Hallo people,
I have the following code that implements a simple recursive tree like
structure.
The trouble is with the GetTreeBranch function, the print statement
prints a valid value but the return immediatley afterward doesn't return
anything.
Can anyone help me with why?
Thanks,
Matt.
Code and output follow;
'''
dirtree
A simple implementation of a filesystem-like tree
datastructure.
'''
def MakeNewTree(rootname='root'):
'''MakeNewTree
Creates an empty tree with a 'root' node.
If the parameter rootname is not given, it
defaults to 'root'.
'''
return [{rootname:[]}]
def DoThingsToTree(path,value,tree,delete=False):
'''_DoThingsToTree
You should not use this function.
'''
if type(path)==type(''):
path=path.lstrip('/').rstrip('/').split('/')
for item in tree:
if type(item)==type({}) and item.has_key(path[0]):
if len(path)==1:
if not delete:
try:
item[path[0]].append(value)
except KeyError:
item[path[0]]=value
else:
if value is not None:
del(item[path[0]][value])
else:
del(tree[tree.index(item)])
break
else:
_DoThingsToTree(path[1:],value,item[path[0]],delete)
def GetTreeBranch(path,tree):
if type(path)==type(''):
path=path.lstrip('/').rstrip('/').split('/')
for item in tree:
if type(item)==type({}) and item.has_key(path[0]):
if len(path)==1:
print 'returning',tree[tree.index(item)]
return tree[tree.index(item)]
else:
GetTreeBranch(path[1:],item[path[0]])
def AddItemToTree(path,value,tree):
'''AddITemToTree
Add an item onto a 'branch' of the tree.
path should be a '/' separated string that
defines a path to the branch required.
value an object to put onto the branch
tree the tree to operate on.
'''
DoThingsToTree(path,value,tree)
def AddBranchToTree(path,branch,tree):
'''AddBranchToTree
Add a new branch to the tree.
path should be a '/' separated string that
defines a path to the branch required.
branch an object used as the branch identifier
(usually a string)
tree the tree to operate on
'''
DoThingsToTree(path,{branch:[]},tree)
def DelItemFromTree(path,index,tree):
'''DelItemFromTree
Remove an item from the tree.
path should be a '/' separated string that
defines a path to the branch required.
index the numeric index of the item to delete
on the branch to delete. items are indexed
in the order they are added, from 0
'''
DoThingsToTree(path,index,tree,delete=True)
def DelBranchFromTree(path,tree):
'''DelBranchFromTree
Remove a branch and all items and subbranches.
path should be a '/' separated string that
defines a path to the branch required.
tree The tree to delete the branch from.
'''
DoThingsToTree(path,None,tree,delete=True)
OUTPUT;
>>> from dirtree import *
>>> MyTree=MakeNewTree('Matt')
>>> AddBranchToTree('Matt','Good',MyTree)
>>> AddBranchToTree('Matt','Bad',MyTree)
>>> AddItemToTree('Matt/Good','Computers',MyTree)
>>> AddItemToTree('Matt/Bad','Drinking',MyTree)
>>> a=GetTreeBranch('Matt/Bad',MyTree)
returning {'Bad': ['Drinking']}
>>> a
>>>
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