Allow deletion of stale templates.

[player-03]

Template files have a habit of sticking around in the output folder, even if the project no longer needs or wants them. But if we save a list of templates after a build, we can compare against that list in future builds to locate no-longer-used files.

The intent is for deleteStaleTemplates() to run every time. It doesn't just delete the files, it saves the list for next time. A drawback of this implementation is that if it gets skipped, the list doesn't get updated, and if the list isn't updated, the next run might not find all the stale templates. This can of course be fixed with a clean build.

Like #27, this is one half of a potential solution to openfl/lime#1546. (The other half is openfl/lime#1550.) And I'd argue it's a better solution, requiring less maintenance and having no 31-character-long function names.

[player-03]

Just for future reference, I considered implementing part of this as a binary search, since that would reduce the time complexity from O(n²) to O(n log n). In the end I didn't think it was worth it, but here's the code in case anyone wants it.

public static function deleteStaleTemplates(targetDirectory:String)
{
	_templates.sort(Reflect.compare);

	var templatesFile = Path.combine(targetDirectory, ".templates");
	if (FileSystem.exists(templatesFile))
	{
		for (template in File.getContent(templatesFile).split("\n"))
		{
			// Do a binary search to save time.
			var stillInUse:Bool = false;
			var start:Int = 0;
			var end:Int = _templates.length - 1;
			while (start <= end)
			{
				var mid = Std.int((end + start) / 2);

				if (template == _templates[mid])
				{
					stillInUse = true;
					break;
				}
				else if (template < _templates[mid])
					end = mid - 1;
				else
					start = mid + 1;
			}

			if (!stillInUse)
			{
				deleteFile(template);
			}
		}
	}

	File.saveContent(templatesFile, _templates.join("\n"));
	_templates.resize(0);
}

[player-03]

Update: I think I've found a better approach.