qapi: Add new visit_complete() function

[mirror_qemu.git] / include / qapi / visitor-impl.h

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index ea252f8e3a525bca3650ea11086e45738ef9de81..16e0b86d5711985f10bc2210fb7e0607d34ffd56 100644 (file)
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -12,59 +12,104 @@
 #ifndef QAPI_VISITOR_IMPL_H
 #define QAPI_VISITOR_IMPL_H
 
-#include "qapi/error.h"
 #include "qapi/visitor.h"
 
+/*
+ * This file describes the callback interface for implementing a QAPI
+ * visitor.  For the client interface, see visitor.h.  When
+ * implementing the callbacks, it is easiest to declare a struct with
+ * 'Visitor visitor;' as the first member.  A callback's contract
+ * matches the corresponding public functions' contract unless stated
+ * otherwise.  In the comments below, some callbacks are marked "must
+ * be set for $TYPE visits to work"; if a visitor implementation omits
+ * that callback, it should also document that it is only useful for a
+ * subset of QAPI.
+ */
+
+/*
+ * There are three classes of visitors; setting the class determines
+ * how QAPI enums are visited, as well as what additional restrictions
+ * can be asserted.
+ */
+typedef enum VisitorType {
+    VISITOR_INPUT,
+    VISITOR_OUTPUT,
+    VISITOR_DEALLOC,
+} VisitorType;
+
 struct Visitor
 {
-    /* Must be set */
+    /* Must be set to visit structs */
     void (*start_struct)(Visitor *v, const char *name, void **obj,
                          size_t size, Error **errp);
-    void (*end_struct)(Visitor *v, Error **errp);
 
-    void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
-                                  Error **errp);
-    /* May be NULL */
-    void (*end_implicit_struct)(Visitor *v);
+    /* Optional; intended for input visitors */
+    void (*check_struct)(Visitor *v, Error **errp);
+
+    /* Must be set to visit structs */
+    void (*end_struct)(Visitor *v, void **obj);
+
+    /* Must be set; implementations may require @list to be non-null,
+     * but must document it. */
+    void (*start_list)(Visitor *v, const char *name, GenericList **list,
+                       size_t size, Error **errp);
 
-    void (*start_list)(Visitor *v, const char *name, Error **errp);
     /* Must be set */
-    GenericList *(*next_list)(Visitor *v, GenericList **list);
+    GenericList *(*next_list)(Visitor *v, GenericList *tail, size_t size);
+
     /* Must be set */
-    void (*end_list)(Visitor *v);
+    void (*end_list)(Visitor *v, void **list);
+
+    /* Must be set by input and dealloc visitors to visit alternates;
+     * optional for output visitors. */
+    void (*start_alternate)(Visitor *v, const char *name,
+                            GenericAlternate **obj, size_t size,
+                            bool promote_int, Error **errp);
 
-    void (*type_enum)(Visitor *v, const char *name, int *obj,
-                      const char *const strings[], Error **errp);
-    /* May be NULL; only needed for input visitors. */
-    void (*get_next_type)(Visitor *v, const char *name, QType *type,
-                          bool promote_int, Error **errp);
+    /* Optional, needed for dealloc visitor */
+    void (*end_alternate)(Visitor *v, void **obj);
 
-    /* Must be set. */
+    /* Must be set */
     void (*type_int64)(Visitor *v, const char *name, int64_t *obj,
                        Error **errp);
-    /* Must be set. */
+
+    /* Must be set */
     void (*type_uint64)(Visitor *v, const char *name, uint64_t *obj,
                         Error **errp);
-    /* Optional; fallback is type_uint64().  */
+
+    /* Optional; fallback is type_uint64() */
     void (*type_size)(Visitor *v, const char *name, uint64_t *obj,
                       Error **errp);
-    /* Must be set. */
+
+    /* Must be set */
     void (*type_bool)(Visitor *v, const char *name, bool *obj, Error **errp);
+
+    /* Must be set */
     void (*type_str)(Visitor *v, const char *name, char **obj, Error **errp);
+
+    /* Must be set to visit numbers */
     void (*type_number)(Visitor *v, const char *name, double *obj,
                         Error **errp);
+
+    /* Must be set to visit arbitrary QTypes */
     void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);
 
-    /* May be NULL; most useful for input visitors. */
+    /* Must be set to visit explicit null values.  */
+    void (*type_null)(Visitor *v, const char *name, Error **errp);
+
+    /* Must be set for input visitors, optional otherwise.  The core
+     * takes care of the return type in the public interface. */
     void (*optional)(Visitor *v, const char *name, bool *present);
 
-    bool (*start_union)(Visitor *v, bool data_present, Error **errp);
-};
+    /* Must be set */
+    VisitorType type;
 
-void input_type_enum(Visitor *v, const char *name, int *obj,
-                     const char *const strings[], Error **errp);
-void output_type_enum(Visitor *v, const char *name, int *obj,
-                      const char *const strings[], Error **errp);
+    /* Must be set for output visitors, optional otherwise. */
+    void (*complete)(Visitor *v, void *opaque);
+
+    /* Must be set */
+    void (*free)(Visitor *v);
+};
 
 #endif