Add support for generating a Make compatible depfile

docs/integration.rst

@@ -32,11 +32,15 @@ very first version of this example)::
       # Generate input file name
       set(infile "${CMAKE_CURRENT_SOURCE_DIR}/${infileName}")
 
+      # Create the dependency file
+      set(depfile "${CMAKE_CURRENT_BINARY_DIR/${outfileName}.d")
+
       # Custom command to do the processing
       add_custom_command(
           OUTPUT "${outfile}"
-          COMMAND fypp "${infile}" "${outfile}"
+          COMMAND fypp "${infile}" "${outfile}" --depfile "${depfile}"
           MAIN_DEPENDENCY "${infile}"
+          DEPFILE "${depfile}"
           VERBATIM)
 
       # Finally add output file to a list

src/fypp.py

@@ -233,6 +233,13 @@ def __init__(self, includedirs=None, encoding='utf-8'):
         # Directory of current file
         self._curdir = None
 
+        # All files that have been included
+        self._included_files = []
+
+
+    def get_dependencies(self):
+        return self._included_files
+
 
     def parsefile(self, fobj):
         '''Parses file or a file like object.
@@ -252,6 +259,9 @@ def parsefile(self, fobj):
 
 
     def _includefile(self, span, fobj, fname, curdir):
+        # Don't add the root file, only later includes
+        if self._curfile:
+            self._included_files.append(fname)
         oldfile = self._curfile
         olddir = self._curdir
         self._curfile = fname
@@ -2413,6 +2423,10 @@ def process_text(self, txt):
         return self._render()
 
 
+    def get_dependencies(self):
+        return self._parser.get_dependencies()
+
+
     def _render(self):
         output = self._renderer.render(self._builder.tree)
         self._builder.reset()
@@ -2579,6 +2593,16 @@ def process_file(self, infile, outfile=None):
         return None
 
 
+    def write_dependencies(self, outfile, depfile):
+        def quote(text):
+            return text.replace('$', '$$').replace(' ', '\\ ').replace('#', '\\#')
+
+        dependencies = [quote(d) for d in self._preprocessor.get_dependencies()]
+
+        with open(depfile, 'w', encoding='utf-8') as f:
+            f.write('{}: {}'.format(quote(outfile), ' '.join(dependencies)))
+
+
     def process_text(self, txt):
         '''Processes a string.
 
@@ -2674,6 +2698,8 @@ class FyppOptions(optparse.Values):
             setting.
         create_parent_folder (bool): Whether the parent folder for the output
             file should be created if it does not exist. Default: False.
+        depfile (str | None): If set, where to write a Makefile compatible
+            dependency file. Default: None.
     '''
 
     def __init__(self):
@@ -2696,6 +2722,7 @@ def __init__(self):
         self.encoding = 'utf-8'
         self.create_parent_folder = False
         self.file_var_root = None
+        self.depfile = None
 
 
 class FortranLineFolder:
@@ -2939,6 +2966,10 @@ def get_option_parser():
     parser.add_option('--file-var-root', metavar='DIR', dest='file_var_root',
                       default=defs.file_var_root, help=msg)
 
+    msg = 'Write a Make-compatible dependency file to this location'
+    parser.add_option('--depfile', metavar='DEPFILE', dest='depfile',
+                      default=defs.depfile, help=msg)
+
     return parser
 
 
@@ -2949,9 +2980,15 @@ def run_fypp():
     opts, leftover = optparser.parse_args(values=options)
     infile = leftover[0] if len(leftover) > 0 else '-'
     outfile = leftover[1] if len(leftover) > 1 else '-'
+
+    if outfile == '-' and opts.depfile:
+        raise optparse.OptParseError("--depfile cannot be used when writing to stdout")
+
     try:
         tool = Fypp(opts)
         tool.process_file(infile, outfile)
+        if opts.depfile:
+            tool.write_dependencies(outfile, opts.depfile)
     except FyppStopRequest as exc:
         sys.stderr.write(_formatted_exception(exc))
         sys.exit(USER_ERROR_EXIT_CODE)

