Releasing the crackfortran as a general-purpose tool for parsing Fortran declarations

dmikushin · dmikushin · commit ee1036e0ab93 · 2023-12-04T15:10:10.000+01:00
The `crackfortran` tool is developed to be a backend for the f2py utility. However, crackfortran could also be very useful on its own.

The use of crackfortran could be demonstrated by the following example:

```json
► crackfortran symbol.f90 -show
Reading fortran codes...
        Reading file 'symbol.f90' (format:free)
Post-processing...
        Block: symbol
Post-processing (stage 2)...
[{'args': ['x', 'y', 'symx', 'opt'],
  'block': 'subroutine',
  'body': [],
  'common': {'pltdat': ['model', 'ploter'], 'symbls': ['nsym', 'symbl']},
  'commonvars': ['model', 'ploter', 'nsym', 'symbl'],
  'entry': {},
  'externals': [],
  'from': 'symbol.f90',
  'implicit': None,
  'interfaced': [],
  'name': 'symbol',
  'sortvars': ['model', 'nsym', 'ploter', 'symbl', 'opt', 'x', 'y', 'symx'],
  'vars': {'model': {'attrspec': [], 'typespec': 'integer'},
           'nsym': {'attrspec': [], 'typespec': 'integer'},
           'opt': {'typespec': 'integer'},
           'ploter': {'attrspec': [], 'typespec': 'integer'},
           'symbl': {'attrspec': [],
                     'dimension': ['20', '2'],
                     'typespec': 'integer'},
           'symx': {'attrspec': [], 'dimension': ['2'], 'typespec': 'integer'},
           'x': {'typespec': 'real'},
           'y': {'typespec': 'real'}}}]
```

The tool presents the subroutine declaration statements as a JSON that can be consumed by other tools for further analysis.

Therefore, this patch adds changes required to expose crackfortran as an entry point, next to f2py3.
diff --git a/numpy/f2py/crackfortran.py b/numpy/f2py/crackfortran.py
@@ -3691,13 +3691,21 @@ def fix_usage(varname, value):
 post_processing_hooks.append(character_backward_compatibility_hook)
 
 
-if __name__ == "__main__":
+def main():
+    if len(sys.argv) < 2:
+        print(__doc__)
+        sys.exit(1)
+
     files = []
     funcs = []
     f = 1
     f2 = 0
     f3 = 0
+    strictf77 = 0
+    f77modulename = 0
+    skipemptyends = 0
     showblocklist = 0
+    pyffilename = None
     for l in sys.argv[1:]:
         if l == '':
             pass
@@ -3757,6 +3765,10 @@ def fix_usage(varname, value):
   statement).
 """, 0)
 
+    if len(files) == 0:
+        print('No input files specified, nothing to do')
+        sys.exit(0)
+
     postlist = crackfortran(files)
     if pyffilename:
         outmess('Writing fortran code to file %s\n' % repr(pyffilename), 0)
@@ -3765,3 +3777,6 @@ def fix_usage(varname, value):
             f.write(pyf)
     if showblocklist:
         show(postlist)
+
+if __name__ == "__main__":
+    main()
diff --git a/pyproject.toml b/pyproject.toml
@@ -43,6 +43,7 @@ classifiers = [
 
 [project.scripts]
 f2py = 'numpy.f2py.f2py2e:main'
+crackfortran = 'numpy.f2py.crackfortran:main'
 
 [project.entry-points.array_api]
 numpy = 'numpy.array_api'
