From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54240) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZVMn8-0008BW-5z for qemu-devel@nongnu.org; Fri, 28 Aug 2015 12:46:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZVMn6-0000Jj-Fh for qemu-devel@nongnu.org; Fri, 28 Aug 2015 12:46:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55858) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZVMn6-0000Iy-2O for qemu-devel@nongnu.org; Fri, 28 Aug 2015 12:46:12 -0400 From: Markus Armbruster Date: Fri, 28 Aug 2015 18:45:48 +0200 Message-Id: <1440780366-7177-9-git-send-email-armbru@redhat.com> In-Reply-To: <1440780366-7177-1-git-send-email-armbru@redhat.com> References: <1440780366-7177-1-git-send-email-armbru@redhat.com> Subject: [Qemu-devel] [PATCH v2 08/26] qapi: Generate a nicer struct for flat unions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: mdroth@linux.vnet.ibm.com The struct generated for a flat union is weird: the members of its base are at the end, except for the union tag, which is at the beginning. Example: qapi-schema-test.json has { 'struct': 'UserDefUnionBase', 'data': { 'string': 'str', 'enum1': 'EnumOne' } } { 'union': 'UserDefFlatUnion', 'base': 'UserDefUnionBase', 'discriminator': 'enum1', 'data': { 'value1' : 'UserDefA', 'value2' : 'UserDefB', 'value3' : 'UserDefB' } } We generate: struct UserDefFlatUnion { EnumOne enum1; union { void *data; UserDefA *value1; UserDefB *value2; UserDefB *value3; }; char *string; }; Change to put all base members at the beginning, unadulterated. Not only is this easier to understand, it also permits casting the flat union to its base, if that should become useful. We now generate: struct UserDefFlatUnion { /* Members inherited from UserDefUnionBase: */ char *string; EnumOne enum1; /* Own members: */ union { /* union tag is @enum1 */ void *data; UserDefA *value1; UserDefB *value2; UserDefB *value3; }; }; Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake --- scripts/qapi-types.py | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py index ac8dad3..82141cd 100644 --- a/scripts/qapi-types.py +++ b/scripts/qapi-types.py @@ -200,13 +200,30 @@ def generate_union(expr, meta): ret = mcgen(''' struct %(name)s { - %(discriminator_type_name)s %(discriminator)s; - union { +''', + name=name) + if base: + ret += mcgen(''' + /* Members inherited from %(c_name)s: */ +''', + c_name=c_name(base)) + base_fields = find_struct(base)['data'] + ret += generate_struct_fields(base_fields) + ret += mcgen(''' + /* Own members: */ +''') + else: + assert not discriminator + ret += mcgen(''' + %(discriminator_type_name)s kind; +''', + discriminator_type_name=c_name(discriminator_type_name)) + + ret += mcgen(''' + union { /* union tag is @%(c_name)s */ void *data; ''', - name=name, - discriminator=c_name(discriminator or 'kind'), - discriminator_type_name=c_name(discriminator_type_name)) + c_name=c_name(discriminator or 'kind')) for key in typeinfo: ret += mcgen(''' @@ -217,17 +234,6 @@ struct %(name)s ret += mcgen(''' }; -''') - - if base: - assert discriminator - base_fields = find_struct(base)['data'].copy() - del base_fields[discriminator] - ret += generate_struct_fields(base_fields) - else: - assert not discriminator - - ret += mcgen(''' }; ''') if meta == 'alternate': -- 2.4.3