misc: add some annoying mpv_node helpers

Sigh.

Some parts of mpv essentially duplicate this code (with varrying levels
of triviality) - this can be fixed "later".

misc/node.c

@@ -0,0 +1,65 @@
+#include "common/common.h"
+
+#include "node.h"
+
+// Init a node with the given format. If parent is not NULL, it is set as
+// parent allocation according to m_option_type_node rules (which means
+// the mpv_node_list allocs are used for chaining the TA allocations).
+// format == MPV_FORMAT_NONE will simply initialize it with all-0.
+void node_init(struct mpv_node *dst, int format, struct mpv_node *parent)
+{
+    // Other formats need to be initialized manually.
+    assert(format == MPV_FORMAT_NODE_MAP || format == MPV_FORMAT_NODE_ARRAY ||
+           format == MPV_FORMAT_FLAG || format == MPV_FORMAT_INT64 ||
+           format == MPV_FORMAT_DOUBLE || format == MPV_FORMAT_NONE);
+
+    void *ta_parent = NULL;
+    if (parent) {
+        assert(parent->format == MPV_FORMAT_NODE_MAP ||
+               parent->format == MPV_FORMAT_NODE_ARRAY);
+        ta_parent = parent->u.list;
+    }
+
+    *dst = (struct mpv_node){ .format = format };
+    if (format == MPV_FORMAT_NODE_MAP || format == MPV_FORMAT_NODE_ARRAY)
+        dst->u.list = talloc_zero(ta_parent, struct mpv_node_list);
+}
+
+// Add an entry to a MPV_FORMAT_NODE_ARRAY.
+// m_option_type_node memory management rules apply.
+struct mpv_node *node_array_add(struct mpv_node *dst, int format)
+{
+    struct mpv_node_list *list = dst->u.list;
+    assert(dst->format == MPV_FORMAT_NODE_ARRAY && dst->u.list);
+    MP_TARRAY_GROW(list, list->values, list->num);
+    node_init(&list->values[list->num], format, dst);
+    return &list->values[list->num++];
+}
+
+// Add an entry to a MPV_FORMAT_NODE_MAP. Keep in mind that this does
+// not check for already existing entries under the same key.
+// m_option_type_node memory management rules apply.
+struct mpv_node *node_map_add(struct mpv_node *dst, const char *key, int format)
+{
+    assert(key);
+
+    struct mpv_node_list *list = dst->u.list;
+    assert(dst->format == MPV_FORMAT_NODE_MAP && dst->u.list);
+    MP_TARRAY_GROW(list, list->values, list->num);
+    MP_TARRAY_GROW(list, list->keys, list->num);
+    list->keys[list->num] = talloc_strdup(list, key);
+    node_init(&list->values[list->num], format, dst);
+    return &list->values[list->num++];
+}
+
+// Add a string entry to a MPV_FORMAT_NODE_MAP. Keep in mind that this does
+// not check for already existing entries under the same key.
+// m_option_type_node memory management rules apply.
+void node_map_add_string(struct mpv_node *dst, const char *key, const char *val)
+{
+    assert(val);
+
+    struct mpv_node *entry = node_map_add(dst, key, MPV_FORMAT_NONE);
+    entry->format = MPV_FORMAT_STRING;
+    entry->u.string = talloc_strdup(dst->u.list, val);
+}

misc/node.h

@@ -0,0 +1,11 @@
+#ifndef MP_MISC_NODE_H_
+#define MP_MISC_NODE_H_
+
+#include "libmpv/client.h"
+
+void node_init(struct mpv_node *dst, int format, struct mpv_node *parent);
+struct mpv_node *node_array_add(struct mpv_node *dst, int format);
+struct mpv_node *node_map_add(struct mpv_node *dst, const char *key, int format);
+void node_map_add_string(struct mpv_node *dst, const char *key, const char *val);
+
+#endif

wscript_build.py

@@ -195,6 +195,7 @@ def build(ctx):
         ( "misc/charset_conv.c" ),
         ( "misc/dispatch.c" ),
         ( "misc/json.c" ),
+        ( "misc/node.c" ),
         ( "misc/ring.c" ),
         ( "misc/rendezvous.c" ),