# See the License for the specific language governing permissions and
# limitations under the License.
-# management and display of ordered trees
+# Manipulation and presentation of ordered trees.
module ordered_tree
# Generic structure to manage and display an ordered tree
#
# Ordered tree are tree where the elements of a same parent are in a specific order
#
-# The class can be used as it to work with generic tree.
-# The class can also be specialized to provide more specific behavior.
+# Elements of the trees are added with the `add` method that takes a parent and
+# a sub-element.
+# If the parent is `null`, then the element is considered a root.
+#
+# ~~~~
+# var t = new OrderedTree[String]
+# t.add(null, "root")
+# t.add("root", "child1")
+# t.add("root", "child2")
+# t.add("child1", "grand-child")
+# assert t.length == 4
+# ~~~~
+#
+# By default, the elements with a same parent
+# are visited in the order they are added.
+#
+# ~~~
+# assert t.to_a == ["root", "child1", "grand-child", "child2"]
+# assert t.write_to_string == """
+# root
+# |--child1
+# | `--grand-child
+# `--child2
+# """
+# ~~~
+#
+# The `sort_with` method can be used reorder elements
+#
+# ~~~
+# t.add("root", "aaa")
+# assert t.to_a == ["root", "child1", "grand-child", "child2", "aaa"]
+# t.sort_with(alpha_comparator)
+# assert t.to_a == ["root", "aaa", "child1", "grand-child", "child2"]
+# ~~~
+#
+# This class can be used as it to work with generic trees but can also be specialized to provide more specific
+# behavior or display. It is why the internal attributes are mutable.
class OrderedTree[E: Object]
- super Streamable
+ super Writable
super Collection[E]
+ super Cloneable
- # Sequence
+ # The roots of the tree (in sequence)
var roots = new Array[E]
+
+ # The branches of the trees.
+ # For each element, the ordered array of its direct sub-elements.
var sub = new HashMap[E, Array[E]]
- # Add a new element `e` in the tree
- # `p` is the parent of `e`.
- # if `p` is null, then `e` is a root element.
+ # The parent of each element.
+ #
+ # Roots have `null` as parent.
+ private var parents = new HashMap[E, nullable E]
+
+ redef fun length do return parents.length
+
+ redef fun has(e) do return parents.has_key(e)
+
+ # The parent of the element `e`
#
- # By defauld, the elements with a same parent
- # are displayed in the order they are added.
+ # Roots have `null` as parent.
#
- # The `sort_with` method can be used reorder elements
+ # ~~~
+ # var tree = new OrderedTree[Int]
+ # tree.add(1, 2)
+ # assert tree.parent(2) == 1
+ # assert tree.parent(1) == null
+ # ~~~
+ fun parent(e: E): nullable E do return parents[e]
+
+ # Add a new element `e` in the tree.
+ #
+ # `p` is the parent of `e`.
+ # If `p` is null, then `e` is a root element.
+ #
+ # If `e` is already in the tree, it is detached from its old
+ # parent and attached to the new parent `p`.
fun add(p: nullable E, e: E)
do
+ detach(e)
+ parents[e] = p
if p == null then
roots.add(e)
- else if sub.has_key(p) then
- sub[p].add(e)
else
- sub[p] = [e]
+ if not has(p) then add(null, p)
+ if sub.has_key(p) then
+ sub[p].add(e)
+ else
+ sub[p] = [e]
+ end
+ end
+ end
+
+ # Append all nodes `es` as children of `p`.
+ fun add_all(p: nullable E, es: Collection[E])
+ do
+ for e in es do add(p, e)
+ end
+
+ # Temporary remove `e`.
+ #
+ # Children of `e` are left untouched in the tree.
+ # This make the tree inconstant until `e` is added back.
