feat(cpp): test for presence of swig during import

Author: mbdevpl

test/test_dependencies.py

@@ -6,10 +6,6 @@
 
 class Tests(unittest.TestCase):
 
-    def test_swig(self):
-        swig_path = shutil.which('swig')
-        self.assertIsNotNone(swig_path)
-
     def test_typed_ast(self):
         from typed_ast import ast3
         self.assertGreaterEqual(ast3.LATEST_MINOR_VERSION, 6)

transpyle/cpp/compiler.py

@@ -9,10 +9,12 @@
 import typing as t
 
 import argunparse
+import version_query
 
 from ..general import \
     temporarily_change_dir, run_tool, \
-    Language, CodeReader, Parser, AstGeneralizer, Unparser, Compiler
+    ExternalTool, Language, CodeReader, Parser, AstGeneralizer, Unparser, Compiler
+from ..general.exc import ExternalToolVersionError
 from .compiler_interface import GppInterface, ClangppInterface
 
 SWIG_INTERFACE_TEMPLATE = '''/* File: {module_name}.i */
@@ -90,6 +92,23 @@
 _LOG = logging.getLogger(__name__)
 
 
+class Swig(ExternalTool):
+    """Define requirements for SWIG."""
+
+    path = pathlib.Path('swig')
+    _version_arg = '-version'
+
+    @classmethod
+    def _version_output_filter(cls, output: str) -> str:
+        for output_line in output.splitlines():
+            if output_line.startswith('SWIG Version '):
+                return output_line.replace('SWIG Version ', '')
+        raise ExternalToolVersionError(f'could not extract version from output: {output}')
+
+
+Swig.assert_version_at_least(version_query.Version(4, 0))
+
+
 class SwigCompiler(Compiler):
 
     # TODO: create SWIG compiler interface similarily to F2PY interface