MATLAB option parser skeleton

parseArgs.m

% I use parts of the code of export_fig for this skeleton, scrapped of its specific details.
% Copyright (C) Oliver Woodford 2008-2014, Yair Altman 2015-, Tim Loderhose 2016
% https://github.com/altmany/export_fig | https://github.com/altmany/export_fig/blob/master/LICENSE

function options = parseArgs(varargin)
% Parse the input arguments
% Set the defaults
options = struct(...
    'opt1', 'arg1default', ...
    'opt2', true, ...
    'opt3', false, ...
    'opt4', 'arg4default', ...
    'opt5', [1 2 3]);

% Go through the other arguments
skipNext = false;
for i = 1:nargin
    % Skip if key value pair was parsed (value would be this iteration but was
    % already read)
    if skipNext
        skipNext = false;
        continue;
    end
    % Check for
    if ischar(varargin{i}) && ~isempty(varargin{i})
        if varargin{i}(1) == '-'
            switch lower(varargin{i}(2:end))
                case 'opt1arg'
                    options.opt1 = false;
                case 'opt1arg'
                    options.opt1 = false;
                case 'opt1arg'
                    options.opt1 = false;
                case 'opt1arg'
                    options.opt1 = false;
                otherwise
                    try
                        wasError = false;
                        % Case of -X<val> - match value next to -letter to
                        % parse the argument, skip next option (that was the
                        % letter in case a space was put in.
                        val = str2double(regexp(varargin{i}, '(?<=-(m|M|r|R|q|Q|p|P))-?\d*.?\d+', 'match'));
                        if isempty(val) || isnan(val)
                            % Issue #51: improved processing of input args (accept space between param name & value)
                            val = str2double(varargin{i+1});
                            if isscalar(val) && ~isnan(val)
                                skipNext = true;
                            end
                        end
                        if ~isscalar(val) || isnan(val)
                            wasError = true;
                            error('Option %s not recognised or cannot be parsed', varargin{i});
                        end
                    catch err
                        % We might have reached here by raising an intentional error
                        if wasError  % intentional raise
                            rethrow(err)
                        else  % unintentional
                            error(['Unrecognized input option: ''' varargin{i} '''']);
                        end
                    end
            end
            
        end
    end
end