python - python re (regex) 是否有 unicode 转义序列的替代方案？

Question

Python 将\uxxxx 视为字符串文字中的 unicode 字符转义(例如 u"\u2014"被解释为 Unicode 字符 U+2014)。但我刚刚发现(Python 2.7)标准正则表达式模块不会将\uxxxx 视为 unicode 字符。示例:

codepoint = 2014 # Say I got this dynamically from somewhere

test = u"This string ends with \u2014"
pattern = r"\u%s$" % codepoint
assert(pattern[-5:] == "2014$") # Ends with an escape sequence for U+2014
assert(re.search(pattern, test) != None) # Failure -- No match (bad)
assert(re.search(pattern, "u2014")!= None) # Success -- This matches (bad)

显然，如果您能够将正则表达式模式指定为字符串文字，那么您可以获得与正则表达式引擎本身理解\uxxxx 转义相同的效果:

test = u"This string ends with \u2014"
pattern = u"\u2014$"
assert(pattern[:-1] == u"\u2014") # Ends with actual unicode char U+2014
assert(re.search(pattern, test) != None)

但是如果您需要动态构建模式怎么办？

Answer 1

使用unichr() function从代码点创建 unicode 字符:

pattern = u"%s$" % unichr(codepoint)