如何实现Python下符合shift-trimmed规则的排序以通过测试？

需要在Python中复现AWS PostgreSQL的排序行为，该排序需遵循shift-trimmed（移位修剪，忽略空格、标点等非核心字符的主权重）和backwards accent（kb-true/[backwards 2]）（重音反向排序）规则。尝试使用ICU的und-u-ka-shifted-kb-true Locale创建Collator后未通过测试，以下是可行的调整方案：

测试用例 #

names = [
    "cote",
    "coté",
    "côte",
    "côté",
    "ReasonE",
    "Reason1",
    "ReasonĔ",
    "Reason Super",
    "ReasonÅ",
    "ReasonA",
    "Reasona",
    "Reasone",
    "death",
    "deluge",
    "de luge",
    "disílva John",
    "diSilva John",
    "di Silva Fred",
    "diSilva Fred",
    "disílva Fred",
    "di Silva John",
]
expected = [
    "cote",
    "côte",
    "coté",
    "côté",
    "death",
    "deluge",
    "de luge",
    "di Silva Fred",
    "diSilva Fred",
    "disílva Fred",
    "di Silva John",
    "diSilva John",
    "disílva John",
    "Reason1",
    "Reasona",
    "ReasonA",
    "ReasonÅ",
    "Reasone",
    "ReasonE",
    "ReasonĔ",
    "Reason Super",
]
assert sorted(names, key=some_sort_key) == expected

最初尝试的代码 #

import icu

loc = icu.Locale("und-u-ka-shifted-kb-true")
c = icu.Collator.createInstance(loc)
assert sorted(names, key=c.getSortKey) == expected

调整后的可行方案 #

问题出在默认Collator的大小写排序规则和强度设置上，需补充以下配置：

import icu

# 初始化包含shift-trimmed和backwards accent规则的Locale
loc = icu.Locale("und-u-ka-shifted-kb-true")
collator = icu.Collator.createInstance(loc)

# 设置小写优先，匹配测试用例中小写字母在大写前的排序逻辑
collator.setCaseFirst(icu.Collator.CaseFirst.LOWER)

# 显式设置排序强度为TERTIARY，确保区分大小写、重音等细节
collator.setStrength(icu.Collator.TERTIARY)

# 执行排序并验证
sorted_result = sorted(names, key=collator.getSortKey)
assert sorted_result == expected

关键调整说明 #

• 小写优先设置：测试用例中Reasona排在ReasonA之前，需通过setCaseFirst(icu.Collator.CaseFirst.LOWER)覆盖ICU默认的大小写排序逻辑。
• 排序强度：TERTIARY强度会区分基础字符、大小写、重音等所有细节，完全匹配PostgreSQL在该规则下的排序精度。
• Locale参数验证：und-u-ka-shifted对应shift-trimmed规则（忽略空格、标点的主权重），kb-true对应backwards accent规则（重音排序方向反转），需确保使用的ICU版本支持这些扩展参数（建议使用ICU 60+版本）。

内容的提问来源于stack exchange，提问作者Marcel Wilson