1 # This file is part of NIT ( http://www.nitlanguage.org ).
3 # Copyright 2012 Jean Privat <jean@pryen.org>
5 # Licensed under the Apache License, Version 2.0 (the "License");
6 # you may not use this file except in compliance with the License.
7 # You may obtain a copy of the License at
9 # http://www.apache.org/licenses/LICENSE-2.0
11 # Unless required by applicable law or agreed to in writing, software
12 # distributed under the License is distributed on an "AS IS" BASIS,
13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 # See the License for the specific language governing permissions and
15 # limitations under the License.
17 # management and display of ordered trees
20 # Generic structure to manage and display an ordered tree
22 # Ordered tree are tree where the elements of a same parent are in a specific order
24 # Elements of the trees are added with the `add` method that takes a parent and
26 # If the parent is `null`, then the element is considered a root.
29 # var t = new OrderedTree[String]
31 # t.add("root", "child1")
32 # t.add("root", "child2")
33 # t.add("child1", "grand-child")
34 # assert t.length == 4
37 # By default, the elements with a same parent
38 # are visited in the order they are added.
41 # assert t.to_a == ["root", "child1", "grand-child", "child2"]
42 # assert t.write_to_string == """
50 # The `sort_with` method can be used reorder elements
53 # t.add("root", "aaa")
54 # assert t.to_a == ["root", "child1", "grand-child", "child2", "aaa"]
55 # t.sort_with(alpha_comparator)
56 # assert t.to_a == ["root", "aaa", "child1", "grand-child", "child2"]
59 # This class can be used as it to work with generic trees but can also be specialized to provide more specific
60 # behavior or display. It is why the internal attributes are mutable.
61 class OrderedTree[E
: Object]
65 # The roots of the tree (in sequence)
66 var roots
= new Array[E
]
68 # The branches of the trees.
69 # For each element, the ordered array of its direct sub-elements.
70 var sub
= new HashMap[E
, Array[E
]]
72 # Add a new element `e` in the tree.
73 # `p` is the parent of `e`.
74 # if `p` is null, then `e` is a root element.
75 fun add
(p
: nullable E
, e
: E
)
79 else if sub
.has_key
(p
) then
86 # print the full tree on `o`
87 # Write a ASCII-style tree and use the `display` method to label elements
88 redef fun write_to
(stream
: OStream)
91 stream
.write display
(r
)
93 sub_write_to
(stream
, r
, "")
97 private fun sub_write_to
(o
: OStream, e
: E
, prefix
: String)
99 if not sub
.has_key
(e
) then return
104 o
.write
"{prefix}|--{display(e2)}\n"
105 sub_write_to
(o
, e2
, prefix
+"| ")
107 o
.write
"{prefix}`--{display(e2)}\n"
108 sub_write_to
(o
, e2
, prefix
+" ")
113 # Sort roots and other elements using a comparator method
114 # This method basically sorts roots then each group of children
115 fun sort_with
(comparator
: Comparator)
117 comparator
.sort
(roots
)
118 for a
in sub
.values
do
123 # How to display a specific element of the tree
124 # By defaut, uses `to_s`
126 # Subclasses should redefine this method to provide a specific output
127 fun display
(e
: E
): String do return e
.to_s
129 # Get an array of the contained elements
132 # var tree = new OrderedTree[Int]
143 # assert tree.to_a == [1, 11, 111, 112, 12, 121, 122, 2, 21, 22]
144 redef fun to_a
: Array[E
] do
145 var res
= new Array[E
]
146 for r
in roots
do sub_to_a
(r
, res
)
150 private fun sub_to_a
(e
: E
, res
: Array[E
]) do
152 if sub
.has_key
(e
) then for e2
in sub
[e
] do sub_to_a
(e2
, res
)
155 # var tree = new OrderedTree[Int]
156 # assert tree.is_empty
158 # assert not tree.is_empty
159 redef fun is_empty
: Bool do return roots
.is_empty
161 # var tree = new OrderedTree[Int]
164 # assert tree.first == 1
165 redef fun first
do return roots
.first
167 # var tree = new OrderedTree[Int]
178 # var order = [1, 11, 111, 112, 12, 121, 122, 2, 21, 22]
179 # var res = new Array[Int]
180 # for i in tree do res.add(i)
181 # assert res == order
182 redef fun iterator
do return new OrderedTreeIterator[E
](self)
185 # An Iterator over an OrderedTree
186 private class OrderedTreeIterator[E
: Object]
189 var tree
: OrderedTree[E
]
191 var iterators
= new Array[Iterator[E
]]
194 if not tree
.is_empty
then
195 iterators
.add tree
.roots
.iterator
199 redef fun is_ok
do return not iterators
.is_empty
203 return iterators
.last
.item
208 if tree
.sub
.has_key
(item
) then
209 iterators
.add tree
.sub
[item
].iterator
212 while is_ok
and not iterators
.last
.is_ok
do
214 if is_ok
and iterators
.last
.is_ok
then
221 redef fun iterator
do return new OrderedTreeIterator[E
](tree
)