step

bin/main.ml

@@ -1,11 +1,5 @@
 type generator = Json | C
 
-let read_file path =
-	let ic = open_in_bin path in
-	Fun.protect
-		~finally:(fun () -> close_in ic)
-		(fun () -> really_input_string ic (in_channel_length ic))
-
 let write_file path content =
 	let oc = open_out_bin path in
 	Fun.protect
@@ -36,14 +30,8 @@ let () =
 		prerr_endline "Missing required --input argument.";
 		Arg.usage specs usage;
 		exit 2);
-	let src =
-		try read_file !input_path
-		with Sys_error msg ->
-			prerr_endline ("Input error: " ^ msg);
-			exit 1
-	in
 	let ast =
-		match Spooky.parse_string src with
+		match Spooky.parse_file !input_path with
 		| Error msg ->
 				prerr_endline msg;
 				exit 1

examples/modules/math.spooky

@@ -0,0 +1,3 @@
+int add(int a, int b) {
+  return a + b;
+}

examples/modules/types.spooky

@@ -0,0 +1,4 @@
+struct Point {
+  int x;
+  int y;
+};

examples/with_imports.spooky

@@ -0,0 +1,9 @@
+import "modules/types.spooky";
+import "modules/math.spooky";
+
+int main() {
+  struct Point p;
+  p.x = 1;
+  p.y = 2;
+  return add(p.x, p.y);
+}

lib/module_system.ml

@@ -0,0 +1,79 @@
+module StringSet = Set.Make (String)
+
+let starts_with ~prefix s =
+  let lp = String.length prefix in
+  String.length s >= lp && String.sub s 0 lp = prefix
+
+let trim = String.trim
+
+let parse_import_line line =
+  let t = trim line in
+  if not (starts_with ~prefix:"import" t) then None
+  else
+    let rest = trim (String.sub t 6 (String.length t - 6)) in
+    if String.length rest < 2 || rest.[0] <> '"' then
+      Some (Error ("malformed import: " ^ line))
+    else
+      try
+        let q2 = String.index_from rest 1 '"' in
+        let path = String.sub rest 1 (q2 - 1) in
+        let tail = trim (String.sub rest (q2 + 1) (String.length rest - q2 - 1)) in
+        let valid_tail =
+          String.equal tail ";"
+          || String.equal tail ""
+          || (starts_with ~prefix:";" tail && starts_with ~prefix:"//" (trim (String.sub tail 1 (String.length tail - 1))))
+        in
+        if not valid_tail then Some (Error ("malformed import terminator: " ^ line)) else Some (Ok path)
+      with Not_found -> Some (Error ("unterminated import string: " ^ line))
+
+let read_file path =
+  let ic = open_in_bin path in
+  Fun.protect
+    ~finally:(fun () -> close_in ic)
+    (fun () -> really_input_string ic (in_channel_length ic))
+
+let resolve_path ~from_dir p = if Filename.is_relative p then Filename.concat from_dir p else p
+
+let load_source_with_imports entry_path =
+  let rec load_file stack visited path =
+    if List.mem path stack then
+      Error ("import cycle detected at: " ^ path)
+    else if StringSet.mem path visited then Ok (visited, "")
+    else
+      let content =
+        try Ok (read_file path) with Sys_error msg -> Error ("cannot read " ^ path ^ ": " ^ msg)
+      in
+      match content with
+      | Error _ as e -> e
+      | Ok content ->
+          let dir = Filename.dirname path in
+          let lines = String.split_on_char '\n' content in
+          let rec scan imports body = function
+            | [] -> Ok (List.rev imports, List.rev body)
+            | ln :: tl ->
+                (match parse_import_line ln with
+                | None -> scan imports (ln :: body) tl
+                | Some (Ok p) -> scan (p :: imports) body tl
+                | Some (Error e) -> Error e)
+          in
+          (match scan [] [] lines with
+          | Error _ as e -> e
+          | Ok (imports, body_lines) ->
+              let rec load_imports vis acc = function
+                | [] -> Ok (vis, List.rev acc)
+                | imp :: tl ->
+                    let resolved = resolve_path ~from_dir:dir imp in
+                    (match load_file (path :: stack) vis resolved with
+                    | Error _ as e -> e
+                    | Ok (vis', src) -> load_imports vis' (src :: acc) tl)
+              in
+              match load_imports visited [] imports with
+              | Error _ as e -> e
+              | Ok (visited', imported_sources) ->
+                  let self_src = String.concat "\n" body_lines in
+                  let full = String.concat "\n" (imported_sources @ [ self_src ]) in
+                  Ok (StringSet.add path visited', full))
+  in
+  match load_file [] StringSet.empty entry_path with
+  | Error _ as e -> e
+  | Ok (_, src) -> Ok src

