Add ocamllex (.mll) file formatting support

.ocamlformat-ignore

@@ -1 +1,3 @@
 vendor/**
+opam-files/**
+opam-files-mll/**

dune-project

@@ -1,4 +1,4 @@
-(lang dune 2.8)
+(lang dune 3.13)
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;                                                                        ;
@@ -13,7 +13,7 @@
 
 (name ocamlformat)
 
-(using menhir 2.1)
+(using menhir 3.0)
 
 (cram enable)
 

lib/Cmts.ml

@@ -454,36 +454,40 @@ let is_only_whitespaces s = String.for_all s ~f:Char.is_whitespace
 module Wrapped = struct
   let fmt ~pro ~epi text =
     let open Fmt in
-    assert (not (String.is_empty text)) ;
-    let prefix = if String.starts_with_whitespace text then " " else ""
-    and suffix = if String.ends_with_whitespace text then " " else "" in
-    let fmt_line line =
-      let words =
-        List.filter ~f:(Fn.non String.is_empty)
-          (String.split_on_chars line
-             ~on:['\t'; '\n'; '\011'; '\012'; '\r'; ' '] )
+    if String.is_empty text then pro $ epi
+    else
+      let prefix = if String.starts_with_whitespace text then " " else ""
+      and suffix = if String.ends_with_whitespace text then " " else "" in
+      let fmt_line line =
+        let words =
+          List.filter ~f:(Fn.non String.is_empty)
+            (String.split_on_chars line
+               ~on:['\t'; '\n'; '\011'; '\012'; '\r'; ' '] )
+        in
+        list words space_break str
       in
-      list words space_break str
-    in
-    let lines =
-      List.remove_consecutive_duplicates
-        ~equal:(fun x y -> String.is_empty x && String.is_empty y)
-        (String.split (String.rstrip text) ~on:'\n')
-    in
-    let groups =
-      List.group lines ~break:(fun _ y -> is_only_whitespaces y)
-    in
-    pro $ str prefix
-    $ hovbox 0
-        (list_fl groups (fun ~first ~last:last_group group ->
-             let group = List.filter group ~f:(Fn.non is_only_whitespaces) in
-             fmt_if (not first) (str "\n" $ force_newline)
-             $ hovbox 0
-                 (list_fl group (fun ~first ~last x ->
-                      fmt_if (not first) space_break
-                      $ fmt_line x
-                      $ fmt_if (last_group && last) (str suffix $ epi) ) ) )
-        )
+      let lines =
+        List.remove_consecutive_duplicates
+          ~equal:(fun x y -> String.is_empty x && String.is_empty y)
+          (String.split (String.rstrip text) ~on:'\n')
+      in
+      let groups =
+        List.group lines ~break:(fun _ y -> is_only_whitespaces y)
+        |> List.filter_map ~f:(fun group ->
+            match List.filter group ~f:(Fn.non is_only_whitespaces) with
+            | [] -> None
+            | group -> Some group )
+      in
+      pro $ str prefix
+      $ hovbox 0
+          (list_fl groups (fun ~first ~last:last_group group ->
+               fmt_if (not first) (str "\n" $ force_newline)
+               $ hovbox 0
+                   (list_fl group (fun ~first ~last x ->
+                        fmt_if (not first) space_break
+                        $ fmt_line x
+                        $ fmt_if (last_group && last) (str suffix $ epi) ) ) )
+          )
 end
 
 module Asterisk_prefixed = struct

lib/Conf.ml

@@ -111,6 +111,7 @@ let conventional_profile from =
   ; stritem_extension_indent= elt 0
   ; type_decl= elt `Compact
   ; type_decl_indent= elt 2
+  ; reformat_mll= elt `Ocaml_block
   ; wrap_comments= elt false
   ; wrap_docstrings= elt true
   ; wrap_fun_args= elt true }
@@ -182,6 +183,7 @@ let ocamlformat_profile from =
   ; stritem_extension_indent= elt 0
   ; type_decl= elt `Compact
   ; type_decl_indent= elt 2
+  ; reformat_mll= elt `Ocaml_block
   ; wrap_comments= elt false
   ; wrap_docstrings= elt true
   ; wrap_fun_args= elt true }
@@ -252,6 +254,7 @@ let janestreet_profile from =
   ; stritem_extension_indent= elt 2
   ; type_decl= elt `Sparse
   ; type_decl_indent= elt 2
+  ; reformat_mll= elt `Ocaml_block
   ; wrap_comments= elt false
   ; wrap_docstrings= elt false
   ; wrap_fun_args= elt false }
@@ -1323,6 +1326,22 @@ module Formatting = struct
         update conf ~f:(fun f -> {f with type_decl_indent= elt}) )
       (fun conf -> conf.fmt_opts.type_decl_indent)
 
+  let reformat_mll =
+    let doc = "How to format .mll (ocamllex) files." in
+    let names = ["reformat-mll"] in
+    let all =
+      [ Decl.Value.make ~name:"ocaml-block" `Ocaml_block
+          "$(b,ocaml-block) formats only the embedded OCaml code blocks, \
+           preserving surrounding syntax and comments."
+      ; Decl.Value.make ~name:"full" `Full
+          "$(b,full) reformats the entire .mll file structure."
+      ; Decl.Value.make ~name:"no" `No
+          "$(b,no) disables formatting of .mll files." ]
+    in
+    Decl.choice ~names ~all ~default ~doc ~kind
+      (fun conf elt -> update conf ~f:(fun f -> {f with reformat_mll= elt}))
+      (fun conf -> conf.fmt_opts.reformat_mll)
+
   let wrap_comments =
     let doc =
       "Comments are divided into paragraphs by open lines (two or more \
@@ -1395,6 +1414,7 @@ module Formatting = struct
       ; elt parens_tuple_patterns
       ; elt parse_docstrings
       ; elt parse_toplevel_phrases
+      ; elt reformat_mll
       ; elt sequence_blank_line
       ; elt sequence_style
       ; elt single_case

lib/Conf_t.ml

@@ -119,6 +119,7 @@ type fmt_opts =
   ; stritem_extension_indent: int elt
   ; type_decl: [`Compact | `Sparse] elt
   ; type_decl_indent: int elt
+  ; reformat_mll: [`No | `Ocaml_block | `Full] elt
   ; wrap_comments: bool elt
   ; wrap_docstrings: bool elt
   ; wrap_fun_args: bool elt }

lib/Conf_t.mli

@@ -117,6 +117,8 @@ type fmt_opts =
   ; stritem_extension_indent: int elt
   ; type_decl: [`Compact | `Sparse] elt
   ; type_decl_indent: int elt
+  ; reformat_mll: [`No | `Ocaml_block | `Full] elt
+        (** How to format .mll files. *)
   ; wrap_comments: bool elt  (** Wrap comments at margin. *)
   ; wrap_docstrings: bool elt
   ; wrap_fun_args: bool elt }