Functions: remove multi-function network

The multi-function network system was able to compose multiple
multi-functions into a new one and to evaluate that efficiently.
This functionality was heavily used by the particle nodes prototype
a year ago. However, since then we only used multi-functions
without the need to compose them in geometry nodes.

The upcoming "fields" in geometry nodes will need a way to
compose multi-functions again. Unfortunately, the code removed
in this commit was not ideal for this different kind of function
composition. I've been working on an alternative that will be added
separately when it becomes needed.

I've had to update all the function nodes, because their interface
depended on the multi-function network data structure a bit.
The actual multi-function implementations are still the same though.

5 files changed, 40 insertions, 471 deletions

diff --git a/source/blender/nodes/intern/node_geometry_exec.cc b/source/blender/nodes/intern/node_geometry_exec.cc
index ffa20579acc..a3bbca90731 100644
--- a/source/blender/nodes/intern/node_geometry_exec.cc
+++ b/source/blender/nodes/intern/node_geometry_exec.cc
@@ -19,7 +19,6 @@
 #include "DEG_depsgraph_query.h"
 
 #include "NOD_geometry_exec.hh"
-#include "NOD_type_callbacks.hh"
 #include "NOD_type_conversions.hh"
 
 #include "node_geometry_util.hh"
diff --git a/source/blender/nodes/intern/node_multi_function.cc b/source/blender/nodes/intern/node_multi_function.cc
new file mode 100644
index 00000000000..c91899ed8c2
--- /dev/null
+++ b/source/blender/nodes/intern/node_multi_function.cc
@@ -0,0 +1,40 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "NOD_multi_function.hh"
+
+namespace blender::nodes {
+
+NodeMultiFunctions::NodeMultiFunctions(const DerivedNodeTree &tree, ResourceScope &resource_scope)
+{
+  for (const NodeTreeRef *tree_ref : tree.used_node_tree_refs()) {
+    bNodeTree *btree = tree_ref->btree();
+    for (const NodeRef *node : tree_ref->nodes()) {
+      bNode *bnode = node->bnode();
+      if (bnode->typeinfo->build_multi_function == nullptr) {
+        continue;
+      }
+      NodeMultiFunctionBuilder builder{resource_scope, *bnode, *btree};
+      bnode->typeinfo->build_multi_function(builder);
+      const MultiFunction *fn = builder.built_fn_;
+      if (fn != nullptr) {
+        map_.add_new(bnode, fn);
+      }
+    }
+  }
+}
+
+}  // namespace blender::nodes
diff --git a/source/blender/nodes/intern/node_socket.cc b/source/blender/nodes/intern/node_socket.cc
index 4be3fd2468b..528616eb23a 100644
--- a/source/blender/nodes/intern/node_socket.cc
+++ b/source/blender/nodes/intern/node_socket.cc
@@ -44,7 +44,6 @@
 
 #include "MEM_guardedalloc.h"
 
-#include "NOD_node_tree_multi_function.hh"
 #include "NOD_socket.h"
 
