X-Git-Url: http://nitlanguage.org?ds=sidebyside

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index eef9360..9da5d60 100644
--- a/lib/standard/ropes.nit
+++ b/lib/standard/ropes.nit
@@ -17,6 +17,29 @@ module ropes
 
 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
@@ -87,6 +110,50 @@ abstract class Rope
 	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)
+
+	# Iterator on the substrings from 0, in forward order
+	fun substrings: IndexedIterator[Text] do return new SubstringsIterator(self, 0)
+
+	# Iterator on the substrings, starting at position `from`, in forward order
+	fun substrings_from(from: Int): IndexedIterator[Text] do return new SubstringsIterator(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
@@ -96,5 +163,317 @@ class RopeString
 
 	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
+
+# Uses the leaves and calculates a new substring on each iteration
+class SubstringsIterator
+	super IndexedIterator[Text]
+
+	private var nodes: IndexedIterator[Leaf]
+
+	# Current position in Rope
+	var pos: Int
+
+	# Current substring, computed from the current Leaf and indexes
+	var substring: Text
+
+	init(tgt: Rope, pos: Int)
+	do
+		nodes = tgt.leaves(pos)
+		self.pos = pos
+		if pos < 0 or pos >= tgt.length then return
+		make_substring
+	end
+
+	# Compute the bounds of the current substring and makes the substring
+	private fun make_substring
+	do
+		substring = nodes.item.str
+		var min = 0
+		var length = substring.length
+		if nodes.index < pos then
+			min = pos - nodes.index
+		end
+		substring = substring.substring(min, length)
+	end
+
+	redef fun is_ok do return nodes.is_ok
+
+	redef fun item
+	do
+		assert is_ok
+		return substring
+	end
+
+	redef fun index do return pos
+
+	redef fun next
+	do
+		pos += substring.length
+		nodes.next
+		if nodes.is_ok then make_substring
+	end
+
 end