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Diffstat (limited to 'src/config_diff.ml')
| -rw-r--r-- | src/config_diff.ml | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/config_diff.ml b/src/config_diff.ml new file mode 100644 index 0000000..604668b --- /dev/null +++ b/src/config_diff.ml @@ -0,0 +1,207 @@ +type change = Unchanged | Added | Subtracted | Updated of string list + +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; + sub: Config_tree.t ref; + inter: Config_tree.t ref; +} + +exception Incommensurable +exception Empty_comparison + +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"); + sub = ref (Config_tree.make "root"); + inter = ref (Config_tree.make "root"); +} + +let name_of n = Vytree.name_of_node n +let data_of n = Vytree.data_of_node n +let children_of n = Vytree.children_of_node n +let make data name children = Vytree.make_full data name children + +let (^~) (node : Config_tree.t) (node' : Config_tree.t) = + name_of node = name_of node' && + (data_of node).values <> (data_of node').values + +let left_opt_pairs n m = + (children_of n) |> List.map (fun x -> + let maybe_node = + (children_of m) |> List.find_opt (fun y -> + name_of y = name_of x) in + (Some x, maybe_node)) + +let right_opt_pairs n m = + (children_of m) |> List.map (fun y -> + let maybe_node = + (children_of n) |> List.find_opt (fun x -> + name_of x = name_of y) in + (maybe_node, Some y)) + +let opt_zip n m = + left_opt_pairs n m @ right_opt_pairs n m |> List.sort_uniq compare + +let get_opt_name left_opt right_opt = + match left_opt, right_opt with + | Some left_node, None -> name_of left_node + | None, Some right_node -> name_of right_node + | Some left_node, Some _ -> name_of left_node + | None, None -> raise Empty_comparison + +let update_path path left_opt right_opt = + let name = get_opt_name left_opt right_opt in + if name = "root" then path + else path @ [name] + +(* tree diff algorithm: walk the tree pair, calling a function of type + diff_func at bifurcation points; f acts as a form of continuation. + The idea of matching on pairs of (node opt) is from + https://github.com/LukeBurgessYeo/tree-diff +*) +let rec diff (path : string list) (f : diff_func) (l : (Config_tree.t option * Config_tree.t option) list) = + match l with + | [] -> () + | (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 Subtracted + | None, Some _ -> f path Added + | Some left_node, Some right_node when left_node = right_node -> + f path Unchanged + | Some left_node, Some right_node when left_node ^~ right_node -> + let values = (data_of right_node).values in + f path (Updated values) + | Some left_node, Some right_node -> + (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 ?(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 = + 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 + | name :: names -> + 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 ~recurse:recurse ~set_values:set_values old_root new_root path_done names + +let clone ?(recurse=true) ?(set_values=None) old_root new_root path = + match path with + | [] -> 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 ~recurse:recurse ~set_values:set_values old_root new_root path_existing path_remaining + +let rec graft_children children stock path = + match children with + | [] -> stock + | x::xs -> + let stock = Vytree.insert ~children:(children_of x) stock (path @ [name_of x]) (data_of x) + in graft_children xs 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) ?(recurse=true) (path : string list) (m : change) = + match m with + | Added -> trees.add := clone trees.right !(trees.add) 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.sub := clone trees.left !(trees.sub) path; + trees.add := clone trees.right !(trees.add) 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 = + try + let node = Vytree.get node path in + make Config_tree.default_data "root" [node] + with Vytree.Nonexistent_path -> raise Empty_comparison + +(* call recursive diff on config_trees with decorate_trees as the diff_func *) +let compare path left right = + if (name_of left) <> (name_of right) then + raise Incommensurable + else + let (left, right) = if not (path = []) then + (tree_at_path path left, tree_at_path path right) else (left, right) in + let trees = make_diff_trees left right in + diff [] (decorate_trees trees) [(Option.some left, Option.some right)]; + trees + +(* wrapper to return diff trees *) +let diff_tree path left right = + let trees = compare path left right in + let add_node = Config_tree.make "add" 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; sub_node; int_node] in + let ret = graft_tree !(trees.add) ret ["add"] 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) |