lib/standard/ropes: Added the insertion of a string in the rope.

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

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index b493de9..f992f66 100644 (file)
--- a/lib/standard/ropes.nit
+++ b/lib/standard/ropes.nit
@@ -151,6 +151,53 @@ 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