utils.py 文件源码

def sededit(a, b, context=0):
    '''
    Take two strings and output a sed-like diff
    '''
    if a == b:
        return ''
    a_len = len(a)
    b_len = len(b)
    start1, end1, start2, end2 = a_len, 0, b_len, 0
    s = difflib.SequenceMatcher(None, a, b)
    for tag, i1, i2, j1, j2 in s.get_opcodes():
        if tag == 'equal':
            continue
        elif tag == 'insert':
            ins = 1
        else:
            ins = 0
        start1 = max(min(i1-context-ins, start1), 0)
        start2 = max(min(j1-context-ins, start2), 0)
        end1 = min(max(i2+context+ins, end1), a_len)
        end2 = min(max(j2+context+ins, end2), b_len)
    return 's/%s%s%s/%s/' % (
            ('' if start1 else '^'), a[start1:end1],
            ('$' if end1 == a_len else ''), b[start2:end2])