Remove Unix Dependency (rescript-lang#45)

* Revert "Prevent race conditions in Reason -> Res printing."

This reverts commit e78c841.
We do not want to rely on the unix module.

* Document usage of temp file in refmt conversion

Author: IwanKaramazow

syntax/Makefile

@@ -34,7 +34,8 @@ FILES = \
 	src/napkin_reason_binary_driver.cmx \
 	src/napkin_binary_driver.cmx \
 	src/napkin_ast_debugger.cmx \
-	src/napkin_outcome_printer.cmx
+	src/napkin_outcome_printer.cmx \
+	src/napkin_multi_printer.cmx
 
 .DEFAULT_GOAL := build-native
 build-native: lib/refmt.exe $(FILES) src/napkin_main.cmx depend
@@ -59,7 +60,7 @@ benchmarks/refmt_main3b.cmx: benchmarks/refmt_main3b.ml
 	$(OCAMLOPT) -c -O2 -I +compiler-libs ocamlcommon.cmxa benchmarks/refmt_main3b.ml
 
 lib/test.exe: tests/napkin_test.cmx
-	$(OCAMLOPT) $(OCAMLFLAGS) -O2 -o ./lib/test.exe -bin-annot -I +compiler-libs ocamlcommon.cmxa unix.cmxa -I src $(FILES) src/napkin_multi_printer.cmx tests/napkin_test.ml
+	$(OCAMLOPT) $(OCAMLFLAGS) -O2 -o ./lib/test.exe -bin-annot -I +compiler-libs ocamlcommon.cmxa -I src $(FILES) tests/napkin_test.ml
 
 test: build-native lib/test.exe
 	./node_modules/.bin/jest

syntax/src/napkin_io.ml

@@ -31,3 +31,9 @@ let readStdin () =
     )
   in
   loop ()
+
+let writeFile ~filename ~content =
+  let chan = open_out_bin filename in
+  output_string chan content;
+  close_out chan
+[@@raises Sys_error]

syntax/src/napkin_io.mli

@@ -5,3 +5,6 @@ val readFile: filename: string -> string
 
 (* read the contents of stdin into a string*)
 val readStdin: unit -> string
+
+(* writes "content" into file with name "filename" *)
+val writeFile: filename: string -> content: string -> unit

syntax/src/napkin_multi_printer.ml

@@ -54,60 +54,67 @@ let printMl ~isInterface ~filename =
       parseResult.parsetree
 
