[pygobject] Refactor signal array length marshalling to support a length policy

[Simon Feltman <sfeltman src gnome org>]

commit c55d029d2d67b5920e9467212e22b0ad58d3ded8
Author: Simon Feltman <sfeltman src gnome org>
Date:   Sun Aug 17 18:15:23 2014 -0700

    Refactor signal array length marshalling to support a length policy
    
    Replace passing arrays of data to non-caching array marshallers with a policy
    closure that can be customized depending on context. In the case of signals,
    this is mostly scaffolding which will be replaced with caching marshallers.
    However, it opens the legacy marshaller for usage with struct and object
    array fields.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=688792

 gi/pygi-argument.c       |   70 +++++++++++++++++++++++++++++++---------------
 gi/pygi-argument.h       |   14 +++++++--
 gi/pygi-signal-closure.c |    8 ++++-
 3 files changed, 64 insertions(+), 28 deletions(-)
---
diff --git a/gi/pygi-argument.c b/gi/pygi-argument.c
index 035c8d9..03c0a9c 100644
--- a/gi/pygi-argument.c
+++ b/gi/pygi-argument.c
@@ -758,16 +758,49 @@ check_number_release:
     return retval;
 }
 
+
+/**
+ * _pygi_argument_array_length_marshal:
+ * @length_arg_index: Index of length argument in the callables args list.
+ * @user_data1: (type Array(GValue)): Array of GValue arguments to retrieve length
+ * @user_data2: (type GICallableInfo): Callable info to get the argument from.
+ *
+ * Generic marshalling policy for array length arguments in callables.
+ *
+ * Returns: The length of the array or -1 on failure.
+ */
+gssize
+_pygi_argument_array_length_marshal (gsize length_arg_index,
+                                     void *user_data1,
+                                     void *user_data2)
+{
+    GIArgInfo length_arg_info;
+    GITypeInfo length_type_info;
+    GIArgument length_arg;
+    gssize array_len = -1;
+    GValue *values = (GValue *)user_data1;
+    GICallableInfo *callable_info = (GICallableInfo *)user_data2;
+
+    g_callable_info_load_arg (callable_info, length_arg_index, &length_arg_info);
+    g_arg_info_load_type (&length_arg_info, &length_type_info);
+
+    length_arg = _pygi_argument_from_g_value (&(values[length_arg_index]),
+                                              &length_type_info);
+    if (!gi_argument_to_gssize (&length_arg,
+                                g_type_info_get_tag (&length_type_info),
+                                &array_len)) {
+        return -1;
+    }
+
+    return array_len;
+}
+
 /**
  * _pygi_argument_to_array
  * @arg: The argument to convert
- * @args: Arguments to method invocation, possibly contaning the array length.
- *        Set to %NULL if this is not for a method call or @args_values is
- *        specified.
- * @args_values: GValue Arguments to method invocation, possibly contaning the
- *               array length. Set to %NULL if this is not for a method call or
- *               @args is specified.
- * @callable_info: Info on the callable, if this a method call; otherwise %NULL
+ * @array_length_policy: Closure for marshalling the array length argument when needed.
+ * @user_data1: Generic user data passed to the array_length_policy.
+ * @user_data2: Generic user data passed to the array_length_policy.
  * @type_info: The type info for @arg
  * @out_free_array: A return location for a gboolean that indicates whether
  *                  or not the wrapped GArray should be freed
@@ -784,9 +817,9 @@ check_number_release:
  */
 GArray *
 _pygi_argument_to_array (GIArgument  *arg,
-                         GIArgument  *args[],
-                         const GValue *args_values,
-                         GICallableInfo *callable_info,                  
+                         PyGIArgArrayLengthPolicy array_length_policy,
+                         void        *user_data1,
+                         void        *user_data2,
                          GITypeInfo  *type_info,
                          gboolean    *out_free_array)
 {
@@ -817,11 +850,8 @@ _pygi_argument_to_array (GIArgument  *arg,
                 length = g_type_info_get_array_fixed_size (type_info);
                 if (length < 0) {
                     gint length_arg_pos;
-                    GIArgInfo length_arg_info;
-                    GITypeInfo length_type_info;
-                    GIArgument length_arg;
 
-                    if (G_UNLIKELY (args_values == NULL)) {
+                    if (G_UNLIKELY (array_length_policy == NULL)) {
                         g_critical ("Unable to determine array length for %p",
                                     arg->v_pointer);
                         g_array = g_array_new (is_zero_terminated, FALSE, item_size);
@@ -831,17 +861,11 @@ _pygi_argument_to_array (GIArgument  *arg,
 
                     length_arg_pos = g_type_info_get_array_length (type_info);
                     g_assert (length_arg_pos >= 0);
-                    g_assert (callable_info);
-                    g_callable_info_load_arg (callable_info, length_arg_pos, &length_arg_info);
-                    g_arg_info_load_type (&length_arg_info, &length_type_info);
-
 
-                    length_arg = _pygi_argument_from_g_value (&(args_values[length_arg_pos]),
-                                                              &length_type_info);
-                    if (!gi_argument_to_gssize (&length_arg,
-                                                g_type_info_get_tag (&length_type_info),
-                                                &length))
+                    length = array_length_policy (length_arg_pos, user_data1, user_data2);
+                    if (length < 0) {
                         return NULL;
+                    }
                 }
             }
 
diff --git a/gi/pygi-argument.h b/gi/pygi-argument.h
index 04888ba..c8f2f1e 100644
--- a/gi/pygi-argument.h
+++ b/gi/pygi-argument.h
@@ -28,6 +28,14 @@ G_BEGIN_DECLS
 
 
 /* Private */
+typedef gssize (*PyGIArgArrayLengthPolicy) (gsize item_index,
+                                            void *user_data1,
+                                            void *user_data2);
+
+gssize _pygi_argument_array_length_marshal (gsize length_arg_index,
+                                            void *user_data1,
+                                            void *user_data2);
+
 gpointer _pygi_arg_to_hash_pointer (const GIArgument *arg,
                                     GITypeTag         type_tag);
 
@@ -47,9 +55,9 @@ gint _pygi_g_registered_type_info_check_object (GIRegisteredTypeInfo *info,
 
 
 GArray* _pygi_argument_to_array (GIArgument  *arg,
-                                 GIArgument  *args[],
-                                 const GValue *args_values,
-                                 GICallableInfo *callable_info,
+                                 PyGIArgArrayLengthPolicy array_length_policy,
+                                 void        *user_data1,
+                                 void        *user_data2,
                                  GITypeInfo  *type_info,
                                  gboolean    *out_free_array);
 
diff --git a/gi/pygi-signal-closure.c b/gi/pygi-signal-closure.c
index 079669c..39e0881 100644
--- a/gi/pygi-signal-closure.c
+++ b/gi/pygi-signal-closure.c
@@ -122,8 +122,12 @@ pygi_signal_closure_marshal(GClosure *closure,
             
             if (g_type_info_get_tag (&type_info) == GI_TYPE_TAG_ARRAY) {
                 /* Skip the self argument of param_values */
-                arg.v_pointer = _pygi_argument_to_array (&arg, NULL, param_values + 1, signal_info,
-                                                         &type_info, &free_array);
+                arg.v_pointer = _pygi_argument_to_array (&arg,
+                                                         _pygi_argument_array_length_marshal,
+                                                         (void *)(param_values + 1),
+                                                         signal_info,
+                                                         &type_info,
+                                                         &free_array);
             }
             
             item = _pygi_argument_to_object (&arg, &type_info, transfer);