Infer target version based on project metadata (#3219)

[etc/vim.git] / src / black / files.py

diff --git a/src/black/files.py b/src/black/files.py
index ea517f4ece9c2c2bbeaef35d2714ccdf50511992..8c0131126b7b29f418a17ca6651a7b2a0f79cbdb 100644 (file)
--- a/src/black/files.py
+++ b/src/black/files.py
@@ -18,6 +18,8 @@ from typing import (
 )
 
 from mypy_extensions import mypyc_attr
+from packaging.specifiers import InvalidSpecifier, Specifier, SpecifierSet
+from packaging.version import InvalidVersion, Version
 from pathspec import PathSpec
 from pathspec.patterns.gitwildmatch import GitWildMatchPatternError
 
@@ -32,6 +34,7 @@ else:
     import tomli as tomllib
 
 from black.handle_ipynb_magics import jupyter_dependencies_are_installed
+from black.mode import TargetVersion
 from black.output import err
 from black.report import Report
 
@@ -108,14 +111,103 @@ def find_pyproject_toml(path_search_start: Tuple[str, ...]) -> Optional[str]:
 
 @mypyc_attr(patchable=True)
 def parse_pyproject_toml(path_config: str) -> Dict[str, Any]:
-    """Parse a pyproject toml file, pulling out relevant parts for Black
+    """Parse a pyproject toml file, pulling out relevant parts for Black.
 
-    If parsing fails, will raise a tomllib.TOMLDecodeError
+    If parsing fails, will raise a tomllib.TOMLDecodeError.
     """
     with open(path_config, "rb") as f:
         pyproject_toml = tomllib.load(f)
-    config = pyproject_toml.get("tool", {}).get("black", {})
-    return {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+    config: Dict[str, Any] = pyproject_toml.get("tool", {}).get("black", {})
+    config = {k.replace("--", "").replace("-", "_"): v for k, v in config.items()}
+
+    if "target_version" not in config:
+        inferred_target_version = infer_target_version(pyproject_toml)
+        if inferred_target_version is not None:
+            config["target_version"] = [v.name.lower() for v in inferred_target_version]
+
+    return config
+
+
+def infer_target_version(
+    pyproject_toml: Dict[str, Any]
+) -> Optional[List[TargetVersion]]:
+    """Infer Black's target version from the project metadata in pyproject.toml.
+
+    Supports the PyPA standard format (PEP 621):
+    https://packaging.python.org/en/latest/specifications/declaring-project-metadata/#requires-python
+
+    If the target version cannot be inferred, returns None.
+    """
+    project_metadata = pyproject_toml.get("project", {})
+    requires_python = project_metadata.get("requires-python", None)
+    if requires_python is not None:
+        try:
+            return parse_req_python_version(requires_python)
+        except InvalidVersion:
+            pass
+        try:
+            return parse_req_python_specifier(requires_python)
+        except (InvalidSpecifier, InvalidVersion):
+            pass
+
+    return None
+
+
+def parse_req_python_version(requires_python: str) -> Optional[List[TargetVersion]]:
+    """Parse a version string (i.e. ``"3.7"``) to a list of TargetVersion.
+
+    If parsing fails, will raise a packaging.version.InvalidVersion error.
+    If the parsed version cannot be mapped to a valid TargetVersion, returns None.
+    """
+    version = Version(requires_python)
+    if version.release[0] != 3:
+        return None
+    try:
+        return [TargetVersion(version.release[1])]
+    except (IndexError, ValueError):
+        return None
+
+
+def parse_req_python_specifier(requires_python: str) -> Optional[List[TargetVersion]]:
+    """Parse a specifier string (i.e. ``">=3.7,<3.10"``) to a list of TargetVersion.
+
+    If parsing fails, will raise a packaging.specifiers.InvalidSpecifier error.
+    If the parsed specifier cannot be mapped to a valid TargetVersion, returns None.
+    """
+    specifier_set = strip_specifier_set(SpecifierSet(requires_python))
+    if not specifier_set:
+        return None
+
+    target_version_map = {f"3.{v.value}": v for v in TargetVersion}
+    compatible_versions: List[str] = list(specifier_set.filter(target_version_map))
+    if compatible_versions:
+        return [target_version_map[v] for v in compatible_versions]
+    return None
+
+
+def strip_specifier_set(specifier_set: SpecifierSet) -> SpecifierSet:
+    """Strip minor versions for some specifiers in the specifier set.
+
+    For background on version specifiers, see PEP 440:
+    https://peps.python.org/pep-0440/#version-specifiers
+    """
+    specifiers = []
+    for s in specifier_set:
+        if "*" in str(s):
+            specifiers.append(s)
+        elif s.operator in ["~=", "==", ">=", "==="]:
+            version = Version(s.version)
+            stripped = Specifier(f"{s.operator}{version.major}.{version.minor}")
+            specifiers.append(stripped)
+        elif s.operator == ">":
+            version = Version(s.version)
+            if len(version.release) > 2:
+                s = Specifier(f">={version.major}.{version.minor}")
+            specifiers.append(s)
+        else:
+            specifiers.append(s)
+
+    return SpecifierSet(",".join(str(s) for s in specifiers))
 
 
 @lru_cache()