Source code for anytree.walker

# -*- coding: utf-8 -*-


[docs]class Walker(object): def __init__(self): """Walk from one node to another.""" super(Walker, self).__init__()
[docs] def walk(self, start, end): """ Walk from `start` node to `end` node. Returns: (upwards, downwards): `upwards` is a list of edges to parent nodes to go upward to. `downwards` is a list of edges to child nodes to go downward to. Raises: WalkError: on no common root node. >>> from anytree import Node, RenderTree, AsciiStyle >>> f = Node("f") >>> b = Node("b", parent=f) >>> a = Node("a", parent=b) >>> d = Node("d", parent=b) >>> c = Node("c", parent=d) >>> e = Node("e", parent=d) >>> g = Node("g", parent=f) >>> i = Node("i", parent=g) >>> h = Node("h", parent=i) >>> print(RenderTree(f, style=AsciiStyle())) Node('/f') |-- Node('/f/b') | |-- Node('/f/b/a') | +-- Node('/f/b/d') | |-- Node('/f/b/d/c') | +-- Node('/f/b/d/e') +-- Node('/f/g') +-- Node('/f/g/i') +-- Node('/f/g/i/h') Create a walker: >>> w = Walker() This class is made for walking: >>> w.walk(f, f) ((), Node('/f'), ()) >>> w.walk(f, b) ((), Node('/f'), (Node('/f/b'),)) >>> w.walk(b, f) ((Node('/f/b'),), Node('/f'), ()) >>> w.walk(h, e) ((Node('/f/g/i/h'), Node('/f/g/i'), Node('/f/g')), Node('/f'), (Node('/f/b'), Node('/f/b/d'), Node('/f/b/d/e'))) >>> w.walk(d, e) ((), Node('/f/b/d'), (Node('/f/b/d/e'),)) For a proper walking the nodes need to be part of the same tree: >>> w.walk(Node("a"), Node("b")) Traceback (most recent call last): ... anytree.walker.WalkError: Node('/a') and Node('/b') are not part of the same tree. """ s = start.path e = end.path if start.root != end.root: msg = "%r and %r are not part of the same tree." % (start, end) raise WalkError(msg) # common c = Walker.__calc_common(s, e) assert c[0] is start.root len_c = len(c) # up if start is c[-1]: up = tuple() else: up = tuple(reversed(s[len_c:])) # down if end is c[-1]: down = tuple() else: down = e[len_c:] return up, c[-1], down
@staticmethod def __calc_common(s, e): return tuple([si for si, ei in zip(s, e) if si is ei])
[docs]class WalkError(RuntimeError): """Walk Error."""