Make pcpp more optional

cxxheaderparser/preprocessor.py

@@ -8,32 +8,37 @@ import os
 import typing
 from .options import PreprocessorFunction
 
-from pcpp import Preprocessor, OutputDirective, Action
-
 
 class PreprocessorError(Exception):
     pass
 
 
-class _CustomPreprocessor(Preprocessor):
-    def __init__(
-        self,
-        encoding: typing.Optional[str],
-        passthru_includes: typing.Optional["re.Pattern"],
-    ):
-        Preprocessor.__init__(self)
-        self.errors: typing.List[str] = []
-        self.assume_encoding = encoding
-        self.passthru_includes = passthru_includes
+try:
+    import pcpp
+    from pcpp import Preprocessor, OutputDirective, Action
 
-    def on_error(self, file, line, msg):
-        self.errors.append(f"{file}:{line} error: {msg}")
+    class _CustomPreprocessor(Preprocessor):
+        def __init__(
+            self,
+            encoding: typing.Optional[str],
+            passthru_includes: typing.Optional["re.Pattern"],
+        ):
+            Preprocessor.__init__(self)
+            self.errors: typing.List[str] = []
+            self.assume_encoding = encoding
+            self.passthru_includes = passthru_includes
 
-    def on_include_not_found(self, *ignored):
-        raise OutputDirective(Action.IgnoreAndPassThrough)
+        def on_error(self, file, line, msg):
+            self.errors.append(f"{file}:{line} error: {msg}")
 
-    def on_comment(self, *ignored):
-        return True
+        def on_include_not_found(self, *ignored):
+            raise OutputDirective(Action.IgnoreAndPassThrough)
+
+        def on_comment(self, *ignored):
+            return True
+
+except ImportError:
+    pcpp = None
 
 
 def _filter_self(fname: str, fp: typing.TextIO) -> str:
@@ -82,6 +87,9 @@ def make_pcpp_preprocessor(
 
     """
 
+    if pcpp is None:
+        raise PreprocessorError("pcpp is not installed")
+
     def _preprocess_file(filename: str, content: str) -> str:
         pp = _CustomPreprocessor(encoding, passthru_includes)
         if include_paths:

tests/test_preprocessor.py

@@ -1,9 +1,13 @@
 import os
 import pathlib
+import pytest
 import re
+import shutil
+import subprocess
+import typing
 
-from cxxheaderparser.options import ParserOptions
-from cxxheaderparser.preprocessor import make_pcpp_preprocessor
+from cxxheaderparser.options import ParserOptions, PreprocessorFunction
+from cxxheaderparser import preprocessor
 from cxxheaderparser.simple import (
     NamespaceScope,
     ParsedData,
@@ -22,12 +26,26 @@ from cxxheaderparser.types import (
 )
 
 
-def test_basic_preprocessor() -> None:
+@pytest.fixture(params=["pcpp"])
+def make_pp(request) -> typing.Callable[..., PreprocessorFunction]:
+    param = request.param
+    if param == "pcpp":
+        if preprocessor.pcpp is None:
+            pytest.skip("pcpp not installed")
+        return preprocessor.make_pcpp_preprocessor
+    else:
+        assert False
+
+
+def test_basic_preprocessor(
+    make_pp: typing.Callable[..., PreprocessorFunction]
+) -> None:
     content = """
       #define X 1
       int x = X;
     """
-    options = ParserOptions(preprocessor=make_pcpp_preprocessor())
+
+    options = ParserOptions(preprocessor=make_pp())
     data = parse_string(content, cleandoc=True, options=options)
 
     assert data == ParsedData(
@@ -45,7 +63,10 @@ def test_basic_preprocessor() -> None:
     )
 
 
-def test_preprocessor_omit_content(tmp_path: pathlib.Path) -> None:
+def test_preprocessor_omit_content(
+    make_pp: typing.Callable[..., PreprocessorFunction],
+    tmp_path: pathlib.Path,
+) -> None:
     """Ensure that content in other headers is omitted"""
     h_content = '#include "t2.h"' "\n" "int x = X;\n"
     h2_content = "#define X 2\n" "int omitted = 1;\n"
@@ -56,7 +77,7 @@ def test_preprocessor_omit_content(tmp_path: pathlib.Path) -> None:
     with open(tmp_path / "t2.h", "w") as fp:
         fp.write(h2_content)
 
-    options = ParserOptions(preprocessor=make_pcpp_preprocessor())
+    options = ParserOptions(preprocessor=make_pp())
     data = parse_file(tmp_path / "t1.h", options=options)
 
     assert data == ParsedData(
@@ -74,7 +95,10 @@ def test_preprocessor_omit_content(tmp_path: pathlib.Path) -> None:
     )
 
 
-def test_preprocessor_omit_content2(tmp_path: pathlib.Path) -> None:
+def test_preprocessor_omit_content2(
+    make_pp: typing.Callable[..., PreprocessorFunction],
+    tmp_path: pathlib.Path,
+) -> None:
     """
     Ensure that content in other headers is omitted while handling pcpp
     relative path quirk
@@ -91,9 +115,7 @@ def test_preprocessor_omit_content2(tmp_path: pathlib.Path) -> None:
     with open(tmp_path2 / "t2.h", "w") as fp:
         fp.write(h2_content)
 
-    options = ParserOptions(
-        preprocessor=make_pcpp_preprocessor(include_paths=[str(tmp_path)])
-    )
+    options = ParserOptions(preprocessor=make_pp(include_paths=[str(tmp_path)]))
 
     # Weirdness happens here
     os.chdir(tmp_path)
@@ -114,7 +136,9 @@ def test_preprocessor_omit_content2(tmp_path: pathlib.Path) -> None:
     )
 
 
-def test_preprocessor_encoding(tmp_path: pathlib.Path) -> None:
+def test_preprocessor_encoding(
+    make_pp: typing.Callable[..., PreprocessorFunction], tmp_path: pathlib.Path
+) -> None:
     """Ensure we can handle alternate encodings"""
     h_content = b"// \xa9 2023 someone\n" b'#include "t2.h"' b"\n" b"int x = X;\n"
 
@@ -126,7 +150,7 @@ def test_preprocessor_encoding(tmp_path: pathlib.Path) -> None:
     with open(tmp_path / "t2.h", "wb") as fp:
         fp.write(h2_content)
 
-    options = ParserOptions(preprocessor=make_pcpp_preprocessor(encoding="cp1252"))
+    options = ParserOptions(preprocessor=make_pp(encoding="cp1252"))
     data = parse_file(tmp_path / "t1.h", options=options, encoding="cp1252")
 
     assert data == ParsedData(
@@ -144,6 +168,7 @@ def test_preprocessor_encoding(tmp_path: pathlib.Path) -> None:
     )
 
 
+@pytest.mark.skipif(preprocessor.pcpp is None, reason="pcpp not installed")
 def test_preprocessor_passthru_includes(tmp_path: pathlib.Path) -> None:
     """Ensure that all #include pass through"""
     h_content = '#include "t2.h"\n'
@@ -155,7 +180,9 @@ def test_preprocessor_passthru_includes(tmp_path: pathlib.Path) -> None:
         fp.write("")
 
     options = ParserOptions(
-        preprocessor=make_pcpp_preprocessor(passthru_includes=re.compile(".+"))
+        preprocessor=preprocessor.make_pcpp_preprocessor(
+            passthru_includes=re.compile(".+")
+        )
     )
     data = parse_file(tmp_path / "t1.h", options=options)