samer@3: % buffer - collect elements of sequence into sequence of arrays
samer@3: %
samer@3: % buffer :: 
samer@3: % 	  seq([Size:[[1,E]]])  ~'sequence of E dimensional arrays',
samer@3: %	  L:natural       ~'buffer width',
samer@3: %    E:natural       ~'effective dimension of input values',
samer@3: %    buffer_tailfn   ~'function to deal with last incomplete buffer'
samer@3: % -> seq([[Size,L]]) ~'buffered sequence (no-overlapping)'.
samer@3: %
samer@3: % buffer_tailfn can be 
samer@3: %    seq.buffer.truncate :: void -> tailfn  ~'discard incomplete buffer'.
samer@3: %    seq.buffer.append   :: void -> tailfn  ~'append smaller buffer to sequence'.
samer@3: %    seq.buffer.pad      :: [[N]]-> tailfn  ~'pad final buffer with value'.
samer@3: 
samer@3: classdef buffer < seq
samer@3: 	properties (GetAccess=private, SetAccess=immutable)
samer@3: 		width
samer@3: 		colons
samer@3: 		tailfn
samer@3: 	end
samer@3: 	properties (GetAccess=private, SetAccess=private)
samer@3: 		source
samer@3: 		buf
samer@3: 	end
samer@3: 	methods
samer@3: 		function a=buffer(source,L,dim,tailfn)
samer@3: 			sz=size1(source);
samer@3: 			if nargin<3, dim=length(sz); end
samer@3: 			if nargin<4, tailfn=seq.buffer.truncate; end
samer@3: 			colons = repmat({':'},1,dim);
samer@3: 			buf=repmat(head(source),tosize([ones(size(colons)),L]));
samer@3: 			source=next(source);
samer@3: 			for i=2:L
samer@3: 				if isempty(source), a=tailfn(buf,i-1,colons); return; end
samer@3: 				buf(colons{:},i)=head(source);
samer@3: 				source=next(source);
samer@3: 			end
samer@3: 			a.source = source;
samer@3: 			a.width = L;
samer@3: 			a.colons=colons;
samer@3: 			a.tailfn = tailfn;
samer@3: 			a.buf=buf;
samer@3: 		end
samer@3: 
samer@3: 		function z=elsize(a), z=size(a.buf); end
samer@3: 		function s=tostring(a), s=sprintf('%s >> buffer(%d,%d)',tostring(a.source),a.width,length(a.colons)+1); end
samer@3: 		function x=head(a), x=a.buf; end
samer@3: 		function a=next(a)
samer@3: 			% read next lot of values and make an array
samer@3: 			for i=1:a.width
samer@3: 				if isempty(a.source), a=a.tailfn(a.buf,i-1,a.colons); return; end
samer@3: 				a.buf(a.colons{:},i)=head(a.source);
samer@3: 				a.source=next(a.source);
samer@3: 			end
samer@3: 		end
samer@3: 	end
samer@3: 
samer@3: 	methods (Static)
samer@3: 		function f=truncate, f=@(buf,i,colons)[]; end
samer@3: 		function f=append,   f=@(buf,i,colons)singleton(buf(colons{:},1:i)); end
samer@3: 		function f=pad(x),   f=@padfn;
samer@3: 			function s=padfn(buf,i,colons)
samer@3: 			L=size(buf,length(colons)+1); 
samer@3: 			buf(colons{:},i+1:L)=repmat(x,tosize([ones(size(colons)),L-i]));
samer@3: 				s=singleton(buf); 
samer@3: 			end
samer@3: 		end
samer@3: 	end
samer@3: end
samer@3: