split_first

test_util.py

class TestUtil(TestCase):
    def test_split_first(self):
        test_cases = [
            (
                ('abcd', ['b']),
                ('a', 'cd')
            ),
            (
                ('abcd', ['c', 'b']),
                ('a', 'cd')),
            (
                ('abcd', []),
                ('abcd', '')
            ),
        ]
        for input, expected in test_cases:
            output = split_first(*input)
            self.assertEqual(output, expected)

util.py

def split_first(s, delims):
    """
    Given a string and an iterable of delimiters, split on the first found
    delimiter. Return two split parts.

    If not found, then the first part is the full input string.
    """
    min_idx = None
    for d in delims:
        idx = s.find(d)
        if idx < 0:
            continue

        if not min_idx:
            min_idx = idx
        else:
            min_idx = min(idx, min_idx)

    if min_idx < 0:
        return s, ''

    return s[:min_idx], s[min_idx+1:]