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.

3 files changed, 20 insertions, 36 deletions

diff --git a/source/blender/simulation/intern/simulation_collect_influences.cc b/source/blender/simulation/intern/simulation_collect_influences.cc
index eebfe8b864e..7554f61404a 100644
--- a/source/blender/simulation/intern/simulation_collect_influences.cc
+++ b/source/blender/simulation/intern/simulation_collect_influences.cc
@@ -122,13 +122,12 @@ static void find_and_deduplicate_particle_attribute_nodes(nodes::MFNetworkTreeMa
     return;
   }
 
-  Map<std::pair<std::string, fn::MFDataType>, Vector<fn::MFNode *>>
+  MultiValueMap<std::pair<std::string, fn::MFDataType>, fn::MFNode *>
       attribute_nodes_by_name_and_type;
   for (int i : attribute_names->index_range()) {
-    attribute_nodes_by_name_and_type
-        .lookup_or_add_default(
-            {(*attribute_names)[i], name_sockets[i]->node().output(0).data_type()})
-        .append(&name_sockets[i]->node());
+    attribute_nodes_by_name_and_type.add(
+        {(*attribute_names)[i], name_sockets[i]->node().output(0).data_type()},
+        &name_sockets[i]->node());
   }
 
   Map<const fn::MFOutputSocket *, std::string> attribute_inputs;
@@ -237,11 +236,11 @@ class ParticleFunctionForce : public ParticleForce {
   }
 };
 
-static Vector<const ParticleForce *> create_forces_for_particle_simulation(
-    const nodes::DNode &simulation_node,
-    nodes::MFNetworkTreeMap &network_map,
-    ResourceCollector &resources,
-    DummyDataSources &data_sources)
+static void create_forces_for_particle_simulation(const nodes::DNode &simulation_node,
+                                                  nodes::MFNetworkTreeMap &network_map,
+                                                  ResourceCollector &resources,
+                                                  DummyDataSources &data_sources,
+                                                  SimulationInfluences &r_influences)
 {
   Vector<const ParticleForce *> forces;
   for (const nodes::DOutputSocket *origin_socket :
@@ -264,7 +263,9 @@ static Vector<const ParticleForce *> create_forces_for_particle_simulation(
     const ParticleForce &force = resources.construct<ParticleFunctionForce>(AT, *particle_fn);
     forces.append(&force);
   }
-  return forces;
+
+  std::string particle_name = dnode_to_path(simulation_node);
+  r_influences.particle_forces.add_multiple(std::move(particle_name), forces);
 }
 
 static void collect_forces(nodes::MFNetworkTreeMap &network_map,
@@ -273,10 +274,8 @@ static void collect_forces(nodes::MFNetworkTreeMap &network_map,
                            SimulationInfluences &r_influences)
 {
   for (const nodes::DNode *dnode : get_particle_simulation_nodes(network_map.tree())) {
-    std::string name = dnode_to_path(*dnode);
-    Vector<const ParticleForce *> forces = create_forces_for_particle_simulation(
-        *dnode, network_map, resources, data_sources);
-    r_influences.particle_forces.add_new(std::move(name), std::move(forces));
+    create_forces_for_particle_simulation(
+        *dnode, network_map, resources, data_sources, r_influences);
   }
 }
 
diff --git a/source/blender/simulation/intern/simulation_solver.cc b/source/blender/simulation/intern/simulation_solver.cc
index 1ed60022e2d..5ab706dbb4b 100644
--- a/source/blender/simulation/intern/simulation_solver.cc
+++ b/source/blender/simulation/intern/simulation_solver.cc
@@ -137,7 +137,7 @@ BLI_NOINLINE static void simulate_particle_chunk(SimulationSolveContext &solve_c
 {
   int particle_amount = attributes.size();
   Array<float3> force_vectors{particle_amount, {0, 0, 0}};
-  Span<const ParticleForce *> forces = solve_context.influences().get_particle_forces(
+  Span<const ParticleForce *> forces = solve_context.influences().particle_forces.lookup_as(
       state.head.name);
 
   ParticleChunkContext particle_chunk_context{IndexMask(particle_amount), attributes};
diff --git a/source/blender/simulation/intern/simulation_solver_influences.hh b/source/blender/simulation/intern/simulation_solver_influences.hh
index 0eb4dfbaf69..95e6463e60d 100644
--- a/source/blender/simulation/intern/simulation_solver_influences.hh
+++ b/source/blender/simulation/intern/simulation_solver_influences.hh
@@ -18,6 +18,7 @@
 #define __SIM_SIMULATION_SOLVER_INFLUENCES_HH__
 
 #include "BLI_float3.hh"
+#include "BLI_multi_value_map.hh"
 #include "BLI_span.hh"
 
 #include "DNA_simulation_types.h"
@@ -48,31 +49,21 @@ class ParticleForce {
 };
 
 struct SimulationInfluences {
-  /* TODO: Use a special type for a map that contains vectors. */
-  Map<std::string, Vector<const ParticleForce *>> particle_forces;
+  MultiValueMap<std::string, const ParticleForce *> particle_forces;
   Map<std::string, fn::AttributesInfoBuilder *> particle_attributes_builder;
   Vector<const ParticleEmitter *> particle_emitters;
-
-  Span<const ParticleForce *> get_particle_forces(StringRef particle_name) const
-  {
-    const Vector<const ParticleForce *> *forces = particle_forces.lookup_ptr(particle_name);
-    if (forces == nullptr) {
-      return {};
-    }
-    return *forces;
-  }
 };
 
 class SimulationStateMap {
  private:
   Map<StringRefNull, SimulationState *> states_by_name_;
-  Map<StringRefNull, Vector<SimulationState *>> states_by_type_;
+  MultiValueMap<StringRefNull, SimulationState *> states_by_type_;
 
  public:
   void add(SimulationState *state)
   {
     states_by_name_.add_new(state->name, state);
-    states_by_type_.lookup_or_add_default(state->type).append(state);
+    states_by_type_.add(state->type, state);
   }
 
   template<typename StateType> StateType *lookup(StringRef name) const
@@ -101,13 +92,7 @@ class SimulationStateMap {
 
   Span<SimulationState *> lookup_type(StringRef type) const
   {
-    const Vector<SimulationState *> *states = states_by_type_.lookup_ptr_as(type);
-    if (states == nullptr) {
-      return {};
-    }
-    else {
-      return states->as_span();
-    }
+    return states_by_type_.lookup_as(type);
   }
 };