Python split string without splitting escaped character

Question

Is there a way to split a string without splitting escaped character? For example, I have a string and want to split by \':\' and not by \'\\:\'

http\\://ww         


        

Answer 1

Here is an efficient solution that handles double-escapes correctly, i.e. any subsequent delimiter is not escaped. It ignores an incorrect single-escape as the last character of the string.

It is very efficient because it iterates over the input string exactly once, manipulating indices instead of copying strings around. Instead of constructing a list, it returns a generator.

def split_esc(string, delimiter):
    if len(delimiter) != 1:
        raise ValueError('Invalid delimiter: ' + delimiter)
    ln = len(string)
    i = 0
    j = 0
    while j < ln:
        if string[j] == '\\':
            if j + 1 >= ln:
                yield string[i:j]
                return
            j += 1
        elif string[j] == delimiter:
            yield string[i:j]
            i = j + 1
        j += 1
    yield string[i:j]

To allow for delimiters longer than a single character, simply advance i and j by the length of the delimiter in the "elif" case. This assumes that a single escape character escapes the entire delimiter, rather than a single character.

Tested with Python 3.5.1.