lib/standard/ropes: Added to_leaf method on RopeNode.

[nit.git] / lib / standard / ropes.nit

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index 976def9..7bc4154 100644 (file)
--- a/lib/standard/ropes.nit
+++ b/lib/standard/ropes.nit
@@ -44,6 +44,11 @@ end
 private abstract class RopeNode
        # Length of the node
        var length = 0
+
+       # Transforms the current node to a Leaf.
+       # This might be costly to invoke since this produces a FlatString concatenation.
+       # Can be used internally to limit the growth of the Rope when working with small leaves.
+       fun to_leaf: Leaf is abstract
 end
 
 # Node that represents a concatenation between two nodes (of any RopeNode type)
@@ -63,6 +68,15 @@ private class Concat
                if r != null then length += r.length
        end
 
+       redef fun to_leaf
+       do
+               if left == null then
+                       if right == null then return new StringLeaf("".as(FlatString))
+                       return right.to_leaf
+               end
+               if right == null then return left.as(not null).to_leaf
+               return new StringLeaf((left.to_leaf.str.as(FlatString) + right.to_leaf.str.as(FlatString)).as(FlatString))
+       end
 end
 
 # Leaf of a Rope, contains a FlatString
@@ -82,6 +96,7 @@ private class StringLeaf
                length = str.length
        end
 
+       redef fun to_leaf do return self
 end
 
 # Basic structure, binary tree with a root node.