3 files changed, 38 insertions, 2 deletions
diff --git a/lib/syntax/t.ml b/lib/syntax/t.ml
index cb9c7ce..882a375 100644
--- a/lib/syntax/t.ml
+++ b/lib/syntax/t.ml
@@ -7,6 +7,13 @@ type 'a literal = Text of string | Expression of 'a
 let map_litteral : f:('a -> 'b) -> 'a literal -> 'b literal =
  fun ~f -> function Text t -> Text t | Expression e -> Expression (f e)
 
+let eq_literal : eq:('a -> 'a -> bool) -> 'a literal -> 'a literal -> bool =
+ fun ~eq l1 l2 ->
+  match (l1, l2) with
+  | Text s1, Text s2 -> String.equal s1 s2
+  | Expression e1, Expression e2 -> eq e1 e2
+  | _ -> false
+
 type boperator =
   | Eq
   | Neq
diff --git a/lib/syntax/tree.ml b/lib/syntax/tree.ml
index b7d9d15..72ae754 100644
--- a/lib/syntax/tree.ml
+++ b/lib/syntax/tree.ml
@@ -45,10 +45,31 @@ module Ast = struct
 end
 
 (** Default implementation for the expression *)
-module Expression : S.Expression with type t' = S.pos Ast.expression = struct
+module Expression : sig
+  include S.Expression with type t' = S.pos Ast.expression
+
+  val eq : (S.pos -> S.pos -> bool) -> t -> t -> bool
+  val hash : (S.pos -> int) -> t -> int
+end = struct
   type t = S.pos Ast.expression
   type t' = t
 
+  let eq : (S.pos -> S.pos -> bool) -> t -> t -> bool = Ast.equal_expression
+
+  let rec hash : (S.pos -> int) -> t -> int =
+   fun f -> function
+    | Integer (pos, v) -> Hashtbl.hash (f pos, v)
+    | Literal (pos, l) ->
+        let litt = List.map ~f:(T.map_litteral ~f:(hash f)) l in
+        Hashtbl.hash (f pos, litt)
+    | Ident { pos; name; index } ->
+        Hashtbl.hash (f pos, name, Option.map (hash f) index)
+    | BinaryOp (pos, op, o1, o2) ->
+        Hashtbl.hash (f pos, op, hash f o1, hash f o2)
+    | Op (pos, op, o1) -> Hashtbl.hash (f pos, op, hash f o1)
+    | Function (pos, name, args) ->
+        Hashtbl.hash (f pos, name, List.map ~f:(hash f) args)
+
   let v : t -> t' = fun t -> t
   let integer : S.pos -> string -> t = fun pos i -> Ast.Integer (pos, i)
 
diff --git a/lib/syntax/tree.mli b/lib/syntax/tree.mli
index 8ce577e..a82c07c 100644
--- a/lib/syntax/tree.mli
+++ b/lib/syntax/tree.mli
@@ -43,9 +43,17 @@ module Ast : sig
   [@@deriving eq, show]
 end
 
+(** Extend the default Expression module with an eq operator *)
+module Expression : sig
+  include S.Expression with type t' = S.pos Ast.expression
+
+  val eq : (S.pos -> S.pos -> bool) -> t -> t -> bool
+  val hash : (S.pos -> int) -> t -> int
+end
+
 include
   S.Analyzer
-    with type Expression.t' = S.pos Ast.expression
+    with module Expression := Expression
      and type Instruction.t' = S.pos Ast.statement
      and type Location.t = S.pos * S.pos Ast.statement list
      and type context = unit