Revert "MAINT: `f2py` cleanup (#22885)"revert-22885-cleanCrackfortran

This reverts commit 6b5cd92675139511b4b24ddfe822e96b03700edb.

3 files changed, 21 insertions, 19 deletions

diff --git a/numpy/distutils/ccompiler.py b/numpy/distutils/ccompiler.py
index 86201174d..f0487cb64 100644
--- a/numpy/distutils/ccompiler.py
+++ b/numpy/distutils/ccompiler.py
@@ -338,8 +338,7 @@ def CCompiler_compile(self, sources, output_dir=None, macros=None,
                 if self.compiler_type=='absoft':
                     obj = cyg2win32(obj)
                     src = cyg2win32(src)
-                if Path(src).suffix.lower() in COMMON_FIXED_EXTENSIONS \
-                   and not has_f90_header(src):
+                if is_f_file(src) and not has_f90_header(src):
                     f77_objects.append((obj, (src, ext)))
                 else:
                     other_objects.append((obj, (src, ext)))
diff --git a/numpy/distutils/fcompiler/__init__.py b/numpy/distutils/fcompiler/__init__.py
index 793f0bccf..ecba3e5d5 100644
--- a/numpy/distutils/fcompiler/__init__.py
+++ b/numpy/distutils/fcompiler/__init__.py
@@ -571,8 +571,7 @@ class FCompiler(CCompiler):
     def _compile(self, obj, src, ext, cc_args, extra_postargs, pp_opts):
         """Compile 'src' to product 'obj'."""
         src_flags = {}
-        if Path(src).suffix.lower() in COMMON_FIXED_EXTENSIONS \
-           and not has_f90_header(src):
+        if is_f_file(src) and not has_f90_header(src):
             flavor = ':f77'
             compiler = self.compiler_f77
             src_flags = get_f77flags(src)
diff --git a/numpy/f2py/crackfortran.py b/numpy/f2py/crackfortran.py
index b831697d8..84579fdcc 100755
--- a/numpy/f2py/crackfortran.py
+++ b/numpy/f2py/crackfortran.py
@@ -147,7 +147,6 @@ import os
 import copy
 import platform
 import codecs
-from pathlib import Path
 try:
     import charset_normalizer
 except ImportError:
@@ -290,15 +289,22 @@ def undo_rmbadname(names):
     return [undo_rmbadname1(_m) for _m in names]
 
 
+def getextension(name):
+    i = name.rfind('.')
+    if i == -1:
+        return ''
+    if '\\' in name[i:]:
+        return ''
+    if '/' in name[i:]:
+        return ''
+    return name[i + 1:]
+
+is_f_file = re.compile(r'.*\.(for|ftn|f77|f)\Z', re.I).match
 _has_f_header = re.compile(r'-\*-\s*fortran\s*-\*-', re.I).search
 _has_f90_header = re.compile(r'-\*-\s*f90\s*-\*-', re.I).search
 _has_fix_header = re.compile(r'-\*-\s*fix\s*-\*-', re.I).search
 _free_f90_start = re.compile(r'[^c*]\s*[^\s\d\t]', re.I).match
 
-# Extensions
-COMMON_FREE_EXTENSIONS = ['.f90', '.f95', '.f03', '.f08']
-COMMON_FIXED_EXTENSIONS = ['.for', '.ftn', '.f77', '.f']
-
 
 def openhook(filename, mode):
     """Ensures that filename is opened with correct encoding parameter.
@@ -331,28 +337,26 @@ def openhook(filename, mode):
     return open(filename, mode, encoding=encoding)
 
 
-def is_free_format(fname):
+def is_free_format(file):
     """Check if file is in free format Fortran."""
     # f90 allows both fixed and free format, assuming fixed unless
     # signs of free format are detected.
-    result = False
-    if Path(fname).suffix.lower() in COMMON_FREE_EXTENSIONS:
-        result = True
-    with openhook(fname, 'r') as fhandle:
-        line = fhandle.readline()
+    result = 0
+    with openhook(file, 'r') as f:
+        line = f.readline()
         n = 15  # the number of non-comment lines to scan for hints
         if _has_f_header(line):
             n = 0
         elif _has_f90_header(line):
             n = 0
-            result = True
+            result = 1
         while n > 0 and line:
             if line[0] != '!' and line.strip():
                 n -= 1
                 if (line[0] != '\t' and _free_f90_start(line[:5])) or line[-2:-1] == '&':
-                    result = True
+                    result = 1
                     break
-            line = fhandle.readline()
+            line = f.readline()
     return result
 
 
@@ -408,7 +412,7 @@ def readfortrancode(ffile, dowithline=show, istop=1):
             strictf77 = 0
             sourcecodeform = 'fix'
             ext = os.path.splitext(currentfilename)[1]
-            if Path(currentfilename).suffix.lower() in COMMON_FIXED_EXTENSIONS and \
+            if is_f_file(currentfilename) and \
                     not (_has_f90_header(l) or _has_fix_header(l)):
                 strictf77 = 1
             elif is_free_format(currentfilename) and not _has_fix_header(l):