qapi: Convert QType into QAPI built-in enum type

What's more meta than using qapi to define qapi? :)

Convert QType into a full-fledged[*] builtin qapi enum type, so
that a subsequent patch can then use it as the discriminator
type of qapi alternate types.  Fortunately, the judicious use of
'prefix' in the qapi definition avoids churn to the spelling of
the enum constants.

To avoid circular definitions, we have to flip the order of
inclusion between "qobject.h" vs. "qapi-types.h".  Back in commit
28770e0, we had the latter include the former, so that we could
use 'QObject *' for our implementation of 'any'.  But that usage
also works with only a forward declaration, whereas the
definition of QObject requires QType to be a complete type.

[*] The type has to be builtin, rather than declared in
qapi/common.json, because we want to use it for alternates even
when common.json is not included. But since it is the first
builtin enum type, we have to add special cases to qapi-types
and qapi-visit to only emit definitions once, even when two
qapi files are being compiled into the same binary (the way we
already handled builtin list types like 'intList').  We may
need to revisit how multiple qapi files share common types,
but that's a project for another day.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1449033659-25497-4-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/qapi-code-gen.txt

@@ -160,6 +160,7 @@ The following types are predefined, and map to C as follows:
                        accepts size suffixes
   bool      bool       JSON true or false
   any       QObject *  any JSON value
+  QType     QType      JSON string matching enum QType values
 
 
 === Includes ===

include/qapi/qmp/qobject.h

@@ -34,23 +34,12 @@
 
 #include <stddef.h>
 #include <assert.h>
+#include "qapi-types.h"
 
-typedef enum {
-    QTYPE_NONE,    /* sentinel value, no QObject has this type code */
-    QTYPE_QNULL,
-    QTYPE_QINT,
-    QTYPE_QSTRING,
-    QTYPE_QDICT,
-    QTYPE_QLIST,
-    QTYPE_QFLOAT,
-    QTYPE_QBOOL,
-    QTYPE_MAX,
-} QType;
-
-typedef struct QObject {
+struct QObject {
     QType type;
     size_t refcnt;
-} QObject;
+};
 
 /* Get the 'base' part of an object */
 #define QOBJECT(obj) (&(obj)->base)
@@ -66,7 +55,7 @@ typedef struct QObject {
 /* Initialize an object to default values */
 static inline void qobject_init(QObject *obj, QType type)
 {
-    assert(QTYPE_NONE < type && type < QTYPE_MAX);
+    assert(QTYPE_NONE < type && type < QTYPE__MAX);
     obj->refcnt = 1;
     obj->type = type;
 }
@@ -102,7 +91,7 @@ static inline void qobject_decref(QObject *obj)
  */
 static inline QType qobject_type(const QObject *obj)
 {
-    assert(QTYPE_NONE < obj->type && obj->type < QTYPE_MAX);
+    assert(QTYPE_NONE < obj->type && obj->type < QTYPE__MAX);
     return obj->type;
 }
 

include/qemu/typedefs.h

@@ -80,6 +80,7 @@ typedef struct QEMUSGList QEMUSGList;
 typedef struct QEMUSizedBuffer QEMUSizedBuffer;
 typedef struct QEMUTimer QEMUTimer;
 typedef struct QEMUTimerListGroup QEMUTimerListGroup;
+typedef struct QObject QObject;
 typedef struct RAMBlock RAMBlock;
 typedef struct Range Range;
 typedef struct SerialState SerialState;

qobject/qobject.c

@@ -15,7 +15,7 @@
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qstring.h"
 
-static void (*qdestroy[QTYPE_MAX])(QObject *) = {
+static void (*qdestroy[QTYPE__MAX])(QObject *) = {
     [QTYPE_NONE] = NULL,               /* No such object exists */
     [QTYPE_QNULL] = NULL,              /* qnull_ is indestructible */
     [QTYPE_QINT] = qint_destroy_obj,
@@ -29,6 +29,6 @@ static void (*qdestroy[QTYPE_MAX])(QObject *) = {
 void qobject_destroy(QObject *obj)
 {
     assert(!obj->refcnt);
-    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE_MAX);
+    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);
     qdestroy[obj->type](obj);
 }

scripts/qapi-types.py

@@ -112,7 +112,7 @@ def gen_alternate_qtypes_decl(name):
 def gen_alternate_qtypes(name, variants):
     ret = mcgen('''
 
-const int %(c_name)s_qtypes[QTYPE_MAX] = {
+const int %(c_name)s_qtypes[QTYPE__MAX] = {
 ''',
                 c_name=c_name(name))
 