lib/module_system.mli

@@ -0,0 +1 @@
+val load_source_with_imports : string -> (string, string) result

lib/spooky.ml

@@ -4,12 +4,19 @@ module Parser = Parser
 module Typechecker = Typechecker
 module Generator_json = Generator_json
 module Generator_c = Generator_c
+module Module_system = Module_system
 
 type program = Ast.program
 
 let parse_string = Parser.parse_string
 let string_of_program = Ast.string_of_program
 let type_check = Typechecker.type_check
+let load_source_with_imports = Module_system.load_source_with_imports
+
+let parse_file path =
+  match load_source_with_imports path with
+  | Error e -> Error e
+  | Ok src -> parse_string src
 
 let parse_and_type_check src =
   match parse_string src with
@@ -19,5 +26,13 @@ let parse_and_type_check src =
       | Ok () -> Ok prog
       | Error e -> Error ("type error: " ^ e))
 
+let parse_and_type_check_file path =
+  match parse_file path with
+  | Error e -> Error e
+  | Ok prog ->
+      (match type_check prog with
+      | Ok () -> Ok prog
+      | Error e -> Error ("type error: " ^ e))
+
 let generate_json = Generator_json.generate
 let generate_c = Generator_c.generate

lib/spooky.mli

@@ -4,12 +4,16 @@ module Parser = Parser
 module Typechecker = Typechecker
 module Generator_json = Generator_json
 module Generator_c = Generator_c
+module Module_system = Module_system
 
 type program = Ast.program
 
 val parse_string : string -> (program, string) result
+val load_source_with_imports : string -> (string, string) result
+val parse_file : string -> (program, string) result
 val string_of_program : program -> string
 val type_check : program -> (unit, string) result
 val parse_and_type_check : string -> (program, string) result
+val parse_and_type_check_file : string -> (program, string) result
 val generate_json : program -> string
 val generate_c : program -> string

test/dune

@@ -1,3 +1,3 @@
 (test
  (name test_spooky)
- (libraries spooky))
+ (libraries spooky unix))

test/test_spooky.ml

@@ -46,7 +46,34 @@ let test_invalid_program () =
 	| Ok _ -> failwith "expected type error, but got success"
 	| Error _ -> ()
 
+let write_file path content =
+	let oc = open_out_bin path in
+	Fun.protect ~finally:(fun () -> close_out oc) (fun () -> output_string oc content)
+
+let test_imports () =
+	let base = Filename.concat (Filename.get_temp_dir_name ()) "spooky_import_test" in
+	let modules_dir = Filename.concat base "modules" in
+	Unix.mkdir base 0o755;
+	Unix.mkdir modules_dir 0o755;
+	let cleanup () =
+		(try Sys.remove (Filename.concat modules_dir "math.spooky") with _ -> ());
+		(try Sys.remove (Filename.concat base "main.spooky") with _ -> ());
+		(try Unix.rmdir modules_dir with _ -> ());
+		(try Unix.rmdir base with _ -> ())
+	in
+	Fun.protect
+		~finally:cleanup
+		(fun () ->
+			write_file (Filename.concat modules_dir "math.spooky")
+				"int add(int a, int b) { return a + b; }\n";
+			write_file (Filename.concat base "main.spooky")
+				"import \"modules/math.spooky\";\nint main() { return add(1, 2); }\n";
+			match Spooky.parse_and_type_check_file (Filename.concat base "main.spooky") with
+			| Ok _ -> ()
+			| Error msg -> failwith ("expected valid import program, got: " ^ msg))
+
 let () =
 	test_valid_program ();
 	test_invalid_program ();
+	test_imports ();
 	print_endline "All parser/type-check tests passed."