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qapi-types/visit.py: Inheritance for structs

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This introduces a new 'base' key for struct definitions that refers to
another struct type. On the JSON level, the fields of the base type are
included directly into the same namespace as the fields of the defined
type, like with unions. On the C level, a pointer to a struct of the
base type is included.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Kevin Wolf 2013-09-19 11:56:36 +02:00
parent 14d36307ff
commit 622f557f5a
3 changed files with 37 additions and 2 deletions
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17
docs/qapi-code-gen.txt
View file

@ -53,6 +53,23 @@ The use of '*' as a prefix to the name means the member is optional. Optional
members should always be added to the end of the dictionary to preserve
backwards compatibility.
A complex type definition can specify another complex type as its base.
In this case, the fields of the base type are included as top-level fields
of the new complex type's dictionary in the QMP wire format. An example
definition is:
{ 'type': 'BlockdevOptionsGenericFormat', 'data': { 'file': 'str' } }
{ 'type': 'BlockdevOptionsGenericCOWFormat',
'base': 'BlockdevOptionsGenericFormat',
'data': { '*backing': 'str' } }
An example BlockdevOptionsGenericCOWFormat object on the wire could use
both fields like this:
{ "file": "/some/place/my-image",
"backing": "/some/place/my-backing-file" }
=== Enumeration types ===
An enumeration type is a dictionary containing a single key whose value is a

4
scripts/qapi-types.py
View file

@ -86,6 +86,7 @@ def generate_struct(expr):
structname = expr.get('type', "")
fieldname = expr.get('field', "")
members = expr['data']
base = expr.get('base')
ret = mcgen('''
struct %(name)s
@ -93,6 +94,9 @@ struct %(name)s
''',
name=structname)
if base:
ret += generate_struct_fields({'base': base})
ret += generate_struct_fields(members)
if len(fieldname):

18
scripts/qapi-visit.py
View file

@ -17,7 +17,7 @@ import os
import getopt
import errno
def generate_visit_struct_fields(name, field_prefix, fn_prefix, members):
def generate_visit_struct_fields(name, field_prefix, fn_prefix, members, base = None):
substructs = []
ret = ''
full_name = name if not fn_prefix else "%s_%s" % (name, fn_prefix)
@ -42,6 +42,19 @@ static void visit_type_%(full_name)s_fields(Visitor *m, %(name)s ** obj, Error *
name=name, full_name=full_name)
push_indent()
if base:
ret += mcgen('''
visit_start_implicit_struct(m, obj ? (void**) &(*obj)->%(c_name)s : NULL, sizeof(%(type)s), &err);
if (!err) {
visit_type_%(type)s_fields(m, obj ? &(*obj)->%(c_prefix)s%(c_name)s : NULL, &err);
error_propagate(errp, err);
err = NULL;
visit_end_implicit_struct(m, &err);
}
''',
c_prefix=c_var(field_prefix),
type=type_name(base), c_name=c_var('base'))
for argname, argentry, optional, structured in parse_args(members):
if optional:
ret += mcgen('''
@ -124,8 +137,9 @@ def generate_visit_struct(expr):
name = expr['type']
members = expr['data']
base = expr.get('base')
ret = generate_visit_struct_fields(name, "", "", members)
ret = generate_visit_struct_fields(name, "", "", members, base)
ret += mcgen('''