feat: add general class for interacting with external tools

test/test_cpp.py

@@ -11,13 +11,29 @@
 import timing
 import typed_astunparse
 
-from transpyle.general.code_reader import CodeReader
-from transpyle.general.binder import Binder
-from transpyle.cpp.parser import CppParser
-from transpyle.cpp.ast_generalizer import CppAstGeneralizer
-from transpyle.cpp.unparser import Cpp14Unparser
-from transpyle.cpp.compiler import CppSwigCompiler
-from transpyle.cpp.compiler_interface import GppInterface
+from transpyle.general import AstGeneralizer, Binder, CodeReader, Parser
+from transpyle.general.exc import ExternalToolError
+
+try:
+    from transpyle.cpp.parser import CppParser
+except (ImportError, ExternalToolError):
+    pass
+try:
+    from transpyle.cpp.ast_generalizer import CppAstGeneralizer
+except ImportError:
+    pass
+try:
+    from transpyle.cpp.unparser import Cpp14Unparser
+except ImportError:
+    pass
+try:
+    from transpyle.cpp.compiler import CppSwigCompiler
+except ImportError:
+    pass
+try:
+    from transpyle.cpp.compiler_interface import GppInterface
+except ImportError:
+    pass
 
 from .common import \
     PERFORMANCE_RESULTS_ROOT, EXAMPLES_ROOT, EXAMPLES_ROOTS, \
@@ -29,6 +45,7 @@
 _TIME = timing.get_timing_group(__name__)
 
 
+@unittest.skipIf(Parser.find('C++') is None, 'skipping due to missing C++ language support')
 class ParserTests(unittest.TestCase):
 
     @execute_on_language_examples('cpp14')
@@ -53,6 +70,7 @@ def test_try_parse_invalid(self):
         _LOG.debug('%s', err.exception)
 
 
+@unittest.skipIf(AstGeneralizer.find('C++') is None, 'skipping due to missing C++ language support')
 class AstGeneralizerTests(unittest.TestCase):
 
     @execute_on_language_examples('cpp14')
@@ -71,6 +89,7 @@ def test_generalize_examples(self, input_path):
         _LOG.debug('%s', typed_astunparse.unparse(syntax))
 
 
+@unittest.skipIf(Unparser.find('C++') is None, 'skipping due to missing C++ language support')
 class UnparserTests(unittest.TestCase):
 
     @execute_on_language_examples('cpp14')
@@ -97,6 +116,7 @@ def test_unparse_examples(self, input_path):
         _LOG.info('unparsed "%s" in %fs', input_path, timer.elapsed)
 
 
+@unittest.skipIf(Compiler.find('C++') is None, 'skipping due to missing C++ language support')
 class CompilerTests(unittest.TestCase):
 
     def test_cpp_paths_exist(self):

transpyle/__init__.py

@@ -3,6 +3,7 @@
 import logging
 
 from .configuration import configure
+from .general.exc import ExternalToolError
 
 configure()
 
@@ -17,7 +18,7 @@
 
 try:
     from .cpp import *
-except ImportError:
+except (ImportError, ExternalToolError):
     _LOG.warning("C++ unavailable")
 
 # try:

transpyle/cpp/parser.py

@@ -7,13 +7,33 @@
 import xml.etree.ElementTree as ET
 
 import argunparse
+import version_query
 
-from ..general import Parser
+from ..general import ExternalTool, Parser
+from ..general.exc import ExternalToolVersionError
 from ..general.tools import run_tool
 
 _LOG = logging.getLogger(__name__)
 
