[stdlib] Transitioning support for 4.05 List functions

Makefile.generating

@@ -134,13 +134,30 @@ else
   SPLIT_ON_CHAR=split_on_char
 endif
 
+ifeq ($(HAS_OCAML405),yes)
+  NTH_OPT=List.nth_opt
+  FIND_OPT=List.find_opt
+  ASSOC_OPT=List.assoc_opt
+  ASSQ_OPT=List.assq_opt
+else
+  NTH_OPT=nth_opt
+  FIND_OPT=find_opt
+  ASSOC_OPT=assoc_opt
+  ASSQ_OPT=assq_opt
+endif
+
 src/libraries/stdlib/transitioning.ml: \
   src/libraries/stdlib/transitioning.ml.in \
   Makefile.generating share/Makefile.config
+	$(PRINT_MAKING) $@
 	rm -f $@
 	sed \
          -e 's/@SPLIT_ON_CHAR@/$(SPLIT_ON_CHAR)/g' \
          -e 's/@STACK_FOLD@/$(STACK_FOLD)/g' \
+         -e 's/@NTH_OPT@/$(NTH_OPT)/g' \
+         -e 's/@FIND_OPT@/$(FIND_OPT)/g' \
+         -e 's/@ASSOC_OPT@/$(ASSOC_OPT)/g' \
+         -e 's/@ASSQ_OPT@/$(ASSQ_OPT)/g' \
         $< > $@
 	$(CHMOD_RO) $@
 

configure.in

@@ -119,6 +119,7 @@ AC_SUBST(OCAMLPATCHNB)
 
 AC_SUBST(HAS_OCAML403)
 AC_SUBST(HAS_OCAML404)
+AC_SUBST(HAS_OCAML405)
 AC_SUBST(HAS_OCAML407)
 
 OCAMLMAJORNB=$(echo $OCAMLVERSION | cut -f 1 -d .)
@@ -127,22 +128,26 @@ OCAMLPATCHNB=$(echo $OCAMLVERSION | cut -f 3 -d .)
 
 if test $OCAMLMAJORNB -gt 4; then
   HAS_OCAML403=yes;
+  HAS_OCAML404=yes;
+  HAS_OCAML405=yes;
   HAS_OCAML407=yes;
-else if test $OCAMLMINORNB -lt 3; then
+else
   HAS_OCAML403=no;
+  HAS_OCAML404=no;
+  HAS_OCAML405=no;
   HAS_OCAML407=no;
-else
-  HAS_OCAML403=yes;
-  if test $OCAMLMINORNB -lt 4; then
-     HAS_OCAML404=no;
-     HAS_OCAML407=no;
-  else if test $OCAMLMINORNB -lt 7; then
-    HAS_OCAML407=no;
-  else
+  if test $OCAMLMINORNB -ge 3; then
+    HAS_OCAML403=yes;
+  fi;
+  if test $OCAMLMINORNB -ge 4; then
+    HAS_OCAML404=yes;
+  fi;
+  if test $OCAMLMINORNB -ge 5; then
+    HAS_OCAML405=yes;
+  fi;
+  if test $OCAMLMINORNB -ge 7; then
     HAS_OCAML407=yes;
   fi;
-  fi; # 404
-fi;   # 403
 fi;   # MAJORNB -gt 4
 
 # Ocaml library path

share/Makefile.config.in

@@ -85,6 +85,7 @@ OCAMLPATCHNB    ?=@OCAMLPATCHNB@
 
 HAS_OCAML403    ?=@HAS_OCAML403@
 HAS_OCAML404    ?=@HAS_OCAML404@
+HAS_OCAML405    ?=@HAS_OCAML405@
 HAS_OCAML407    ?=@HAS_OCAML407@
 
 NATIVE_THREADS	?=@HAS_NATIVE_THREADS@

src/libraries/stdlib/transitioning.ml.in

@@ -37,10 +37,25 @@ let stack_fold f x s =
   Stack.iter do_it s;
   !res
 
+let nth_opt l n =
+  try Some (List.nth l n)
+  with Failure _ when n >= 0 -> None
+(* OCaml manual states that a negative argument still raises a Failure. *)
+
+let find_opt f l = try Some (List.find f l) with Not_found -> None
+
+let assoc_opt x l = try Some (List.assoc x l) with Not_found -> None
+
+let assq_opt x l = try Some (List.assq x l) with Not_found -> None
+
 (* the implementations above are only used in case we compile against an
    old OCaml version. Avoid unused warning in other cases. *)
 let _: char -> string -> string list = split_on_char
 let _: ('a -> 'b -> 'a) -> 'a -> 'b Stack.t -> 'a = stack_fold
+let _: 'a list -> int -> 'a option = nth_opt
+let _: ('a -> bool) -> 'a list -> 'a option = find_opt
+let _: 'a -> ('a * 'b) list -> 'b option = assoc_opt
+let _: 'a -> ('a * 'b) list -> 'b option = assq_opt
 
 [@@@ warning "-3"]
 
@@ -61,6 +76,13 @@ module Stack = struct
   let fold = @STACK_FOLD@
 end
 
+module List = struct
+  let nth_opt = @NTH_OPT@
+  let find_opt = @FIND_OPT@
+  let assoc_opt = @ASSOC_OPT@
+  let assq_opt = @ASSQ_OPT@
+end
+
 module Q = struct
 
   let round_to_float x exact =

src/libraries/stdlib/transitioning.mli

@@ -58,6 +58,13 @@ module Stack: sig
   val fold: ('a -> 'b -> 'a) -> 'a -> 'b Stack.t -> 'a (** 4.03 *)
 end
 
+module List: sig
+  val nth_opt: 'a list -> int -> 'a option (** 4.05 *)
+  val find_opt: ('a -> bool) -> 'a list -> 'a option (** 4.05 *)
+  val assoc_opt: 'a -> ('a * 'b) list -> 'b option (** 4.05 *)
+  val assq_opt: 'a -> ('a * 'b) list -> 'b option (** 4.05 *)
+end
+
 (** {1 Zarith} *)
 
 (** Function [Q.to_float] was introduced in Zarith 1.5 *)