Changed ScreenSelectMusic and Song to look for preview.ogg and use it for a sample if it exists instead of the music file. Sample length still comes from simfile. Changed foreach_ordered to work on tables with string and number keys.

Docs/Changelog_sm5.txt

@@ -4,22 +4,29 @@ The StepMania 5 Changelog covers all post-sm-ssc changes. For a list of changes
 from StepMania 4 alpha 5 to sm-ssc v1.2.5, see Changelog_sm-ssc.txt.
 ________________________________________________________________________________
 
+2015/03/01
+----------
+* [SelectMusic] Select Music now plays preview.ogg for a simfile if it exists
+  instead of using the song file for the sample music.  The sample length
+  from the simfile is used and the sample start is treated as 0. [kyzentun]
+* [foreach] foreach_ordered lua function now works on tables that have both
+  number and string keys.  Number keys are iterated over first. [kyzentun]
 
 2015/02/27
 ----------
 * [ActorFrame] Fixed RemoveChild and RemoveAllChildren lua functions to
-	delete the children instead of leaking memory. [kyzentun]
+  delete the children instead of leaking memory. [kyzentun]
 
 2015/02/26
 ----------
 * [PaneDisplay] Changed to print an error when metrics or player number are
-	omitted instead of crashing. [kyzentun]
+  omitted instead of crashing. [kyzentun]
 * [Screen] Fixed crash when AddInputCallback is passed nil. [kyzentun]
 
 2015/02/22
 ----------
 * [BitmapText] Place characters of right-to-left alphabets correctly.
-	(untested) [roothorick]
+  (untested) [roothorick]
 
 ================================================================================
 StepMania 5.0.6 | 20150217
@@ -28,7 +35,7 @@ StepMania 5.0.6 | 20150217
 2015/02/16
 ----------
 * [EditMode] Fixed mistake in TimingData that broke editing bpms. [kyzentun]
-	Fixed crash when deleting steps. [kyzentun]
+  Fixed crash when deleting steps. [kyzentun]
 * [InputMapper] Backslash can be mapped now. [kyzentun]
 
 ================================================================================

Themes/_fallback/Scripts/01 IniFile.lua

@@ -6,14 +6,26 @@ Note that this is a namespace, not a class per se.
 
 -- TODO: move this into a more general section
 -- func takes a key and a value
+function foreach_by_sorted_keys(tbl, keys, func)
+	table.sort(keys)
+	for _, key in ipairs(keys) do func(key, tbl[key]) end
+end
+
 function foreach_ordered( tbl, func )
-	local keys = { }
-	for k,_ in pairs(tbl) do keys[#keys+1] = k end
-
-	table.sort( keys )
-
+	local string_keys= {}
+	local number_keys= {}
+	-- First person to to use this on a table that uses something else as keys
+	-- gets to extend this function to cover more types.  And a beating. -Kyz
+	for k,_ in pairs(tbl) do
+		if type(k) == "string" then
+			table.insert(string_keys, k)
+		elseif type(k) == "number" then
+			table.insert(number_keys, k)
+		end
+	end
 	-- iterate in sorted order
-	for _,key in ipairs(keys) do func( key, tbl[key]) end
+	foreach_by_sorted_keys(tbl, number_keys, func)
+	foreach_by_sorted_keys(tbl, string_keys, func)
 end
 
 -- redeclared here for my sanity's sake

src/ScreenSelectMusic.cpp

@@ -1796,9 +1796,9 @@ void ScreenSelectMusic::AfterMusicChange()
 			case SampleMusicPreviewMode_Normal:
 			case SampleMusicPreviewMode_LastSong: // fall through
 				// play the sample music
-				m_sSampleMusicToPlay = pSong->GetMusicPath();
+				m_sSampleMusicToPlay = pSong->GetPreviewMusicPath();
 				m_pSampleMusicTimingData = &pSong->m_SongTiming;
-				m_fSampleStartSeconds = pSong->m_fMusicSampleStartSeconds;
+				m_fSampleStartSeconds = pSong->GetPreviewStartSeconds();
 				m_fSampleLengthSeconds = pSong->m_fMusicSampleLengthSeconds;
 				break;
 			default:

src/Song.cpp

@@ -1477,6 +1477,26 @@ RString Song::GetPreviewVidPath() const
 	return GetSongAssetPath( m_sPreviewVidFile, m_sSongDir );
 }
 
+RString Song::GetPreviewMusicPath() const
+{
+	RString preview= GetSongDir() + "preview.ogg";
+	if(FILEMAN->DoesFileExist(preview))
+	{
+		return preview;
+	}
+	return GetMusicPath();
+}
+
+float Song::GetPreviewStartSeconds() const
+{
+	RString preview= GetSongDir() + "preview.ogg";
+	if(FILEMAN->DoesFileExist(preview))
+	{
+		return 0.0f;
+	}
+	return m_fMusicSampleStartSeconds;
+}
+
 RString Song::GetDisplayMainTitle() const
 {
 	if(!PREFSMAN->m_bShowNativeLanguage) return GetTranslitMainTitle();

src/Song.h

@@ -257,6 +257,8 @@ public:
 	RString GetBackgroundPath() const;
 	RString GetCDTitlePath() const;
 	RString GetPreviewVidPath() const;
+	RString GetPreviewMusicPath() const;
+	float GetPreviewStartSeconds() const;
 
 	// For loading only:
 	bool m_bHasMusic, m_bHasBanner, m_bHasBackground;