[CI] enforce import regex instead of re

.pre-commit-config.yaml

@@ -128,6 +128,12 @@ repos:
     name: Update Dockerfile dependency graph
     entry: tools/update-dockerfile-graph.sh
     language: script
+  - id: enforce-import-regex-instead-of-re
+    name: Enforce import regex as re
+    entry: python tools/enforce_regex_import.py
+    language: python
+    types: [python]
+    pass_filenames: false
   # forbid directly import triton
   - id: forbid-direct-triton-import
     name: "Forbid direct 'import triton'"

tools/enforce_regex_import.py

@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import re
+import subprocess
+from pathlib import Path
+
+FORBIDDEN_PATTERNS = re.compile(
+    r'^\s*(?:import\s+re(?:$|\s|,)|from\s+re\s+import)')
+ALLOWED_PATTERNS = [
+    re.compile(r'^\s*import\s+regex\s+as\s+re\s*$'),
+    re.compile(r'^\s*import\s+regex\s*$'),
+]
+
+
+def get_staged_python_files() -> list[str]:
+    try:
+        result = subprocess.run(
+            ['git', 'diff', '--cached', '--name-only', '--diff-filter=AM'],
+            capture_output=True,
+            text=True,
+            check=True)
+        files = result.stdout.strip().split(
+            '\n') if result.stdout.strip() else []
+        return [f for f in files if f.endswith('.py')]
+    except subprocess.CalledProcessError:
+        return []
+
+
+def is_forbidden_import(line: str) -> bool:
+    line = line.strip()
+    return FORBIDDEN_PATTERNS.match(line) and not any(
+        pattern.match(line) for pattern in ALLOWED_PATTERNS)
+
+
+def check_file(filepath: str) -> list[tuple[int, str]]:
+    violations = []
+    try:
+        with open(filepath, encoding='utf-8') as f:
+            for line_num, line in enumerate(f, 1):
+                if is_forbidden_import(line):
+                    violations.append((line_num, line.strip()))
+    except (OSError, UnicodeDecodeError):
+        pass
+    return violations
+
+
+def main() -> int:
+    files = get_staged_python_files()
+    if not files:
+        return 0
+
+    total_violations = 0
+
+    for filepath in files:
+        if not Path(filepath).exists():
+            continue
+
+        violations = check_file(filepath)
+        if violations:
+            print(f"\n❌ {filepath}:")
+            for line_num, line in violations:
+                print(f"  Line {line_num}: {line}")
+                total_violations += 1
+
+    if total_violations > 0:
+        print(f"\n💡 Found {total_violations} violation(s).")
+        print("❌ Please replace 'import re' with 'import regex as re'")
+        print(
+            "   Also replace 'from re import ...' with 'from regex import ...'"
+        )  # noqa: E501
+        print("✅ Allowed imports:")
+        print("   - import regex as re")
+        print("   - import regex")  # noqa: E501
+        return 1
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())