+redef class FlatString
+
+ redef fun append(s) do return (new RopeString.from(self)) + s
+
+ redef fun prepend(s) do return (new RopeString.from(self)).prepend(s)
+
+ redef fun insert_at(s, pos)
+ do
+ if pos == 0 then return prepend(s)
+ if pos == length then return append(s)
+
+ var l = substring(0,pos)
+ var r = substring_from(pos)
+ var ret: String = new RopeString.from(l)
+ ret += s
+ return ret + r
+ end
+
+end
+
+private class RopeStringChars
+ super SequenceRead[Char]
+
+ var tgt: Rope
+
+ redef fun [](pos)
+ do
+ assert pos < tgt.length
+ var path = tgt.node_at(pos)
+ return path.leaf.str.chars[path.offset]
+ end
+
+ redef fun iterator do return iterator_from(0)
+
+ redef fun iterator_from(pos) do return new RopeCharIterator(tgt, pos)
+
+ redef fun reverse_iterator do return reverse_iterator_from(tgt.length-1)
+
+ redef fun reverse_iterator_from(pos) do return new ReverseRopeCharIterator(tgt, pos)
+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
+
+class RopeCharIterator
+ super IndexedIterator[Char]
+
+ var substrings: IndexedIterator[Text]
+
+ var pos: Int
+
+ var max: Int
+
+ var substr_iter: IndexedIterator[Char]
+
+ init(tgt: Rope, from: Int)
+ do
+ substrings = tgt.substrings_from(from)
+ max = tgt.length - 1
+ if not substrings.is_ok then
+ pos = tgt.length
+ return
+ end
+ pos = from
+ substr_iter = substrings.item.chars.iterator
+ end
+
+ redef fun item do return substr_iter.item
+
+ redef fun is_ok do return pos <= max
+
+ redef fun index do return pos
+
+ redef fun next
+ do
+ pos += 1
+ if substr_iter.is_ok then
+ substr_iter.next
+ end
+ if not substr_iter.is_ok then
+ substrings.next
+ if substrings.is_ok then
+ substr_iter = substrings.item.chars.iterator
+ end
+ end
+ end
+end
+
+private class ReversePostfix
+ super IndexedIterator[RopeNode]
+
+ var target: Rope
+
+ var pos: Int
+
+ var min = 0
+
+ var stack = new List[IteratorElement]
+
+ init from(tgt: Rope, pos: Int)
+ do
+ self.pos = pos
+ target = tgt
+ 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 elemt = new IteratorElement(i.node)
+ elemt.right = true
+ if i.left then
+ elemt.left = true
+ end
+ stack.push elemt
+ end
+ stack.push(new IteratorElement(path.leaf))
+ stack.last.done = true
+ 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 < min then
+ stack.clear
+ return
+ end
+ var lst = stack.last
+ if lst.done then
+ stack.pop
+ next
+ return
+ end
+ if not lst.right then
+ var nod = lst.node.as(Concat)
+ var rgt = nod.right
+ lst.right = true
+ if rgt != null then
+ stack.push(new IteratorElement(rgt))
+ next
+ return
+ end
+ end
+ if not lst.left then
+ var nod = lst.node.as(Concat)
+ var lft = nod.left
+ lst.left = true
+ if lft != null then
+ stack.push(new IteratorElement(lft))
+ next
+ return
+ end
+ end
+ if lst.node isa Leaf then pos -= lst.node.length
+ lst.done = true
+ end
+end
+
+private class ReverseLeavesIterator
+ super IndexedIterator[Leaf]
+
+ var nodes: ReversePostfix
+
+ init(tgt: Rope, from: Int)
+ do
+ nodes = tgt.reverse_postfix(from)
+ 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 next do
+ while nodes.is_ok do
+ nodes.next
+ if nodes.is_ok then if nodes.item isa Leaf then break
+ end
+ end
+
+ redef fun index do return nodes.index
+
+end
+
+private class ReverseSubstringsIterator
+ super IndexedIterator[Text]
+
+ var leaves: ReverseLeavesIterator
+
+ var pos: Int
+
+ var str: Text
+
+ init(tgt: Rope, from: Int)
+ do
+ leaves = tgt.reverse_leaves(from)
+ pos = from
+ if not leaves.is_ok then return
+ str = leaves.item.str
+ make_substring
+ end
+
+ fun make_substring
+ do
+ if pos >= (leaves.index + str.length - 1) then return
+ str = str.substring(0, (pos - leaves.index + 1))
+ end
+
+ redef fun is_ok do return leaves.is_ok
+
+ redef fun item do
+ assert is_ok
+ return str
+ end
+
+ redef fun index do return pos
+
+ redef fun next do
+ pos -= str.length
+ leaves.next
+ if not leaves.is_ok then return
+ str = leaves.item.str
+ make_substring
+ end
+end
+
+private class ReverseRopeCharIterator
+ super IndexedIterator[Char]
+
+ var substrs: IndexedIterator[Text]
+
+ var pos: Int
+
+ var subiter: IndexedIterator[Char]
+
+ init(tgt: Rope, from: Int)
+ do
+ substrs = tgt.reverse_substrings_from(from)
+ if not substrs.is_ok then
+ pos = -1
+ return
+ end
+ subiter = substrs.item.chars.reverse_iterator
+ pos = from
+ end
+
+ redef fun is_ok do return pos >= 0
+
+ redef fun item do
+ assert is_ok
+ return subiter.item
+ end
+
+ redef fun index do return pos
+
+ redef fun next do
+ pos -= 1
+ if subiter.is_ok then subiter.next
+ if not subiter.is_ok then
+ if substrs.is_ok then substrs.next
+ if substrs.is_ok then subiter = substrs.item.chars.reverse_iterator
+ end
+ end
+end
+