+ private fun detach(e: E)
+ do
+ var old_parent = parents.get_or_null(e)
+ if old_parent != null then
+ var subs = sub[old_parent]
+ subs.remove(e)
+ if subs.is_empty then
+ # remove the sub when all children are detached
+ # so that `==` and `hash` are sane
+ # Otherwise an empty array will be considered
+ # differently than no array.
+ sub.keys.remove(old_parent)
+ end
+ else if roots.has(e) then
+ roots.remove(e)
end
end
# print the full tree on `o`
# Write a ASCII-style tree and use the `display` method to label elements
- redef fun write_to(stream: OStream)
+ redef fun write_to(stream: Writer)
do
for r in roots do
stream.write display(r)
end
end
- private fun sub_write_to(o: OStream, e: E, prefix: String)
+ private fun sub_write_to(o: Writer, e: E, prefix: String)
do
if not sub.has_key(e) then return
var subs = sub[e]
+ if subs.is_empty then return
var last = subs.last
for e2 in subs do
if e2 != last then
# Order is preserved
#
# var tree = new OrderedTree[Int]
- # tree.add(null, 1)
- # tree.add(1, 11)
- # tree.add(11, 111)
- # tree.add(11, 112)
- # tree.add(1, 12)
- # tree.add(12, 121)
- # tree.add(12, 122)
- # tree.add(null, 2)
- # tree.add(2, 21)
- # tree.add(2, 22)
+ # tree.add_all(null, [1, 2])
+ # tree.add_all(1, [11, 12])
+ # tree.add_all(11, [111, 112])
+ # tree.add_all(12, [121, 122])
+ # tree.add_all(2, [21, 22])
# assert tree.to_a == [1, 11, 111, 112, 12, 121, 122, 2, 21, 22]
redef fun to_a: Array[E] do
var res = new Array[E]
redef fun first do return roots.first
# var tree = new OrderedTree[Int]
- # tree.add(null, 1)
- # tree.add(1, 11)
- # tree.add(11, 111)
- # tree.add(11, 112)
- # tree.add(1, 12)
- # tree.add(12, 121)
- # tree.add(12, 122)
- # tree.add(null, 2)
- # tree.add(2, 21)
- # tree.add(2, 22)
+ # tree.add_all(null, [1, 2])
+ # tree.add_all(1, [11, 12])
+ # tree.add_all(11, [111, 112])
+ # tree.add_all(12, [121, 122])
+ # tree.add_all(2, [21, 22])
# var order = [1, 11, 111, 112, 12, 121, 122, 2, 21, 22]
- # var res = new Array[Int]
- # for i in tree do res.add(i)
- # assert res == order
+ # assert tree.iterator.to_a == order
redef fun iterator do return new OrderedTreeIterator[E](self)
+
+ # Two trees are equal if they have the same nodes in the same order
+ #
+ # ~~~
+ # var t1 = new OrderedTree[Int]
+ # t1.add_all(null, [1, 2])
+ # t1.add_all(1, [11, 12])
+ #
+ # var t2 = new OrderedTree[Int]
+ # t2.add_all(null, [1, 2])
+ #
+ # assert t1 != t2
+ #
+ # t2.add_all(1, [11, 12])
+ #
+ # assert t1 == t2
+ # ~~~
+ redef fun ==(other)
+ do
+ if not other isa OrderedTree[Object] then return false
+ return roots == other.roots and sub == other.sub
+ end
+
+ redef fun hash
+ do
+ return roots.hash + sub.hash
+ end
+
+ # Shallow clone of the tree.
+ #
+ # ~~~
+ # var t = new OrderedTree[Int]
+ # t.add_all(null, [1, 2])
+ # t.add_all(1, [11, 12])
+ #
+ # assert t.clone == t
+ # ~~~
+ redef fun clone
+ do
+ var res = new OrderedTree[E]
+ res.add_all(null, roots)
+ for p, es in sub do
+ res.add_all(p, es)
+ end
+ return res
+ end
end
# An Iterator over an OrderedTree
nitlanguage / nit.git / blobdiff