Files
openswarm/linter/checks/cycles.py
T

239 lines
8.4 KiB
Python

"""Import-cycle detection: flags RUNTIME circular imports (a strongly-connected
component of more than one file).
Only module-load-time edges count, because those are the ones that can blow up
at import with a "cannot access before initialization" TDZ error:
- Python: top-level (module-scope) imports.
- JS/TS: static `import ... from`, `export ... from`, side-effect `import`,
and `require(...)`.
Deliberately ignored, since neither runs during module init so neither can
deadlock:
- `import type` / `export type` (the bundler erases them).
- dynamic `import(...)` (deferred into its own chunk).
That is exactly why the idiomatic Redux store<->hooks cycle, whose closing edge
is an `import type`, is correctly NOT flagged.
Resolution is intentionally lossy in the safe direction: an import that does not
resolve to a real file in the repo is dropped, so a missed edge can only hide a
cycle (false negative), never invent one (false positive that would redden CI).
"""
from __future__ import annotations
import ast
import os
import re
from pathlib import Path
from . import _matches_any, is_excluded, is_lintignored
_JS_EXTS = (".ts", ".tsx", ".js", ".jsx")
# `import|export [type] <stuff> from '<spec>'`. The optional `type` right after
# the keyword marks a type-only edge we skip; a `type` buried inside { } (inline)
# is treated as runtime, which is the conservative choice.
_FROM_RE = re.compile(
r"\b(?P<kw>import|export)\b(?P<typ>\s+type\b)?"
r"(?:[^;{}]|\{[^{}]*\})*?\bfrom\s*['\"](?P<spec>[^'\"]+)['\"]",
re.S,
)
_SIDE_EFFECT_RE = re.compile(r"^\s*import\s+['\"](?P<spec>[^'\"]+)['\"]", re.M)
_REQUIRE_RE = re.compile(r"\brequire\s*\(\s*['\"](?P<spec>[^'\"]+)['\"]")
_BLOCK_COMMENT_RE = re.compile(r"/\*.*?\*/", re.S)
def _strip_js_comments(src: str) -> str:
"""Drop /* */ blocks and full-line // comments so a commented-out import
can't fabricate an edge. Only ever removes text, never adds, so it can't
create a false cycle."""
src = _BLOCK_COMMENT_RE.sub("", src)
return "\n".join(
"" if line.lstrip().startswith("//") else line
for line in src.splitlines()
)
def _module_name(fp: Path, root: Path) -> str:
parts = list(fp.relative_to(root).with_suffix("").parts)
if parts and parts[-1] == "__init__":
parts = parts[:-1]
return ".".join(parts)
def _py_edges(fp: Path, src: str, root: Path, mod_to_file: dict[str, Path]) -> set[Path]:
try:
tree = ast.parse(src, filename=str(fp))
except SyntaxError:
return set()
out: set[Path] = set()
def add(dotted: str) -> None:
parts = dotted.split(".")