 #include "FN_cpp_type_make.hh"
diff --git a/source/blender/nodes/intern/node_tree_multi_function.cc b/source/blender/nodes/intern/node_tree_multi_function.cc
deleted file mode 100644
index 7ab6495f733..00000000000
--- a/source/blender/nodes/intern/node_tree_multi_function.cc
+++ /dev/null
@@ -1,409 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
-
-#include "NOD_node_tree_multi_function.hh"
-#include "NOD_type_conversions.hh"
-
-#include "FN_multi_function_network_evaluation.hh"
-
-#include "BLI_color.hh"
-#include "BLI_float2.hh"
-#include "BLI_float3.hh"
-
-namespace blender::nodes {
-
-const fn::MultiFunction &NodeMFNetworkBuilder::get_default_fn(StringRef name)
-{
-  Vector<fn::MFDataType, 10> input_types;
-  Vector<fn::MFDataType, 10> output_types;
-
-  for (const InputSocketRef *dsocket : dnode_->inputs()) {
-    if (dsocket->is_available()) {
-      std::optional<fn::MFDataType> data_type = socket_mf_type_get(*dsocket->typeinfo());
-      if (data_type.has_value()) {
-        input_types.append(*data_type);
-      }
-    }
-  }
-  for (const OutputSocketRef *dsocket : dnode_->outputs()) {
-    if (dsocket->is_available()) {
-      std::optional<fn::MFDataType> data_type = socket_mf_type_get(*dsocket->typeinfo());
-      if (data_type.has_value()) {
-        output_types.append(*data_type);
-      }
-    }
-  }
-
-  const fn::MultiFunction &fn = this->construct_fn<fn::CustomMF_DefaultOutput>(
-      name, input_types, output_types);
-  return fn;
-}
-
-static void insert_dummy_node(CommonMFNetworkBuilderData &common, const DNode &dnode)
-{
-  constexpr int stack_capacity = 10;
-
-  Vector<fn::MFDataType, stack_capacity> input_types;
-  Vector<StringRef, stack_capacity> input_names;
-  Vector<const InputSocketRef *, stack_capacity> input_dsockets;
-
-  for (const InputSocketRef *dsocket : dnode->inputs()) {
-    if (dsocket->is_available()) {
-      std::optional<fn::MFDataType> data_type = socket_mf_type_get(*dsocket->bsocket()->typeinfo);
-      if (data_type.has_value()) {
-        input_types.append(*data_type);
-        input_names.append(dsocket->name());
-        input_dsockets.append(dsocket);
-      }
-    }
-  }
-
-  Vector<fn::MFDataType, stack_capacity> output_types;
-  Vector<StringRef, stack_capacity> output_names;
-  Vector<const OutputSocketRef *, stack_capacity> output_dsockets;
-
-  for (const OutputSocketRef *dsocket : dnode->outputs()) {
-    if (dsocket->is_available()) {
-      std::optional<fn::MFDataType> data_type = socket_mf_type_get(*dsocket->bsocket()->typeinfo);
-      if (data_type.has_value()) {
-        output_types.append(*data_type);
-        output_names.append(dsocket->name());
-        output_dsockets.append(dsocket);
-      }
-    }
-  }
-
-  fn::MFDummyNode &dummy_node = common.network.add_dummy(
-      dnode->name(), input_types, output_types, input_names, output_names);
-
-  common.network_map.add(*dnode.context(), input_dsockets, dummy_node.inputs());
-  common.network_map.add(*dnode.context(), output_dsockets, dummy_node.outputs());
-}
-
-static bool has_data_sockets(const DNode &dnode)
-{
-  for (const InputSocketRef *socket : dnode->inputs()) {
-    if (socket_is_mf_data_socket(*socket->bsocket()->typeinfo)) {
-      return true;
-    }
-  }
-  for (const OutputSocketRef *socket : dnode->outputs()) {
-    if (socket_is_mf_data_socket(*socket->bsocket()->typeinfo)) {
-      return true;
-    }
-  }
-  return false;
-}
-
-static void foreach_node_to_insert(CommonMFNetworkBuilderData &common,
-                                   FunctionRef<void(DNode)> callback)
-{
-  common.tree.foreach_node([&](const DNode dnode) {
-    if (dnode->is_group_node()) {
-      return;
-    }
-    /* Don't insert non-root group input/output nodes, because they will be inlined. */
-    if (!dnode.context()->is_root()) {
-      if (dnode->is_group_input_node() || dnode->is_group_output_node()) {
-        return;
-      }
-    }
-    callback(dnode);
-  });
-}
-
-/**
- * Expands all function nodes in the multi-function network. Nodes that don't have an expand
