Mauch MIREX 2010

%

% PARSENOTE

% 

% [natural, accidentals, success, errormessage] = parsenote(note, {verbose})

% 

% Parse a note to a natural character value and a number of accidentals

% if accidentals is positive it denotes number of sharps,

% if it is negative it denotes number of flats.

%

% Success = 1 if symbols parsed correctly, 0 otherwise.

%

% If optional argument 'verbose' is 1, function prints any errormessage to 

% the screen.

% 

% returns:  natural     (char)

%           accidentals (integer) 

%           success     (boolean)

%           errormessage (string)

%

% Author: Christopher Harte,  August 2005

% 

% Copyright: Centre for Digital Music, Queen Mary University of London 2005 

%

% This file is part of the C4DM Chord Toolkit.  

%

% The C4DM Chord Toolkit is free software; you can redistribute it and/or 

% modify it under the terms of the GNU General Public License as published 

% by the Free Software Foundation; either version 2 of the License, or

% (at your option) any later version.

%

% The C4DM Chord Toolkit is distributed in the hope that it will be useful,

% but WITHOUT ANY WARRANTY; without even the implied warranty of

% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

% GNU General Public License for more details.

%

% You should have received a copy of the GNU General Public License

% along with the C4DM Toolkit; if not, write to the Free Software

% Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

%

function [natural,accidentals,success, errormessage] = parsenote(note, verbose)

if nargin < 2

    verbose = 0;

end

errormessage = '';

ilength = length(note);

accidentals = 0;

natural = [];

success=1;

index = 1;

if (isempty(note))  % if we have been passed an empty string

    success=0;

else  % parse the note string

    switch(note(index))

        case {'A','B','C','D','E','F','G'}

            %first character should be a natural

            natural = note(index);

            index= index+1;

            %remaining characters should be sharps or flats

            while index <= ilength

                switch note(index)

                    case 'b' % FLAT

                        accidentals = accidentals - 1; %decrement accidental count

                        index = index + 1;

                    case '#' % SHARP

                        accidentals = accidentals + 1; %increment accidental count

                        index = index + 1;

                    otherwise

                        % if neither of the above then the note is incorrect

                        success=0;

                        index = ilength+1;

                end

            end

        otherwise

            success=0;        

    end

end

if(success==0) % correct note therefore return success = 1 

    % if not an integer then the note string is incorrect

    errormessage = sprintf(['Error in parsenote: Unrecognised note "' note '"\n']); 

    if verbose ==1

        fprintf(1,errormessage);

    end

end