regex: Improper handling of Unicode Properties in character set 3.16a2

未關閉
  • 哪裡不對？
#161,814 1 則留言 0 個 reaction 已指派 0 人 在 GitHub 檢視

維護者通常 1 天內回覆

還沒有人認領這個 Issue。

評估

難度
4/5
預估耗時
3-5 天
新手友好度
56/100
Issue 類型
缺陷
描述清晰度
描述清楚
活躍度
活躍
技術堆疊
python
領域
backend

研究方向

Start in Lib/re/_compiler.py at _optimize_charset() and inspect how IN_UNI_IGNORE handles category items when a set contains cased literals or ranges. Use the examples in the issue as regression cases, then run the relevant regular expression tests. Done means the category properties and their negations preserve the reported IGNORECASE behavior while existing set matching continues to work.

由索引模型根據 Issue 內容生成。

描述

type-bug
Bug report

I found this when evaluating the Unicode Properties in the recent alpha release for Re. I realize this work is a WIP, but figured I'd share in case this issue wasn't already known.

With re.IGNORECASE, a character set that contains a case-sensitive property escape (\p{Lu}, \p{Lt}, \p{Uppercase}, \p{Lowercase}, or their \P{...} forms) together with a cased literal or range gives the wrong results. Adding a member to a set can remove matches:

>>> import re
>>> re.fullmatch(r'[\p{Lu}]', 'A', re.IGNORECASE)
<re.Match object; span=(0, 1), match='A'>
>>> re.fullmatch(r'[\p{Lu}x]', 'A', re.IGNORECASE)    # expected a match
>>> re.fullmatch(r'[\p{Lu}x]', 'A')
<re.Match object; span=(0, 1), match='A'>

Below is info gathered by AI, hopefully it is helpful, but the important part is the behavior that doesn't match expectations.

More examples, all with re.IGNORECASE:

Pattern String Result Expected
[\p{Lu}x] 'A' no match match
[\p{Lu}a-c] 'Z' no match match
[^\p{Lu}x] 'A' match no match
[\P{Lu}x] 'A' match no match
[\p{Lt}x] 'Dž' no match match
[\p{Uppercase}x] 'A' no match match
[\p{Lowercase}x] 'A' match no match

"Expected" is how these properties already behave with IGNORECASE outside a set, or as the only member of a
set: \p{Lu} and [\p{Lu}] match 'A' but not 'a'.

The same happens with an inline (?i:...), and with re.ASCII | re.IGNORECASE for ASCII characters. Sets without
a cased literal or range, such as [\p{Lu}1] and [\p{Lu}\d], are not affected.

Cause: in Lib/re/_compiler.py, when a set under IGNORECASE contains a cased literal or range (hascased
from _optimize_charset()), the whole set is compiled as IN_UNI_IGNORE (IN_IGNORE with ASCII). Those
opcodes lowercase the character before testing it against every item in the set, including CATEGORY items. The
literals in the set are already lowercased, so they still match correctly, but the categories are now tested
against the lowercased character: 'A' becomes 'a' before the Lu test.

For the categories that existed before 3.16 (\d, \s, \w), lowercasing a character never changes whether it is
in the category, so this was harmless. It does for the new CATEGORY_LU, CATEGORY_TITLE, CATEGORY_UPPER and
CATEGORY_LOWER, and their negations. Checking every code point that changes when lowercased, these are the only
supported properties whose membership changes (Lu, Lt, Uppercase, Lowercase).

A fix could test CATEGORY items against the original character rather than the lowercased one in the
ignore-case set opcodes, or have the compiler keep those categories out of the ignore-case check.

CPython versions tested on:

3.16

Operating systems tested on:

macOS

主要語言
Python
星號
78.2k
分支
36.6k
平均合併
19 小時 57 分鐘
30 天內合併 PR
630

環境準備

在 Codespaces 中開啟

在瀏覽器裡用你自己的 GitHub 帳號啟動這個專案的開發容器。

從這裡開始

  1. 先讀完整個 Issue，再讀專案的貢獻指南。
  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
  3. Fork 儲存庫，在一個分支上完成修改。
  4. 送出 Pull Request，並在描述裡引用這個 Issue 編號。

python/cpython 的其他 Issue

查看 python/cpython 的全部 Issue

相似的 Issue

更多 Python Issue

把新 issue 寄到你的電子郵件信箱

精選適合新手參與的 GitHub issue 摘要。