2 files changed, 58 insertions, 0 deletions
diff --git a/src/session.ml b/src/session.ml
new file mode 100644
index 0000000..5b99a4b
--- /dev/null
+++ b/src/session.ml
@@ -0,0 +1,42 @@
+module CT = Config_tree
+
+type cfg_op =
+    | CfgSet of string list * string option * CT.value_behaviour
+    | CfgDelete of string list * string	option
+
+type session_data = {
+    id: string;
+    running_config: Config_tree.t ref;
+    proposed_config : Config_tree.t ref;
+    reference_tree: Reference_tree.t ref;
+    validators: (string, string) Hashtbl.t;
+    modified: bool;
+    changeset: cfg_op list
+}
+
+let make i c r v = {
+    id = i;
+    running_config = c;
+    proposed_config = c;
+    reference_tree = r;
+    validators = v;
+    modified = false;
+    changeset = []
+}
+
+let set_modified s =
+    if s.modified = true then s
+    else {s with modified = true}
+
+let apply_cfg_op op config =
+    match op with
+    | CfgSet (path, value, value_behaviour) ->
+        CT.set config path value value_behaviour
+    | CfgDelete (path, value) -> 
+        CT.delete config path value
+
+let rec apply_changes changeset config =
+    match changeset with
+    | [] -> config
+    | c :: cs -> apply_changes cs (apply_cfg_op c config)
+
diff --git a/src/session.mli b/src/session.mli
new file mode 100644
index 0000000..51e9292
--- /dev/null
+++ b/src/session.mli
@@ -0,0 +1,16 @@
+type cfg_op =
+    | CfgSet of string list * string option * Config_tree.value_behaviour
+    | CfgDelete of string list * string option
+
+type session_data = {
+    id: string;
+    running_config: Config_tree.t ref;
+    proposed_config: Config_tree.t ref;
+    reference_tree: Reference_tree.t ref;
+    validators: (string, string) Hashtbl.t;
+    modified: bool;
+    changeset: cfg_op list
+}
+
+val make : string -> Config_tree.t ref -> Reference_tree.t ref -> (string, string) Hashtbl.t -> session_data
+