@@ -233,8 +233,15 @@ def _gen_type_cleanup(self, name):
         self.defn += gen_type_cleanup(name)
 
     def visit_enum_type(self, name, info, values, prefix):
-        self._fwdecl += gen_enum(name, values, prefix)
-        self._fwdefn += gen_enum_lookup(name, values, prefix)
+        # Special case for our lone builtin enum type
+        # TODO use something cleaner than existence of info
+        if not info:
+            self._btin += gen_enum(name, values, prefix)
+            if do_builtins:
+                self.defn += gen_enum_lookup(name, values, prefix)
+        else:
+            self._fwdecl += gen_enum(name, values, prefix)
+            self._fwdefn += gen_enum_lookup(name, values, prefix)
 
     def visit_array_type(self, name, info, element_type):
         if isinstance(element_type, QAPISchemaBuiltinType):
@@ -316,10 +323,11 @@ def visit_alternate_type(self, name, info, variants):
 ''',
                  prefix=prefix))
 
+# To avoid circular headers, use only typedefs.h here, not qobject.h
 fdecl.write(mcgen('''
 #include <stdbool.h>
 #include <stdint.h>
-#include "qapi/qmp/qobject.h"
+#include "qemu/typedefs.h"
 '''))
 
 schema = QAPISchema(input_file)

scripts/qapi-visit.py

@@ -347,8 +347,15 @@ def visit_needed(self, entity):
                     isinstance(entity, QAPISchemaObjectType))
 
     def visit_enum_type(self, name, info, values, prefix):
-        self.decl += gen_visit_decl(name, scalar=True)
-        self.defn += gen_visit_enum(name)
+        # Special case for our lone builtin enum type
+        # TODO use something cleaner than existence of info
+        if not info:
+            self._btin += gen_visit_decl(name, scalar=True)
+            if do_builtins:
+                self.defn += gen_visit_enum(name)
+        else:
+            self.decl += gen_visit_decl(name, scalar=True)
+            self.defn += gen_visit_enum(name)
 
     def visit_array_type(self, name, info, element_type):
         decl = gen_visit_decl(name)

scripts/qapi.py

@@ -34,6 +34,7 @@
     'uint64':   'QTYPE_QINT',
     'size':     'QTYPE_QINT',
     'any':      None,           # any QType possible, actually
+    'QType':    'QTYPE_QSTRING',
 }
 
 # Whitelist of commands allowed to return a non-dictionary
@@ -1244,6 +1245,11 @@ def _def_predefineds(self):
         self.the_empty_object_type = QAPISchemaObjectType(':empty', None, None,
                                                           [], None)
         self._def_entity(self.the_empty_object_type)
+        self._def_entity(QAPISchemaEnumType('QType', None,
+                                            ['none', 'qnull', 'qint',
+                                             'qstring', 'qdict', 'qlist',
+                                             'qfloat', 'qbool'],
+                                            'QTYPE'))
 
     def _make_implicit_enum_type(self, name, info, values):
         name = name + 'Kind'   # Use namespace reserved by add_name()

tests/qapi-schema/alternate-empty.out

@@ -2,3 +2,5 @@ object :empty
 alternate Alt
     case i: int
 enum AltKind ['i']
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE

tests/qapi-schema/comments.out

@@ -1,2 +1,4 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 enum Status ['good', 'bad', 'ugly']

tests/qapi-schema/empty.out

@@ -1 +1,3 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE

tests/qapi-schema/event-case.out

@@ -1,2 +1,4 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 event oops None

tests/qapi-schema/flat-union-empty.out

@@ -2,6 +2,8 @@ object :empty
 object Base
     member type: Empty optional=False
 enum Empty []
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 object Union
     base Base
     tag type

tests/qapi-schema/ident-with-escape.out

@@ -1,5 +1,7 @@
 object :empty
 object :obj-fooA-arg
     member bar1: str optional=False
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 command fooA :obj-fooA-arg -> None
    gen=True success_response=True

tests/qapi-schema/include-relpath.out

@@ -1,2 +1,4 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 enum Status ['good', 'bad', 'ugly']

tests/qapi-schema/include-repetition.out

@@ -1,2 +1,4 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 enum Status ['good', 'bad', 'ugly']

tests/qapi-schema/include-simple.out

@@ -1,2 +1,4 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 enum Status ['good', 'bad', 'ugly']

tests/qapi-schema/indented-expr.out

@@ -1,4 +1,6 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 command eins None -> None
    gen=True success_response=True
 command zwei None -> None

tests/qapi-schema/qapi-schema-test.out

@@ -101,6 +101,8 @@ object NestedEnumsOne
     member enum4: EnumOne optional=True
 enum QEnumTwo ['value1', 'value2']
     prefix QENUM_TWO
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 object TestStruct
     member integer: int optional=False
     member boolean: bool optional=False

tests/qapi-schema/union-clash-data.out

@@ -1,6 +1,8 @@
 object :empty
 object :obj-int-wrapper
     member data: int optional=False
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 object TestUnion
     member type: TestUnionKind optional=False
     case data: :obj-int-wrapper

tests/qapi-schema/union-empty.out

@@ -1,4 +1,6 @@
 object :empty
+enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
+    prefix QTYPE
 object Union
     member type: UnionKind optional=False
 enum UnionKind []