chore: pattern matching (#2434)

* chore: use match for stringify_setting

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

* chore: more match statements

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

---------

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>
Co-authored-by: Joe Rickerby <joerick@mac.com>

cibuildwheel/oci_container.py

@@ -95,7 +95,8 @@ def _check_engine_version(engine: OCIContainerEngineConfig) -> None:
     try:
         version_string = call(engine.name, "version", "-f", "{{json .}}", capture_stdout=True)
         version_info = json.loads(version_string.strip())
-        if engine.name == "docker":
+        match engine.name:
+            case "docker":
                 client_api_version = FlexibleVersion(version_info["Client"]["ApiVersion"])
                 server_api_version = FlexibleVersion(version_info["Server"]["ApiVersion"])
                 # --platform support was introduced in 1.32 as experimental, 1.41 removed the experimental flag
@@ -110,7 +111,7 @@ def _check_engine_version(engine: OCIContainerEngineConfig) -> None:
                     The API version found by cibuildwheel is {version}.
                     """
                 )
-        elif engine.name == "podman":
+            case "podman":
                 # podman uses the same version string for "Version" & "ApiVersion"
                 client_version = FlexibleVersion(version_info["Client"]["Version"])
                 if "Server" in version_info:
@@ -128,10 +129,12 @@ def _check_engine_version(engine: OCIContainerEngineConfig) -> None:
                     The version found by cibuildwheel is {version}.
                     """
                 )
-        else:
+            case _:
                 assert_never(engine.name)
+
         if version < minimum_version:
             raise OCIEngineTooOldError(error_msg) from None
+
     except (subprocess.CalledProcessError, KeyError, ValueError) as e:
         msg = f"Build failed because {engine.name} is too old or is not working properly."
         raise OCIEngineTooOldError(msg) from e

cibuildwheel/options.py

@@ -343,11 +343,12 @@ def _apply_inherit_rule(
         msg = f"Don't know how to merge {before!r} and {after!r} with {rule}"
         raise OptionsReaderError(msg)
 
-    if rule == InheritRule.APPEND:
+    match rule:
+        case InheritRule.APPEND:
             return option_format.merge_values(before, after)
-    if rule == InheritRule.PREPEND:
+        case InheritRule.PREPEND:
             return option_format.merge_values(after, before)
-
+        case _:
             assert_never(rule)
 
 
@@ -355,27 +356,32 @@ def _stringify_setting(
     setting: SettingValue,
     option_format: OptionFormat | None,
 ) -> str:
-    if isinstance(setting, Mapping):
+    match setting:
+        case {}:
+            assert isinstance(setting, Mapping)  # MyPy 1.15 doesn't narrow this for us
             try:
                 if option_format is None:
                     raise OptionFormat.NotSupported
                 return option_format.format_table(setting)
             except OptionFormat.NotSupported:
-            msg = f"Error converting {setting!r} to a string: this setting doesn't accept a table"
+                msg = (
+                    f"Error converting {setting!r} to a string: this setting doesn't accept a table"
+                )
                 raise OptionsReaderError(msg) from None
-
+        case bool() | int():
-    if not isinstance(setting, str) and isinstance(setting, Sequence):
+            return str(setting)
+        case [*_]:
             try:
                 if option_format is None:
                     raise OptionFormat.NotSupported
                 return option_format.format_list(setting)
             except OptionFormat.NotSupported:
-            msg = f"Error converting {setting!r} to a string: this setting doesn't accept a list"
+                msg = (
+                    f"Error converting {setting!r} to a string: this setting doesn't accept a list"
+                )
                 raise OptionsReaderError(msg) from None
-
+        case _:
-    if isinstance(setting, bool | int):
+            assert isinstance(setting, str)  # MyPy 1.15 doesn't narrow this for us
-        return str(setting)
-
             return setting
 
