Source code for pyconll.tree.tree

A general immutable tree module. This module is used when parsing a serial
sentence into a Tree structure.

[docs]class Tree: """ A tree node. This is the base representation for a tree, which can have many children which are accessible via child index. The tree's structure is immutable, so the data, parent, children cannot be changed once created. As is this class is useless, and must be created with the TreeBuilder module which is a sort of friend class of Tree to maintain its immutable public contract. """
[docs] def __init__(self): """ Create a new empty tree. To create a useful Tree, use TreeBuilder. """ self._data = None self._parent = None self._children = []
@property def data(self): """ The data on the tree node. The property ensures it is readonly. Returns: The data stored on the Tree. No data is represented as None. """ return self._data @property def parent(self): """ Provides the parent of the Tree. The property ensures it is readonly. Returns: A pointer to the parent Tree reference. None if there is no parent. """ return self._parent
[docs] def __getitem__(self, key): """ Get specific children from the Tree. This can be an integer or slice. Args: key: The indexer for the item. """ return self._children[key]
[docs] def __iter__(self): """ Provides an iterator over the children. """ for child in self._children: yield child
[docs] def __len__(self): """ Provides the number of direct children on the tree. Returns: The number of direct children on the tree. """ return len(self._children)