-CASTXML_PATH = pathlib.Path('castxml')
+
+class CastXml(ExternalTool):
+    """Define how to execute CastXML tool.
+
+    https://github.com/CastXML/CastXML
+    """
+
+    path = pathlib.Path('castxml')
+    _version_arg = '--version'
+
+    @classmethod
+    def _version_output_filter(cls, output: str) -> str:
+        for output_line in output.splitlines():
+            if output_line.startswith('castxml version '):
+                return output_line.replace('castxml version ', '')
+        raise ExternalToolVersionError(f'could not extract version from output: {output}')
+
+
+CastXml.assert_version_at_least(version_query.Version(0, 4))
 
 
 def run_castxml(input_path: pathlib.Path, output_path: pathlib.Path, gcc: bool = False):
@@ -29,7 +49,7 @@ def run_castxml(input_path: pathlib.Path, output_path: pathlib.Path, gcc: bool =
     elif platform.system() == 'Darwin':
         kwargs['castxml-cc-gnu'] = 'clang++'
     kwargs['o'] = str(output_path)
-    return run_tool(CASTXML_PATH, args, kwargs,
+    return run_tool(CastXml.path, args, kwargs,
                     argunparser=argunparse.ArgumentUnparser(opt_value=' '))
 
 

transpyle/general/__init__.py

@@ -1,6 +1,7 @@
 """Language-agnostic modules and base classes for language-specific modules in transpyle."""
 
 from .tools import temporarily_change_dir, redirect_stdout_and_stderr, run_tool, call_tool
+from .external_tool import ExternalTool
 
 from .language import Language
 
@@ -19,6 +20,7 @@
 from .transpiler import Transpiler, AutoTranspiler
 
 __all__ = ['temporarily_change_dir', 'redirect_stdout_and_stderr', 'run_tool', 'call_tool',
+           'ExternalTool',
            'Language',
            'CodeReader', 'Parser', 'AstGeneralizer', 'IdentityAstGeneralizer', 'XmlAstGeneralizer',
            'GeneralizingAutoParser',

transpyle/general/exc.py

@@ -1,5 +1,16 @@
 """Non-standard exception types used in transpyle."""
 
+class ExternalToolError(Exception):
+    """Indicates an issue with an external tool."""
+
+
+class ExternalToolMissingError(ExternalToolError, FileNotFoundError):
+    """Raised when an external tool is not found."""
+
+
+class ExternalToolVersionError(ExternalToolError, AssertionError):
+    """Raised when an external tool doesn't satisfy the version requirements."""
+
 
 class ContinueIteration(StopIteration):
 

transpyle/general/external_tool.py

@@ -0,0 +1,55 @@
+"""Evaluate external tool and ."""
+
+import pathlib
+import shutil
+
+import version_query
+
+from .exc import ExternalToolMissingError, ExternalToolVersionError
+from .tools import run_tool
+
+
+class ExternalTool:
+    """Generic tool definition.
+    
+    When inheriting, the following has to be defined:
+    * path: path to the tool
+    * _version_arg: argument to get the version of the tool when executing it
+    * _version_output_filter: function to filter the output of the version command
+    """
+
+    path: pathlib.Path
+    _version_arg: str
+    _version: version_query.Version | None = None
+
+    @classmethod
+    def exists(cls) -> bool:
+        path = shutil.which(cls.path.as_posix())
+        return path is not None
+
+    @classmethod
+    def assert_exists(cls) -> None:
+        """Assert that the external tool exists."""
+        if not cls.exists():
+            raise ExternalToolMissingError(f'{cls.path} not found')
+
+    @classmethod
+    def version(cls) -> version_query.Version:
+        """Determine the version of the external tool."""
+        if cls._version is None:
+            result = run_tool(cls.path, [cls._version_arg])
+            version_str = cls._version_output_filter(result.stdout)
+            cls._version = version_query.Version.from_str(version_str)
+        return cls._version
+
+    @classmethod
+    def _version_output_filter(cls, output: str) -> str:
+        raise NotImplementedError('this method needs to be implemented')
+
+    @classmethod
+    def assert_version_at_least(cls, version: version_query.Version) -> None:
+        """Assert that the external tool is at least the given version."""
+        cls.assert_exists()
+        if cls.version() < version:
+            raise ExternalToolVersionError(
+                f'{cls.path} version {cls.version} does not satisfy the requirement >= {version}')