Merge pull request #12 from nberth/remove-weak-fold

Remove fold on ephemerons

src/lsp/cobol_common/srcloc.ml

@@ -374,7 +374,7 @@ let pp_file_loc ppf loc =
 let raw ?(in_area_a = false) ((s, e): lexloc) : srcloc =
   assert Lexing.(s.pos_cnum <= e.pos_cnum);               (* ensure proper use *)
   let loc = Raw (s, e, in_area_a) in
-  if Lexing.(s.pos_fname != e.pos_fname) then
+  if Lexing.(s.pos_fname <> e.pos_fname) then
     Pretty.error
       "%a@\n>> Internal warning in `%s.raw`: file names mismatch (`%s` != `%s`)\
       " pp_srcloc loc __MODULE__ s.pos_fname e.pos_fname;
@@ -402,13 +402,27 @@ let replacement ~old ~new_ ~in_area_a ~replloc : srcloc =
 (*       end *)
 (*   | Cpy {copyloc = {filename; _}; _} -> Some filename *)
 
+(** [may_join_as_single_raw a b] checks whether a lexloc {i l{_ a}} with a a
+    left-hand lexing position [a] and a lexloc {i l{_ b}} with a right-hand
+    position [b], may be joined to form a single raw source location
+    (internal). *)
+let may_join_as_single_raw (a: Lexing.position) (b: Lexing.position) =
+  a.pos_fname = b.pos_fname &&
+  a.pos_lnum  == b.pos_lnum &&           (* ensure we are stay on a single line *)
+  a.pos_cnum  >= b.pos_cnum - 1
+
 (** [concat l1 l2] concatenates two adjacent source locations [l1] and [l2]. *)
 let rec concat: srcloc -> srcloc -> srcloc = fun l1 l2 -> match l1, l2 with
   | Raw (s1, e1, in_area_a),
     Raw (s2, e2, _)
-    when e1.pos_fname = s2.pos_fname && e1.pos_cnum = s2.pos_cnum - 1 ->
+    when may_join_as_single_raw e1 s2 ->
       Raw (s1, e2, in_area_a)
 
+  | Cat { left; right = Raw (s1, e1, in_area_a) },
+    Raw (s2, e2, _)
+    when may_join_as_single_raw e1 s2 ->
+      Cat { left; right = Raw (s1, e2, in_area_a) }
+
   | Cpy { copied = l1; copyloc = c1 },
     Cpy { copied = l2; copyloc = c2 }
     when same_copyloc c1 c2 ->

src/lsp/cobol_parser/parser_engine.ml

@@ -220,7 +220,7 @@ module Make (Config: Cobol_config.T) = struct
 
   (* --- *)
 
-  let do_parse: type m. m state -> _ -> _ * m state =
+  let do_parse: type m. m state -> _ -> _ -> _ * m state =
 
     let rec next_tokens ({ preproc = { tokzr; _ }; _ } as ps) tokens =
       match Tokzr.next_token tokzr tokens with
@@ -424,16 +424,22 @@ module Make (Config: Cobol_config.T) = struct
       Some v, ps
 
     in
-    fun ps c -> normal ps [] c
+    fun ps tokens c -> normal ps tokens c
 
   let parse ?verbose ?show ~recovery
-      (type m) ~(memory: m memory) pp checkpoint
+      (type m) ~(memory: m memory) pp make_checkpoint
     : ('a option, m) output * _ =
     let ps = init_parser ?verbose ?show ~recovery
         ~tokenizer_memory:memory pp in
     let res, ps =
       (* TODO: catch in a deeper context to grab parsed tokens *)
-      try do_parse ps checkpoint with e -> None, add_diag (DIAGS.of_exn e) ps
+      let ps, tokens = produce_tokens ps in
+      let first_pos = match tokens with
+        | [] -> Cobol_preproc.position ps.preproc.pp
+        | t :: _ -> Cobol_common.Srcloc.start_pos ~@t
+      in
+      try do_parse ps tokens (make_checkpoint first_pos)
+      with e -> None, add_diag (DIAGS.of_exn e) ps
     in
     match memory with
     | Amnesic ->
@@ -480,9 +486,8 @@ let parse
                                          init_source_format = source_format}
           in
           let module P = Make (val config) in
-          P.parse ?verbose ?show ~memory ~recovery pp @@
-          Grammar.Incremental.compilation_group @@
-          Cobol_preproc.position pp
+          P.parse ?verbose ?show ~memory ~recovery pp
+          Grammar.Incremental.compilation_group
         end
     in
     {

src/lsp/cobol_preproc/src_overlay.ml

@@ -33,19 +33,26 @@ module Limit = struct
   type t = limit
 
   let make_virtual: unit -> t =
-    let id = ref 0 in
+    let id = ref (-1) in (* Actually start at -2 (-1 is used in Lexing.dummy) *)
     fun () ->
       decr id;
-      Lexing.{ dummy_pos with pos_lnum = !id }
+      Lexing.{ dummy_pos with pos_cnum = !id }
 
-  let is_virtual: t -> bool =
-    fun l -> l.Lexing.pos_lnum < 0
+  let is_virtual (l: t) : bool =
+    l.pos_cnum < (-1)
 
-  (* Structural equality is required below, to deal with cases where we
-     construct the limits of a token several times, for instance at the
-     beginning of recovery. *)
-  let equal = (=)
-  let hash = Hashtbl.hash
+  let equal (l1: t) (l2: t) =
+    l1.pos_cnum == l2.pos_cnum  &&
+    l1.pos_fname = l2.pos_fname
+
+  let hash (l: limit) = l.pos_cnum
+
+  (* l1 = l2, or l1 was emitted before l2 *)
+  let surely_predates (l1: limit) (l2: limit) =                  (* or equals *)
+    if l1.pos_cnum < (-1)
+    then l2.pos_cnum <= l1.pos_cnum
+    else l1.pos_cnum > 0 && l1.pos_cnum <= l2.pos_cnum &&
+         l1.pos_fname = l2.pos_fname
 end
 
