intrude import string
+# Used when searching for a particular node
+# Returns the path to the node from the root of the rope
+# Also, the node and the offset for seeked position in the rope
+private class Path
+ # Leaf found
+ var leaf: Leaf
+ # Offset in leaf
+ var offset: Int
+ # Stack of the nodes traversed, and the path used
+ var stack: List[PathElement]
+end
+
+# An element for a Path, has the concat node and whether or not
+# left or right child was visited.
+private class PathElement
+ # Visited node
+ var node: Concat
+ # Was the left child visited ?
+ var left = false
+ # Was the right child visited ?
+ var right = false
+end
+
# A node for a Rope
private abstract class RopeNode
# Length of the node
end
+# Basic structure, binary tree with a root node.
+#
+# Also shared services by subsequent implementations.
+abstract class Rope
+ super Text
+
+ # Root node, entry point of a Rope.
+ private var root: RopeNode
+
+ # Empty Rope
+ init do from("")
+
+ # Creates a new Rope with `s` as root
+ init from(s: String) do
+ if s isa RopeString then root = s.root else root = new Leaf(s.as(FlatString))
+ end
+
+ private init from_root(r: RopeNode)
+ do
+ root = r
+ end
+
+ redef fun length do return root.length
+
+ # Iterator on the nodes of the rope, in forward postfix order
+ private fun postfix(from: Int): Postfix do return new Postfix.from(self, from)
+
+ # Iterator on the leaves of the rope, forward order
+ private fun leaves(from: Int): LeavesIterator do return new LeavesIterator(self, from)
+
+ # Path to the Leaf for `position`
+ private fun node_at(position: Int): Path
+ do
+ assert position >= 0 and position < length
+ return get_node_from(root.as(not null), 0, position, new List[PathElement])
+ end
+
+ # Builds the path to Leaf at position `seek_pos`
+ private fun get_node_from(node: RopeNode, curr_pos: Int, seek_pos: Int, stack: List[PathElement]): Path
+ do
+ assert curr_pos >= 0
+ if node isa Leaf then return new Path(node, seek_pos - curr_pos, stack)
+ node = node.as(Concat)
+
+ if node.left != null then
+ var next_pos = curr_pos + node.left.length
+ stack.add(new PathElement(node))
+ if next_pos > seek_pos then
+ stack.last.left = true
+ return get_node_from(node.left.as(not null), curr_pos, seek_pos, stack)
+ end
+ stack.last.right = true
+ return get_node_from(node.right.as(not null), next_pos, seek_pos, stack)
+ else
+ var vis = new PathElement(node)
+ vis.right = true
+ stack.add(vis)
+ return get_node_from(node.right.as(not null), curr_pos, seek_pos, stack)
+ end
+ end
+
+end
+
+# Rope that cannot be modified
+class RopeString
+ super Rope
+ super String
+
+ redef fun to_s do return self
+
+ # Inserts a String `str` at position `pos`
+ fun insert_at(str: String, pos: Int): RopeString
+ do
+ if str.length == 0 then return self
+ if self.length == 0 then return new RopeString.from(str)
+
+ assert pos >= 0 and pos <= length
+
+ if pos == length then return append(str).as(RopeString)
+
+ var path = node_at(pos)
+
+ var last_concat = new Concat
+
+ if path.offset == 0 then
+ last_concat.right = path.leaf
+ if str isa FlatString then last_concat.left = new Leaf(str) else last_concat.left = str.as(RopeString).root
+ else if path.offset == path.leaf.length then
+ if str isa FlatString then last_concat.right = new Leaf(str) else last_concat.right = str.as(RopeString).root
+ last_concat.left = path.leaf
+ else
+ var s = path.leaf.str
+ var l_half = s.substring(0, s.length - path.offset)
+ var r_half = s.substring_from(s.length - path.offset)
+ var cct = new Concat
+ cct.right = new Leaf(r_half)
+ last_concat.left = new Leaf(l_half)
+ if str isa FlatString then last_concat.right = new Leaf(str) else last_concat.right = str.as(RopeString).root
+ cct.left = last_concat
+ last_concat = cct
+ end
+
+ for i in path.stack.reverse_iterator do
+ var nod = new Concat
+ if i.left then
+ nod.right = i.node.right.as(not null)
+ nod.left = last_concat
+ else
+ nod.left = i.node.left.as(not null)
+ nod.right = last_concat
+ end
+ last_concat = nod
+ end
+
+ return new RopeString.from_root(last_concat)
+ end
+
+ # Adds `s` at the end of self
+ fun append(s: String): String
+ do
+ if self.is_empty then return s
+ return new RopeString.from_root(append_to_path(root,s))
+ end
+
