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

scenenodegroups.h

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+/*
+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/.
+*/
+
+#pragma once
+
+#include "scenenode.h"
+
+namespace scene {
+
+// holds lists of grouped scene nodes
+class node_groups {
+    // NOTE: during scenario deserialization encountering *.inc file causes creation of a new group on the group stack
+    // this allows all nodes listed in this *.inc file to be grouped and potentially modified together by the editor.
+private:
+    // types
+    using node_sequence = std::vector<scene::basic_node *>;
+
+public:
+// constructors
+    node_groups() = default;
+// methods
+    // requests creation of a new node group. returns: handle to the group
+    group_handle
+        begin();
+    // indicates creation of current group ended. returns: handle to the parent group or null_handle if group stack is empty
+    group_handle
+        end();
+    // returns current active group, or null_handle if group stack is empty
+    group_handle
+        handle() const;
+    // places provided node in specified group
+    void
+        register_node( scene::basic_node *Node, scene::group_handle const Group );
+    std::pair<node_sequence::iterator, node_sequence::iterator>
+        group( scene::group_handle const Group ) {
+            auto &group { m_groupmap[ Group ] };
+            return { std::begin( group ), std::end( group ) }; }
+
+private:
+// types
+    using group_map = std::unordered_map<scene::group_handle, node_sequence>;
+// methods
+    // removes specified group from the group list and group information from the group's nodes
+    void
+        erase( group_map::const_iterator Group );
+    // creates handle for a new group
+    group_handle
+        create_handle();
+// members
+    group_map m_groupmap; // map of established node groups
+    std::stack<scene::group_handle> m_activegroup; // helper, group to be assigned to newly created nodes
+};
+
+extern node_groups Groups;
+
+} // scene
+
+//---------------------------------------------------------------------------