[interpreter] Change how wast.js is built by using Js_of_ocaml

interpreter/Makefile

@@ -109,12 +109,9 @@ _build/$(LIB).cmxa: $(FILES) $(LIB).mllib _tags Makefile
 # Building JavaScript library
 
 .PHONY:		$(JSLIB)
-$(JSLIB):	$(UNOPT)
-		mkdir -p _build/jslib/src
-		cp meta/jslib/* _build/jslib
-		cp $(DIRS:%=_build/%/*.ml*) meta/jslib/*.ml _build/jslib/src
-		rm _build/jslib/src/*.ml[^i]
-		(cd _build/jslib; ./build.sh ../../$@)
+$(JSLIB):
+		dune build wast.bc.js
+		cp ../_build/default/interpreter/wast.bc.js ./wast.js
 
 
 # Building Windows build file

interpreter/dune

@@ -7,7 +7,7 @@
  ; We also need to exclude the 'wasm' module as it overlaps with the library
  ; name.
  ; 'smallint' is a separate test module.
- (modules :standard \ main wasm smallint))
+ (modules :standard \ main wasm smallint wast))
 
 (executable
  (name main)
@@ -23,6 +23,16 @@
  (flags
   (-open Wasm)))
 
+(executable
+ (name wast)
+ (modules wast)
+ (libraries wasm js_of_ocaml)
+ (flags
+  (-open Wasm))
+ (optional)
+ (modes js)
+ (preprocess (pps js_of_ocaml-ppx)))
+
 (subdir
  text
  (rule

interpreter/meta/jslib/wast.ml

@@ -0,0 +1,25 @@
+open Js_of_ocaml
+
+let decode (buf : Typed_array.arrayBuffer Js.t) width : (Js.js_string Js.t) =
+  let s = Typed_array.String.of_uint8Array (new%js Typed_array.uint8Array_fromBuffer buf) in
+  let m = Decode.decode "(decode)" s in
+  Js.string (Sexpr.to_string width (Arrange.module_ m))
+
+let _ =
+  Js.export "WebAssemblyText"
+    (object%js (_self)
+
+      method encode (s : Js.js_string Js.t) : (Typed_array.arrayBuffer Js.t) =
+        let def = Parse.string_to_module (Js.to_string s) in
+        let bs =
+          match def.Source.it with
+          | Script.Textual m -> (Encode.encode m)
+          | Script.Encoded (_, bs) -> bs in
+        let buf = new%js Typed_array.arrayBuffer (String.length bs) in
+        let u8arr = new%js Typed_array.uint8Array_fromBuffer buf in
+        String.iteri (fun i c -> Typed_array.set u8arr i (int_of_char c)) bs; buf
+
+      method decode buf = decode buf 80
+      method decode2 buf width = decode buf width
+
+    end)