Merge: Rope api

Small modifications of the API that will be required for future pull requests such as Splay ropes and Bufferized ropes.

Pull-Request: #518
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Jean Privat <jean@pryen.org>

diff --git a/lib/ropes_debug.nit b/lib/ropes_debug.nit
index b9ba5ab..a122a02 100644 (file)
--- a/lib/ropes_debug.nit
+++ b/lib/ropes_debug.nit
@@ -53,13 +53,24 @@ redef class Concat
        end
 end
 
+redef class FlatText
+       fun to_dot(s: String): String is abstract
+end
+
 redef class FlatString
-       fun to_dot(s: String): String
+       redef fun to_dot(s: String): String
        do
                return s + "n{object_id} [label=\"FlatString\\nindex_from = {index_from}\\nindex_to = {index_to}\\nNativeString = {items.to_s_with_length(items.cstring_length)}\"];\n"
        end
 end
 
+redef class FlatBuffer
+       redef fun to_dot(s: String): String
+       do
+               return s + "n{object_id} [label=\"FlatBuffer\\length = {length}\\ncapacity = {capacity}\\nitems = {items.to_s_with_length(items.cstring_length)}\"];\n"
+       end
+end
+
 redef class RopeString
        redef fun to_dot(filepath: String)
        do

diff --git a/lib/standard/ropes.nit b/lib/standard/ropes.nit
index 45c1cbd..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)
@@ -51,40 +56,47 @@ private class Concat
        super RopeNode
 
        # Left child of the node
-       var _left: nullable RopeNode = null
+       var left: nullable RopeNode
        # Right child of the node
-       var _right: nullable RopeNode = null
-
-       fun left: nullable RopeNode do return _left
-       fun right: nullable RopeNode do return _right
+       var right: nullable RopeNode
 
-       fun left=(l: RopeNode)
+       init(l: nullable RopeNode, r: nullable RopeNode)
        do
-               _left = l
-               length = l.length
-               if _right != null then length += _right.length
+               left = l
+               right = r
+               if l != null then length += l.length
+               if r != null then length += r.length
        end
 
-       fun right=(r: RopeNode)
+       redef fun to_leaf
        do
-               _right = r
-               length = r.length
-               if _left != null then length += _left.length
+               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
-private class Leaf
+private abstract class Leaf
        super RopeNode
 
        # Encapsulated FlatString in the leaf node
-       var str: FlatString
+       var str: FlatText
+
+end
+
+private class StringLeaf
+       super Leaf
 
        init(val: FlatString) do
                self.str = val
                length = str.length
        end
 
+       redef fun to_leaf do return self
 end
 
 # Basic structure, binary tree with a root node.
@@ -104,7 +116,7 @@ abstract class Rope
 
        # Creates a new Rope with `s` as root
        init from(s: String) do
-               if s isa RopeString then root = s.root else root = new Leaf(s.as(FlatString))
+               if s isa RopeString then root = s.root else root = new StringLeaf(s.as(FlatString))
        end
 
        private init from_root(r: RopeNode)
@@ -276,36 +288,40 @@ class RopeString
 
                var path = node_at(pos)
 
-               var last_concat = new Concat
+               var last_concat: 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
+                       if str isa FlatString then
+                               last_concat = new Concat(new StringLeaf(str), path.leaf)
+                       else
+                               last_concat = new Concat(str.as(RopeString).root, path.leaf)
+                       end
                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
+                       if str isa FlatString then
+                               last_concat = new Concat(path.leaf, new StringLeaf(str))
+                       else
+                               last_concat = new Concat(path.leaf, str.as(RopeString).root)
+                       end
                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.as(FlatString))
-                       last_concat.left = new Leaf(l_half.as(FlatString))
-                       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
+                       var cct: Concat
+                       var ll = new StringLeaf(l_half.as(FlatString))
+                       if str isa FlatString then
+                               cct = new Concat(ll, new StringLeaf(str))
+                       else
+                               cct = new Concat(ll, str.as(RopeString).root)
+                       end
+                       last_concat = new Concat(cct, new StringLeaf(r_half.as(FlatString)))
                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
+                               last_concat = new Concat(last_concat, i.node.right)
                        else
-                               nod.left = i.node.left.as(not null)
-                               nod.right = last_concat
+                               last_concat = new Concat(i.node.left, last_concat)
                        end
-                       last_concat = nod
                end
 
                return new RopeString.from_root(last_concat)
@@ -324,17 +340,25 @@ class RopeString
        # 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
+               var cct: 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 s isa FlatString then
+                               cct = new Concat(node, new StringLeaf(s))
+                       else
+                               cct = new Concat(node, s.as(RopeString).root)
+                       end
+               else
+                       var n = node.as(Concat)
+                       var right = n.right
+                       var lft = n.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
+                               if s isa FlatString then
+                                       cct = new Concat(lft, new StringLeaf(s))
+                               else
+                                       cct = new Concat(lft, s.as(RopeString).root)
+                               end
                        else
-                               cct.right = append_to_path(right, s)
+                               cct = new Concat(lft, append_to_path(right, s))
                        end
                end
                return cct
@@ -364,17 +388,13 @@ class RopeString
                var lf = path.leaf
                var offset = path.offset
 
-               if path.leaf.str.length - offset > len then lf = new Leaf(lf.str.substring(offset,len).as(FlatString)) else lf = new Leaf(lf.str.substring_from(offset).as(FlatString))
+               if path.leaf.str.length - offset > len then lf = new StringLeaf(lf.str.substring(offset,len).as(FlatString)) else lf = new StringLeaf(lf.str.substring_from(offset).as(FlatString))
 
                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
+                       nod = new Concat(nod, i.node.right)
                end
 
                var ret = new RopeString
@@ -383,15 +403,11 @@ class RopeString
                path = ret.node_at(len-1)
 
                offset = path.offset
-               nod = new Leaf(path.leaf.str.substring(0, offset+1).as(FlatString))
+               nod = new StringLeaf(path.leaf.str.substring(0, offset+1).as(FlatString))
 
                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
+                       nod = new Concat(i.node.left, nod)
                end
 
                ret.root = nod