test/include/escaped_includes.inc

@@ -0,0 +1 @@
+#:include 'need$ #escape.inc'

test/include/multi_includes.inc

@@ -0,0 +1,2 @@
+#:include 'fypp1.inc'
+#:include 'fypp2.inc'

test/include/subfolder/need$ #escape.inc

@@ -0,0 +1 @@
+#:include 'fypp2.inc'

test/runtests.sh

@@ -6,11 +6,6 @@ else
   pythons="python3"
 fi
 root=".."
-if [ -z "$PYTHONPATH" ]; then
-  export PYTHONPATH="$root/src"
-else
-  export PYTHONPATH="$root/src:$PYTHONPATH"
-fi
 cd $testdir
 failed="0"
 failing_pythons=""

test/test_fypp.py

@@ -1,7 +1,14 @@
 '''Unit tests for testing Fypp.'''
 from pathlib import Path
+import os
 import platform
+import sys
+import tempfile
 import unittest
+
+# Allow for importing fypp
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'src'))
+
 import fypp
 
 
@@ -3055,6 +3062,27 @@ def _importmodule(module):
     ),
 ]
 
+DEPFILE_TESTS = [
+    ('basic',
+     ([_incdir('include')],
+      'include/subfolder/include_fypp1.inc',
+      '{output}: include/fypp1.inc',
+      )
+    ),
+    ('multiple includes',
+     ([_incdir('include/subfolder')],
+      'include/multi_includes.inc',
+      '{output}: include/fypp1.inc include/subfolder/fypp2.inc',
+      )
+    ),
+    ('escapes',
+     ([_incdir('include'), _incdir('include/subfolder')],
+      'include/escaped_includes.inc',
+      '{output}: include/subfolder/need$$\\ \\#escape.inc include/subfolder/fypp2.inc',
+      )
+    ),
+]
+
 
 def _get_test_output_method(args, inp, out):
     '''Returns a test method for checking correctness of Fypp output.
@@ -3102,6 +3130,36 @@ def test_output_from_file_input(self):
     return test_output_from_file_input
 
 
+def _get_test_depfile_method(args, inputfile, expected):
+    '''Returns a test method for checking correctness of depfile.
+
+    Args:
+        args (list of str): Command-line arguments to pass to Fypp.
+        inputfile (str): Input file with Fypp directives.
+        out (str): Expected output.
+
+    Returns:
+       method: Method to test equality of depfile with result delivered by Fypp.
+    '''
+
+    def test_depfile(self):
+        '''Tests whether Fypp result matches expected output when input is in a file.'''
+        output = self._get_tempfile()
+        depfile = self._get_tempfile()
+
+        optparser = fypp.get_option_parser()
+        options, leftover = optparser.parse_args(args + ['--depfile', depfile])
+        self.assertEqual(len(leftover), 0)
+        tool = fypp.Fypp(options)
+        tool.process_file(inputfile, output)
+        tool.write_dependencies(output, depfile)
+
+        with open(depfile, 'r', encoding='utf-8') as f:
+            got = f.read().strip()
+        self.assertEqual(got, expected.format(output=output))
+    return test_depfile
+
+
 
 def _get_test_exception_method(args, inp, exceptions):
     '''Returns a test method for checking correctness of thrown exception.
@@ -3199,6 +3257,16 @@ class ExceptionTest(_TestContainer): pass
 class ImportTest(_TestContainer): pass
 ImportTest.add_test_methods(IMPORT_TESTS, _get_test_output_method)
 
+class DepfileTest(_TestContainer):
+
+    def _get_tempfile(self):
+        _fd, output = tempfile.mkstemp()
+        os.close(_fd)
+        self.addCleanup(os.unlink, output)
+        return output
+
+DepfileTest.add_test_methods(DEPFILE_TESTS, _get_test_depfile_method)
+
 
 if __name__ == '__main__':
     unittest.main()