build 180809. scenery node groups, AI shunt mode braking tweaks

scenenodegroups.cpp

@@ -0,0 +1,97 @@
+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#include "stdafx.h"
+#include "scenenodegroups.h"
+
+namespace scene {
+
+node_groups Groups;
+
+// requests creation of a new node group. returns: handle to the group
+scene::group_handle
+node_groups::begin() {
+
+    m_activegroup.push( create_handle() );
+
+    return handle();
+}
+
+// indicates creation of current group ended. returns: handle to the parent group or null_handle if group stack is empty
+scene::group_handle
+node_groups::end() {
+
+    if( false == m_activegroup.empty() ) {
+
+        auto const closinggroup { m_activegroup.top() };
+        m_activegroup.pop();
+        // if the completed group holds only one item and there's no chance more items will be added, disband it
+        if( ( true == m_activegroup.empty() )
+         || ( m_activegroup.top() != closinggroup ) ) {
+
+            auto lookup { m_groupmap.find( closinggroup ) };
+            if( ( lookup != m_groupmap.end() )
+             && ( lookup->second.size() <= 1 ) ) {
+
+                erase( lookup );
+            }
+        }
+    }
+    return handle();
+}
+
+// returns current active group, or null_handle if group stack is empty
+group_handle
+node_groups::handle() const {
+
+    return (
+        m_activegroup.empty() ?
+            null_handle :
+            m_activegroup.top() );
+}
+
+// places provided node in specified group
+void
+node_groups::register_node( scene::basic_node *Node, scene::group_handle const Group ) {
+
+    // TBD, TODO: automatically unregister the node from its current group?
+    Node->group( Group );
+
+    if( Group == null_handle ) { return; }
+
+    auto &nodesequence { m_groupmap[ Group ] };
+    if( std::find( std::begin( nodesequence ), std::end( nodesequence ), Node ) == std::end( nodesequence ) ) {
+        // don't add the same node twice
+        nodesequence.emplace_back( Node );
+    }
+}
+
+// removes specified group from the group list and group information from the group's nodes
+void
+node_groups::erase( group_map::const_iterator Group ) {
+
+    for( auto *node : Group->second ) {
+        node->group( null_handle );
+    }
+    m_groupmap.erase( Group );
+}
+
+// creates handle for a new group
+group_handle
+node_groups::create_handle() {
+    // NOTE: for simplification nested group structure are flattened
+    return(
+        m_activegroup.empty() ?
+            m_groupmap.size() + 1 : // new group isn't created until node registration
+            m_activegroup.top() );
+}
+
+} // scene
+
+//---------------------------------------------------------------------------