refactors a case insensitive map (#3184)

This PR aims to spark the retirement of a questionable pattern I have found all over our code base. I will illustrate how this pattern encourages code duplication, lacks type safety, requires documentation and can be prone to bugs.
```
std::map<std::string, Object> mMap; // Stored in all lowercase for a case-insensitive lookup

std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.emplace(lowerKey, object);

std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.find(lowerKey);

mMap.find(key); // Not found. Oops!
```
An alternative approach produces no such issues.
```
std::unordered_map<std::string, Object, Misc::StringUtils::CiHash, Misc::StringUtils::CiEqual> mMap;

mMap.emplace(key, object);

mMap.find(key);
```
Of course, such an alternative will work for a `map` as well, but an `unordered_map` is generally preferable over a `map` with these changes because we have moved `lowerCase` into the comparison operator. 

In this PR I have refactored `Animation::mNodeMap` accordingly. I have reviewed and adapted all direct and indirect usage of `Animation::mNodeMap` to ensure we do not change behaviour with this PR.

apps/openmw/mwrender/actoranimation.cpp

@@ -74,7 +74,7 @@ PartHolderPtr ActorAnimation::attachMesh(const std::string& model, const std::st
     osg::ref_ptr<osg::Node> instance = mResourceSystem->getSceneManager()->getInstance(model, parent);
 
     const NodeMap& nodeMap = getNodeMap();
-    NodeMap::const_iterator found = nodeMap.find(Misc::StringUtils::lowerCase(bonename));
+    NodeMap::const_iterator found = nodeMap.find(bonename);
     if (found == nodeMap.end())
         return PartHolderPtr();
 

apps/openmw/mwrender/animation.cpp

@@ -1510,7 +1510,7 @@ namespace MWRender
             parentNode = mInsert;
         else
         {
-            NodeMap::const_iterator found = getNodeMap().find(Misc::StringUtils::lowerCase(bonename));
+            NodeMap::const_iterator found = getNodeMap().find(bonename);
             if (found == getNodeMap().end())
                 throw std::runtime_error("Can't find bone " + bonename);
 
@@ -1619,8 +1619,7 @@ namespace MWRender
 
     const osg::Node* Animation::getNode(const std::string &name) const
     {
-        std::string lowerName = Misc::StringUtils::lowerCase(name);
-        NodeMap::const_iterator found = getNodeMap().find(lowerName);
+        NodeMap::const_iterator found = getNodeMap().find(name);
         if (found == getNodeMap().end())
             return nullptr;
         else

apps/openmw/mwrender/animation.hpp

@@ -7,8 +7,10 @@
 #include <components/sceneutil/textkeymap.hpp>
 #include <components/sceneutil/util.hpp>
 #include <components/sceneutil/nodecallback.hpp>
+#include <components/misc/stringops.hpp>
 
 #include <vector>
+#include <unordered_map>
 
 namespace ESM
 {
@@ -157,6 +159,8 @@ public:
 
     virtual bool updateCarriedLeftVisible(const int weaptype) const { return false; };
 
+    typedef std::unordered_map<std::string, osg::ref_ptr<osg::MatrixTransform>, Misc::StringUtils::CiHash, Misc::StringUtils::CiEqual> NodeMap;
+
 protected:
     class AnimationTime : public SceneUtil::ControllerSource
     {
@@ -250,8 +254,6 @@ protected:
 
     std::shared_ptr<AnimationTime> mAnimationTimePtr[sNumBlendMasks];
 
-    // Stored in all lowercase for a case-insensitive lookup
-    typedef std::map<std::string, osg::ref_ptr<osg::MatrixTransform> > NodeMap;
     mutable NodeMap mNodeMap;
     mutable bool mNodeMapCreated;
 

apps/openmw/mwrender/creatureanimation.cpp

@@ -126,7 +126,7 @@ void CreatureWeaponAnimation::updatePart(PartHolderPtr& scene, int slot)
             if (bonename != "Weapon Bone")
             {
                 const NodeMap& nodeMap = getNodeMap();
-                NodeMap::const_iterator found = nodeMap.find(Misc::StringUtils::lowerCase(bonename));
+                NodeMap::const_iterator found = nodeMap.find(bonename);
                 if (found == nodeMap.end())
                     bonename = "Weapon Bone";
             }
@@ -161,7 +161,7 @@ void CreatureWeaponAnimation::updatePart(PartHolderPtr& scene, int slot)
         osg::ref_ptr<const osg::Node> node = mResourceSystem->getSceneManager()->getTemplate(itemModel);
 
         const NodeMap& nodeMap = getNodeMap();
-        NodeMap::const_iterator found = nodeMap.find(Misc::StringUtils::lowerCase(bonename));
+        NodeMap::const_iterator found = nodeMap.find(bonename);
         if (found == nodeMap.end())
             throw std::runtime_error("Can't find attachment node " + bonename);
         osg::ref_ptr<osg::Node> attached = SceneUtil::attach(node, mObjectRoot, bonename, found->second.get(), mResourceSystem->getSceneManager());

apps/openmw/mwrender/npcanimation.cpp

@@ -713,7 +713,7 @@ PartHolderPtr NpcAnimation::insertBoundedPart(const std::string& model, const st
     osg::ref_ptr<const osg::Node> templateNode = mResourceSystem->getSceneManager()->getTemplate(model);
 
     const NodeMap& nodeMap = getNodeMap();
-    NodeMap::const_iterator found = nodeMap.find(Misc::StringUtils::lowerCase(bonename));
+    NodeMap::const_iterator found = nodeMap.find(bonename);
     if (found == nodeMap.end())
         throw std::runtime_error("Can't find attachment node " + bonename);
 
