Remove seq.pyx and import it as cyseq

Signed-off-by: Jono Yang <jyang@nexb.com>

Author: JonoYang

setup.cfg

@@ -117,6 +117,7 @@ install_requires =
     typecode >= 30.0.1
     typecode[full] >= 30.0.1
     extractcode[full] >= 31.0.0
+    cyseq; platform_system == 'Linux'
 
 
 [options.packages.find]

setup.py

@@ -1,14 +1,6 @@
 #!/usr/bin/env python
 
 import setuptools
-from Cython.Build import cythonize
-
-
-extensions = [
-    setuptools.Extension("licensedcode.seq", ["src/licensedcode/seq.pyx"], language="c++"),
-]
 
 if __name__ == "__main__":
-    setuptools.setup(
-        ext_modules=cythonize(extensions)
-    )
+    setuptools.setup()

src/licensedcode/index.py

@@ -28,13 +28,19 @@
 from licensedcode import match_spdx_lid
 from licensedcode import match_unknown
 from licensedcode.dmp import match_blocks as match_blocks_dmp
-from licensedcode.seq import match_blocks as match_blocks_seq
 from licensedcode import query
 from licensedcode import tokenize
 from licensedcode.spans import Span
 from typing import NamedTuple
 from typing import Callable
 
+try:
+    # Use Cython seq.py implementation
+    from cyseq import match_blocks as match_blocks_seq
+except ImportError:
+    # Use Python seq.py if it is not available
+    from licensedcode.seq import match_blocks as match_blocks_seq
+
 """
 Main license index construction, query processing and matching entry points for
 license detection.

src/licensedcode/match_seq.py

@@ -63,7 +63,12 @@ def match_sequence(
         return []
 
     if not match_blocks:
-        from licensedcode.seq import match_blocks
+        try:
+            # Use Cython seq.py implementation
+            from cyseq import match_blocks
+        except ImportError:
+            # Use Python seq.py if it is not available
+            from licensedcode.seq import match_blocks
 
     rid = rule.rid
     itokens = idx.tids_by_rid[rid]