代碼如下:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import os
import optparse

LOCATION_NONE     = 'NONE'
LOCATION_MID      = 'MID'
LOCATION_MID_GAP  = 'MID_GAP'
LOCATION_TAIL     = 'TAIL'
LOCATION_TAIL_GAP = 'TAIL_GAP'

Notations = {
    LOCATION_NONE: '',
    LOCATION_MID: '├─',
    LOCATION_MID_GAP: '│  ',
    LOCATION_TAIL: '└─',
    LOCATION_TAIL_GAP: '    '
}

class Node(object):
    def __init__(self, name, depth, parent=None, location=LOCATION_NONE):
        self.name = name
        self.depth = depth
        self.parent = parent
        self.location = location
        self.children = []

    def __str__(self):
        sections = [self.name]
        parent = self.has_parent()
        if parent:
            if self.is_tail():
                sections.insert(0, Notations[LOCATION_TAIL])
            else:
                sections.insert(0, Notations[LOCATION_MID])
            self.__insert_gaps(self, sections)
        return ''.join(sections)

    def __insert_gaps(self, node, sections):
        parent = node.has_parent()
        # parent exists and parent's parent is not the root node
        if parent and parent.has_parent():
            if parent.is_tail():
                sections.insert(0, Notations[LOCATION_TAIL_GAP])
            else:
                sections.insert(0, Notations[LOCATION_MID_GAP])
            self.__insert_gaps(parent, sections)

    def has_parent(self):
        return self.parent

    def has_children(self):
        return self.children

    def add_child(self, node):