#!/usr/bin/env python3
"""Check mro_hierarchy's n/i declarations and guarded subclass loop timing."""
import re
from pathlib import Path

source = Path("cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nstatic int\nmro_hierarchy\(PyTypeObject \*type, PyObject \*temp\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "mro_hierarchy definition missing"
body = re.sub(r"/\*.*?\*/|//[^\n]*", "", match.group(1), flags=re.S)
assert re.match(
    r"\s*PyObject \*old_mro;\s*PyObject \*new_mro;\s*PyObject \*tuple;"
    r"\s*Py_ssize_t n;\s*Py_ssize_t i;\s*int res = mro_internal\(", body
), "mro_hierarchy: n and i must be uninitialized opening function declarations"
for name in ("n", "i"):
    assert len(re.findall(rf"\bPy_ssize_t\s+{name}\b", body)) == 1, (
        f"mro_hierarchy: declare {name} exactly once"
    )
    assert len(re.findall(rf"\b{name}\s*=(?!=)", body)) == 1, (
        f"mro_hierarchy: initialize {name} exactly once at its original point"
    )
expected = """
    if (type->tp_subclasses != NULL) {
        PyObject *subclasses = _PyType_GetSubclasses(type);
        if (subclasses == NULL) {
            return -1;
        }
        n = PyList_GET_SIZE(subclasses);
        for (i = 0; i < n; i++) {
            PyTypeObject *subclass = _PyType_CAST(PyList_GET_ITEM(subclasses, i));
            res = mro_hierarchy(subclass, temp);
            if (res < 0) {
                break;
            }
        }
        Py_DECREF(subclasses);
    }
    return res;
"""
tail = body[body.index("if (type->tp_subclasses != NULL)"):]
assert tail.split() == expected.split(), (
    "mro_hierarchy: preserve NULL guard, size read, loop, cleanup, and return"
)
print("mro_hierarchy n/i C89 declarations and guarded subclass loop timing: PASS")