我有一个工作正则表达式来解析PinYin,它匹配每个有效的PinYin并且与无效的PinYin不匹配.我想知道如何优化它.
^(?P<initial>ch|zh|sh|r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z|) (?P<final> (?:(?<=ch)uang|(?<=ch)ang|(?<=ch)eng|(?<=ch)ong|(?<=ch)uai|(?<=ch)uan|(?<=ch)ai|(?<=ch)an|(?<=ch)ao|(?<=ch)en|(?<=ch)ou|(?<=ch)ua|(?<=ch)ui|(?<=ch)un|(?<=ch)uo|(?<=ch)a|(?<=ch)e|(?<=ch)i|(?<=ch)u) |(?:(?<=zh)uang|(?<=zh)ang|(?<=zh)eng|(?<=zh)ong|(?<=zh)uai|(?<=zh)uan|(?<=zh)ai|(?<=zh)an|(?<=zh)ao|(?<=zh)ei|(?<=zh)en|(?<=zh)ou|(?<=zh)ua|(?<=zh)ui|(?<=zh)un|(?<=zh)uo|(?<=zh)a|(?<=zh)e|(?<=zh)i|(?<=zh)u) |(?:(?<=sh)uang|(?<=sh)ang|(?<=sh)eng|(?<=sh)uai|(?<=sh)uan|(?<=sh)ai|(?<=sh)an|(?<=sh)ao|(?<=sh)ei|(?<=sh)en|(?<=sh)ou|(?<=sh)ua|(?<=sh)ui|(?<=sh)un|(?<=sh)uo|(?<=sh)a|(?<=sh)e|(?<=sh)i|(?<=sh)u) |(?:(?<=c)ang|(?<=c)eng|(?<=c)ong|(?<=c)uan|(?<=c)ai|(?<=c)an|(?<=c)ao|(?<=c)en|(?<=c)ou|(?<=c)ui|(?<=c)un|(?<=c)uo|(?<=c)a|(?<=c)e|(?<=c)i|(?<=c)u) |(?:(?<=b)ang|(?<=b)eng|(?<=b)ian|(?<=b)iao|(?<=b)ing|(?<=b)ai|(?<=b)an|(?<=b)ao|(?<=b)ei|(?<=b)en|(?<=b)ie|(?<=b)in|(?<=b)a|(?<=b)i|(?<=b)o|(?<=b)u) |(?:(?<=d)ang|(?<=d)eng|(?<=d)ian|(?<=d)iao|(?<=d)ing|(?<=d)ong|(?<=d)uan|(?<=d)ai|(?<=d)an|(?<=d)ao|(?<=d)ei|(?<=d)en|(?<=d)ia|(?<=d)ie|(?<=d)iu|(?<=d)ou|(?<=d)ui|(?<=d)un|(?<=d)uo|(?<=d)a|(?<=d)e|(?<=d)i|(?<=d)u) |(?:(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)a|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ai |(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)an|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ang |(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ao|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)e
以上是为了便于阅读的缩写版本.整个表达可以在这篇文章的最后找到.
我特别想知道是否将两个或多个前缀传递给结束匹配器可以提高性能：
(<=ch|zh|sh)uang|(<=ch|zh|sh)ang...
感谢您的时间和建议.