while parts: # longest known prefix wins
cand = ".".join(parts)
if cand in mod_to_file and mod_to_file[cand] != fp:
out.add(mod_to_file[cand])
return
parts = parts[:-1]
me = _module_name(fp, root)
is_pkg = fp.name == "__init__.py"
for node in tree.body: # module scope only -> these are the load-time imports
if isinstance(node, ast.Import):
for alias in node.names:
add(alias.name)
elif isinstance(node, ast.ImportFrom):
if node.level:
pkg_parts = me.split(".") if is_pkg else me.split(".")[:-1]
up = node.level - 1
base_parts = pkg_parts[: len(pkg_parts) - up] if up <= len(pkg_parts) else []
full = ".".join([*base_parts, node.module] if node.module else base_parts)
else:
full = node.module or ""
if not full:
continue
add(full)
for alias in node.names:
add(f"{full}.{alias.name}")
return out
def _resolve_ts(spec: str, fp: Path, root: Path, aliases: dict[str, str], fileset: set[Path]) -> Path | None:
base: Path | None = None
for prefix, target in aliases.items():
if spec.startswith(prefix):
base = root / (target + spec[len(prefix):])
break
if base is None:
if spec.startswith("."):
base = fp.parent / spec
else:
return None # bare package import, not our code
base = Path(os.path.normpath(str(base)))
candidates: list[Path] = []
if base.suffix in _JS_EXTS:
candidates.append(base)
candidates += [Path(f"{base}{ext}") for ext in _JS_EXTS]
candidates += [base / f"index{ext}" for ext in _JS_EXTS]
for cand in candidates:
if cand in fileset and cand != fp:
return cand
return None
def _ts_edges(fp: Path, src: str, root: Path, aliases: dict[str, str], fileset: set[Path]) -> set[Path]:
src = _strip_js_comments(src)
specs: list[str] = []
for m in _FROM_RE.finditer(src):
if m.group("typ"): # `import type` / `export type` -> erased, no runtime edge
continue
specs.append(m.group("spec"))
specs += [m.group("spec") for m in _SIDE_EFFECT_RE.finditer(src)]
specs += [m.group("spec") for m in _REQUIRE_RE.finditer(src)]
out: set[Path] = set()
for spec in specs:
tgt = _resolve_ts(spec, fp, root, aliases, fileset)
if tgt:
out.add(tgt)
return out
def _sccs(graph: dict[Path, set[Path]]) -> list[list[Path]]:
"""Tarjan's SCC, iterative so a deep import chain can't overflow the stack."""
index: dict[Path, int] = {}
low: dict[Path, int] = {}
on_stack: set[Path] = set()
stack: list[Path] = []
result: list[list[Path]] = []
counter = 0
for root_node in list(graph):
if root_node in index:
continue
work: list[tuple[Path, object]] = [(root_node, iter(graph.get(root_node, ())))]
index[root_node] = low[root_node] = counter
counter += 1
stack.append(root_node)
on_stack.add(root_node)
while work:
v, it = work[-1]
descended = False
for w in it: # type: ignore[assignment]
if w not in index:
index[w] = low[w] = counter
counter += 1
stack.append(w)
on_stack.add(w)
work.append((w, iter(graph.get(w, ()))))
descended = True
break
if w in on_stack:
low[v] = min(low[v], index[w])
if descended:
continue
if low[v] == index[v]:
comp: list[Path] = []
while True:
w = stack.pop()
on_stack.discard(w)
comp.append(w)
if w == v:
break
if len(comp) > 1:
result.append(comp)
work.pop()
if work:
low[work[-1][0]] = min(low[work[-1][0]], low[v])
return result
def run_cycle_check(
root: Path,
excludes: list[str],
aliases: dict[str, str],
exceptions: dict[str, list[str]],
ignores: dict[Path, set[str]],
) -> list[str]:
files: list[Path] = []
for dirpath, dirnames, filenames in os.walk(root):
dp = Path(dirpath)
if is_excluded(dp, root, excludes):
dirnames.clear()
continue
for fname in filenames:
fp = dp / fname
if (fp.suffix == ".py" or fp.suffix in _JS_EXTS) and not is_excluded(fp, root, excludes):
files.append(fp)
fileset = set(files)
mod_to_file = {_module_name(p, root): p for p in files if p.suffix == ".py"}
graph: dict[Path, set[Path]] = {}
for fp in files:
try:
src = fp.read_text(errors="ignore")
except OSError:
continue
if fp.suffix == ".py":
edges = _py_edges(fp, src, root, mod_to_file)
else:
edges = _ts_edges(fp, src, root, aliases, fileset)
if edges:
graph[fp] = edges
patterns = exceptions.get("import-cycles", [])
errors: list[str] = []
for comp in _sccs(graph):
members = sorted(str(p.relative_to(root)) for p in comp)
if any(_matches_any(m, patterns) for m in members):
continue
if any(is_lintignored(p, root, "import-cycles", ignores) for p in comp):
continue
anchor = members[0]
errors.append(
f"{anchor}:1:1: error: "
f"[import-cycles] Circular import ({len(members)} files): {', '.join(members)}"
)
return errors