 

cibuildwheel/platforms/ios.py

@@ -387,10 +387,11 @@ def setup_python(
     env.setdefault("IPHONEOS_DEPLOYMENT_TARGET", "13.0")
 
     log.step("Installing build tools...")
-    if build_frontend == "pip":
+    match build_frontend:
+        case "pip":
             # No additional build tools required
             pass
-    elif build_frontend == "build":
+        case "build":
             call(
                 "pip",
                 "install",
@@ -399,7 +400,7 @@ def setup_python(
                 *constraint_flags(dependency_constraint),
                 env=env,
             )
-    else:
+        case _:
             assert_never(build_frontend)
 
     return target_install_path, env
@@ -494,7 +495,8 @@ def build(options: Options, tmp_path: Path) -> None:
                 if constraints_path:
                     combine_constraints(build_env, constraints_path, None)
 
-                if build_frontend.name == "pip":
+                match build_frontend.name:
+                    case "pip":
                         # Path.resolve() is needed. Without it pip wheel may try to
                         # fetch package from pypi.org. See
                         # https://github.com/pypa/cibuildwheel/pull/369
@@ -509,7 +511,7 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                elif build_frontend.name == "build":
+                    case "build":
                         call(
                             "python",
                             "-m",
@@ -520,7 +522,7 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                else:
+                    case _:
                         assert_never(build_frontend)
 
                 test_wheel = built_wheel = next(built_wheel_dir.glob("*.whl"))

cibuildwheel/platforms/linux.py

@@ -275,7 +275,8 @@ def build_in_container(
                 build_frontend, build_options.build_verbosity, build_options.config_settings
             )
 
-            if build_frontend.name == "pip":
+            match build_frontend.name:
+                case "pip":
                     container.call(
                         [
                             "python",
@@ -289,7 +290,7 @@ def build_in_container(
                         ],
                         env=env,
                     )
-            elif build_frontend.name == "build" or build_frontend.name == "build[uv]":
+                case "build" | "build[uv]":
                     if use_uv and "--no-isolation" not in extra_flags and "-n" not in extra_flags:
                         extra_flags += ["--installer=uv"]
                     container.call(
@@ -304,7 +305,7 @@ def build_in_container(
                         ],
                         env=env,
                     )
-            else:
+                case _:
                     assert_never(build_frontend)
 
             built_wheel = container.glob(built_wheel_dir, "*.whl")[0]

cibuildwheel/platforms/macos.py

@@ -345,7 +345,8 @@ def setup_python(
             env.setdefault("SDKROOT", arm64_compatible_sdks[0])
 
     log.step("Installing build tools...")
-    if build_frontend == "pip":
+    match build_frontend:
+        case "pip":
             call(
                 "pip",
                 "install",
@@ -354,7 +355,7 @@ def setup_python(
                 *constraint_flags(dependency_constraint),
                 env=env,
             )
-    elif build_frontend == "build":
+        case "build":
             call(
                 "pip",
                 "install",
@@ -364,7 +365,7 @@ def setup_python(
                 *constraint_flags(dependency_constraint),
                 env=env,
             )
-    elif build_frontend == "build[uv]":
+        case "build[uv]":
             assert uv_path is not None
             call(
                 uv_path,
@@ -376,7 +377,7 @@ def setup_python(
                 *constraint_flags(dependency_constraint),
                 env=env,
             )
-    else:
+        case _:
             assert_never(build_frontend)
 
     return base_python, env
@@ -467,7 +468,8 @@ def build(options: Options, tmp_path: Path) -> None:
                         build_env, constraints_path, identifier_tmp_dir if use_uv else None
                     )
 
