opts=optndfts(args,varargin)

function opts=optndfts(args,varargin)
% optndfts  Create option struct with default values for those not given
%  2012-10-31  Matlab8  Copyright (c) 2012, W J Whiten  BSD License 
%
% opts=optndfts(args,varargin)
%  args     Either a struct, giving a cell array of name 
%             or first element of cell array containing cell 
%            of name value pairs. Matches containing routine using 
%            varargin for a list of name values pairs, (or struct or cell 
%            array of name for value pairs).
%  varargin Either a list of name value pairs, or a struct, or a cell 
%            array of name value pairs.
%
%  opts     Struct giving option values
%
% Use to process optional arguments given as name value pairs,  a cell 
%  array of name value pairs, or as a struct. Default values from 
%  optndfts call are used for values not given in args.
% 
% Example:
% Using optndft within a function as follows: 
%    function strt=demo(a,vargargin)
%    strt=optndft(varargin,'aa',1,'bb',2,'cc',3);
%    end
% Then demo could be called as:
%    demo(1,'bb',22)
% And optndft fills in default values for those not given::
%    ans = 
%        aa: 1
%        bb: 22
%        cc: 3
% 
% See also:  inputParser

% if input args not a struct convert to struct
if(iscell(args))
    if(~isempty(args) && iscell(args{1}))
        args=args{1};
        if(iscell(args))
            args=struct(args{:});
        end
    else
        args=struct(args{:});
    end
end

% convert varargin inputs to a struct
if(~isempty(varargin) && iscell(varargin{1}))
    dft=varargin{1};
    if(iscell(dft))
        dft=struct(dft{:});
    end
else
    dft=struct(varargin{:});
end

% start with default values
opts=dft;

% copy new values over default values
names=fieldnames(args);
for i=1:length(names)
    if(~isfield(opts,names{i}))
       error(['Invalid field name  ',names{i}])
    end
    opts.(names{i})=args.(names{i});
end

return
end