+ # Builds a new path from root to the rightmost node with s appended
+ private fun append_to_path(node: RopeNode, s: String): RopeNode
+ do
+ var cct = new Concat
+ if node isa Leaf then
+ cct.left = node
+ if s isa FlatString then cct.right = new Leaf(s) else cct.right = s.as(RopeString).root
+ else if node isa Concat then
+ var right = node.right
+ if node.left != null then cct.left = node.left.as(not null)
+ if right == null then
+ if s isa FlatString then cct.right = new Leaf(s) else cct.right = s.as(RopeString).root
+ else
+ cct.right = append_to_path(right, s)
+ end
+ end
+ return cct
+ end
+
+ # O(log(n))
+ #
+ # var rope = new RopeString.from("abcd")
+ # assert rope.substring(1, 2) == "bc"
+ # assert rope.substring(-1, 2) == "a"
+ # assert rope.substring(1, 0) == ""
+ # assert rope.substring(2, 5) == "cd"
+ #
+ redef fun substring(pos, len)
+ do
+ if pos < 0 then
+ len += pos
+ pos = 0
+ end
+
+ if pos + len > length then len = length - pos
+
+ if len <= 0 then return new RopeString.from("")
+
+ var path = node_at(pos)
+
+ var lf = path.leaf
+ var offset = path.offset
+
+ if path.leaf.str.length - offset > len then lf = new Leaf(lf.str.substring(offset,len)) else lf = new Leaf(lf.str.substring_from(offset))
+
+ var nod: RopeNode = lf
+
+ for i in path.stack.reverse_iterator do
+ if i.right then continue
+ var tmp = new Concat
+ tmp.left = nod
+ var r = i.node.right
+ if r != null then tmp.right = r
+ nod = tmp
+ end
+
+ var ret = new RopeString
+ ret.root = nod
+
+ path = ret.node_at(len-1)
+
+ offset = path.offset
+ nod = new Leaf(path.leaf.str.substring(0, offset+1))
+
+ for i in path.stack.reverse_iterator do
+ if i.left then continue
+ var tmp = new Concat
+ tmp.right = nod
+ var l = i.node.left
+ if l != null then tmp.left = l
+ nod = tmp
+ end
+
+ ret.root = nod
+
+ return ret
+ end
+end
+
+# Used to iterate on a Rope
+private class IteratorElement
+
+ init(e: RopeNode)
+ do
+ if e isa Leaf then
+ left = true
+ right = true
+ end
+ node = e
+ end
+
+ # The node being visited
+ var node: RopeNode
+ # If the node has a left child, was it visited ?
+ var left = false
+ # If the node has a right child, was it visited ?
+ var right = false
+ # Was the current node visited ?
+ var done = false
+end
+
+# Simple Postfix iterator on the nodes of a Rope
+private class Postfix
+ super IndexedIterator[RopeNode]
+
+ # Target Rope to iterate on
+ var target: Rope
+
+ # Current position in Rope
+ var pos: Int
+
+ # Visited nodes
+ var stack = new List[IteratorElement]
+
+ init from(tgt: Rope, pos: Int)
+ do
+ self.target = tgt
+ self.pos = pos
+ if pos < 0 or pos >= tgt.length then return
+ var path = tgt.node_at(pos)
+ self.pos -= path.offset
+ for i in path.stack do
+ var item = new IteratorElement(i.node)
+ item.left = true
+ if i.right then item.right = true
+ stack.push item
+ end
+ var item = new IteratorElement(path.leaf)
+ item.done = true
+ stack.push item
+ end
+
+ redef fun item
+ do
+ assert is_ok
+ return stack.last.node
+ end
+
+ redef fun is_ok do return not stack.is_empty
+
+ redef fun index do return pos
+
+ redef fun next do
+ if stack.is_empty then return
+ if pos > target.length-1 then
+ stack.clear
+ return
+ end
+ var lst = stack.last
+ if lst.done then
+ if lst.node isa Leaf then
+ pos += lst.node.length
+ end
+ stack.pop
+ next
+ return
+ end
+ if not lst.left then
+ lst.left = true
+ var nod = lst.node
+ if nod isa Concat and nod.left != null then
+ stack.push(new IteratorElement(nod.left.as(not null)))
+ next
+ return
+ end
+ end
+ if not lst.right then
+ lst.right = true
+ var nod = lst.node
+ if nod isa Concat and nod.right != null then
+ stack.push(new IteratorElement(nod.right.as(not null)))
+ next
+ return
+ end
+ end
+ lst.done = true
+ end
+end
+
+# Iterates on the leaves (substrings) of the Rope
+class LeavesIterator
+ super IndexedIterator[Leaf]
+
+ private var nodes: Postfix
+
+ init(tgt: Rope, pos: Int)
+ do
+ nodes = tgt.postfix(pos)
+ end
+
+ redef fun is_ok do return nodes.is_ok
+
+ redef fun item
+ do
+ assert is_ok
+ return nodes.item.as(Leaf)
+ end
+
+ redef fun index do return nodes.index
+
+ redef fun next
+ do
+ while nodes.is_ok do
+ nodes.next
+ if nodes.is_ok and nodes.item isa Leaf then break
+ end
+ end
+end
+
nitlanguage / nit.git / blobdiff