Fix/mac openmp

.gitignore

@@ -36,3 +36,5 @@ nosetests.xml
 .project
 .pydevproject
 .python-version
+build-test.sh
+.idea

pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+requires = ["setuptools>=42", "wheel"]
+build-backend = "setuptools.build_meta"

setup.py

@@ -1,20 +1,66 @@
-from setuptools import setup, Extension
-
+import logging
 import os
+import platform
+import shutil
+import subprocess
+
+from setuptools import setup, Extension
 
 OPENMP_DISABLED = os.environ.get('OPENMP_DISABLED', False)
-libraries=['clustalo', 'stdc++']
-extra_compile_args = []
+libraries = ['clustalo', 'stdc++']
+
+
+class BuildFlags:
+    _tools_formulae = {
+        'Darwin': ('brew', 'libomp'),
+    }
+    _args = {
+        'Darwin': {
+            'compiler': ['-Xpreprocessor', '-fopenmp'],
+            'linker': ['-lomp']
+        }
+    }
+    _default_args = {
+        'compiler': ['-fopenmp'],
+        'linker': ['-fopenmp']
+    }
+    compiler: list
+    linker: list
+
+    def __init__(self):
+        self._system = platform.system()
+        tool, formula = self._tools_formulae.get(self._system, ('apt', 'libomp-dev'))
+        args = self._args.get(self._system, self._default_args)
+
+        not_found = self._libomp_check(tool, formula)
+        if not_found is not None:
+            logging.warning(f'{repr(not_found)} not found -- cannot compile parallelized code')
+            for key in args:
+                args[key] = []
+
+        for key, val in args.items():
+            self.__setattr__(key, val)
+
+    @staticmethod
+    def _libomp_check(tool, formula):
+        if shutil.which(tool) is None:
+            return tool
+
+        formulae = subprocess.check_output([tool, 'list']).decode()
+        if formula not in formulae:
+            return formula
+
+        return None
 
-if not OPENMP_DISABLED:
-    libraries.append('gomp')
-    extra_compile_args.append('-fopenmp')
 
+flags = BuildFlags()
 module = Extension('clustalo',
-                   sources = ['clustalo.c'],
+                   sources=['clustalo.c'],
                    include_dirs=['/usr/include/clustalo', '/usr/local/include/clustalo'],
+                   library_dirs=['/usr/local/lib'],
                    libraries=libraries,
-                   extra_compile_args=extra_compile_args)
+                   extra_compile_args=flags.compiler,
+                   extra_link_args=flags.linker)
 
 setup(name='clustalo',
       version='0.1.2',