From 51e72bc1dd6ace6e91d675f41a1f09bd00ab8043 Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Fri, 29 Jan 2016 06:48:54 -0700
Subject: qapi: Swap visit_* arguments for consistent 'name' placement
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JSON uses "name":value, but many of our visitor interfaces were
called with visit_type_FOO(v, &value, name, errp).  This can be
a bit confusing to have to mentally swap the parameter order to
match JSON order.  It's particularly bad for visit_start_struct(),
where the 'name' parameter is smack in the middle of the
otherwise-related group of 'obj, kind, size' parameters! It's
time to do a global swap of the parameter ordering, so that the
'name' parameter is always immediately after the Visitor argument.

Additional reason in favor of the swap: the existing include/qjson.h
prefers listing 'name' first in json_prop_*(), and I have plans to
unify that file with the qapi visitors; listing 'name' first in
qapi will minimize churn to the (admittedly few) qjson.h clients.

Later patches will then fix docs, object.h, visitor-impl.h, and
those clients to match.

Done by first patching scripts/qapi*.py by hand to make generated
files do what I want, then by running the following Coccinelle
script to affect the rest of the code base:
 $ spatch --sp-file script `git grep -l '\bvisit_' -- '**/*.[ch]'`
I then had to apply some touchups (Coccinelle insisted on TAB
indentation in visitor.h, and botched the signature of
visit_type_enum() by rewriting 'const char *const strings[]' to
the syntactically invalid 'const char*const[] strings').  The
movement of parameters is sufficient to provoke compiler errors
if any callers were missed.

    // Part 1: Swap declaration order
    @@
    type TV, TErr, TObj, T1, T2;
    identifier OBJ, ARG1, ARG2;
    @@
     void visit_start_struct
    -(TV v, TObj OBJ, T1 ARG1, const char *name, T2 ARG2, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
     { ... }

    @@
    type bool, TV, T1;
    identifier ARG1;
    @@
     bool visit_optional
    -(TV v, T1 ARG1, const char *name)
    +(TV v, const char *name, T1 ARG1)
     { ... }

    @@
    type TV, TErr, TObj, T1;
    identifier OBJ, ARG1;
    @@
     void visit_get_next_type
    -(TV v, TObj OBJ, T1 ARG1, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, TErr errp)
     { ... }

    @@
    type TV, TErr, TObj, T1, T2;
    identifier OBJ, ARG1, ARG2;
    @@
     void visit_type_enum
    -(TV v, TObj OBJ, T1 ARG1, T2 ARG2, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
     { ... }

    @@
    type TV, TErr, TObj;
    identifier OBJ;
    identifier VISIT_TYPE =~ "^visit_type_";
    @@
     void VISIT_TYPE
    -(TV v, TObj OBJ, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, TErr errp)
     { ... }

    // Part 2: swap caller order
    @@
    expression V, NAME, OBJ, ARG1, ARG2, ERR;
    identifier VISIT_TYPE =~ "^visit_type_";
    @@
    (
    -visit_start_struct(V, OBJ, ARG1, NAME, ARG2, ERR)
    +visit_start_struct(V, NAME, OBJ, ARG1, ARG2, ERR)
    |
    -visit_optional(V, ARG1, NAME)
    +visit_optional(V, NAME, ARG1)
    |
    -visit_get_next_type(V, OBJ, ARG1, NAME, ERR)
    +visit_get_next_type(V, NAME, OBJ, ARG1, ERR)
    |
    -visit_type_enum(V, OBJ, ARG1, ARG2, NAME, ERR)
    +visit_type_enum(V, NAME, OBJ, ARG1, ARG2, ERR)
    |
    -VISIT_TYPE(V, OBJ, NAME, ERR)
    +VISIT_TYPE(V, NAME, OBJ, ERR)
    )

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <1454075341-13658-19-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 scripts/qapi.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'scripts/qapi.py')

diff --git a/scripts/qapi.py b/scripts/qapi.py
index 9254e48fe3..7519cf8e7a 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1647,7 +1647,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
     for memb in members:
         if memb.optional:
             ret += mcgen('''
-    if (visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s")) {
+    if (visit_optional(v, "%(name)s", &%(prefix)shas_%(c_name)s)) {
 ''',
                          prefix=prefix, c_name=c_name(memb.name),
                          name=memb.name)
@@ -1660,7 +1660,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
             cast = ''
 
         ret += mcgen('''
-    visit_type_%(c_type)s(v, %(cast)s&%(prefix)s%(c_name)s, "%(name)s", %(errp)s);
+    visit_type_%(c_type)s(v, "%(name)s", %(cast)s&%(prefix)s%(c_name)s, %(errp)s);
 ''',
                      c_type=memb.type.c_name(), prefix=prefix, cast=cast,
                      c_name=c_name(memb.name), name=memb.name,
-- 
cgit 1.4.1