整个正则表达式：
^(?P<initial>ch|zh|sh|r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z|)(?P<final>(?:(?<=ch)uang|(?<=ch)ang|(?<=ch)eng|(?<=ch)ong|(?<=ch)uai|(?<=ch)uan|(?<=ch)ai|(?<=ch)an|(?<=ch)ao|(?<=ch)en|(?<=ch)ou|(?<=ch)ua|(?<=ch)ui|(?<=ch)un|(?<=ch)uo|(?<=ch)a|(?<=ch)e|(?<=ch)i|(?<=ch)u)|(?:(?<=zh)uang|(?<=zh)ang|(?<=zh)eng|(?<=zh)ong|(?<=zh)uai|(?<=zh)uan|(?<=zh)ai|(?<=zh)an|(?<=zh)ao|(?<=zh)ei|(?<=zh)en|(?<=zh)ou|(?<=zh)ua|(?<=zh)ui|(?<=zh)un|(?<=zh)uo|(?<=zh)a|(?<=zh)e|(?<=zh)i|(?<=zh)u)|(?:(?<=sh)uang|(?<=sh)ang|(?<=sh)eng|(?<=sh)uai|(?<=sh)uan|(?<=sh)ai|(?<=sh)an|(?<=sh)ao|(?<=sh)ei|(?<=sh)en|(?<=sh)ou|(?<=sh)ua|(?<=sh)ui|(?<=sh)un|(?<=sh)uo|(?<=sh)a|(?<=sh)e|(?<=sh)i|(?<=sh)u)|(?:(?<=c)ang|(?<=c)eng|(?<=c)ong|(?<=c)uan|(?<=c)ai|(?<=c)an|(?<=c)ao|(?<=c)en|(?<=c)ou|(?<=c)ui|(?<=c)un|(?<=c)uo|(?<=c)a|(?<=c)e|(?<=c)i|(?<=c)u)|(?:(?<=b)ang|(?<=b)eng|(?<=b)ian|(?<=b)iao|(?<=b)ing|(?<=b)ai|(?<=b)an|(?<=b)ao|(?<=b)ei|(?<=b)en|(?<=b)ie|(?<=b)in|(?<=b)a|(?<=b)i|(?<=b)o|(?<=b)u)|(?:(?<=d)ang|(?<=d)eng|(?<=d)ian|(?<=d)iao|(?<=d)ing|(?<=d)ong|(?<=d)uan|(?<=d)ai|(?<=d)an|(?<=d)ao|(?<=d)ei|(?<=d)en|(?<=d)ia|(?<=d)ie|(?<=d)iu|(?<=d)ou|(?<=d)ui|(?<=d)un|(?<=d)uo|(?<=d)a|(?<=d)e|(?<=d)i|(?<=d)u)|(?:(?<=g)uang|(?<=g)ang|(?<=g)eng|(?<=g)ong|(?<=g)uai|(?<=g)uan|(?<=g)ai|(?<=g)an|(?<=g)ao|(?<=g)ei|(?<=g)en|(?<=g)ou|(?<=g)ua|(?<=g)ui|(?<=g)un|(?<=g)uo|(?<=g)a|(?<=g)e|(?<=g)u)|(?:(?<=f)ang|(?<=f)eng|(?<=f)iao|(?<=f)an|(?<=f)ei|(?<=f)en|(?<=f)ou|(?<=f)a|(?<=f)o|(?<=f)u)|(?:(?<!sh|ch|zh)(?<=h)uang|(?<!sh|ch|zh)(?<=h)ang|(?<!sh|ch|zh)(?<=h)eng|(?<!sh|ch|zh)(?<=h)ong|(?<!sh|ch|zh)(?<=h)uai|(?<!sh|ch|zh)(?<=h)uan|(?<!sh|ch|zh)(?<=h)ai|(?<!sh|ch|zh)(?<=h)an|(?<!sh|ch|zh)(?<=h)ao|(?<!sh|ch|zh)(?<=h)ei|(?<!sh|ch|zh)(?<=h)en|(?<!sh|ch|zh)(?<=h)ou|(?<!sh|ch|zh)(?<=h)ua|(?<!sh|ch|zh)(?<=h)ui|(?<!sh|ch|zh)(?<=h)un|(?<!sh|ch|zh)(?<=h)uo|(?<!sh|ch|zh)(?<=h)a|(?<!sh|ch|zh)(?<=h)e|(?<!sh|ch|zh)(?<=h)u)|(?:(?<=k)uang|(?<=k)ang|(?<=k)eng|(?<=k)ong|(?<=k)uai|(?<=k)uan|(?<=k)ai|(?<=k)an|(?<=k)ao|(?<=k)en|(?<=k)ou|(?<=k)ua|(?<=k)ui|(?<=k)un|(?<=k)uo|(?<=k)a|(?<=k)e|(?<=k)u)|(?:(?<=j)iang|(?<=j)iong|(?<=j)ian|(?<=j)iao|(?<=j)ing|(?<=j)üan|(?<=j)ia|(?<=j)ie|(?<=j)in|(?<=j)iu|(?<=j)üe|(?<=j)ün|(?<=j)i|(?<=j)ü)|(?:(?<=m)ang|(?<=m)eng|(?<=m)ian|(?