# -*- coding: utf-8 -*- # vim: tabstop=4 shiftwidth=4 softtabstop=4 # Copyright (C) 2014 Yahoo! Inc. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); you may # not use this file except in compliance with the License. You may obtain # a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the # License for the specific language governing permissions and limitations # under the License. import collections import os import six class FrozenNode(Exception): """Exception raised when a frozen node is modified.""" def __init__(self): super(FrozenNode, self).__init__("Frozen node(s) can't be modified") class _DFSIter(object): """Depth first iterator (non-recursive) over the child nodes.""" def __init__(self, root, include_self=False): self.root = root self.include_self = bool(include_self) def __iter__(self): stack = [] if self.include_self: stack.append(self.root) else: stack.extend(self.root.reverse_iter()) while stack: node = stack.pop() # Visit the node. yield node # Traverse the left & right subtree. stack.extend(node.reverse_iter()) class _BFSIter(object): """Breadth first iterator (non-recursive) over the child nodes.""" def __init__(self, root, include_self=False): self.root = root self.include_self = bool(include_self) def __iter__(self): q = collections.deque() if self.include_self: q.append(self.root) else: q.extend(self.root.reverse_iter()) while q: node = q.popleft() # Visit the node. yield node # Traverse the left & right subtree. q.extend(node.reverse_iter()) class Node(object): """A n-ary node class that can be used to create tree structures.""" # Constants used when pretty formatting the node (and its children). STARTING_PREFIX = "" EMPTY_SPACE_SEP = " " HORIZONTAL_CONN = "__" VERTICAL_CONN = "|" LINE_SEP = os.linesep def __init__(self, item, **kwargs): self.item = item self.parent = None self.metadata = dict(kwargs) self.frozen = False self._children = [] def freeze(self): if not self.frozen: # This will DFS until all children are frozen as well, only # after that works do we freeze ourselves (this makes it so # that we don't become frozen if a child node fails to perform # the freeze operation). for n in self: n.freeze() self.frozen = True def add(self, child): if self.frozen: raise FrozenNode() child.parent = self self._children.append(child) def empty(self): """Returns if the node is a leaf node.""" return self.child_count() == 0 def path_iter(self, include_self=True): """Yields back the path from this node to the root node.""" if include_self: node = self else: node = self.parent while node is not None: yield node node = node.parent def find(self, item): """Returns the node for an item if it exists in this node. This will search not only this node but also any children nodes and finally if nothing is found then None is returned instead of a node object. """ for n in self.dfs_iter(include_self=True): if n.item == item: return n return None def __contains__(self, item): """Returns if this item exists in this node or this nodes children.""" return self.find(item) is not None def __getitem__(self, index): # NOTE(harlowja): 0 is the right most index, len - 1 is the left most return self._children[index] def pformat(self): """Recursively formats a node into a nice string representation. **Example**:: >>> from taskflow.types import tree >>> yahoo = tree.Node("CEO") >>> yahoo.add(tree.Node("Infra")) >>> yahoo[0].add(tree.Node("Boss")) >>> yahoo[0][0].add(tree.Node("Me")) >>> yahoo.add(tree.Node("Mobile")) >>> yahoo.add(tree.Node("Mail")) >>> print(yahoo.pformat()) CEO |__Infra | |__Boss | |__Me |__Mobile |__Mail """ def _inner_pformat(node, level): if level == 0: yield six.text_type(node.item) prefix = self.STARTING_PREFIX else: yield self.HORIZONTAL_CONN + six.text_type(node.item) prefix = self.EMPTY_SPACE_SEP * len(self.HORIZONTAL_CONN) child_count = node.child_count() for (i, child) in enumerate(node): for (j, text) in enumerate(_inner_pformat(child, level + 1)): if j == 0 or i + 1 < child_count: text = prefix + self.VERTICAL_CONN + text else: text = prefix + self.EMPTY_SPACE_SEP + text yield text expected_lines = self.child_count(only_direct=False) accumulator = six.StringIO() for i, line in enumerate(_inner_pformat(self, 0)): accumulator.write(line) if i < expected_lines: accumulator.write(self.LINE_SEP) return accumulator.getvalue() def child_count(self, only_direct=True): """Returns how many children this node has. This can be either only the direct children of this node or inclusive of all children nodes of this node (children of children and so-on). NOTE(harlowja): it does not account for the current node in this count. """ if not only_direct: count = 0 for _node in self.dfs_iter(): count += 1 return count return len(self._children) def __iter__(self): """Iterates over the direct children of this node (right->left).""" for c in self._children: yield c def reverse_iter(self): """Iterates over the direct children of this node (left->right).""" for c in reversed(self._children): yield c def index(self, item): """Finds the child index of a given item, searches in added order.""" index_at = None for (i, child) in enumerate(self._children): if child.item == item: index_at = i break if index_at is None: raise ValueError("%s is not contained in any child" % (item)) return index_at def dfs_iter(self, include_self=False): """Depth first iteration (non-recursive) over the child nodes.""" return _DFSIter(self, include_self=include_self) def bfs_iter(self, include_self=False): """Breadth first iteration (non-recursive) over the child nodes.""" return _BFSIter(self, include_self=include_self)