lib/standard/ropes: Added a forward postfix iterator on Rope.

Signed-off-by: Lucas Bajolet <r4pass@hotmail.com>

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index d1f7398..01e09c4 100644 (file)
--- a/lib/standard/ropes.nit
+++ b/lib/standard/ropes.nit
@@ -111,6 +111,9 @@ abstract class Rope
 
        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)
+
        # Path to the Leaf for `position`
        private fun node_at(position: Int): Path
        do
@@ -306,3 +309,81 @@ private class IteratorElement
        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
+