add -o option to emit .wat files

src/bin/owi.ml

@@ -39,6 +39,10 @@ let files =
   let f = existing_non_dir_file in
   Cmdliner.Arg.(value & pos_all f [] (info [] ~doc))
 
+let emit_files =
+  let doc = "emit (.wat) files from corresponding (.wasm) files" in
+  Cmdliner.Arg.(value & flag & info [ "o" ] ~doc)
+
 let no_exhaustion =
   let doc = "no exhaustion tests" in
   Cmdliner.Arg.(value & flag & info [ "no-exhaustion" ] ~doc)
@@ -245,7 +249,7 @@ let wasm2wat_cmd =
     let man = [] @ shared_man in
     Cmd.info "wasm2wat" ~version ~doc ~sdocs ~man
   in
-  Cmd.v info Term.(const Cmd_wasm2wat.cmd $ files)
+  Cmd.v info Term.(const Cmd_wasm2wat.cmd $ files $ emit_files)
 
 let wat2wasm_cmd =
   let open Cmdliner in

src/cmd/cmd_wasm2wat.ml

@@ -4,13 +4,19 @@
 
 open Syntax
 
-let cmd_one file =
+(* Utility function to handle writing to a file or printing to stdout *)
+
+let cmd_one emitfile file =
   let ext = Fpath.get_ext file in
+  let wat_file = Fpath.set_ext "wat" file in
+
   match ext with
   | ".wasm" ->
     let* m = Parse.Binary.Module.from_file file in
     let m = Binary_to_text.modul m in
-    Ok (Fmt.pr "%a@\n" Text.pp_modul m)
+    let wat_module = Fmt.str "%a@\n" Text.pp_modul m in
+    if emitfile then Bos.OS.File.write wat_file wat_module
+    else Ok (Fmt.pr "%s" wat_module)
   | ext -> Error (`Unsupported_file_extension ext)
 
-let cmd files = list_iter cmd_one files
+let cmd files emitfile = list_iter (cmd_one emitfile) files

src/cmd/cmd_wasm2wat.mli

@@ -2,4 +2,4 @@
 (* Copyright © 2021-2024 OCamlPro *)
 (* Written by the Owi programmers *)
 
-val cmd : Fpath.t list -> unit Result.t
+val cmd : Fpath.t list -> bool -> unit Result.t