samer@36: % merger - Combine several seq sources using a given function
samer@3: %
samer@36: % merger :: 
samer@3: % 	( (A1,...,An)->natural 	~ chooser function,
samer@3: % 	  n:natural          	~ number of sources to combine,
samer@3: % 	  seq A1,...,seq An	~ n seq sources,
samer@3: % 	  ...                 	~ options
samer@3: % 	) -> seq B
samer@36: classdef merger < seq
samer@3: 	properties (GetAccess=private, SetAccess=private)
samer@3: 		fn
samer@3: 		sources
samer@3: 		hd
samer@3: 	end
samer@3: 	methods
samer@36: 		function d=merger(c,sources,varargin)
samer@3: 			d.fn=c;
samer@3: 			d.hd=[];
samer@3: 			d.sources=sources;
samer@3: 		end
samer@3: 
samer@3: 
samer@3: 		function x=head(d), x=d.hd; end
samer@3: 		function d=next(d)
samer@3: 			data=cellmap(@head,d.sources);
samer@23: 			if isempty(data), d=nil
samer@3: 			else
samer@3: 				k=d.fn(data);
samer@3: 				d.hd=data{k};
samer@3: 				nk=next(d.sources{k});
samer@3: 				if isempty(nk), d.sources(k)=[];
samer@3: 				else d.sources{k}=nk; end
samer@3: 			end
samer@3: 		end
samer@3: 					
samer@3: 		function z=elsize(d), z=size(d.hd); end
samer@3: 		function s=tostring(d)
samer@8: 			s=sprintf('{ %s } >> merge(%s)',catsep(',',cellmap(@tostring,d.sources)),tostring(d.fn));
samer@3: 		end
samer@3: 	end
samer@3: end