How one can write a String Case Conversion Helper in Python

The problem

On this problem, you’ll make a perform that converts between camelCase, snake_case, and kebab-case.

You could write a perform that modifications to a given case. It should have the ability to deal with all three case varieties:

change_case("snakeCase", "snake") # "snake_case"
change_case("some-lisp-name", "camel") # "someLispName"
change_case("map_to_all", "kebab") # "map-to-all"
change_case("doHTMLRequest", "kebab") # "do-h-t-m-l-request"
change_case("invalid-inPut_bad", "kebab") # None
change_case("valid-input", "huh???") # None
change_case("", "camel") # ""

Your perform should take care of invalid enter as proven, although it would solely be handed strings. Moreover, all legitimate identifiers will likely be lowercase besides when obligatory, in different phrases on phrase boundaries in camelCase.

The answer in Python code

Choice 1:

import re
def change_case(label, goal):
    if ('_' in label) + ('-' in label) + (label != label.decrease()) > 1:
        return
    if goal == 'snake':
        return re.sub('([A-Z])', r'_1', label.substitute('-', '_')).decrease()
    if goal == 'kebab':
        return re.sub('([A-Z])', r'-1', label.substitute('_', '-')).decrease()
    if goal == 'camel':
        return re.sub('([_-])([a-z])', lambda m: m.group(2).higher(), label)

Choice 2:

def change_case(id, t):
    q = ('_' in id) + ('-' in id) + any(x.isupper() for x in set(id))
    if q > 1: return
    d = {'kebab': '-', 'snake': '_'}
    l, index = [''], 0
    for x in id:
        if not l[index] or not x.isupper() and x.isalpha() and l[index][-1].isalpha():
            l[index] += x
        elif x.isalpha():
            l.append(x)
            index += 1
        else:
            l.append('')
            index += 1
    if t in d:
        return f'{d[t]}'.be part of(x.decrease() for x in l)
    if t == 'camel':
        return ''.be part of(w.capitalize() if i else w for i,w in enumerate(l))

Choice 3:

def change_case(id, t):
    if '_' in id and '-' in id or t not in ['snake','camel','kebab']:return None
    if not id: return ''
    if not id.islower():
        if '_' in id or '-' in id: return None
    if '-' in id:
        l=id.cut up('-')
    elif '_' in id:
        l=id.cut up('_')
    else:
        l,temp=[],''
        for i in id:
            if i.isupper():
                l.append(temp)
                temp=i.decrease()
            else:
                temp+=i.decrease()
        l.append(temp)
    if t=='snake':return '_'.be part of(l)
    elif t=='kebab':return '-'.be part of(l)
    else:return l[0][0]+''.be part of(i.capitalize() for i in l)[1:]

Check circumstances to validate our resolution

take a look at.it("Fundamental assessments")
take a look at.assert_equals(change_case("snakeCase", "snake"), "snake_case", "camelCase to snake_case conversion ought to work")    
take a look at.assert_equals(change_case("some-lisp-name", "camel"), "someLispName", "kebab-case to camelCase conversion ought to work")    
take a look at.assert_equals(change_case("map_to_all", "kebab"), "map-to-all", "snake_case to kebab-case conversion ought to work")    
take a look at.assert_equals(change_case("doHTMLRequest", "kebab"), "do-h-t-m-l-request", "camelCase to kebab-case conversion ought to work")    
take a look at.assert_equals(change_case("invalid-inPut_bad", "kebab"), None, "mIx-ed_cAse enter needs to be thought of invalid")    
take a look at.assert_equals(change_case("valid-input", "huh???"), None, "Invalid goal circumstances needs to be handled")    
take a look at.assert_equals(change_case("", "camel"), "", "An empty string shouldn't be modified.")