->Begin(), w->End());
-}
-
 void SearchEngine::reverseSelection()
 {
 	reverseSelectionHelper(w->Begin()+std::min(StaticOptions, w->Size()), w->End());

src/search_engine.h

@@ -96,12 +96,10 @@ class SearchEngine : public Screen< NC::Menu<SEItem> >, public Filterable, publi
 		virtual void prevFound(bool wrap);
 		
 		/// HasSongs implementation
-		virtual MPD::Song *getSong(size_t pos);
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
-		virtual MPD::Song *currentSong();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual NC::List *GetList() { return w->Size() >= StaticOptions ? w : 0; }

src/song_info.cpp

@@ -84,10 +84,7 @@ void SongInfo::SwitchTo()
 	if (myLockedScreen)
 		UpdateInactiveScreen(this);
 	
-	auto hs = dynamic_cast<HasSongs *>(myScreen);
+	auto s = currentSong(myScreen);
-	if (!hs)
-		return;
-	auto s = hs->currentSong();
 	if (!s)
 		return;
 	

src/tag_editor.cpp

@@ -854,33 +854,21 @@ void TagEditor::prevFound(bool wrap)
 
 /***********************************************************************/
 
-MPD::Song *TagEditor::getSong(size_t pos)
+std::shared_ptr<ProxySongList> TagEditor::getProxySongList()
 {
-	MPD::Song *ptr = 0;
+	auto ptr = nullProxySongList();
 	if (w == Tags)
-		ptr = &(*Tags)[pos].value();
+		ptr = mkProxySongList(*Tags, [](NC::Menu<MPD::MutableSong>::Item &item) {
+			return &item.value();
+		});
 	return ptr;
 }
 
-MPD::Song *TagEditor::currentSong()
-{
-	if (w == Tags && !Tags->Empty())
-		return getSong(Tags->Choice());
-	else
-		return 0;
-}
-
 bool TagEditor::allowsSelection()
 {
 	return w == Tags;
 }
 
-void TagEditor::removeSelection()
-{
-	if (w == Tags)
-		removeSelectionHelper(Tags->Begin(), Tags->End());
-}
-
 void TagEditor::reverseSelection()
 {
 	if (w == Tags)

src/tag_editor.h

@@ -61,12 +61,10 @@ class TagEditor : public Screen<NC::Window>, public Filterable, public HasSongs,
 		virtual void prevFound(bool wrap);
 		
 		/// HasSongs implementation
-		virtual MPD::Song *getSong(size_t pos);
+		virtual std::shared_ptr<ProxySongList> getProxySongList();
-		virtual MPD::Song *currentSong();
 		
 		virtual bool allowsSelection();
 		virtual void reverseSelection();
-		virtual void removeSelection();
 		virtual MPD::SongList getSelectedSongs();
 		
 		virtual NC::List *GetList();