<=m)iao|(?<=m)ing|(?<=m)ai|(?<=m)an|(?<=m)ao|(?<=m)ei|(?<=m)en|(?<=m)ie|(?<=m)in|(?<=m)iu|(?<=m)ou|(?<=m)a|(?<=m)e|(?<=m)i|(?<=m)o|(?<=m)u)|(?:(?<=l)iang|(?<=l)ang|(?<=l)eng|(?<=l)ian|(?<=l)iao|(?<=l)ing|(?<=l)ong|(?<=l)uan|(?<=l)ai|(?<=l)an|(?<=l)ao|(?<=l)ei|(?<=l)ia|(?<=l)ie|(?<=l)in|(?<=l)iu|(?<=l)ou|(?<=l)un|(?<=l)uo|(?<=l)üe|(?<=l)a|(?<=l)e|(?<=l)i|(?<=l)o|(?<=l)u|(?<=l)ü)|(?:(?<=n)iang|(?<=n)ang|(?<=n)eng|(?<=n)ian|(?<=n)iao|(?<=n)ing|(?<=n)ong|(?<=n)uan|(?<=n)ai|(?<=n)an|(?<=n)ao|(?<=n)ei|(?<=n)en|(?<=n)ie|(?<=n)in|(?<=n)iu|(?<=n)ou|(?<=n)un|(?<=n)uo|(?<=n)üe|(?<=n)a|(?<=n)e|(?<=n)i|(?<=n)u|(?<=n)ü)|(?:(?<=q)iang|(?<=q)iong|(?<=q)ian|(?<=q)iao|(?<=q)ing|(?<=q)üan|(?<=q)ia|(?<=q)ie|(?<=q)in|(?<=q)iu|(?<=q)üe|(?<=q)ün|(?<=q)i|(?<=q)ü)|(?:(?<=p)ang|(?<=p)eng|(?<=p)ian|(?<=p)iao|(?<=p)ing|(?<=p)ai|(?<=p)an|(?<=p)ao|(?<=p)ei|(?<=p)en|(?<=p)ie|(?<=p)in|(?<=p)ou|(?<=p)a|(?<=p)i|(?<=p)o|(?<=p)u)|(?:(?<=s)ang|(?<=s)eng|(?<=s)ong|(?<=s)uan|(?<=s)ai|(?<=s)an|(?<=s)ao|(?<=s)en|(?<=s)ou|(?<=s)ui|(?<=s)un|(?<=s)uo|(?<=s)a|(?<=s)e|(?<=s)i|(?<=s)u)|(?:(?<=r)ang|(?<=r)eng|(?<=r)ong|(?<=r)uan|(?<=r)an|(?<=r)ao|(?<=r)en|(?<=r)ou|(?<=r)ua|(?<=r)ui|(?<=r)un|(?<=r)uo|(?<=r)e|(?<=r)i|(?<=r)u)|(?:(?<=t)ang|(?<=t)eng|(?<=t)ian|(?<=t)iao|(?<=t)ing|(?<=t)ong|(?<=t)uan|(?<=t)ai|(?<=t)an|(?<=t)ao|(?<=t)ei|(?<=t)ie|(?<=t)ou|(?<=t)ui|(?<=t)un|(?<=t)uo|(?<=t)a|(?<=t)e|(?<=t)i|(?<=t)u)|(?:(?<=w)ang|(?<=w)eng|(?<=w)ai|(?<=w)an|(?<=w)ei|(?<=w)en|(?<=w)a|(?<=w)o|(?<=w)u)|(?:(?<=y)ang|(?<=y)ing|(?<=y)ong|(?<=y)uan|(?<=y)ai|(?<=y)an|(?<=y)ao|(?<=y)in|(?<=y)ou|(?<=y)ue|(?<=y)un|(?<=y)a|(?<=y)e|(?<=y)e|(?<=y)i|(?<=y)o|(?<=y)u)|(?:(?<=x)iang|(?<=x)iong|(?<=x)ian|(?<=x)iao|(?<=x)ing|(?<=x)üan|(?<=x)ia|(?<=x)ie|(?<=x)in|(?<=x)iu|(?<=x)üe|(?<=x)ün|(?<=x)i|(?<=x)ü)|(?:(?<=z)ang|(?<=z)eng|(?<=z)ong|(?<=z)uan|(?<=z)ai|(?<=z)an|(?<=z)ao|(?<=z)ei|(?<=z)en|(?<=z)ou|(?<=z)ui|(?<=z)un|(?<=z)uo|(?<=z)a|(?<=z)e|(?<=z)i|(?<=z)u)|(?:(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)a|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ai|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)an|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ang|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ao|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)e|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ei|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)en|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)eng|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)er|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)o|(?