Merge pull request #9865 from raphael-proust/pp_print_seq

Stdlib.Format: add pp_print_seq

Changes

@@ -146,6 +146,9 @@ Working version
 
 ### Standard library:
 
+- #9865: add Format.pp_print_seq
+  (Raphaël Proust, review by Nicolás Ojeda Bär)
+
 - #9781: add injectivity annotations to parameterized abstract types
   (Jeremy Yallop, review by Nicolás Ojeda Bär)
 

stdlib/.depend

@@ -263,6 +263,7 @@ stdlib__format.cmo : \
     stdlib__string.cmi \
     stdlib.cmi \
     stdlib__stack.cmi \
+    stdlib__seq.cmi \
     stdlib__queue.cmi \
     stdlib__list.cmi \
     stdlib__int.cmi \
@@ -274,6 +275,7 @@ stdlib__format.cmx : \
     stdlib__string.cmx \
     stdlib.cmx \
     stdlib__stack.cmx \
+    stdlib__seq.cmx \
     stdlib__queue.cmx \
     stdlib__list.cmx \
     stdlib__int.cmx \
@@ -283,6 +285,7 @@ stdlib__format.cmx : \
     stdlib__format.cmi
 stdlib__format.cmi : \
     stdlib.cmi \
+    stdlib__seq.cmi \
     stdlib__buffer.cmi
 stdlib__fun.cmo : \
     stdlib__printexc.cmi \

stdlib/format.ml

@@ -1191,6 +1191,22 @@ let rec pp_print_list ?(pp_sep = pp_print_cut) pp_v ppf = function
     pp_sep ppf ();
     pp_print_list ~pp_sep pp_v ppf vs
 
+(* To format a sequence *)
+let rec pp_print_seq_in ~pp_sep pp_v ppf seq =
+  match seq () with
+  | Seq.Nil -> ()
+  | Seq.Cons (v, seq) ->
+    pp_sep ppf ();
+    pp_v ppf v;
+    pp_print_seq_in ~pp_sep pp_v ppf seq
+
+let pp_print_seq ?(pp_sep = pp_print_cut) pp_v ppf seq =
+  match seq () with
+  | Seq.Nil -> ()
+  | Seq.Cons (v, seq) ->
+    pp_v ppf v;
+    pp_print_seq_in ~pp_sep pp_v ppf seq
+
 (* To format free-flowing text *)
 let pp_print_text ppf s =
   let len = String.length s in

stdlib/format.mli

@@ -1084,6 +1084,19 @@ val pp_print_list:
   @since 4.02.0
 *)
 
+val pp_print_seq:
+  ?pp_sep:(formatter -> unit -> unit) ->
+  (formatter -> 'a -> unit) -> (formatter -> 'a Seq.t -> unit)
+(** [pp_print_seq ?pp_sep pp_v ppf s] prints items of sequence [s],
+  using [pp_v] to print each item, and calling [pp_sep]
+  between items ([pp_sep] defaults to {!pp_print_cut}.
+  Does nothing on empty sequences.
+
+  This function does not terminate on infinite sequences.
+
+  @since 4.12
+*)
+
 val pp_print_text : formatter -> string -> unit
 (** [pp_print_text ppf s] prints [s] with spaces and newlines respectively
   printed using {!pp_print_space} and {!pp_force_newline}.

testsuite/tests/lib-format/print_seq.ml

@@ -0,0 +1,33 @@
+(* TEST
+   include testing
+*)
+
+(*
+
+A test file for the Format module.
+
+*)
+
+open Testing;;
+open Format;;
+
+let say s = Printf.printf s;;
+
+let pp_print_intseq = pp_print_seq ~pp_sep:(fun fmt () -> pp_print_char fmt ' ') pp_print_int;;
+
+try
+
+  say "empty\n%!";
+  test (asprintf "%a%!" pp_print_intseq Seq.empty = "");
+
+  say "\nmisc\n%!";
+  test (asprintf "%a" pp_print_intseq (List.to_seq [0]) = "0");
+  test (asprintf "%a" pp_print_intseq (List.to_seq [0;1;2]) = "0 1 2");
+  test (asprintf "%a" pp_print_intseq (List.to_seq [0;0]) = "0 0");
+
+  say "\nend of tests\n%!";
+
+with e ->
+  say "unexpected exception: %s\n%!" (Printexc.to_string e);
+  test false;
+;;

testsuite/tests/lib-format/print_seq.reference

@@ -0,0 +1,7 @@
+empty
+ 0
+misc
+ 1 2 3
+end of tests
+
+All tests succeeded.