Translate 'Lwt_io.read' without '~count'

Author: Julow

bin/lwt_to_direct_style/ast_rewrite.ml

@@ -160,6 +160,11 @@ let lwt_io_open ~backend ~state ~mode src =
          [Lwt_io.output].";
       None
 
+let lwt_io_read ~backend ~state:_ count in_chan =
+  match count with
+  | Some count_arg -> backend#io_read_string_count in_chan count_arg
+  | None -> Some (backend#io_read_all in_chan)
+
 let mk_cstr c = Some (mk_constr_exp [ c ])
 
 (* Rewrite calls to functions from the [Lwt] module. See [rewrite_apply] for
@@ -371,6 +376,9 @@ let rewrite_apply ~backend ~state full_ident args =
       return (lwt_io_open ~backend ~state ~mode (`Fname fname))
   | "Lwt_io", "read_line" ->
       take @@ fun in_chan -> return (Some (backend#io_read_line in_chan))
+  | "Lwt_io", "read" ->
+      take_lblopt "count" @@ fun count ->
+      take @@ fun in_chan -> return (lwt_io_read ~backend ~state count in_chan)
   | "Lwt_io", "write" ->
       take @@ fun chan ->
       take @@ fun str -> return (Some (backend#io_write_str chan str))

bin/lwt_to_direct_style/concurrency_backend.ml

@@ -219,6 +219,16 @@ let eio ~eio_sw_as_fiber_var ~eio_env_as_fiber_var add_comment =
       add_comment_dropped_exp ~label:"buffer length" buf_len;
       mk_apply_simple [ "Eio"; "Flow"; "single_read" ] [ input; buffer ]
 
+    method io_read_all input =
+      mk_apply_simple [ "Eio"; "Buf_read"; "take_all" ] [ input ]
+
+    method io_read_string_count _input _count_arg =
+      add_comment
+        "Eio doesn't have a direct equivalent of [Lwt_io.read ~count]. Rewrite \
+         the code using [Eio.Buf_read]'s lower level API or switch to \
+         unbuffered IO.";
+      None
+
     method fd_close fd =
       (* TODO: See [of_unix_file_descr]. mk_apply_simple [ "Eio_unix"; "Fd" ] [ fd ] *)
       mk_apply_simple [ "Unix"; "close" ] [ fd ]

test/lwt_to_direct_style/eio-switch.t/run.t

@@ -5,8 +5,7 @@ Make a writable directory tree:
   $ dune build @ocaml-index
   $ lwt-to-direct-style --migrate --eio-sw-as-fiber-var Fiber_var.sw --eio-env-as-fiber-var Fiber_var.env
   Formatted 1 files
-  Warning: main.ml: 2 occurrences have not been rewritten.
-    Lwt_io.read (line 15 column 12)
+  Warning: main.ml: 1 occurrences have not been rewritten.
     Lwt_io.printf (line 16 column 3)
 
   $ cat main.ml
@@ -39,7 +38,7 @@ Make a writable directory tree:
            ~close_unix:true fd
           : [ `R | `Flow | `Close ] r)
     in
-    let s = Lwt_io.read in_chan in
+    let s = Eio.Buf_read.take_all in_chan in
     Lwt_io.printf "%s" s
   
   let () =

test/lwt_to_direct_style/to_direct_style.t/run.t

@@ -228,7 +228,7 @@ Make a writable directory tree:
     Lwt_mutex.lock (line 136 column 9)
     Lwt_mutex.unlock (line 137 column 9)
     Lwt_mutex.with_lock (line 138 column 9)
-  lib/test_lwt_unix.ml: (35 occurrences)
+  lib/test_lwt_unix.ml: (38 occurrences)
     Lwt_io (line 7 column 8)
     Lwt.return (line 11 column 3)
     Lwt.let* (line 10 column 3)
@@ -248,6 +248,9 @@ Make a writable directory tree:
     Lwt_io.of_fd (line 22 column 13)
     Lwt_io.of_fd (line 23 column 13)
     Lwt_io.read_line (line 28 column 15)
+    Lwt_io.read (line 41 column 15)
+    Lwt_io.read (line 42 column 15)
+    Lwt_io.read (line 43 column 15)
     Lwt_io.read_into (line 10 column 19)
     Lwt_io.write (line 24 column 19)
     Lwt_io.length (line 36 column 3)
@@ -294,8 +297,10 @@ Make a writable directory tree:
     Lwt.Fail (line 147 column 5)
     Lwt.let* (line 163 column 21)
     Lwt.Fail (line 179 column 9)
-  Warning: lib/test_lwt_unix.ml: 1 occurrences have not been rewritten.
+  Warning: lib/test_lwt_unix.ml: 3 occurrences have not been rewritten.
     Lwt_io.stdout (line 26 column 33)
+    Lwt_io.read (line 42 column 15)
+    Lwt_io.read (line 43 column 15)
   Warning: lib/test.mli: 2 occurrences have not been rewritten.
     Lwt_mutex.t (line 2 column 10)
     Lwt_mutex.t (line 3 column 10)
@@ -772,3 +777,17 @@ Make a writable directory tree:
       (Eio.Path.( / ) env#cwd
          (* TODO: lwt-to-direct-style: [env] must be propagated from the main loop *)
          fname)
+  
+  let _f chan = Eio.Buf_read.take_all chan
+  
+  let _f chan =
+    Lwt_io.read
+    (* TODO: lwt-to-direct-style: Eio doesn't have a direct equivalent of [Lwt_io.read ~count]. Rewrite the code using [Eio.Buf_read]'s lower level API or switch to unbuffered IO. *)
+    (* TODO: lwt-to-direct-style: Eio doesn't have a direct equivalent of [Lwt_io.read ~count]. Rewrite the code using [Eio.Buf_read]'s lower level API or switch to unbuffered IO. *)
+      ~count:42 chan
+  
+  let _f chan =
+    Lwt_io.read
+    (* TODO: lwt-to-direct-style: Eio doesn't have a direct equivalent of [Lwt_io.read ~count]. Rewrite the code using [Eio.Buf_read]'s lower level API or switch to unbuffered IO. *)
+    (* TODO: lwt-to-direct-style: Eio doesn't have a direct equivalent of [Lwt_io.read ~count]. Rewrite the code using [Eio.Buf_read]'s lower level API or switch to unbuffered IO. *)
+      ?count:(Some 42) chan

test/lwt_to_direct_style/to_direct_style.t/src/lib/test_lwt_unix.ml

@@ -37,3 +37,7 @@ let _f fname =
 
 let _f fname = Lwt_unix.stat fname
 let _f fname = Lwt_unix.lstat fname
+
+let _f chan = Lwt_io.read chan
+let _f chan = Lwt_io.read ~count:42 chan
+let _f chan = Lwt_io.read ?count:(Some 42) chan