regex

이를 위해 다음 정규식을 사용할 수 있습니다.

^M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$

세분화 M{0,4}하고 천 단위 섹션을 지정하고 기본적으로 0와 사이를 제한합니다 4000. 비교적 간단합니다.

   0: <empty>  matched by M{0}
1000: M        matched by M{1}
2000: MM       matched by M{2}
3000: MMM      matched by M{3}
4000: MMMM     matched by M{4}

물론 더 큰 숫자를 허용하려면 수천의 숫자 (0 포함) M*를 허용 하는 것과 같은 것을 사용할 수 있습니다.

다음은 (CM|CD|D?C{0,3})약간 더 복잡합니다. 이것은 수백 섹션을위한 것이며 모든 가능성을 다룹니다.

  0: <empty>  matched by D?C{0} (with D not there)
100: C        matched by D?C{1} (with D not there)
200: CC       matched by D?C{2} (with D not there)
300: CCC      matched by D?C{3} (with D not there)
400: CD       matched by CD
500: D        matched by D?C{0} (with D there)
600: DC       matched by D?C{1} (with D there)
700: DCC      matched by D?C{2} (with D there)
800: DCCC     matched by D?C{3} (with D there)
900: CM       matched by CM

셋째, (XC|XL|L?X{0,3})이전 섹션과 동일한 규칙을 따르지만 수십 자리에 해당합니다.

 0: <empty>  matched by L?X{0} (with L not there)
10: X        matched by L?X{1} (with L not there)
20: XX       matched by L?X{2} (with L not there)
30: XXX      matched by L?X{3} (with L not there)
40: XL       matched by XL
50: L        matched by L?X{0} (with L there)
60: LX       matched by L?X{1} (with L there)
70: LXX      matched by L?X{2} (with L there)
80: LXXX     matched by L?X{3} (with L there)
90: XC       matched by XC

그리고 마지막으로, (IX|IV|V?I{0,3})처리, 단위의 섹션 0을 통해 9이전 두 섹션 (당신은 그들이 무엇인지 파악하면 로마 숫자는, 자신의 보이는 불확실성에도 불구하고, 몇 가지 논리적 규칙을 따라야)에 유사한 :

0: <empty>  matched by V?I{0} (with V not there)
1: I        matched by V?I{1} (with V not there)
2: II       matched by V?I{2} (with V not there)
3: III      matched by V?I{3} (with V not there)
4: IV       matched by IV
5: V        matched by V?I{0} (with V there)
6: VI       matched by V?I{1} (with V there)
7: VII      matched by V?I{2} (with V there)
8: VIII     matched by V?I{3} (with V there)
9: IX       matched by IX

정규식도 빈 문자열과 일치합니다. 이것을 원하지 않는다면 (그리고 정규식 엔진이 충분히 현대적이라면) 긍정적 인 룩 앤비와 룩어 헤드를 사용할 수 있습니다.

(?<=^)M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})(?=$)

(다른 대안은 길이가 미리 0이 아닌지 확인하는 것입니다).

답변

(^(?=[MDCLXVI])M*(C[MD]|D?C{0,3})(X[CL]|L?X{0,3})(I[XV]|V?I{0,3})$)

(M{1,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})|M{0,4}(CM|C?D|D?C{1,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})|M{0,4}(CM|CD|D?C{0,3})(XC|X?L|L?X{1,3})(IX|IV|V?I{0,3})|M{0,4}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|I?V|V?I{1,3}))

<opt-thousands-part><opt-hundreds-part><opt-tens-part><opt-units-part>

<opt-hundreds-part> = m/(CM|DC{0,3}|CD|C{1,3})?/;

<opt-hundreds-part> = m/(C[MD]|D?C{0,3})/;

<opt-hundreds-part> = m/(?:C[MD]|D?C{0,3})/;

<opt-hundreds-part> = m/(?:[IXC][MD]|D?C{0,4})/;

import re
pattern = '^M{0,3}(CM|CD|D?C{0,3})(XC|XL|L?X{0,3})(IX|IV|V?I{0,3})$'
if re.search(pattern, 'XCCMCI'):
    print 'Valid Roman'
else:
    print 'Not valid Roman'

>>> import re
>>> target = (
... r"this should pass v" + "\n"
... r"this is a test iii" + "\n"
... )
>>>
>>> re.findall( r"(?m)\s(i{1,3}v*|v)$", target )
['v', 'iii']

 (?m)
 \s
 (                     # (1 start)
      i{1,3}
      v*
   |  v
 )                     # (1 end)
 $