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