Fix the handling of options nopreprocessoroutput, onlyjson and onlymacro when they appear at the top of the .mod file

The nopathchange is still not supported in this context, so document it.

Also recommend the whitespace-separated syntax instead of the comma-separated
syntax, since the latter is inconsistent with the way options are passed on the
command-line.

Closes: #1667

doc/manual/source/running-dynare.rst

@@ -397,13 +397,14 @@ by the ``dynare`` command.
     after the name of the ``.mod`` file. They can alternatively be
     defined in the first line of the ``.mod`` file, this avoids typing
     them on the command line each time a ``.mod`` file is to be
-    run. This line must be a Dynare comment (ie must begin with //)
-    and the options must be comma separated between ``--+`` options:
+    run. This line must be a Dynare one-line comment (i.e. must begin with ``//``)
+    and the options must be whitespace separated between ``--+ options:``
     and ``+--``. Note that any text after the ``+--`` will be
     discarded. As in the command line, if an option admits a value the
     equal symbol must not be surrounded by spaces. For instance ``json
     = compute`` is not correct, and should be written
-    ``json=compute``.
+    ``json=compute``. The ``nopathchange`` option cannot be specified in
+    this way, it must be passed on the command-line.
 
     *Output*
 

matlab/dynare.m

@@ -48,21 +48,18 @@ end
 % The following needs to come early, to avoid spurious warnings (especially under Octave)
 warning_config;
 
-% Set default local options
+% Handle nopathchange option
+% Note that it is only handled if it appears on the command-line, and not at
+% the top of the .mod file (since the treatment needs to take place very early,
+% even before we make the various checks on the filename)
 change_path_flag = true;
-
-% Filter out some options.
-preprocessoroutput = true;
 if nargin>1
     id = ismember(varargin, 'nopathchange');
     if any(id)
         change_path_flag = false;
         varargin(id) = [];
     end
-    preprocessoroutput = ~ismember('nopreprocessoroutput', varargin);
 end
-
-% Check matlab path
 check_matlab_path(change_path_flag);
 
 % Detect if MEX files are present; if not, use alternative M-files
@@ -187,6 +184,14 @@ if exist(fname(1:end-4),'dir') && exist([fname(1:end-4) filesep 'hooks'],'dir')
     run([fname(1:end-4) filesep 'hooks/priorprocessing'])
 end
 
+% Parse some options, either for the command-line or from the top of the .mod file
+file_opts = parse_options_line(fname);
+preprocessoroutput = ~ismember('nopreprocessoroutput', varargin) && ...
+                     ~ismember('nopreprocessoroutput', file_opts);
+nolog = ismember('nolog', varargin) || ismember('nolog', file_opts);
+onlymacro = ismember('onlymacro', varargin) || ismember('onlymacro', file_opts);
+onlyjson = ismember('onlyjson', varargin) || ismember('onlyjson', file_opts);
+
 if ispc
     arch = getenv('PROCESSOR_ARCHITECTURE');
 else
@@ -234,14 +239,14 @@ end
 if status ~= 0 || preprocessoroutput
     disp(result)
 end
-if ismember('onlymacro', varargin)
+if onlymacro
     if preprocessoroutput
         disp('Preprocessor stopped after macroprocessing step because of ''onlymacro'' option.');
     end
     return
 end
 
-if ismember('onlyjson', varargin)
+if onlyjson
     if preprocessoroutput
         disp('Preprocessor stopped after preprocessing step because of ''onlyjson'' option.');
     end
@@ -254,11 +259,7 @@ if exist(fname(1:end-4),'dir') && exist([fname(1:end-4) filesep 'hooks'],'dir')
 end
 
 % Save preprocessor result in logfile (if `no_log' option not present)
-fid = fopen(fname, 'r');
-firstline = fgetl(fid);
-fclose(fid);
-if ~ismember('nolog', varargin) ...
-        && isempty(regexp(firstline, '//\s*--\+\s*options:(|.*\s|.*,)nolog(|\s.*|,.*)\+--'))
+if ~nolog
     logname = [fname(1:end-4) '.log'];
     fid = fopen(logname, 'w');
     fprintf(fid, '%s', result);
@@ -279,3 +280,38 @@ end
 clear(['+' fname '/driver'])
 
 evalin('base',[fname '.driver']) ;
+
+end
+
+% Looks for an options list in the first non-empty line of the .mod file
+% Should be kept in sync with the function of the same name in preprocessor/src/DynareMain.cc
+%
+% Note that separating options with commas is accepted, but is deprecated (and undocumented)
+%
+% Also, the parser does not handle correctly some corner cases: for example, it
+% will fail on something like -Dfoo="a b,c" (will split at whitespace and comma)
+function opts = parse_options_line(fname)
+    opts = {};
+    fid = fopen(fname, 'r');
+    while true
+        firstline = fgetl(fid);
+        if firstline == -1
+            fclose(fid);
+            return
+        end
+        if ~isempty(firstline)
+            break
+        end
+    end
+    fclose(fid);
+    t = regexp(firstline, '^\s*//\s*--\+\s*options:([^\+]*)\+--', 'tokens');
+    if isempty(t)
+        return
+    end
+
+    opts = regexp(t{1}{1}, '[^,\s]+', 'match');
+
+    if ismember(opts, 'nopathchange')
+        warning('The ''nopathchange'' option is not taken into account when it appears at the top of ''.mod'' file. You should rather pass it on the command-line.')
+    end
+end