-                if build_frontend.name == "pip":
+                match build_frontend.name:
+                    case "pip":
                         # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
                         # see https://github.com/pypa/cibuildwheel/pull/369
                         call(
@@ -481,8 +483,12 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                elif build_frontend.name == "build" or build_frontend.name == "build[uv]":
+                    case "build" | "build[uv]":
-                    if use_uv and "--no-isolation" not in extra_flags and "-n" not in extra_flags:
+                        if (
+                            use_uv
+                            and "--no-isolation" not in extra_flags
+                            and "-n" not in extra_flags
+                        ):
                             extra_flags.append("--installer=uv")
                         call(
                             "python",
@@ -494,7 +500,7 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                else:
+                    case _:
                         assert_never(build_frontend)
 
                 built_wheel = next(built_wheel_dir.glob("*.whl"))

cibuildwheel/platforms/windows.py

@@ -305,7 +305,8 @@ def setup_python(
         call("pip", "--version", env=env)
 
     log.step("Installing build tools...")
-    if build_frontend == "build":
+    match build_frontend:
+        case "build":
             call(
                 "pip",
                 "install",
@@ -314,7 +315,7 @@ def setup_python(
                 *constraint_flags(dependency_constraint),
                 env=env,
             )
-    elif build_frontend == "build[uv]":
+        case "build[uv]":
             assert uv_path is not None
             call(
                 uv_path,
@@ -467,7 +468,8 @@ def build(options: Options, tmp_path: Path) -> None:
                 if constraints_path:
                     combine_constraints(build_env, constraints_path, identifier_tmp_dir)
 
-                if build_frontend.name == "pip":
+                match build_frontend.name:
+                    case "pip":
                         # Path.resolve() is needed. Without it pip wheel may try to fetch package from pypi.org
                         # see https://github.com/pypa/cibuildwheel/pull/369
                         call(
@@ -481,8 +483,12 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                elif build_frontend.name == "build" or build_frontend.name == "build[uv]":
+                    case "build" | "build[uv]":
-                    if use_uv and "--no-isolation" not in extra_flags and "-n" not in extra_flags:
+                        if (
+                            use_uv
+                            and "--no-isolation" not in extra_flags
+                            and "-n" not in extra_flags
+                        ):
                             extra_flags.append("--installer=uv")
 
                         call(
@@ -495,7 +501,7 @@ def build(options: Options, tmp_path: Path) -> None:
                             *extra_flags,
                             env=build_env,
                         )
-                else:
+                    case _:
                         assert_never(build_frontend)
 
                 built_wheel = next(built_wheel_dir.glob("*.whl"))

cibuildwheel/projectfiles.py

@@ -14,32 +14,16 @@ def get_parent(node: ast.AST | None, depth: int = 1) -> ast.AST | None:
 
 
 def is_main(parent: ast.AST | None) -> bool:
-    if parent is None:
+    match parent:
-        return False
+        case ast.If(test=ast.Compare(left=left, ops=[ast.Eq()], comparators=[comp])):
-
+            values = {left, comp}
-    # This would be much nicer with 3.10's pattern matching!
-    if not isinstance(parent, ast.If):
-        return False
-    if not isinstance(parent.test, ast.Compare):
-        return False
-
-    try:
-        (op,) = parent.test.ops
-        (comp,) = parent.test.comparators
-    except ValueError:
-        return False
-
-    if not isinstance(op, ast.Eq):
-        return False
-
-    values = {comp, parent.test.left}
-
             mains = {x for x in values if isinstance(x, ast.Constant) and x.value == "__main__"}
             if len(mains) != 1:
                 return False
             consts = {x for x in values if isinstance(x, ast.Name) and x.id == "__name__"}
-
             return len(consts) == 1
+        case _:
+            return False
 
 
 class Analyzer(ast.NodeVisitor):
@@ -65,12 +49,10 @@ class Analyzer(ast.NodeVisitor):
             parent is not None and get_parent(parent) is None and is_main(get_parent(node, 3))
         )
 
-        if (
+        match node:
-            node.arg == "python_requires"
+            case ast.keyword(arg="python_requires", value=ast.Constant(value=version)):
-            and isinstance(node.value, ast.Constant)
+                if unnested or name_main_unnested:
-            and (unnested or name_main_unnested)
+                    self.requires_python = version
-        ):
-            self.requires_python = node.value.value
 
 
 def setup_py_python_requires(content: str) -> str | None: