feat: support variable declaration statement

lib/ast/print.ml

@@ -2,6 +2,15 @@
 
 open Syntax
 
+(** [string_of_type t] returns a string representation of the type [t]. *)
+let string_of_type = function
+  | Type_Integer -> "Type_Integer"
+  | Type_Float -> "Type_Float"
+  | Type_Character -> "Type_Character"
+  | Type_String -> "Type_String"
+  | Type_Boolean -> "Type_Boolean"
+  | Type_Void -> "Type_Void"
+
 (** [string_of_binary_operator op] returns a string representation of the binary operator [op]. *)
 let string_of_binary_operator = function
   | Add -> "Add"
@@ -42,10 +51,18 @@ let rec string_of_expression = function
       ^ string_of_binary_operator op
       ^ ", " ^ string_of_expression e1 ^ ", " ^ string_of_expression e2 ^ ")"
 
+let string_of_variable_declaration = function
+  | VariableDeclaration (t, id, e) ->
+      "VariableDeclaration(" ^ string_of_type t ^ ", " ^ string_of_expression id
+      ^ ", " ^ string_of_expression e ^ ")"
+
 (** [string_of_statement s] returns a string representation of the statement [s]. *)
 let string_of_statement = function
   | ExpressionStatement e ->
       "ExpressionStatement(" ^ string_of_expression e ^ ")"
+  | VariableStatement decls ->
+      let decl_strings = List.map string_of_variable_declaration decls in
+      "VariableStatement([" ^ String.concat ", " decl_strings ^ "])"
 
 (** [string_of_source_file f] returns a string representation of the source file [f]. *)
 let string_of_source_file = function

lib/ast/syntax.ml

@@ -1,5 +1,13 @@
 (* lib/ast/syntax.ml *)
 
+type _type =
+  | Type_Integer
+  | Type_Float
+  | Type_Character
+  | Type_String
+  | Type_Boolean
+  | Type_Void
+
 type literal =
   | Integer of int
   | Float of float
@@ -30,5 +38,11 @@ type expression =
   | UnaryExpression of unary_operator * expression
   | BinaryExpression of binary_operator * expression * expression
 
-type statement = ExpressionStatement of expression
+type variable_declaration =
+  | VariableDeclaration of _type * expression * expression
+
+type statement =
+  | ExpressionStatement of expression
+  | VariableStatement of variable_declaration list
+
 type source_file = SourceFile of statement list