scikit-build-core Support (#133)

Author: Behemyth

.vscode/extensions.json

@@ -1,6 +1,5 @@
 {
     "recommendations": [
-        "asciidoctor.asciidoctor-vscode",
         "charliermarsh.ruff",
         "tamasfe.even-better-toml",
         "meta.pyrefly"

.vscode/settings.json

@@ -15,5 +15,9 @@
         },
         "editor.defaultFormatter": "charliermarsh.ruff"
     },
-    "cmake.ignoreCMakeListsMissing": true
+    "cmake.ignoreCMakeListsMissing": true,
+    "files.associations": {
+        "*.md": "markdown",
+        "xstring": "cpp"
+    }
 }

cppython/build/__init__.py

@@ -0,0 +1,33 @@
+"""CPPython build backend wrapping scikit-build-core.
+
+This module provides PEP 517/518 build backend hooks that wrap scikit-build-core,
+automatically running CPPython's provider workflow before building
+to inject the generated toolchain file into the CMake configuration.
+
+Usage in pyproject.toml:
+    [build-system]
+    requires = ["cppython[conan, cmake]"]
+    build-backend = "cppython.build"
+"""
+
+from cppython.build.backend import (
+    build_editable,
+    build_sdist,
+    build_wheel,
+    get_requires_for_build_editable,
+    get_requires_for_build_sdist,
+    get_requires_for_build_wheel,
+    prepare_metadata_for_build_editable,
+    prepare_metadata_for_build_wheel,
+)
+
+__all__ = [
+    'build_editable',
+    'build_sdist',
+    'build_wheel',
+    'get_requires_for_build_editable',
+    'get_requires_for_build_sdist',
+    'get_requires_for_build_wheel',
+    'prepare_metadata_for_build_editable',
+    'prepare_metadata_for_build_wheel',
+]

