refactor: improve metadata module

packer/src/sarasacw_omrf_packer/metadata.py

@@ -18,7 +18,14 @@ from re import Pattern, compile
 from typing import Any, Callable
 from semver import Version
 from . import utils
-from .utils import Triple, VERSION, dict_chain_get, dict_typed_get, dict_typed_get_required
+from .utils import (
+    Triple,
+    VERSION,
+    dict_chain_get,
+    dict_typed_get,
+    dict_typed_get_required,
+    list_typed_iter,
+)
 
 
 @dataclass(frozen=True)
@@ -104,15 +111,14 @@ class MetadataCMake:
     def from_dict(d: dict[str, Any]) -> "MetadataCMake":
         """Build a :class:`MetadataCMake` from its raw TOML table."""
         raw_dependencies = dict_typed_get(d, "dependencies", list)
-        if raw_dependencies is not None:
-            dependencies_list: list[MetadataCMakeDependency] = []
-            for i, item in enumerate(raw_dependencies):
-                if not isinstance(item, dict):
-                    raise TypeError(f"dependencies[{i}] must be a table")
-                dependencies_list.append(MetadataCMakeDependency.from_dict(item))
-            dependencies = tuple(dependencies_list)
-        else:
-            dependencies = None
+        dependencies = (
+            tuple(
+                MetadataCMakeDependency.from_dict(item)
+                for item in list_typed_iter(raw_dependencies, dict)
+            )
+            if raw_dependencies is not None
+            else None
+        )
 
         return MetadataCMake(
             namespace_name=dict_typed_get(d, "namespace_name", str),
@@ -157,15 +163,11 @@ class MetadataPkgConfig:
     def from_dict(d: dict[str, Any]) -> "MetadataPkgConfig":
         """Build a :class:`MetadataPkgConfig` from its raw TOML table."""
         raw_requires = dict_typed_get(d, "requires", list)
-        if raw_requires is not None:
-            requires_list: list[str] = []
-            for i, item in enumerate(raw_requires):
-                if not isinstance(item, str):
-                    raise TypeError(f"requires[{i}] must be a string")
-                requires_list.append(item)
-            requires = tuple(requires_list)
-        else:
-            requires = None
+        requires = (
+            tuple(list_typed_iter(raw_requires, str))
+            if raw_requires is not None
+            else None
+        )
 
         return MetadataPkgConfig(
             id=dict_typed_get(d, "id", str),
@@ -210,13 +212,12 @@ class Metadata:
         else:
             min_version = None
 
-        raw_headers = dict_typed_get_required(d, "headers", list)
-        headers_list: list[MetadataHeader] = []
-        for i, item in enumerate(raw_headers):
-            if not isinstance(item, dict):
-                raise TypeError(f"headers[{i}] must be a table")
-            headers_list.append(MetadataHeader.from_dict(item))
-        headers = tuple(headers_list)
+        headers = tuple(
+            MetadataHeader.from_dict(item)
+            for item in list_typed_iter(
+                dict_typed_get_required(d, "headers", list), dict
+            )
+        )
 
         raw_cmake = dict_typed_get(d, "cmake", dict)
         cmake = MetadataCMake.from_dict(raw_cmake) if raw_cmake is not None else None
@@ -260,6 +261,7 @@ _SUBPROCESS_TIMEOUT_SEC: int = 10
 _HOST_TRIPLE_PATTERN: Pattern = compile(r"(?m)^host:\s*(\S+)$")
 """The pattern for match host triple in ``rustc -vV``. The group 1 is the triple result."""
 
+
 class MetadataExtractor:
     """Access layer over ``cargo metadata`` and the OMRF metadata table.
 
@@ -313,8 +315,7 @@ class MetadataExtractor:
             raise RuntimeError("fail to fetch host triple: timed out")
         if proc.returncode != 0:
             raise RuntimeError(
-                "fail to fetch host triple: "
-                + stderr.decode("utf-8", errors="ignore")
+                "fail to fetch host triple: " + stderr.decode("utf-8", errors="ignore")
             )
         m = _HOST_TRIPLE_PATTERN.search(stdout.decode("utf-8", errors="strict"))
         if m is None:
@@ -367,11 +368,8 @@ class MetadataExtractor:
         :returns: The matching package item.
         :raises RuntimeError: if no matching package is found.
         """
-        packages: list[Any] = dict_typed_get_required(cargo_metadata, "packages", list)
-        for i, package in enumerate(packages):
-            if not isinstance(package, dict):
-                raise TypeError(f"packages[{i}] must be a table")
-
+        packages = dict_typed_get_required(cargo_metadata, "packages", list)
+        for package in list_typed_iter(packages, dict):
             raw_manifest_path = dict_typed_get_required(package, "manifest_path", str)
             manifest_path = Path(raw_manifest_path)
             if manifest_path == cargo_toml_path:
@@ -393,11 +391,8 @@ class MetadataExtractor:
         # build the path to lib.rs for comparing
         librs = cargo_toml_path.parent / "src" / "lib.rs"
         # start checking
-        targets: list[Any] = dict_typed_get_required(cargo_package, "targets", list)
-        for i, target in enumerate(targets):
-            if not isinstance(target, dict):
-                raise TypeError(f"targets[{i}] must be a table")
-
+        targets = dict_typed_get_required(cargo_package, "targets", list)
+        for target in list_typed_iter(targets, dict):
             raw_src_path = dict_typed_get_required(target, "src_path", str)
             src_path = Path(raw_src_path)
             if src_path == librs:

packer/src/sarasacw_omrf_packer/utils.py

@@ -7,7 +7,7 @@ validation and template-directory resolution.
 from dataclasses import dataclass
 from pathlib import Path
 from re import Pattern, compile
-from typing import Any, overload
+from typing import Any, Iterator, overload
 from semver import Version
 
 VERSION: Version = Version(1, 0, 0)
@@ -106,6 +106,20 @@ def dict_chain_get(d: dict[str, Any], *args: str) -> dict[str, Any]:
     return d
 
 
+def list_typed_iter[T](lst: list[Any], ty: type[T]) -> Iterator[T]:
+    """Yield each element of ``lst`` after checking it is an instance of ``ty``.
+
+    :param lst: The list to iterate.
+    :param ty: Expected type of every element.
+    :returns: An iterator over the validated elements, typed ``T``.
+    :raises TypeError: if an element is not an instance of ``ty``.
+    """
+    for i, item in enumerate(lst):
+        if not isinstance(item, ty):
+            raise TypeError(f"item {i} of the given list is not a {ty.__name__}")
+        yield item
+
+
 _NAME_PATTERN: Pattern = compile(r"[a-zA-Z0-9_+-]+")