Merge pull request #4 from jestabro/delete-tree

T4235: distinguish between sub(-tract) tree and delete tree

2 files changed, 72 insertions, 37 deletions

diff --git a/src/config_diff.ml b/src/config_diff.ml
index 565d64f..604668b 100644
--- a/src/config_diff.ml
+++ b/src/config_diff.ml
@@ -1,12 +1,12 @@
-type change = Unchanged | Added | Deleted | Updated of string list
+type change = Unchanged | Added | Subtracted | Updated of string list
 
-type diff_func = ?with_children:bool -> string list -> change -> unit
+type diff_func = ?recurse:bool -> string list -> change -> unit
 
 type diff_trees = {
     left: Config_tree.t;
     right: Config_tree.t;
     add: Config_tree.t ref;
-    del: Config_tree.t ref;
+    sub: Config_tree.t ref;
     inter: Config_tree.t ref;
 }
 
@@ -17,7 +17,7 @@ module ValueS = Set.Make(struct type t = string let compare = compare end)
 
 let make_diff_trees l r = { left = l; right = r;
                            add = ref (Config_tree.make "root");
-                           del = ref (Config_tree.make "root");
+                           sub = ref (Config_tree.make "root");
                            inter = ref (Config_tree.make "root");
 }
 
@@ -70,7 +70,7 @@ let rec diff (path : string list) (f : diff_func) (l : (Config_tree.t option * C
     | (left_node_opt, right_node_opt) :: ls ->
         (let path = update_path path left_node_opt right_node_opt in
         match left_node_opt, right_node_opt with
-        | Some _, None -> f path Deleted
+        | Some _, None -> f path Subtracted
         | None, Some _ -> f path Added
         | Some left_node, Some right_node when left_node = right_node ->
                 f path Unchanged
@@ -78,20 +78,23 @@ let rec diff (path : string list) (f : diff_func) (l : (Config_tree.t option * C
                 let values = (data_of right_node).values in
                 f path (Updated values)
         | Some left_node, Some right_node ->
-                (f ~with_children:false path Unchanged;
+                (f ~recurse:false path Unchanged;
                 diff path f (opt_zip left_node right_node))
         | None, None -> raise Empty_comparison)
         ; diff path f ls
 
 (* copy node paths between trees *)
-let rec clone_path ?(with_children=true) ?(set_values=[]) old_root new_root path_done path_remaining =
+let rec clone_path ?(recurse=true) ?(set_values=None) old_root new_root path_done path_remaining =
     match path_remaining with
     | [] | [_] ->
         let path_total = path_done @ path_remaining in
         let old_node = Vytree.get old_root path_total in
-        let data = if not (set_values = []) then
-            { (data_of old_node) with Config_tree.values = set_values } else (data_of old_node) in
-        if with_children then
+        let data =
+            match set_values with
+            | Some v -> { (data_of old_node) with Config_tree.values = v }
+            | None -> data_of old_node
+        in
+        if recurse then
             Vytree.insert ~children:(children_of old_node) new_root path_total data
         else
             Vytree.insert new_root path_total data
@@ -99,15 +102,15 @@ let rec clone_path ?(with_children=true) ?(set_values=[]) old_root new_root path
         let path_done = path_done @ [name] in
         let old_node = Vytree.get old_root path_done in
         let new_root = Vytree.insert new_root path_done (data_of old_node) in
-        clone_path ~with_children:with_children ~set_values:set_values old_root new_root path_done names
+        clone_path ~recurse:recurse ~set_values:set_values old_root new_root path_done names
 
-let clone ?(with_children=true) ?(set_values=[]) old_root new_root path =
+let clone ?(recurse=true) ?(set_values=None) old_root new_root path =
     match path with
-    | [] -> if with_children then old_root else new_root
+    | [] -> if recurse then old_root else new_root
     | _ ->
             let path_existing = Vytree.get_existent_path new_root path in
             let path_remaining = Vylist.complement path path_existing in
-            clone_path ~with_children:with_children ~set_values:set_values old_root new_root path_existing path_remaining
+            clone_path ~recurse:recurse ~set_values:set_values old_root new_root path_existing path_remaining
 
 let rec graft_children children stock path =
     match children with
@@ -119,29 +122,54 @@ let rec graft_children children stock path =
 let graft_tree stem stock path =
     graft_children (children_of stem) stock path
 
