Feature: Added igloo_ro_get_interface()

include/igloo/ro.h

@@ -113,6 +113,24 @@ typedef igloo_ro_t (*igloo_ro_clone_t)(igloo_ro_t self, igloo_ro_cf_t required,
  */
 typedef igloo_ro_t (*igloo_ro_convert_t)(igloo_ro_t self, const igloo_ro_type_t *type, igloo_ro_cf_t required, igloo_ro_cf_t allowed, const char *name, igloo_ro_t associated);
 
+/* Type used for callback called when a specific interface to the object is requested.
+ *
+ * There are two cases that must be handled by the callback:
+ * 0) The object self is of the same type as this callback is set for and type is pointing to different type that is an interface.
+ * 1) The object self is of any type and type is pointing to the type this callback was set to which is an interface.
+ *
+ * This must not be used for converting to non-interface types. Use igloo_ro_convert() for that.
+ *
+ * Parameters:
+ *  self
+ *      The object to convert.
+ *  type
+ *      The type of the interface requested.
+ *  name, associated
+ *      See igloo_ro_new().
+ */
+typedef igloo_ro_t (*igloo_ro_get_interface_t)(igloo_ro_t self, const igloo_ro_type_t *type, const char *name, igloo_ro_t associated);
+
 /* Type used for callback called when the object needs to be converted to a string.
  *
  * This is used mostly for debugging or preseting the object to the user.
@@ -186,6 +204,8 @@ struct igloo_ro_type_tag {
     igloo_ro_clone_t            type_clonecb;
     /* Callback to be called by igloo_ro_convert() */
     igloo_ro_convert_t          type_convertcb;
+    /* Callback to be called by igloo_ro_get_interface() */
+    igloo_ro_get_interface_t    type_get_interfacecb;
     /* Callback to be called by igloo_ro_stringify() */
     igloo_ro_stringify_t        type_stringifycb;
     /* Callback to be called by igloo_ro_compare() */
@@ -301,6 +321,25 @@ igloo_ro_t      igloo_ro_clone(igloo_ro_t self, igloo_ro_cf_t required, igloo_ro
  */
 igloo_ro_t      igloo_ro_convert(igloo_ro_t self, const igloo_ro_type_t *type, igloo_ro_cf_t required, igloo_ro_cf_t allowed, const char *name, igloo_ro_t associated);
 
+/* Request a specific interface from the object.
+ *
+ * This must not be used to convert the object. This can only be used for requesting a specific interface.
+ *
+ * The object may return the same object for the same requested interface multiple times.
+ * However each time the same object is returned a new reference to it is returned.
+ *
+ * Parameters:
+ *  self
+ *      The object to copy and convert.
+ *  type
+ *      The interface requested.
+ *  name, associated
+ *      See igloo_ro_new().
+ * Returns:
+ *  An object that represents the given interface or igloo_RO_NULL.
+ */
+igloo_ro_t igloo_ro_get_interface(igloo_ro_t self, const igloo_ro_type_t *type, const char *name, igloo_ro_t associated);
+
 /* Convert a object to a string.
  * This is used for debugging and presenting to the user.
  *

include/igloo/typedef.h

@@ -51,6 +51,7 @@ static const igloo_ro_type_t igloo_ro__typedef__ ## type = \
 #define igloo_RO_TYPEDECL_NEW_NOOP()                .type_newcb = igloo_ro_new__return_zero
 #define igloo_RO_TYPEDECL_CLONE(cb)                 .type_clonecb = (cb)
 #define igloo_RO_TYPEDECL_CONVERT(cb)               .type_convertcb = (cb)
+#define igloo_RO_TYPEDECL_GET_INTERFACE(cb)         .type_get_interfacecb = (cb)
 #define igloo_RO_TYPEDECL_STRINGIFY(cb)             .type_stringifycb = (cb)
 #define igloo_RO_TYPEDECL_COMPARE(cb)               .type_comparecb = (cb)
 

src/ro.c

@@ -372,6 +372,26 @@ igloo_ro_t      igloo_ro_convert(igloo_ro_t self, const igloo_ro_type_t *type, i
     return ret;
 }
 
+igloo_ro_t igloo_ro_get_interface(igloo_ro_t self, const igloo_ro_type_t *type, const char *name, igloo_ro_t associated)
+{
+    igloo_ro_base_t *base = igloo_RO__GETBASE(self);
+    igloo_ro_t ret = igloo_RO_NULL;
+
+    if (!base || !type)
+        return igloo_RO_NULL;
+
+    igloo_thread_mutex_lock(&(base->lock));
+    if (!base->refc) {
+        igloo_thread_mutex_unlock(&(base->lock));
+        return igloo_RO_NULL;
+    }
+    if (base->type->type_get_interfacecb)
+        ret = base->type->type_get_interfacecb(self, type, name, associated);
+    igloo_thread_mutex_unlock(&(base->lock));
+
+    return ret;
+}
+
 char *          igloo_ro_stringify(igloo_ro_t self)
 {
     igloo_ro_base_t *base = igloo_RO__GETBASE(self);