 (* How does printing Reason to Res work?
- * -> Run refmt in parallel with the program,
- *    the standard input and standard output of the refmt command are redirected
- *    to pipes connected to the two returned channels
- * -> Read the source code of "filename"
- * -> Write the source code to output channel (i.e. the input of refmt)
- * -> Read the marshalled ast from the input channel (i.e. the output of refmt)
+ * -> open a tempfile
+ * -> write the source code found in "filename" into the tempfile
+ * -> run refmt in-place in binary mode on the tempfile,
+ *    mutates contents tempfile with marshalled AST.j
+ * -> read the marshalled ast (from the binary output in the tempfile)
  * -> re-read the original "filename" and extract string + comment data
  * -> put the comment- and string data back into the unmarshalled parsetree
- * -> normalize the ast to conform to the napkin printer
  * -> pretty print to res
  * -> take a deep breath and exhale slowly *)
 let printReason ~refmtPath ~isInterface ~filename =
-  (* Run refmt in parallel with the program *)
-  let refmtCmd = Printf.sprintf "%s --print=binary --interface=%b" refmtPath isInterface in
-  let (refmtOutput, refmtInput) = Unix.open_process refmtCmd in
-  (* Read the source code of "filename" *)
-  let source = IO.readFile ~filename in
-  (* Write the source code to output channel (i.e. the input of refmt) *)
-  output_string refmtInput source;
-  close_out refmtInput;
-  (* Read the marshalled ast from the input channel (i.e. the output of refmt) *)
-  let magic = if isInterface then Config.ast_intf_magic_number else Config.ast_impl_magic_number in
-  ignore ((really_input_string [@doesNotRaise]) refmtOutput (String.length magic));
-  ignore (input_value refmtOutput);
-  let ast = input_value refmtOutput in
-  close_in refmtOutput;
-  (* re-read the original "filename" and extract string + comment data *)
-  let (comments, stringData) = Napkin_reason_binary_driver.extractConcreteSyntax filename in
-  if isInterface then
-    let ast = ast
+  (* open a tempfile *)
+  let (tempFilename, chan) =
+    (* refmt is just a prefix, `open_temp_file` takes care of providing a random name
+     * It tries 1000 times in the case of a name conflict.
+     * In practise this means that we shouldn't worry too much about filesystem races *)
+    Filename.open_temp_file "refmt" (if isInterface then ".rei" else ".re") in
+  close_out chan;
+  (* Write the source code found in "filename" into the tempfile *)
+  IO.writeFile ~filename:tempFilename ~content:(IO.readFile ~filename);
+  let cmd = Printf.sprintf "%s --print=binary --in-place --interface=%b %s" refmtPath isInterface tempFilename in
+  (* run refmt in-place in binary mode on the tempfile *)
+  ignore (Sys.command cmd);
+  let result =
+    if isInterface then
+      let parseResult =
+        (* read the marshalled ast (from the binary output in the tempfile) *)
+        Napkin_reason_binary_driver.parsingEngine.parseInterface ~forPrinter:true ~filename:tempFilename in
+      (* re-read the original "filename" and extract string + comment data *)
+      let (comments, stringData) = Napkin_reason_binary_driver.extractConcreteSyntax filename in
       (* put the comment- and string data back into the unmarshalled parsetree *)
-      |> Napkin_ast_conversion.replaceStringLiteralSignature stringData
-      (* normalize the ast to conform to the napkin printer *)
-      |> Napkin_ast_conversion.normalizeReasonAritySignature ~forPrinter:true
-      |> Napkin_ast_conversion.signature
-    in
-    (* pretty print to res *)
-    Napkin_printer.printInterface
-      ~width:defaultPrintWidth
-      ~comments:comments
-      ast
-  else
-    let ast = ast
+      let parseResult = {
+        parseResult with
+        parsetree =
+          parseResult.parsetree |> Napkin_ast_conversion.replaceStringLiteralSignature stringData;
+        comments = comments;
+      } in
+      (* pretty print to res *)
+      Napkin_printer.printInterface
+        ~width:defaultPrintWidth
+        ~comments:parseResult.comments
+        parseResult.parsetree
+    else
+      let parseResult =
+        (* read the marshalled ast (from the binary output in the tempfile) *)
+        Napkin_reason_binary_driver.parsingEngine.parseImplementation ~forPrinter:true ~filename:tempFilename in
+      let (comments, stringData) = Napkin_reason_binary_driver.extractConcreteSyntax filename in
       (* put the comment- and string data back into the unmarshalled parsetree *)
-      |> Napkin_ast_conversion.replaceStringLiteralStructure stringData
-      (* normalize the ast to conform to the napkin printer *)
-      |> Napkin_ast_conversion.normalizeReasonArityStructure ~forPrinter:true
-      |> Napkin_ast_conversion.structure
-    in
-    (* pretty print to res *)
-    Napkin_printer.printImplementation
-      ~width:defaultPrintWidth
-      ~comments:comments
-      ast
+      let parseResult = {
+        parseResult with
+        parsetree =
+          parseResult.parsetree |> Napkin_ast_conversion.replaceStringLiteralStructure stringData;
+        comments = comments;
+      } in
+      (* pretty print to res *)
+      Napkin_printer.printImplementation
+        ~width:defaultPrintWidth
+        ~comments:parseResult.comments
+        parseResult.parsetree
+  in
+  Sys.remove tempFilename;
+  result
 [@@raises Sys_error]
 
 (* print the given file named input to from "language" to res, general interface exposed by the compiler *)