Nodes: add utilities to access all node links and toposort index

source/blender/blenkernel/BKE_node_runtime.hh

@@ -291,6 +291,9 @@ class bNodeRuntime : NonCopyable, NonMovable {
   bool has_available_linked_outputs = false;
   Vector<bNode *> direct_children_in_frame;
   bNodeTree *owner_tree = nullptr;
+  /** Can be used to toposort a subset of nodes. */
+  int toposort_left_to_right_index = -1;
+  int toposort_right_to_left_index = -1;
 };
 
 namespace node_tree_runtime {
@@ -515,6 +518,18 @@ inline blender::Span<bNode *> bNodeTree::root_frames() const
   return this->runtime->root_frames;
 }
 
+inline blender::Span<bNodeLink *> bNodeTree::all_links()
+{
+  BLI_assert(blender::bke::node_tree_runtime::topology_cache_is_available(*this));
+  return this->runtime->links;
+}
+
+inline blender::Span<const bNodeLink *> bNodeTree::all_links() const
+{
+  BLI_assert(blender::bke::node_tree_runtime::topology_cache_is_available(*this));
+  return this->runtime->links;
+}
+
 inline blender::Span<const bNodePanel *> bNodeTree::panels() const
 {
   return blender::Span(panels_array, panels_num);
@@ -525,6 +540,8 @@ inline blender::MutableSpan<bNodePanel *> bNodeTree::panels_for_write()
   return blender::MutableSpan(panels_array, panels_num);
 }
 
+/** \} */
+
 /* -------------------------------------------------------------------- */
 /** \name #bNode Inline Methods
  * \{ */

source/blender/blenkernel/intern/node_runtime.cc

@@ -506,11 +506,19 @@ static void ensure_topology_cache(const bNodeTree &ntree)
                           ToposortDirection::LeftToRight,
                           tree_runtime.toposort_left_to_right,
                           tree_runtime.has_available_link_cycle);
+          for (const int i : tree_runtime.toposort_left_to_right.index_range()) {
+            const bNode &node = *tree_runtime.toposort_left_to_right[i];
+            node.runtime->toposort_left_to_right_index = i;
+          }
         },
         [&]() {
           bool dummy;
           update_toposort(
               ntree, ToposortDirection::RightToLeft, tree_runtime.toposort_right_to_left, dummy);
+          for (const int i : tree_runtime.toposort_right_to_left.index_range()) {
+            const bNode &node = *tree_runtime.toposort_right_to_left[i];
+            node.runtime->toposort_right_to_left_index = i;
+          }
         },
         [&]() { update_root_frames(ntree); },
         [&]() { update_direct_frames_childrens(ntree); });

source/blender/blenkernel/intern/node_tree_dot_export.cc

@@ -57,7 +57,7 @@ std::string node_tree_to_dot(const bNodeTree &tree, const bNodeTreeToDotOptions
     dot_nodes.add_new(node, dot::NodeWithSocketsRef(dot_node, dot_node_with_sockets));
   }
 
-  LISTBASE_FOREACH (const bNodeLink *, link, &tree.links) {
+  for (const bNodeLink *link : tree.all_links()) {
     const dot::NodeWithSocketsRef &from_dot_node = dot_nodes.lookup(link->fromnode);
     const dot::NodeWithSocketsRef &to_dot_node = dot_nodes.lookup(link->tonode);
     const dot::NodePort from_dot_port = from_dot_node.output(link->fromsock->index());

source/blender/editors/space_node/node_draw.cc

@@ -3246,14 +3246,14 @@ static void node_draw_nodetree(const bContext &C,
   GPU_blend(GPU_BLEND_ALPHA);
   nodelink_batch_start(snode);
 
-  LISTBASE_FOREACH (const bNodeLink *, link, &ntree.links) {
+  for (const bNodeLink *link : ntree.all_links()) {
     if (!nodeLinkIsHidden(link) && !bke::nodeLinkIsSelected(link)) {
       node_draw_link(C, region.v2d, snode, *link, false);
     }
   }
 
   /* Draw selected node links after the unselected ones, so they are shown on top. */
-  LISTBASE_FOREACH (const bNodeLink *, link, &ntree.links) {
+  for (const bNodeLink *link : ntree.all_links()) {
     if (!nodeLinkIsHidden(link) && bke::nodeLinkIsSelected(link)) {
       node_draw_link(C, region.v2d, snode, *link, true);
     }

source/blender/makesdna/DNA_node_types.h

@@ -646,6 +646,9 @@ typedef struct bNodeTree {
   blender::Span<const bNode *> nodes_by_type(blender::StringRefNull type_idname) const;
   /** Frame nodes without any parents. */
   blender::Span<bNode *> root_frames() const;
+  /** A span containing all links in the node tree. */
+  blender::Span<bNodeLink *> all_links();
+  blender::Span<const bNodeLink *> all_links() const;
   /**
    * Cached toposort of all nodes. If there are cycles, the returned array is not actually a
    * toposort. However, if a connected component does not contain a cycle, this component is sorted