Libguestfs - Aug 2009 - Code snippet to work out which RStruct/RStructList structs are used and how

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
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>From 9efa77d717bd9bba5f61965eb6920429b7ae5d8e Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Fri, 14 Aug 2009 16:54:55 +0100
Subject: [PATCH] Work out which RStruct/RStructList structs are really used, and
how.

---
 src/generator.ml |   58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 58 insertions(+), 0 deletions(-)

diff --git a/src/generator.ml b/src/generator.ml
index b8f9ace..b76f502 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -3645,6 +3645,64 @@ let java_structs = [
   "inotify_event", "INotifyEvent";
 ]
 
+(* What structs are actually returned. *)
+type rstructs_used_t = RStructOnly | RStructListOnly | RStructAndList
+
+(* Returns a list of RStruct/RStructList structs that are returned
+ * by any function.  Each element of returned list is a pair:
+ *
+ * (structname, RStructOnly)
+ *    == there exists function which returns RStruct (_, structname)
+ * (structname, RStructListOnly)
+ *    == there exists function which returns RStructList (_, structname)
+ * (structname, RStructAndList)
+ *    == there are functions returning both RStruct (_, structname)
+ *                                      and RStructList (_, structname)
+ *)
+let rstructs_used +  (* ||| is a "logical OR" for rstructs_used_t *)
+  let (|||) a b +    match a, b with
+    | RStructAndList, _
+    | _, RStructAndList -> RStructAndList
+    | RStructOnly, RStructListOnly
+    | RStructListOnly, RStructOnly -> RStructAndList
+    | RStructOnly, RStructOnly -> RStructOnly
+    | RStructListOnly, RStructListOnly -> RStructListOnly
+  in
+
+  let h = Hashtbl.create 13 in
+
+  (* if elem->oldv exists, update entry using ||| operator,
+   * else just add elem->newv to the hash
+   *)
+  let update elem newv +    try  let oldv = Hashtbl.find h elem in
+         Hashtbl.replace h elem (newv ||| oldv)
+    with Not_found -> Hashtbl.add h elem newv
+  in
+
+  List.iter (
+    fun (_, style, _, _, _, _, _) ->
+      match fst style with
+      | RStruct (_, structname) -> update structname RStructOnly
+      | RStructList (_, structname) -> update structname RStructListOnly
+      | _ -> ()
+  ) all_functions;
+
+  (* return key->values as a list of (key,value) *)
+  Hashtbl.fold (fun key value xs -> (key, value) :: xs) h []
+
+(* debug:
+let () +  List.iter (
+    function
+    | sn, RStructOnly -> printf "%s RStructOnly\n" sn
+    | sn, RStructListOnly -> printf "%s RStructListOnly\n" sn
+    | sn, RStructAndList -> printf "%s RStructAndList\n" sn
+  ) rstructs_used
+*)
+
 (* Used for testing language bindings. *)
 type callt    | CallString of string
-- 
1.6.2.5

Richard W.M. Jones wrote:
> Subject: [PATCH] Work out which RStruct/RStructList structs are really
used, and how.
Thanks.  That was just what I needed.
When I apply that along with the following two patches,
the four unused functions are no longer emitted.
>From 71b6bb79fbae53f1f4f2465e693a2c3e9f1a6faa Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Fri, 14 Aug 2009 19:12:18 +0200
Subject: [PATCH libguestfs 1/2] generator.ml: factor out a function

* src/generator.ml (emit_print_list_function): New function.
---
 src/generator.ml |   28 ++++++++++++++++------------
 1 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/src/generator.ml b/src/generator.ml
index b76f502..3dc2ae5 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -7445,6 +7445,21 @@ py_guestfs_close (PyObject *self, PyObject *args)

 ";

+  let emit_print_list_function typ +    pr "static PyObject *\n";
+    pr "put_%s_list (struct guestfs_%s_list *%ss)\n" typ typ typ;
+    pr "{\n";
+    pr "  PyObject *list;\n";
+    pr "  int i;\n";
+    pr "\n";
+    pr "  list = PyList_New (%ss->len);\n" typ;
+    pr "  for (i = 0; i < %ss->len; ++i)\n" typ;
+    pr "    PyList_SetItem (list, i, put_%s
(&%ss->val[i]));\n" typ typ;
+    pr "  return list;\n";
+    pr "};\n";
+    pr "\n"
+  in
+
   (* Structures, turned into Python dictionaries. *)
   List.iter (
     fun (typ, cols) ->
@@ -7501,18 +7516,7 @@ py_guestfs_close (PyObject *self, PyObject *args)
       pr "};\n";
       pr "\n";

-      pr "static PyObject *\n";
-      pr "put_%s_list (struct guestfs_%s_list *%ss)\n" typ typ typ;
-      pr "{\n";
-      pr "  PyObject *list;\n";
-      pr "  int i;\n";
-      pr "\n";
-      pr "  list = PyList_New (%ss->len);\n" typ;
-      pr "  for (i = 0; i < %ss->len; ++i)\n" typ;
-      pr "    PyList_SetItem (list, i, put_%s
(&%ss->val[i]));\n" typ typ;
-      pr "  return list;\n";
-      pr "};\n";
-      pr "\n"
+      emit_print_list_function typ
   ) structs;

   (* Python wrapper functions. *)
--
1.6.4.357.gfd68c

>From bf64b6fa512012e2a15fa5b40037218b5159d659 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Fri, 14 Aug 2009 19:33:35 +0200
Subject: [PATCH libguestfs 2/2] generator.ml: don't emit unused functions

* src/generator.ml: Use "rstructs_used" to emit definitions only for
put_TYPE_list functions that are used.
---
 src/generator.ml |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/src/generator.ml b/src/generator.ml
index 3dc2ae5..01a4436 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -7516,9 +7516,17 @@ py_guestfs_close (PyObject *self, PyObject *args)
       pr "};\n";
       pr "\n";

-      emit_print_list_function typ
   ) structs;

+  (* Emit a put_TYPE_list function definition only if that function is used. *)
+  List.iter (
+    function
+    | typ, (RStructListOnly | RStructAndList) ->
+        (* generate the function for typ *)
+        emit_print_list_function typ
+    | typ, _ -> () (* empty *)
+  ) rstructs_used;
+
   (* Python wrapper functions. *)
   List.iter (
     fun (name, style, _, _, _, _, _) ->
--
1.6.4.357.gfd68c