[python] difflib, show differences between two strings

• difflib
• diff highlighting

def show_diff(text, n_text):
    """
    http://stackoverflow.com/a/788780
    Unify operations between two compared strings seqm is a difflib.
    SequenceMatcher instance whose a & b are strings
    """
    seqm = difflib.SequenceMatcher(None, text, n_text)
    output= []
    for opcode, a0, a1, b0, b1 in seqm.get_opcodes():
        if opcode == 'equal':
            output.append(seqm.a[a0:a1])
        elif opcode == 'insert':
            output.append("<font color=red>^" + seqm.b[b0:b1] + "</font>")
        elif opcode == 'delete':
            output.append("<font color=blue>^" + seqm.a[a0:a1] + "</font>")
        elif opcode == 'replace':
            # seqm.a[a0:a1] -> seqm.b[b0:b1]
            output.append("<font color=green>^" + seqm.b[b0:b1] + "</font>")
        else:
            raise RuntimeError, "unexpected opcode"
    return ''.join(output)