function conf = conf_check(conf, spec, prog)%% Check the legality of a configuration against its specification.%% Checks configuration parameters (in the form of a structure)% against the specifications they are meant to conform to.% Fills in any defaults for fields which are present in the% specification but missing from the structure.%if isempty(conf)  % Just fill in all the defaults.  for i = 1:length(spec)    eval(['conf.' spec(i).name ' = spec(i).default;']);  endelseif isstruct(conf)  % Warn about inappropriate fields.  allowed = {spec.name};  actual = fieldnames(conf);  for i = 1:length(actual)    if isempty(find(strcmp(actual{i}, allowed)))      fprintf('%s: (warning) unrecognised configuration field ''%s''\n', prog, actual{i})      conf = rmfield(conf, actual{i});    end  end  % Check types and options and fill in missing fields.  for i = 1:length(spec)    if isfield(conf, spec(i).name)      obj = getfield(conf, spec(i).name);      % Check type.      if iscell(spec(i).type)        types = spec(i).type;      else        types = {spec(i).type};      end      for t = 1:length(types)        okay = 0;        switch types{t}        case 'structure'          okay = isstruct(obj);        case 'string'          okay = ischar(obj) & ndims(obj) == 2 & (size(obj,1) == 1 | isempty(obj));        case 'number'          okay = isnumeric(obj) & ndims(obj) == 2 & max(size(obj)) == 1;        case 'vector'          okay = isnumeric(obj) & ndims(obj) == 2 & min(size(obj)) == 1;        case 'row vector'          okay = isnumeric(obj) & ndims(obj) == 2 & size(obj,1) == 1;        case {'col vector', 'column vector'}          okay = isnumeric(obj) & ndims(obj) == 2 & size(obj,2) == 1;        case 'matrix'          okay = isnumeric(obj) & ndims(obj) == 2;        case 'length 2'          okay = length(obj) == 2;        case 'integer'          okay = isempty(find(obj ~= round(obj)));        case 'positive'          okay = isempty(find(obj <= 0));        case {'nonnegative', 'non-negative'}          okay = isempty(find(obj < 0));        case 'negative'          okay = isempty(find(obj >= 0));        case {'nonpositive', 'non-positive'}          okay = isempty(find(obj > 0));        case 'even'          okay = isempty(find(rem(obj,2) ~= 0));        case 'odd'          okay = isempty(find(rem(obj,2) ~= 1));        case 'cellstr'          okay = iscellstr(obj);        otherwise          error(['conf_check: field type ''' types{t} ''' unknown'])        end        if ~okay          error([prog ': configuration field ''' spec(i).name ''' does not match type ''' types{t} ''''])        end      end      % Check object matches options (if specified).      opts = spec(i).options;      if ~isempty(opts)        if ~iscell(opts)          opts = {opts};        end        omatch = 0;        for o = 1:length(opts)          alts = opts{o};          if ~iscell(alts)            alts = {alts};          end          amatch = 0;          for a = 1:length(alts)            if isnumeric(obj)              amatch = (alts{a} == obj);            else              amatch = strcmp(alts{a}, lower(obj));            end            if amatch              break;            end          end          if amatch            eval(['conf.' spec(i).name ' = alts{1};']);            omatch = 1;            break;          end        end        if ~omatch          error([prog ': contents of field ''' spec(i).name ''' do not match any options'])        end      end    else      % Set default.      eval(['conf.' spec(i).name ' = spec(i).default;'])    end  endelse  % Shouldn't happen.  error([prog ': configuration parameter should be struct'])end