FA-3101 / Regular expressions / Open access

A capturing subexpression changes the token result · case 01

A capturing subexpression changes the token result.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The implementation applies an operation whose text or grammar semantics violate this contract: Return complete signed ASCII integers embedded in text.

VERIFIED REPAIR

Implement the complete stated contract, including the boundary fixtures: Return complete signed ASCII integers embedded in text.

Unsuccessful approach: The attempted repair handles the primary example but still violates a separate boundary of the same contract.

Case contract

Return complete signed ASCII integers embedded in text.

Why this case matters

A local executable model for consumers of structured text; oracle values are authored literals, not outputs copied from the repaired implementation.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'([+-]?)[0-9]+',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('a-12 b+3'), ['-12', '+3'])
check('boundary 2', solve('42'), ['42'])
check('boundary 3', solve('none'), [])
check('boundary 4', solve('--1'), ['-1'])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
boundary 1	`['-', '+']`	`['-12', '+3']`	Failed
boundary 2	`['']`	`['42']`	Failed
boundary 3	`[]`	`[]`	Passed
boundary 4	`['-']`	`['-1']`	Failed

SHA-256 / f5b15fbf78cfc90a13550a0ee629455562241ed4619ffe2fef00a3256562edb8

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'[0-9]+',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('a-12 b+3'), ['-12', '+3'])
check('boundary 2', solve('42'), ['42'])
check('boundary 3', solve('none'), [])
check('boundary 4', solve('--1'), ['-1'])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
boundary 1	`['12', '3']`	`['-12', '+3']`	Failed
boundary 2	`['42']`	`['42']`	Passed
boundary 3	`[]`	`[]`	Passed
boundary 4	`['1']`	`['-1']`	Failed

SHA-256 / 0ee61ac37760532ac5005cc19cb9f49688abcb43122fcca30863605c7e0f6231

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re, unicodedata, json, csv, io, html, base64, binascii, codecs, struct
from urllib.parse import quote, unquote, unquote_to_bytes, urlencode, parse_qsl, urlsplit, urlunsplit
from email.header import decode_header, make_header
from email.utils import getaddresses
from xml.etree import ElementTree as ET
import shlex, string, textwrap

N = 1
observations = []
def solve(x):
    try:
        return re.findall(r'[+-]?[0-9]+',x)
    except Exception as exc:
        return {"error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('boundary 1', solve('a-12 b+3'), ['-12', '+3'])
check('boundary 2', solve('42'), ['42'])
check('boundary 3', solve('none'), [])
check('boundary 4', solve('--1'), ['-1'])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
boundary 1	`['-12', '+3']`	`['-12', '+3']`	Passed
boundary 2	`['42']`	`['42']`	Passed
boundary 3	`[]`	`[]`	Passed
boundary 4	`['-1']`	`['-1']`	Passed

SHA-256 / 8dc057b78d6d49f93a436ec5e3401fb5314b07b8674f0f769a1a72e08bc953b9

Verification & scope

This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:37:21.398575+00:00.

Case digest / eb4cfd03384eaaa1e7983dfdd7673b18d0dcc56e837e67eed79f9ee1c1385703