與正則表達式有關：sre_yield

sre_yield 是用于生成正則表達式匹配結果的 Python 模塊，并盡可能的匹配到所有有效值。它采用了解析正則表達式的方式，所以你可以得到一個更加精確的結果，而不僅僅只是分散的字符串。

sre_yield 通常都無法處理反向引用、lookarounds 正則表達式，除此之外，還有在這幾種情況下也無法處理；

• The maximum value for repeats is system-dependant -- CPython'ssremodule there's a special value which is treated as infinite (either 2**16-1 or 2**32-1 depending on build).  In sre_yield, this is taken as a literal, rather than infinite, thus (on a 2**16-1 platform):

• Theremodule docs say "Regular expression pattern strings may not contain null bytes" yet this appears to work fine.

• Order does not depend on greediness.

• The regex is treated as fullmatch.

• sre_yieldis confused by even the simplest of anchors:

代碼示例：

>>> import random
>>> v = sre_yield.AllStrings('[abc]{1,4}')
>>> len(v)
120

# Now random.choice(v) has a 3/120 chance of choosing a single letter.
>>> random.seed(1)
>>> sum([1 if len(random.choice(v)) == 1 else 0 for _ in range(120)])
3

# xeger(v) has ~25% chance of choosing a single letter, because the length
and match are chosen independently.
> from rstr import xeger
> sum([1 if len(xeger('[abc]{1,4}')) == 1 else 0 for _ in range(120)])
26

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