feat(submission): add ruff/clang-format code formatting helper

submission/utils.py

@@ -0,0 +1,61 @@
+import subprocess
+
+CLANG_FORMAT_STYLE = "{BasedOnStyle: LLVM, IndentWidth: 4, BreakBeforeBraces: Attach}"
+
+
+class FormatSyntaxError(Exception):
+    """格式化工具因代码本身存在语法错误而失败（目前只有 ruff format 会触发）"""
+
+
+class FormatToolError(Exception):
+    """格式化工具执行本身失败：超时、二进制缺失、非预期的非零退出码"""
+
+
+def format_code(code, language):
+    """
+    :param code: 用户代码
+    :param language: "python" | "c" | "cpp"
+    :return: 格式化后的代码字符串
+    :raises FormatSyntaxError: 代码语法错误导致格式化失败（仅 python）
+    :raises FormatToolError: 格式化工具本身执行失败
+    """
+    if language == "python":
+        return _format_with_ruff(code)
+    return _format_with_clang(code, language)
+
+
+def _format_with_ruff(code):
+    try:
+        result = subprocess.run(
+            ["ruff", "format", "--stdin-filename", "code.py", "-"],
+            input=code,
+            capture_output=True,
+            text=True,
+            timeout=5,
+        )
+    except (subprocess.TimeoutExpired, OSError) as e:
+        raise FormatToolError(str(e))
+    if result.returncode != 0:
+        raise FormatSyntaxError(result.stderr)
+    return result.stdout
+
+
+def _format_with_clang(code, language):
+    filename = "code.c" if language == "c" else "code.cpp"
+    try:
+        result = subprocess.run(
+            [
+                "clang-format",
+                f"-assume-filename={filename}",
+                f"-style={CLANG_FORMAT_STYLE}",
+            ],
+            input=code,
+            capture_output=True,
+            text=True,
+            timeout=5,
+        )
+    except (subprocess.TimeoutExpired, OSError) as e:
+        raise FormatToolError(str(e))
+    if result.returncode != 0:
+        raise FormatToolError(result.stderr)
+    return result.stdout