<!r|c|b|d|g|f|h|k|j|m|l|n|q|p|s|t|w|y|x|z)ou))$
假设您的正则表达式引擎支持lookbehinds,原子组和占有量词(即PCRE功能)：
可以替换的一些例子：
>全部(？：by(？>
>开始(所有第一个命名组)：
^(？P< initial>(？> [csz] h？| [bdfghj-npqrtwxy])？)
>这部分*由：
|(？<！[csz] h)(？< = h)(？> a(？> [io] | ng？)？| e(？> | i | ng？)？| o( ？> u | ng)| u(？> [ino] | a(？> i | ng？)？)？)
*(即：|(？:(？<！sh | ch | zh)(？< = h)uang |(？<！sh | ch | ... |(？<！sh | ch | | | zh)(？< = h)u))
>最后一部分*由：
|(？<！[bcdfghj-np-tw-z])(？> a(？> [io] | ng？)？| e(？> [ir] | ng？)？| ou？ ))$
*(即：|(？:(？<！r | c | b | d | g | f | h | k | j | m | l | n | q | p | s | t | w | y | x | z)a |(？<！r | c | b | d | ...))$) 如何处理其他部分： 例：
(?:(?<=ch)uang|(?<=ch)ang|(?<=ch)eng|(?<=ch)ong|(?<=ch)uai|(?<=ch)uan|(?<=ch)ai|(?<=ch)an|(?<=ch)ao|(?<=ch)en|(?<=ch)ou|(?<=ch)ua|(?<=ch)ui|(?<=ch)un|(?<=ch)uo|(?<=ch)a|(?<=ch)e|(?<=ch)i|(?<=ch)u)
_所有这些部件具有相同的外观,你必须为每个_做这些步骤
# step 1: lookarounds factorization (?<=ch)(?>ang|eng|ong|uai|uan|ai|an|ao|en|ou|ua|ui|un|uo|a|e|i|u) # step 2: sort all the content by alphabetic order (?<=ch)(?>a|ai|an|ang|ao|e|en|eng|i|ong|ou|u|ua|uai|uan|ui|un|uo) # step 3: group by first letter: don't forget the ? if the letter can be alone (?<=ch)(?>a(?>i|n|ng|o)?|e(?>n|ng)?|i|o(?>ng|u)|u(?>a|ai|an|i|n|o)?) # step 4: reduce the terminations (ie: n & ng => ng?+) (?<=ch)(?>a(?>i|ng?+|o)?|e(?>ng?+)?|i|o(?>ng|u)|u(?>a[in]?+|i|n|o)?) # step 5: put single letters in a character class (?<=ch)(?>a(?>[io]|ng?+)?|e(?>ng?+)?|i|o(?>ng|u)|u(?>a[in]?+|[ino])?)
结论
虽然结果较短,但这里的目标是优化.我使用原子组和占有量词来减少因子分解和回溯数量的测试次数.
一些限制
请注意,所有正则表达式都不支持atomic groups和possessive quantifiers等正则表达式功能,但可以解决此问题：
>对于不支持占有量词的风味：改变？至 ？
>对于不支持原子团的香精：改变(？>到(？：
(请注意,有一个使用Python的原子组的技巧,您可以使用计时器测试,以包围所有模式.请参阅此令人难以置信的帖子：Do Python regular expressions have an equivalent to Ruby’s atomic grouping?)
一些正则表达式引擎(如javascript)不支持lookbehinds.在这种情况下,您必须仅使用替换(即|)重写所有模式,这不是坏事,因为lookbehinds使您的模式更慢;并放弃不受支持的命名捕获. (在这种情况下,应该注意的是,为了消除负面的外观,你需要将这些部分中描述的音节放在所有其他部分之前,以便它们首先匹配.)
其他优化方式
>重写你的模式没有lookbehinds和|代替>按最常用的音节对不同的行进行排序
