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.

1 files changed, 7 insertions, 6 deletions

diff --git a/source/blender/functions/intern/multi_function_network_optimization.cc b/source/blender/functions/intern/multi_function_network_optimization.cc
index e8fd7afc2ee..af1e77aa355 100644
--- a/source/blender/functions/intern/multi_function_network_optimization.cc
+++ b/source/blender/functions/intern/multi_function_network_optimization.cc
@@ -28,6 +28,7 @@
 #include "BLI_disjoint_set.hh"
 #include "BLI_ghash.h"
 #include "BLI_map.hh"
+#include "BLI_multi_value_map.hh"
 #include "BLI_rand.h"
 #include "BLI_stack.hh"
 
@@ -403,15 +404,15 @@ static Array<uint64_t> compute_node_hashes(MFNetwork &network)
   return node_hashes;
 }
 
-static Map<uint64_t, Vector<MFNode *, 1>> group_nodes_by_hash(MFNetwork &network,
-                                                              Span<uint64_t> node_hashes)
+static MultiValueMap<uint64_t, MFNode *> group_nodes_by_hash(MFNetwork &network,
+                                                             Span<uint64_t> node_hashes)
 {
-  Map<uint64_t, Vector<MFNode *, 1>> nodes_by_hash;
+  MultiValueMap<uint64_t, MFNode *> nodes_by_hash;
   for (int id : IndexRange(network.node_id_amount())) {
     MFNode *node = network.node_or_null_by_id(id);
     if (node != nullptr) {
       uint64_t node_hash = node_hashes[id];
-      nodes_by_hash.lookup_or_add_default(node_hash).append(node);
+      nodes_by_hash.add(node_hash, node);
     }
   }
   return nodes_by_hash;
@@ -456,7 +457,7 @@ static bool nodes_output_same_values(DisjointSet &cache, const MFNode &a, const
 }
 
 static void relink_duplicate_nodes(MFNetwork &network,
-                                   Map<uint64_t, Vector<MFNode *, 1>> &nodes_by_hash)
+                                   MultiValueMap<uint64_t, MFNode *> &nodes_by_hash)
 {
   DisjointSet same_node_cache{network.node_id_amount()};
 
@@ -494,7 +495,7 @@ static void relink_duplicate_nodes(MFNetwork &network,
 void common_subnetwork_elimination(MFNetwork &network)
 {
   Array<uint64_t> node_hashes = compute_node_hashes(network);
-  Map<uint64_t, Vector<MFNode *, 1>> nodes_by_hash = group_nodes_by_hash(network, node_hashes);
+  MultiValueMap<uint64_t, MFNode *> nodes_by_hash = group_nodes_by_hash(network, node_hashes);
   relink_duplicate_nodes(network, nodes_by_hash);
 }