configurator: add write_lines function

The `write_flags` only works with `(:include` directives, and it
is also useful to be able to write a list of lines so that the
discovered information can be used in variable expansion actions.

For example, ocaml-yaml discovers CFLAGS and then directly has
`(run ${CC} ${read-lines:cflags})` actions that use this new
write_lines function to list cflags instead of s-expressions.
They must be line-by-line or else variable expansion doesnt work
since CFLAGS contain spaces.

Signed-off-by: Anil Madhavapeddy <anil@recoil.org>

src/configurator/v1.ml

@@ -61,6 +61,24 @@ module Temp = struct
     dir
 end
 
+module Flags = struct
+  let extract_words = String.extract_words
+
+  let extract_comma_space_separated_words =
+    String.extract_comma_space_separated_words
+
+  let extract_blank_separated_words = String.extract_blank_separated_words
+
+  let write_lines fname s =
+    let path = Path.of_string fname in
+    Io.write_lines path s
+
+  let write_sexp fname s =
+    let path = Path.in_source fname in
+    let sexp = Usexp.List (List.map s ~f:(fun s -> Usexp.Quoted_string s)) in
+    Io.write_file path (Usexp.to_string sexp ~syntax:Dune)
+end
+
 module Find_in_path = struct
   let path_sep =
     if Sys.win32 then
@@ -485,18 +503,13 @@ module Pkg_config = struct
       None
 end
 
-let write_flags fname s =
-  let path = Path.in_source fname in
-  let sexp = Usexp.List (List.map s ~f:(fun s -> Usexp.Quoted_string s)) in
-  Io.write_file path (Usexp.to_string sexp ~syntax:Dune)
-
 let main ?(args=[]) ~name f =
   let ocamlc  = ref (
     match Sys.getenv "DUNE_CONFIGURATOR" with
     | s -> Some s
     | exception Not_found ->
-      die "Configurator scripts must be ran with jbuilder. \
-           To manually run a script, use $ jbuilder exec."
+      die "Configurator scripts must be run with Dune. \
+           To manually run a script, use $ dune exec."
   ) in
   let verbose = ref false in
   let dest_dir = ref None in

src/configurator/v1.mli

@@ -87,10 +87,32 @@ module Pkg_config : sig
   val query : t -> package:string -> package_conf option
 end with type configurator := t
 
-val write_flags : string -> string list -> unit
-(** [write_flags fname s] write the list of strings [s] to the file
-   [fname] in an appropriate format so that it can used in jbuild
-   files with "(:include [fname])". *)
+module Flags : sig
+
+  val write_sexp : string -> string list -> unit
+  (** [write_sexp fname s] writes the list of strings [s] to the file [fname] in
+      an appropriate format so that it can used in jbuild files with [(:include
+      [fname])]. *)
+
+  val write_lines : string -> string list -> unit
+  (** [write_lines fname s] writes the list of string [s] to the file [fname]
+      with one line per string so that it can be used in Dune action rules with
+      [%{read-lines:<path>}]. *)
+
+  val extract_comma_space_separated_words : string -> string list
+  (** [extract_comma_space_separated_words s] returns a list of words in
+      [s] that are separated by a newline, tab, space or comma character. *)
+
+  val extract_blank_separated_words : string -> string list
+  (** [extract_blank_separated_words s] returns a list of words in [s]
+      that are separated by a tab or space character. *)
+
+  val extract_words : string -> is_word_char:(char -> bool) -> string list
+  (** [extract_words s ~is_word_char] will split the string [s] into
+      a list of words.  A valid word character is defined by the [is_word_char]
+      predicate returning true and anything else is considered a separator.
+      Any blank words are filtered out of the results. *)
+end
 
 (** Typical entry point for configurator programs *)
 val main