@@ -813,7 +813,7 @@ bool NpcAnimation::addOrReplaceIndividualPart(ESM::PartReferenceType type, int g
                 if (weaponBonename != bonename)
                 {
                     const NodeMap& nodeMap = getNodeMap();
-                    NodeMap::const_iterator found = nodeMap.find(Misc::StringUtils::lowerCase(weaponBonename));
+                    NodeMap::const_iterator found = nodeMap.find(weaponBonename);
                     if (found != nodeMap.end())
                         bonename = weaponBonename;
                 }

apps/openmw/mwrender/weaponanimation.cpp

@@ -172,14 +172,13 @@ void WeaponAnimation::releaseArrow(MWWorld::Ptr actor, float attackStrength)
     }
 }
 
-void WeaponAnimation::addControllers(const std::map<std::string, osg::ref_ptr<osg::MatrixTransform> >& nodes,
-    std::vector<std::pair<osg::ref_ptr<osg::Node>, osg::ref_ptr<osg::Callback>>> &map, osg::Node* objectRoot)
+void WeaponAnimation::addControllers(const Animation::NodeMap& nodes, std::vector<std::pair<osg::ref_ptr<osg::Node>, osg::ref_ptr<osg::Callback>>> &map, osg::Node* objectRoot)
 {
     for (int i=0; i<2; ++i)
     {
         mSpineControllers[i] = nullptr;
 
-        std::map<std::string, osg::ref_ptr<osg::MatrixTransform> >::const_iterator found = nodes.find(i == 0 ? "bip01 spine1" : "bip01 spine2");
+        Animation::NodeMap::const_iterator found = nodes.find(i == 0 ? "bip01 spine1" : "bip01 spine2");
         if (found != nodes.end())
         {
             osg::Node* node = found->second;

apps/openmw/mwrender/weaponanimation.hpp

@@ -42,8 +42,7 @@ namespace MWRender
         void releaseArrow(MWWorld::Ptr actor, float attackStrength);
 
         /// Add WeaponAnimation-related controllers to \a nodes and store the added controllers in \a map.
-        void addControllers(const std::map<std::string, osg::ref_ptr<osg::MatrixTransform> >& nodes,
-                std::vector<std::pair<osg::ref_ptr<osg::Node>, osg::ref_ptr<osg::Callback>>>& map, osg::Node* objectRoot);
+        void addControllers(const Animation::NodeMap& nodes, std::vector<std::pair<osg::ref_ptr<osg::Node>, osg::ref_ptr<osg::Callback>>>& map, osg::Node* objectRoot);
 
         void deleteControllers();
 

components/misc/stringops.hpp

@@ -6,6 +6,7 @@
 #include <algorithm>
 #include <string_view>
 #include <iterator>
+#include <functional>
 
 #include "utf8stream.hpp"
 
@@ -182,6 +183,21 @@ public:
         return out;
     }
 
+    struct CiEqual
+    {
+        bool operator()(const std::string& left, const std::string& right) const
+        {
+            return ciEqual(left, right);
+        }
+    };
+    struct CiHash
+    {
+        std::size_t operator()(std::string str) const
+        {
+            lowerCaseInPlace(str);
+            return std::hash<std::string>{}(str);
+        }
+    };
     struct CiComp
     {
         bool operator()(const std::string& left, const std::string& right) const

components/sceneutil/visitor.cpp

@@ -51,18 +51,17 @@ namespace SceneUtil
 
     void NodeMapVisitor::apply(osg::MatrixTransform& trans)
     {
-        // Take transformation for first found node in file
-        std::string originalNodeName = Misc::StringUtils::lowerCase(trans.getName());
+        // Choose first found node in file
 
         if (trans.libraryName() == std::string("osgAnimation"))
         {
+            std::string nodeName = trans.getName();
             // Convert underscores to whitespaces as a workaround for Collada (OpenMW's animation system uses whitespace-separated names)
-            std::replace(originalNodeName.begin(), originalNodeName.end(), '_', ' ');
+            std::replace(nodeName.begin(), nodeName.end(), '_', ' ');
+            mMap.emplace(nodeName, &trans);
         }
-
-        const std::string nodeName = originalNodeName;
-
-        mMap.emplace(nodeName, &trans);
+        else
+            mMap.emplace(trans.getName(), &trans);
 
         traverse(trans);
     }

components/sceneutil/visitor.hpp

@@ -4,6 +4,10 @@
 #include <osg/MatrixTransform>
 #include <osg/NodeVisitor>
 
+#include <unordered_map>
+
+#include <components/misc/stringops.hpp>
+
 // Commonly used scene graph visitors
 namespace SceneUtil
 {
@@ -49,7 +53,7 @@ namespace SceneUtil
     class NodeMapVisitor : public osg::NodeVisitor
     {
     public:
-        typedef std::map<std::string, osg::ref_ptr<osg::MatrixTransform> > NodeMap;
+        typedef std::unordered_map<std::string, osg::ref_ptr<osg::MatrixTransform>, Misc::StringUtils::CiHash, Misc::StringUtils::CiEqual> NodeMap;
 
         NodeMapVisitor(NodeMap& map)
             : osg::NodeVisitor(osg::NodeVisitor::TRAVERSE_ALL_CHILDREN)