 (** Weak hashtable where keys are overlay limits (internal) *)
@@ -59,6 +66,7 @@ type manager =
                                             corresponding right limit. *)
     over_right_gap: limit Links.t;  (** associates the right limit of a token to
                                         the left limit of the next *)
+    cache: (srcloc * limit) Links.t;
     id: string;                (** manager identifier (for logging/debugging) *)
   }
 
@@ -70,11 +78,13 @@ let new_manager: string -> manager =
     {
       right_of = Links.create 42;
       over_right_gap = Links.create 42;
+      cache = Links.create 42;
       id = Pretty.to_string "%s-%u" manager_name !id;
     }
 
 (** Returns left and right (potentially fresh) limits for the given source
-    location *)
+    location; for any given file, must be called with the leftmost location
+    first. *)
 let limits: manager -> srcloc -> limit * limit = fun ctx loc ->
   let s, e = match Cobol_common.Srcloc.as_unique_lexloc loc with
     | Some lexloc -> lexloc
@@ -88,17 +98,6 @@ let link_limits ctx left right =
   (* Replace to deal with overriding of limits during recovery. *)
   Links.replace ctx.over_right_gap left right
 
-(** [leftmost_limit_in ~filename ctx] finds the leftmost limit from a location
-    in [filename] that is registered in [ctx] (internal).  Use with moderation
-    as this is quite inefficient. *)
-let leftmost_limit_in ~filename ctx =
-  Links.fold begin fun l _ -> function
-    | None when l.Lexing.pos_fname = filename -> Some l
-    | Some l' when l.Lexing.pos_cnum < l'.pos_cnum &&
-                   l.Lexing.pos_fname = filename -> Some l
-    | res -> res
-  end ctx.right_of None
-
 (** Returns a source location that spans between two given limits; returns a
     valid pointwise location if the two given limits are physically equal. *)
 let join_limits: manager -> limit * limit -> srcloc = fun ctx (s, e) ->
@@ -112,19 +111,37 @@ let join_limits: manager -> limit * limit -> srcloc = fun ctx (s, e) ->
     in
     Cobol_common.Srcloc.raw (pos, pos)
   in
-  let try_limits (s, e) =
-    let rec jump_right loc e' =
-      let s' = Links.find ctx.over_right_gap e' in
-      let loc', e' = Links.find ctx.right_of s' in
-      check (Cobol_common.Srcloc.concat loc loc') e'
-    and check loc e' =
-      if e == e'                                        (* physical comparison *)
-      then loc
-      else jump_right loc e'
+  let try_limits (s, e: limit * limit) =
+
+    let rec proceed_from ?loc s =         (* start search from left limit [s] *)
+      check ?loc @@ Links.find ctx.right_of s
+
+    and check ?loc (loc', e') =
+      (* continue search with ([loc] concatenated with) [loc'] if [e'] is not
+         the sought after right limit; raises {!Not_found} when reaching an
+         unknown gap or limit *)
+      let loc = match loc with
+        | None -> loc'
+        | Some loc -> Cobol_common.Srcloc.concat loc loc'
+      in
+      if e.pos_cnum  = e'.pos_cnum &&   (* compare only the fields that matter *)
+         e.pos_fname = e'.pos_fname
+      then (Links.replace ctx.cache s (loc, e); loc)
+      else try_cache_from ~loc @@ Links.find ctx.over_right_gap e'
+
+    and try_cache_from ?loc s =
+      (* attempt with cache first; proceed via small-step upon miss or
+         failure *)
+      match Links.find_opt ctx.cache s with
+      | Some ((_, e') as hit) when Limit.surely_predates e' e ->
+          (try check ?loc hit with Not_found -> proceed_from ?loc s)
+      | Some _ | None ->
+          proceed_from ?loc s
     in
+
     if s == e
     then pointwise s
-    else let loc, e' = Links.find ctx.right_of s in check loc e'
+    else try_cache_from s
   in
   let join_failure (s, e) =
     let loc = Cobol_common.Srcloc.raw (s, e) in
@@ -134,18 +151,14 @@ let join_limits: manager -> limit * limit -> srcloc = fun ctx (s, e) ->
     (* Printexc.(print_raw_backtrace Stdlib.stderr @@ get_callstack 10); *)
     loc
   in
-  (* first attempt assumes proper token limits: `s` is a left and `e` is a right
-     of tokens *)
-  try try_limits (s, e) with Not_found ->
-  (* try assuming `s` is an end of token *)
-  try try_limits (Links.find ctx.over_right_gap s, e) with Not_found ->
-    if s.pos_cnum = 0 (* potential special case with left-position forged by the
-                         parser: retry with leftmost limit if it differs from
-                         s *)
-    then match leftmost_limit_in ~filename:s.pos_fname ctx with
-      | Some l when l != s -> try_limits (l, e)  (* physical equality is enough *)
-      | Some _ | None -> join_failure (s, e)
-    else join_failure (s, e)
+  try   (* first attempt assumes proper token limits: `s` is a left and `e` is a
+           right of tokens *)
+    try_limits (s, e)
+  with Not_found ->
+  try                        (* otherwise try assuming `s` is an end of token *)
+    try_limits (Links.find ctx.over_right_gap s, e)
+  with Not_found ->
+    join_failure (s, e)
 
 module New_manager (Id: sig val name: string end) : MANAGER = struct
   let ctx = new_manager Id.name