- * function, but do have data sockets, will get corresponding dummy nodes.
- */
-static void insert_nodes(CommonMFNetworkBuilderData &common)
-{
-  foreach_node_to_insert(common, [&](const DNode dnode) {
-    const bNodeType *node_type = dnode->typeinfo();
-    if (node_type->expand_in_mf_network != nullptr) {
-      NodeMFNetworkBuilder builder{common, dnode};
-      node_type->expand_in_mf_network(builder);
-    }
-    else if (has_data_sockets(dnode)) {
-      insert_dummy_node(common, dnode);
-    }
-  });
-}
-
-static fn::MFOutputSocket &insert_default_value_for_type(CommonMFNetworkBuilderData &common,
-                                                         fn::MFDataType type)
-{
-  const fn::MultiFunction *default_fn;
-  if (type.is_single()) {
-    default_fn = &common.scope.construct<fn::CustomMF_GenericConstant>(
-        AT, type.single_type(), type.single_type().default_value());
-  }
-  else {
-    default_fn = &common.scope.construct<fn::CustomMF_GenericConstantArray>(
-        AT, fn::GSpan(type.vector_base_type()));
-  }
-
-  fn::MFNode &node = common.network.add_function(*default_fn);
-  return node.output(0);
-}
-
-static fn::MFOutputSocket *insert_unlinked_input(CommonMFNetworkBuilderData &common,
-                                                 const DInputSocket &dsocket)
-{
-  BLI_assert(socket_is_mf_data_socket(*dsocket->typeinfo()));
-
-  SocketMFNetworkBuilder builder{common, dsocket};
-  socket_expand_in_mf_network(builder);
-
-  fn::MFOutputSocket *built_socket = builder.built_socket();
-  BLI_assert(built_socket != nullptr);
-  return built_socket;
-}
-
-static void insert_links_and_unlinked_inputs(CommonMFNetworkBuilderData &common)
-{
-  foreach_node_to_insert(common, [&](const DNode dnode) {
-    for (const InputSocketRef *socket_ref : dnode->inputs()) {
-      const DInputSocket to_dsocket{dnode.context(), socket_ref};
-      if (!to_dsocket->is_available()) {
-        continue;
-      }
-      if (!socket_is_mf_data_socket(*to_dsocket->typeinfo())) {
-        continue;
-      }
-
-      Span<fn::MFInputSocket *> to_sockets = common.network_map.lookup(to_dsocket);
-      BLI_assert(to_sockets.size() >= 1);
-      const fn::MFDataType to_type = to_sockets[0]->data_type();
-
-      Vector<DSocket> from_dsockets;
-      to_dsocket.foreach_origin_socket([&](DSocket socket) { from_dsockets.append(socket); });
-      if (from_dsockets.size() > 1) {
-        fn::MFOutputSocket &from_socket = insert_default_value_for_type(common, to_type);
-        for (fn::MFInputSocket *to_socket : to_sockets) {
-          common.network.add_link(from_socket, *to_socket);
-        }
-        continue;
-      }
-      if (from_dsockets.is_empty()) {
-        /* The socket is not linked. Need to use the value of the socket itself. */
-        fn::MFOutputSocket *built_socket = insert_unlinked_input(common, to_dsocket);
-        for (fn::MFInputSocket *to_socket : to_sockets) {
-          common.network.add_link(*built_socket, *to_socket);
-        }
-        continue;
-      }
-      if (from_dsockets[0]->is_input()) {
-        DInputSocket from_dsocket{from_dsockets[0]};
-        fn::MFOutputSocket *built_socket = insert_unlinked_input(common, from_dsocket);
-        for (fn::MFInputSocket *to_socket : to_sockets) {
-          common.network.add_link(*built_socket, *to_socket);
-        }
-        continue;
-      }
-      DOutputSocket from_dsocket{from_dsockets[0]};
-      fn::MFOutputSocket *from_socket = &common.network_map.lookup(from_dsocket);
-      const fn::MFDataType from_type = from_socket->data_type();
-
-      if (from_type != to_type) {
-        const fn::MultiFunction *conversion_fn =
-            get_implicit_type_conversions().get_conversion_multi_function(from_type, to_type);
-        if (conversion_fn != nullptr) {
-          fn::MFNode &node = common.network.add_function(*conversion_fn);
-          common.network.add_link(*from_socket, node.input(0));
-          from_socket = &node.output(0);
