# HG changeset patch
# User Daichi TOMA <toma@cr.ie.u-ryukyu.ac.jp>
# Date 1363078851 -32400
# Node ID 329f462d5dadcfc8515b4a62b873979eba7e4056

add nondestructive tree structure.

diff -r 000000000000 -r 329f462d5dad tree.hs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tree.hs	Tue Mar 12 18:00:51 2013 +0900
@@ -0,0 +1,71 @@
+import qualified Data.Map as Map
+import Data.Maybe (isNothing, fromJust)
+
+type Attribute = Map.Map String String
+type Children  = Map.Map Int Node
+
+data Node = Empty
+          | Node { attribute :: Attribute
+                 , children  :: Children
+                 } deriving (Show, Eq)
+
+addChild :: Node -> Node -> Int -> Node
+addChild node child pos = Node (attribute node) (Map.insert pos child (children node))
+
+getChild :: Node -> Int -> Maybe Node
+getChild node pos = Map.lookup pos (children node)
+
+putAttribute :: Node -> String -> String -> Node
+putAttribute node key value = Node (Map.insert key value (attribute node)) (children node)
+
+getAttribute :: Node -> String -> Maybe String
+getAttribute node key = Map.lookup key (attribute node)
+
+getNode :: [Int] -> Node -> Maybe Node
+getNode path node = if null path
+                    then Just node
+                    else (getChild node (head path)) >>= getNode (tail path)
+
+editNode :: [Int] -> Node -> String -> String -> Maybe Node
+editNode path node key value = if isNothing (getNode path node)
+                               then Nothing
+                               else _editNode path node Empty 0 key value
+
+_editNode :: [Int] -> Node -> Node -> Int -> String -> String -> Maybe Node
+_editNode [] node newnode pos _ _ = Just (addChild (fromJust (getNode [] node)) newnode pos)
+_editNode (xs) node newnode pos key value  = if newnode == Empty
+                                             then _editNode (init xs) node (putAttribute (fromJust (getNode xs node)) key value ) (last xs) [] []
+                                             else _editNode (init xs) node (addChild (fromJust (getNode xs node)) newnode pos) (last xs) [] []
+
+addChildAt :: [Int] -> Node -> Node -> Int -> Maybe Node
+addChildAt path node child pos = if isNothing (getNode (init path) node)
+                                 then Nothing
+                                 else _addChildAt path node child pos
+
+_addChildAt :: [Int] -> Node -> Node -> Int -> Maybe Node
+_addChildAt [] node child pos = Just (addChild (fromJust (getNode [] node)) child pos)
+_addChildAt (xs) node child pos = _addChildAt (init xs) node (addChild (fromJust (getNode xs node)) child pos) (last xs)
+
+-- test 用
+a = Node Map.empty Map.empty
+b = Node Map.empty Map.empty
+c = Node Map.empty Map.empty
+d = Node Map.empty Map.empty
+e = Node Map.empty Map.empty
+f = Node Map.empty Map.empty
+g = Node Map.empty Map.empty
+
+a2 = putAttribute a "node" "a"
+b2 = putAttribute b "node" "b"
+c2 = putAttribute c "node" "c"
+d2 = putAttribute d "node" "d"
+e2 = putAttribute e "node" "e"
+f2 = putAttribute f "node" "f"
+g2 = putAttribute g "node" "g"
+
+b3 = addChild (addChild b2 d2 0) e2 1
+c3 = addChild c2 f2 0
+node = addChild g2 (addChild (addChild a2 b3 0) c3 1) 0
+
+new = editNode [0,1,0] node "node" "x"
+new1 = addChildAt [0,1,0] (fromJust new) z1 5