def get_line_current_indent(string, tab_size=4):
    """Return the index of the first non-blank character of the given string.

    If there is no non-blank characters, return the length of the string.

    argument
    --------
    tab_size: tabs are count as 'tab_size' spaces (default 4).

    """
    indent = 0
    for c in string:
        if c == ' ':
            indent += 1
        elif c == '\t':
            indent += tab_size
        else:
            break
    return indent