BLI: add MultiValueMap

This is a convenience wrapper for `Map<Key, Vector<Value>>`.
It does not provide any performance benefits (yet). I need this
kind of map in a couple of places and before I was duplicating
the lookup logic in many places.

4 files changed, 7 insertions, 18 deletions

diff --git a/source/blender/nodes/NOD_derived_node_tree.hh b/source/blender/nodes/NOD_derived_node_tree.hh
index d79bd9031b8..b39c9fd1a23 100644
--- a/source/blender/nodes/NOD_derived_node_tree.hh
+++ b/source/blender/nodes/NOD_derived_node_tree.hh
@@ -181,7 +181,7 @@ class DerivedNodeTree : NonCopyable, NonMovable {
   Vector<DInputSocket *> input_sockets_;
   Vector<DOutputSocket *> output_sockets_;
 
-  Map<const bNodeType *, Vector<DNode *>> nodes_by_type_;
+  MultiValueMap<const bNodeType *, DNode *> nodes_by_type_;
 
  public:
   DerivedNodeTree(bNodeTree *btree, NodeTreeRefMap &node_tree_refs);
@@ -483,13 +483,7 @@ inline Span<const DNode *> DerivedNodeTree::nodes_by_type(StringRefNull idname)
 
 inline Span<const DNode *> DerivedNodeTree::nodes_by_type(const bNodeType *nodetype) const
 {
-  const Vector<DNode *> *nodes = nodes_by_type_.lookup_ptr(nodetype);
-  if (nodes == nullptr) {
-    return {};
-  }
-  else {
-    return *nodes;
-  }
+  return nodes_by_type_.lookup(nodetype);
 }
 
 inline Span<const DSocket *> DerivedNodeTree::sockets() const
diff --git a/source/blender/nodes/NOD_node_tree_ref.hh b/source/blender/nodes/NOD_node_tree_ref.hh
index ebf5709ef50..13656c2e940 100644
--- a/source/blender/nodes/NOD_node_tree_ref.hh
+++ b/source/blender/nodes/NOD_node_tree_ref.hh
@@ -47,6 +47,7 @@
 #include "BLI_array.hh"
 #include "BLI_linear_allocator.hh"
 #include "BLI_map.hh"
+#include "BLI_multi_value_map.hh"
 #include "BLI_string_ref.hh"
 #include "BLI_timeit.hh"
 #include "BLI_utility_mixins.hh"
@@ -162,7 +163,7 @@ class NodeTreeRef : NonCopyable, NonMovable {
   Vector<SocketRef *> sockets_by_id_;
   Vector<InputSocketRef *> input_sockets_;
   Vector<OutputSocketRef *> output_sockets_;
-  Map<const bNodeType *, Vector<NodeRef *>> nodes_by_type_;
+  MultiValueMap<const bNodeType *, NodeRef *> nodes_by_type_;
 
  public:
   NodeTreeRef(bNodeTree *btree);
@@ -411,13 +412,7 @@ inline Span<const NodeRef *> NodeTreeRef::nodes_by_type(StringRefNull idname) co
 
 inline Span<const NodeRef *> NodeTreeRef::nodes_by_type(const bNodeType *nodetype) const
 {
-  const Vector<NodeRef *> *nodes = nodes_by_type_.lookup_ptr(nodetype);
-  if (nodes == nullptr) {
-    return {};
-  }
-  else {
-    return *nodes;
-  }
+  return nodes_by_type_.lookup(nodetype);
 }
 
 inline Span<const SocketRef *> NodeTreeRef::sockets() const
diff --git a/source/blender/nodes/intern/derived_node_tree.cc b/source/blender/nodes/intern/derived_node_tree.cc
index b7c78cb1499..5414ea9208a 100644
--- a/source/blender/nodes/intern/derived_node_tree.cc
+++ b/source/blender/nodes/intern/derived_node_tree.cc
@@ -321,7 +321,7 @@ BLI_NOINLINE void DerivedNodeTree::store_in_this_and_init_ids(
     node->id_ = node_index;
 
     const bNodeType *nodetype = node->node_ref_->bnode()->typeinfo;
-    nodes_by_type_.lookup_or_add_default(nodetype).append(node);
+    nodes_by_type_.add(nodetype, node);
 
     for (DInputSocket *socket : node->inputs_) {
       socket->id_ = sockets_by_id_.append_and_get_index(socket);
diff --git a/source/blender/nodes/intern/node_tree_ref.cc b/source/blender/nodes/intern/node_tree_ref.cc
index 186ca750f10..47669bc5ca2 100644
--- a/source/blender/nodes/intern/node_tree_ref.cc
+++ b/source/blender/nodes/intern/node_tree_ref.cc
@@ -79,7 +79,7 @@ NodeTreeRef::NodeTreeRef(bNodeTree *btree) : btree_(btree)
 
   for (NodeRef *node : nodes_by_id_) {
     const bNodeType *nodetype = node->bnode_->typeinfo;
-    nodes_by_type_.lookup_or_add_default(nodetype).append(node);
+    nodes_by_type_.add(nodetype, node);
   }
 }