-        }
-        else {
-          from_socket = &insert_default_value_for_type(common, to_type);
-        }
-      }
-
-      for (fn::MFInputSocket *to_socket : to_sockets) {
-        common.network.add_link(*from_socket, *to_socket);
-      }
-    }
-  });
-}
-
-/**
- * Expands all function nodes contained in the given node tree within the given multi-function
- * network.
- *
- * Returns a mapping between the original node tree and the generated nodes/sockets for further
- * processing.
- */
-MFNetworkTreeMap insert_node_tree_into_mf_network(fn::MFNetwork &network,
-                                                  const DerivedNodeTree &tree,
-                                                  ResourceScope &scope)
-{
-  MFNetworkTreeMap network_map{tree, network};
-
-  CommonMFNetworkBuilderData common{scope, network, network_map, tree};
-
-  insert_nodes(common);
-  insert_links_and_unlinked_inputs(common);
-
-  return network_map;
-}
-
-/**
- * A single node is allowed to expand into multiple nodes before evaluation. Depending on what
- * nodes it expands to, it belongs a different type of the ones below.
- */
-enum class NodeExpandType {
-  SingleFunctionNode,
-  MultipleFunctionNodes,
-  HasDummyNodes,
-};
-
-/**
- * Checks how the given node expanded in the multi-function network. If it is only a single
- * function node, the corresponding function is returned as well.
- */
-static NodeExpandType get_node_expand_type(MFNetworkTreeMap &network_map,
-                                           const DNode &dnode,
-                                           const fn::MultiFunction **r_single_function)
-{
-  const fn::MFFunctionNode *single_function_node = nullptr;
-  bool has_multiple_nodes = false;
-  bool has_dummy_nodes = false;
-
-  auto check_mf_node = [&](fn::MFNode &mf_node) {
-    if (mf_node.is_function()) {
-      if (single_function_node == nullptr) {
-        single_function_node = &mf_node.as_function();
-      }
-      if (&mf_node != single_function_node) {
-        has_multiple_nodes = true;
-      }
-    }
-    else {
-      BLI_assert(mf_node.is_dummy());
-      has_dummy_nodes = true;
-    }
-  };
-
-  for (const InputSocketRef *dsocket : dnode->inputs()) {
-    if (dsocket->is_available()) {
-      for (fn::MFInputSocket *mf_input :
-           network_map.lookup(DInputSocket(dnode.context(), dsocket))) {
-        check_mf_node(mf_input->node());
-      }
-    }
-  }
-  for (const OutputSocketRef *dsocket : dnode->outputs()) {
-    if (dsocket->is_available()) {
-      fn::MFOutputSocket &mf_output = network_map.lookup(DOutputSocket(dnode.context(), dsocket));
-      check_mf_node(mf_output.node());
-    }
-  }
-
-  if (has_dummy_nodes) {
-    return NodeExpandType::HasDummyNodes;
-  }
-  if (has_multiple_nodes) {
-    return NodeExpandType::MultipleFunctionNodes;
-  }
-  *r_single_function = &single_function_node->function();
-  return NodeExpandType::SingleFunctionNode;
-}
-
-static const fn::MultiFunction &create_function_for_node_that_expands_into_multiple(
-    const DNode &dnode,
-    fn::MFNetwork &network,
-    MFNetworkTreeMap &network_map,
-    ResourceScope &scope)
-{
-  Vector<const fn::MFOutputSocket *> dummy_fn_inputs;
-  for (const InputSocketRef *dsocket : dnode->inputs()) {
-    if (dsocket->is_available()) {
-      MFDataType data_type = *socket_mf_type_get(*dsocket->typeinfo());
-      fn::MFOutputSocket &fn_input = network.add_input(data_type.to_string(), data_type);
-      for (fn::MFInputSocket *mf_input :
-           network_map.lookup(DInputSocket(dnode.context(), dsocket))) {
-        network.add_link(fn_input, *mf_input);
-        dummy_fn_inputs.append(&fn_input);
-      }
-    }
-  }
-  Vector<const fn::MFInputSocket *> dummy_fn_outputs;
-  for (const OutputSocketRef *dsocket : dnode->outputs()) {
-    if (dsocket->is_available()) {
-      fn::MFOutputSocket &mf_output = network_map.lookup(DOutputSocket(dnode.context(), dsocket));
-      MFDataType data_type = mf_output.data_type();