+let is_empty l = (l = [])
+
 (* define the diff_func; in this instance, we imperatively build the difference trees *)
-let decorate_trees (trees : diff_trees) ?(with_children=true) (path : string list) (m : change) =
+let decorate_trees (trees : diff_trees) ?(recurse=true) (path : string list) (m : change) =
     match m with
     | Added -> trees.add := clone trees.right !(trees.add) path
-    | Deleted -> trees.del := clone ~with_children:false trees.left !(trees.del) path
-    | Unchanged -> trees.inter := clone ~with_children:with_children trees.left !(trees.inter) path
+    | Subtracted -> trees.sub := clone trees.left !(trees.sub) path
+    | Unchanged -> trees.inter := clone ~recurse:recurse trees.left !(trees.inter) path
     | Updated v ->
             (* if in this case, node at path is guaranteed to exist *)
             let ov = Config_tree.get_values trees.left path in
             match ov, v with
-            | [_], [_] -> trees.del := clone trees.left !(trees.del) path;
+            | [_], [_] -> trees.sub := clone trees.left !(trees.sub) path;
                           trees.add := clone trees.right !(trees.add) path
-            | _, _ -> let ovs = ValueS.of_list ov in
-                      let vs = ValueS.of_list v in
-                      let set_ov = ValueS.elements (ValueS.diff ovs vs) in
-                      let set_v = ValueS.elements (ValueS.diff vs ovs) in
-                      let set_inter = ValueS.elements (ValueS.inter ovs vs) in
-                      if not (set_ov = []) then
-                          trees.del := clone ~set_values:set_ov trees.left !(trees.del) path;
-                      if not (set_v = []) then
-                          trees.add := clone ~set_values:set_v trees.right !(trees.add) path;
-                      if not (set_inter = []) then
-                          trees.inter := clone ~set_values:set_inter trees.left !(trees.inter) path
+            | _, _ -> let ov_set = ValueS.of_list ov in
+                      let v_set = ValueS.of_list v in
+                      let sub_vals = ValueS.elements (ValueS.diff ov_set v_set) in
+                      let add_vals = ValueS.elements (ValueS.diff v_set ov_set) in
+                      let inter_vals = ValueS.elements (ValueS.inter ov_set v_set) in
+                      if not (is_empty sub_vals) then
+                          trees.sub := clone ~set_values:(Some sub_vals) trees.left !(trees.sub) path;
+                      if not (is_empty add_vals) then
+                          trees.add := clone ~set_values:(Some add_vals) trees.right !(trees.add) path;
+                      if not (is_empty inter_vals) then
+                          trees.inter := clone ~set_values:(Some inter_vals) trees.left !(trees.inter) path
+
+let trim_trees (trees : diff_trees) ?(recurse=false) (path : string list) (m : change) =
+    match m with
+    | Added -> ()
+    | Subtracted -> trees.sub := clone ~recurse:recurse ~set_values:(Some []) trees.left !(trees.sub) path
+    | Unchanged -> ()
+    | Updated v ->
+            (* if in this case, node at path is guaranteed to exist *)
+            let ov = Config_tree.get_values trees.left path in
+            match ov, v with
+            | [_], [_] -> trees.sub := clone trees.left !(trees.sub) path;
+            | _, _ -> let ov_set = ValueS.of_list ov in
+                      let v_set = ValueS.of_list v in
+                      let sub_vals = ValueS.elements (ValueS.diff ov_set v_set) in
+                      let add_vals = ValueS.elements (ValueS.diff v_set ov_set) in
+                      (* in practice, the above sets will be disjoint *)
+                      let inter_vals = ValueS.elements (ValueS.inter ov_set v_set) in
+                      if not (is_empty sub_vals) then
+                          if (is_empty add_vals) && (is_empty inter_vals) then
+                              (* delete whole node, not just values *)
+                              trees.sub := clone ~set_values:(Some []) trees.left !(trees.sub) path
+                          else
+                              trees.sub := clone ~set_values:(Some sub_vals) trees.left !(trees.sub) path
 
 (* get sub trees for path-relative comparison *)
 let tree_at_path path node =
@@ -165,10 +193,15 @@ let compare path left right =
 let diff_tree path left right =
     let trees = compare path left right in
     let add_node = Config_tree.make "add" in
-    let del_node = Config_tree.make "delete" in
+    let sub_node = Config_tree.make "sub" in
     let int_node = Config_tree.make "inter" in
-    let ret = make Config_tree.default_data "root" [add_node; del_node; int_node] in
+    let ret = make Config_tree.default_data "root" [add_node; sub_node; int_node] in
     let ret = graft_tree !(trees.add) ret ["add"] in
-    let ret = graft_tree !(trees.del) ret ["delete"] in
+    let ret = graft_tree !(trees.sub) ret ["sub"] in
     let ret = graft_tree !(trees.inter) ret ["inter"] in
     ret
+
+let trim_tree left right =
+    let trees = make_diff_trees left right in
+    diff [] (trim_trees trees) [(Option.some left, Option.some right)];
+    !(trees.sub)
diff --git a/src/config_diff.mli b/src/config_diff.mli
index 5f96209..70fb2e0 100644
--- a/src/config_diff.mli
+++ b/src/config_diff.mli
@@ -1,12 +1,12 @@
-type change = Unchanged | Added | Deleted | Updated of string list
+type change = Unchanged | Added | Subtracted | Updated of string list
 
-type diff_func = ?with_children:bool -> string list -> change -> unit
+type diff_func = ?recurse:bool -> string list -> change -> unit
 
 type diff_trees = {
     left: Config_tree.t;
     right: Config_tree.t;
     add: Config_tree.t ref;
-    del: Config_tree.t ref;
+    sub: Config_tree.t ref;
     inter: Config_tree.t ref;
 }
 
@@ -14,8 +14,10 @@ exception Incommensurable
 exception Empty_comparison
 
 val make_diff_trees : Config_tree.t -> Config_tree.t -> diff_trees
-val clone : ?with_children:bool -> ?set_values:string list -> Config_tree.t -> Config_tree.t -> string list -> Config_tree.t
-val decorate_trees : diff_trees -> ?with_children:bool -> string list -> change -> unit
+val clone : ?recurse:bool -> ?set_values:(string list) option -> Config_tree.t -> Config_tree.t -> string list -> Config_tree.t
+val decorate_trees : diff_trees -> ?recurse:bool -> string list -> change -> unit
+val trim_trees : diff_trees -> ?recurse:bool -> string list -> change -> unit
 val compare : string list -> Config_tree.t -> Config_tree.t -> diff_trees
 val diff_tree : string list -> Config_tree.t -> Config_tree.t -> Config_tree.t
+val trim_tree : Config_tree.t -> Config_tree.t -> Config_tree.t