Regex for Matching Pinyin

Question

I'm looking for a regular expression that can correctly match valid pinyin (e.g. "sheng", "sou" (while ignoring invalid pinyin, e.g. "shong", "sei"). Most of the regex provided in the top Google results match invalid pinyin in some cases.

Obviously, no matter what approach one takes, this will be a monster regex, and I'm especially interested in the different approaches one could take to solve this problem. For example, "Optimizing a regular expression to parse chinese pinyin" uses lookbacks.

A table of valid pinyin can be found here: http://pinyin.info/rules/initials_finals.html

Answer 1

I went for a regex that grouped smaller regexes by the pinyin's initial (usually the first letter). So, the first group includes all "b", "p" and "m" sounds, then "f", then "d" and "t", etc.

This approach seems easy to read and should be easy to edit (if it needs corrections or additions). I also added exceptions to the begging of groups in order to improve readability.

([mM]iu|[pmPM]ou|[bpmBPM](o|e(i|ng?)?|a(ng?|i|o)?|i(e|ng?|a[no])?|u))| ([fF](ou?|[ae](ng?|i)?|u))|([dD](e(i|ng?)|i(a[on]?|u))| [dtDT](a(i|ng?|o)?|e(i|ng)?|i(a[on]?|e|ng|u)?|o(ng?|u)|u(o|i|an?|n)?))| ([nN]eng?|[lnLN](a(i|ng?|o)?|e(i|ng)?|i(ang|a[on]?|e|ng?|u)?|o(ng?|u)|u(o|i|an?|n)?|ve?))| ([ghkGHK](a(i|ng?|o)?|e(i|ng?)?|o(u|ng)|u(a(i|ng?)?|i|n|o)?))| ([zZ]h?ei|[czCZ]h?(e(ng?)?|o(ng?|u)?|ao|u?a(i|ng?)?|u?(o|i|n)?))| ([sS]ong|[sS]hua(i|ng?)?|[sS]hei|[sS][h]?(a(i|ng?|o)?|en?g?|ou|u(a?n|o|i)?|i))| ([rR]([ae]ng?|i|e|ao|ou|ong|u[oin]|ua?n?))| ([jqxJQX](i(a(o|ng?)?|[eu]|ong|ng?)?|u(e|a?n)?))| (([aA](i|o|ng?)?|[oO]u?|[eE](i|ng?|r)?))| ([wW](a(i|ng?)?|o|e(i|ng?)?|u))| [yY](a(o|ng?)?|e|in?g?|o(u|ng)?|u(e|a?n)?) 

Here's the Debuggex example I created.

Answer 2

I would use a combination approach that is not solely regex.

Check for valid pinyin:

1. grab word

2. grab letters from the beginning of the word as long as they are consonants. This separates the initial sound from the final sound.

3. check that the initial and final are valid...

4. ...and if so, see if their combination is allowed (via a table like this, but the entries are simply 1's and 0's).