-      fn::MFInputSocket &fn_output = network.add_output(data_type.to_string(), data_type);
-      network.add_link(mf_output, fn_output);
-      dummy_fn_outputs.append(&fn_output);
-    }
-  }
-
-  fn::MFNetworkEvaluator &fn_evaluator = scope.construct<fn::MFNetworkEvaluator>(
-      __func__, std::move(dummy_fn_inputs), std::move(dummy_fn_outputs));
-  return fn_evaluator;
-}
-
-/**
- * Returns a single multi-function for every node that supports it. This makes it easier to reuse
- * the multi-function implementation of nodes in different contexts.
- */
-MultiFunctionByNode get_multi_function_per_node(const DerivedNodeTree &tree, ResourceScope &scope)
-{
-  /* Build a network that nodes can insert themselves into. However, the individual nodes are not
-   * connected. */
-  fn::MFNetwork &network = scope.construct<fn::MFNetwork>(__func__);
-  MFNetworkTreeMap network_map{tree, network};
-  MultiFunctionByNode functions_by_node;
-
-  CommonMFNetworkBuilderData common{scope, network, network_map, tree};
-
-  tree.foreach_node([&](DNode dnode) {
-    const bNodeType *node_type = dnode->typeinfo();
-    if (node_type->expand_in_mf_network == nullptr) {
-      /* This node does not have a multi-function implementation. */
-      return;
-    }
-
-    NodeMFNetworkBuilder builder{common, dnode};
-    node_type->expand_in_mf_network(builder);
-
-    const fn::MultiFunction *single_function = nullptr;
-    const NodeExpandType expand_type = get_node_expand_type(network_map, dnode, &single_function);
-
-    switch (expand_type) {
-      case NodeExpandType::HasDummyNodes: {
-        /* Dummy nodes cannot be executed, so skip them. */
-        break;
-      }
-      case NodeExpandType::SingleFunctionNode: {
-        /* This is the common case. Most nodes just expand to a single function. */
-        functions_by_node.add_new(dnode, single_function);
-        break;
-      }
-      case NodeExpandType::MultipleFunctionNodes: {
-        /* If a node expanded into multiple functions, a new function has to be created that
-         * combines those. */
-        const fn::MultiFunction &fn = create_function_for_node_that_expands_into_multiple(
-            dnode, network, network_map, scope);
-        functions_by_node.add_new(dnode, &fn);
-        break;
-      }
-    }
-  });
-
-  return functions_by_node;
-}
-
-}  // namespace blender::nodes
diff --git a/source/blender/nodes/intern/type_callbacks.cc b/source/blender/nodes/intern/type_callbacks.cc
deleted file mode 100644
index 881a02c92e9..00000000000
--- a/source/blender/nodes/intern/type_callbacks.cc
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
-
-#include "NOD_node_tree_multi_function.hh"
-#include "NOD_type_callbacks.hh"
-
-namespace blender::nodes {
-
-std::optional<MFDataType> socket_mf_type_get(const bNodeSocketType &stype)
-{
-  const CPPType *cpp_type = stype.get_base_cpp_type ? stype.get_base_cpp_type() : nullptr;
-  if (cpp_type != nullptr) {
-    return MFDataType::ForSingle(*cpp_type);
-  }
-  return {};
-}
-
-bool socket_is_mf_data_socket(const bNodeSocketType &stype)
-{
-  if (!socket_mf_type_get(stype).has_value()) {
-    return false;
-  }
-  if (stype.expand_in_mf_network == nullptr && stype.get_base_cpp_value == nullptr) {
-    return false;
-  }
-  return true;
-}
-
-void socket_expand_in_mf_network(SocketMFNetworkBuilder &builder)
-{
-  bNodeSocket &socket = builder.bsocket();
-  if (socket.typeinfo->expand_in_mf_network != nullptr) {
-    socket.typeinfo->expand_in_mf_network(builder);
-  }
-  else if (socket.typeinfo->get_base_cpp_value != nullptr) {
-    const CPPType &type = *socket.typeinfo->get_base_cpp_type();
-    void *buffer = builder.resource_scope().linear_allocator().allocate(type.size(),
-                                                                        type.alignment());
-    socket.typeinfo->get_base_cpp_value(socket, buffer);
-    builder.set_constant_value(type, buffer);
-  }
-  else {
-    BLI_assert_unreachable();
-  }
-}
-
-}  // namespace blender::nodes