#!/usr/bin/env python3
"""Check structseq_repr's loop declaration and unchanged iteration order."""
import re
import sys
from pathlib import Path

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/structseq.c")
match = re.search(
    r"static PyObject \*\nstructseq_repr\(PyStructSequence \*obj\)\n\{(.*?)\n\}",
    source.read_text(),
    re.S,
)
assert match, "structseq_repr definition not found"
body = match.group(1)
assert not re.search(r"for\s*\(\s*Py_ssize_t\b", body), (
    "structseq_repr: VC6 rejects the C99 loop initializer declaration; "
    "declare i in the function declaration block"
)
assert re.match(
    r"\s*PyTypeObject \*typ = Py_TYPE\(obj\);"
    r"\s*_PyUnicodeWriter writer;\s*Py_ssize_t i;",
    body,
), "i must be declared without initialization in the function declaration block"
assert len(re.findall(r"\bPy_ssize_t\s+i\s*;", body)) == 1, (
    "declare i exactly once"
)
assert re.search(
    r"if \(_PyUnicodeWriter_WriteChar\(&writer, '\('\) < 0\) "
    r"\{\s*goto error;\s*\}\s*"
    r"for \(i\s*=\s*0; i < VISIBLE_SIZE\(obj\); i\+\+\) \{",
    body,
), "preserve zero initialization after '(' output, per-iteration size lookup, and increment"
assert len(re.findall(r"\bfor\s*\(", body)) == 1, "preserve the single item loop"
assert "typ->tp_members[i].name" in body, "preserve member-name indexing"
assert "PyStructSequence_GET_ITEM(obj, i)" in body, "preserve item indexing"
print("structseq_repr C89 loop declaration and iteration order: PASS")