diff sequences/+seq/buffer.m @ 3:3f77126f7b5f

First major revision of sequence library, now using classdef form, STILL A BIT BROKEN!

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sequences/+seq/buffer.m	Wed Jan 09 22:22:21 2013 +0000
@@ -0,0 +1,70 @@
+% buffer - collect elements of sequence into sequence of arrays
+%
+% buffer :: 
+% 	  seq([Size:[[1,E]]])  ~'sequence of E dimensional arrays',
+%	  L:natural       ~'buffer width',
+%    E:natural       ~'effective dimension of input values',
+%    buffer_tailfn   ~'function to deal with last incomplete buffer'
+% -> seq([[Size,L]]) ~'buffered sequence (no-overlapping)'.
+%
+% buffer_tailfn can be 
+%    seq.buffer.truncate :: void -> tailfn  ~'discard incomplete buffer'.
+%    seq.buffer.append   :: void -> tailfn  ~'append smaller buffer to sequence'.
+%    seq.buffer.pad      :: [[N]]-> tailfn  ~'pad final buffer with value'.
+
+classdef buffer < seq
+	properties (GetAccess=private, SetAccess=immutable)
+		width
+		colons
+		tailfn
+	end
+	properties (GetAccess=private, SetAccess=private)
+		source
+		buf
+	end
+	methods
+		function a=buffer(source,L,dim,tailfn)
+			sz=size1(source);
+			if nargin<3, dim=length(sz); end
+			if nargin<4, tailfn=seq.buffer.truncate; end
+			colons = repmat({':'},1,dim);
+			buf=repmat(head(source),tosize([ones(size(colons)),L]));
+			source=next(source);
+			for i=2:L
+				if isempty(source), a=tailfn(buf,i-1,colons); return; end
+				buf(colons{:},i)=head(source);
+				source=next(source);
+			end
+			a.source = source;
+			a.width = L;
+			a.colons=colons;
+			a.tailfn = tailfn;
+			a.buf=buf;
+		end
+
+		function z=elsize(a), z=size(a.buf); end
+		function s=tostring(a), s=sprintf('%s >> buffer(%d,%d)',tostring(a.source),a.width,length(a.colons)+1); end
+		function x=head(a), x=a.buf; end
+		function a=next(a)
+			% read next lot of values and make an array
+			for i=1:a.width
+				if isempty(a.source), a=a.tailfn(a.buf,i-1,a.colons); return; end
+				a.buf(a.colons{:},i)=head(a.source);
+				a.source=next(a.source);
+			end
+		end
+	end
+
+	methods (Static)
+		function f=truncate, f=@(buf,i,colons)[]; end
+		function f=append,   f=@(buf,i,colons)singleton(buf(colons{:},1:i)); end
+		function f=pad(x),   f=@padfn;
+			function s=padfn(buf,i,colons)
+			L=size(buf,length(colons)+1); 
+			buf(colons{:},i+1:L)=repmat(x,tosize([ones(size(colons)),L-i]));
+				s=singleton(buf); 
+			end
+		end
+	end
+end
+