cppython/build/backend.py

@@ -0,0 +1,223 @@
+"""PEP 517 build backend implementation wrapping scikit-build-core.
+
+This module provides the actual build hooks that delegate to scikit-build-core
+after running CPPython's preparation workflow.
+"""
+
+import logging
+from pathlib import Path
+from typing import Any
+
+from scikit_build_core import build as skbuild
+
+from cppython.build.prepare import prepare_build
+
+logger = logging.getLogger('cppython.build')
+
+
+def _inject_toolchain(config_settings: dict[str, Any] | None, toolchain_file: Path | None) -> dict[str, Any]:
+    """Inject the toolchain file into config settings for scikit-build-core.
+
+    Args:
+        config_settings: The original config settings (may be None)
+        toolchain_file: Path to the toolchain file to inject
+
+    Returns:
+        Updated config settings with toolchain file injected
+    """
+    settings = dict(config_settings) if config_settings else {}
+
+    if toolchain_file and toolchain_file.exists():
+        # scikit-build-core accepts cmake.args for passing CMake arguments
+        # Using cmake.args passes the toolchain via -DCMAKE_TOOLCHAIN_FILE=...
+        args_key = 'cmake.args'
+        toolchain_arg = f'-DCMAKE_TOOLCHAIN_FILE={toolchain_file.absolute()}'
+
+        # Append to existing args or create new
+        if args_key in settings:
+            existing = settings[args_key]
+            # Check if toolchain is already specified
+            if 'CMAKE_TOOLCHAIN_FILE' not in existing:
+                settings[args_key] = f'{existing};{toolchain_arg}'
+                logger.info('CPPython: Appended CMAKE_TOOLCHAIN_FILE to cmake.args')
+            else:
+                logger.info('CPPython: User-specified toolchain file takes precedence')
+        else:
+            settings[args_key] = toolchain_arg
+            logger.info('CPPython: Injected CMAKE_TOOLCHAIN_FILE=%s', toolchain_file)
+
+    return settings
+
+
+def _prepare_and_get_settings(
+    config_settings: dict[str, Any] | None,
+) -> dict[str, Any]:
+    """Run CPPython preparation and merge toolchain into config settings.
+
+    Args:
+        config_settings: The original config settings
+
+    Returns:
+        Config settings with CPPython toolchain injected
+    """
+    # Determine source directory (current working directory during build)
+    source_dir = Path.cwd()
+
+    # Run CPPython preparation
+    toolchain_file = prepare_build(source_dir)
+
+    # Inject toolchain into config settings
+    return _inject_toolchain(config_settings, toolchain_file)
+
+
+# PEP 517 Hooks - delegating to scikit-build-core after preparation
+
+
+def get_requires_for_build_wheel(
+    config_settings: dict[str, Any] | None = None,
+) -> list[str]:
+    """Get additional requirements for building a wheel.
+
+    Args:
+        config_settings: Build configuration settings
+
+    Returns:
+        List of additional requirements
+    """
+    return skbuild.get_requires_for_build_wheel(config_settings)
+
+
+def get_requires_for_build_sdist(
+    config_settings: dict[str, Any] | None = None,
+) -> list[str]:
+    """Get additional requirements for building an sdist.
+
+    Args:
+        config_settings: Build configuration settings
+
+    Returns:
+        List of additional requirements
+    """
+    return skbuild.get_requires_for_build_sdist(config_settings)
+
+
+def get_requires_for_build_editable(
+    config_settings: dict[str, Any] | None = None,
+) -> list[str]:
+    """Get additional requirements for building an editable install.
+
+    Args:
+        config_settings: Build configuration settings
+
+    Returns:
+        List of additional requirements
+    """
+    return skbuild.get_requires_for_build_editable(config_settings)
+
+
+def build_wheel(
+    wheel_directory: str,
+    config_settings: dict[str, Any] | None = None,
+    metadata_directory: str | None = None,
+) -> str:
+    """Build a wheel from the source distribution.
+
+    This runs CPPython's provider workflow first to ensure C++ dependencies
+    are installed and the toolchain file is generated, then delegates to
+    scikit-build-core for the actual wheel build.
+
+    Args:
+        wheel_directory: Directory to place the built wheel
+        config_settings: Build configuration settings
+        metadata_directory: Directory containing wheel metadata
+
+    Returns:
+        The basename of the built wheel
+    """
+    logger.info('CPPython: Starting wheel build')
+
+    # Prepare CPPython and get updated settings
+    settings = _prepare_and_get_settings(config_settings)
+
+    # Delegate to scikit-build-core
+    return skbuild.build_wheel(wheel_directory, settings, metadata_directory)
+
+
+def build_sdist(
+    sdist_directory: str,
+    config_settings: dict[str, Any] | None = None,
+) -> str:
+    """Build a source distribution.
+
+    For sdist, we don't run the full CPPython workflow since the C++ dependencies
+    should be resolved at wheel build time, not sdist creation time.
+
+    Args:
+        sdist_directory: Directory to place the built sdist
+        config_settings: Build configuration settings
+
+    Returns:
+        The basename of the built sdist
+    """
+    logger.info('CPPython: Starting sdist build')
+
+    # Delegate directly to scikit-build-core (no preparation needed for sdist)
+    return skbuild.build_sdist(sdist_directory, config_settings)
+
+
+def build_editable(
+    wheel_directory: str,
+    config_settings: dict[str, Any] | None = None,
+    metadata_directory: str | None = None,
+) -> str:
+    """Build an editable wheel.
+
+    This runs CPPython's provider workflow first, similar to build_wheel.
+
+    Args:
+        wheel_directory: Directory to place the built wheel
+        config_settings: Build configuration settings
+        metadata_directory: Directory containing wheel metadata
+
+    Returns:
+        The basename of the built wheel
+    """
+    logger.info('CPPython: Starting editable build')
+
+    # Prepare CPPython and get updated settings
+    settings = _prepare_and_get_settings(config_settings)
+
+    # Delegate to scikit-build-core
+    return skbuild.build_editable(wheel_directory, settings, metadata_directory)
+
+
+def prepare_metadata_for_build_wheel(
+    metadata_directory: str,
+    config_settings: dict[str, Any] | None = None,
+) -> str:
+    """Prepare metadata for wheel build.
+
+    Args:
+        metadata_directory: Directory to place the metadata
+        config_settings: Build configuration settings
+
+    Returns:
+        The basename of the metadata directory
+    """
+    return skbuild.prepare_metadata_for_build_wheel(metadata_directory, config_settings)
+
+
+def prepare_metadata_for_build_editable(
+    metadata_directory: str,
+    config_settings: dict[str, Any] | None = None,
+) -> str:
+    """Prepare metadata for editable build.
+
+    Args:
+        metadata_directory: Directory to place the metadata
+        config_settings: Build configuration settings
+
+    Returns:
+        The basename of the metadata directory
+    """
+    return skbuild.prepare_metadata_for_build_editable(metadata_directory, config_settings)