irfmatching: add function to check for existence of irf_matching_file

matlab/+mom/check_irf_matching_file.m

+function [irf_matching_file_name, irf_matching_file_path] = check_irf_matching_file(irf_matching_file)
+% [irf_matching_file_name, irf_matching_file_path] = check_irf_matching_file(irf_matching_file)
+% -------------------------------------------------------------------------
+% Check if the provided irf_matching_file is a valid MATLAB function with
+% .m extension and return name, path and extension of the file.
+% -------------------------------------------------------------------------
+% INPUTS
+% - irf_matching_file:  [string] user provided name (with possible path and extension)
+%                                of the MATLAB function that transforms model irfs
+% -------------------------------------------------------------------------
+% OUTPUTS
+% - irf_matching_file_name: [string] name of the MATLAB function (without extension)
+% - irf_matching_file_path: [string] path to irf_matching_file_name
+% -------------------------------------------------------------------------
+% This function is called by
+% - mom.run
+% -------------------------------------------------------------------------
+
+% Copyright © 2023 Dynare Team
+%
+% This file is part of Dynare.
+%
+% Dynare 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 3 of the License, or
+% (at your option) any later version.
+%
+% Dynare 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 Dynare.  If not, see <https://www.gnu.org/licenses/>.
+
+
+if isempty(irf_matching_file)
+    % no irf_matching_file provided, so no transformations will be done
+    irf_matching_file_name = '';
+    irf_matching_file_path = '';
+else
+    [irf_matching_file_path, irf_matching_file_name, irf_matching_file_ext] = fileparts(irf_matching_file);
+    % make sure file is a MATLAB function with .m extension
+    if ~strcmp(irf_matching_file_ext,'.m')
+        if strcmp(irf_matching_file_ext,'')
+            irf_matching_file_ext = '.m';
+        else
+            error('method_of_moments: ''irf_matching_file'' needs to point towards a MATLAB function with extension ''.m''!');
+        end
+    end
+    if isempty(irf_matching_file_path)
+        irf_matching_file_path = '.';
+    end
+    if exist([irf_matching_file_path filesep irf_matching_file_name irf_matching_file_ext],'file') ~= 2
+        error('method_of_moments: Could not find a ''irf_matching_file'' called ''%s''!',[irf_matching_file_path filesep irf_matching_file_name irf_matching_file_ext]);
+    end
+end
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