Add EnumMap container for bidirectional key, enum mapping

OpenRCT2.xcodeproj/project.pbxproj

@@ -767,6 +767,7 @@
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 		B9B6F97CE24E4A559C7BBA0A /* RideConstruction.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 6BCCA2EF0F5A40D5B83A83AC /* RideConstruction.cpp */; };
+		317B766A750D4365B22A1682 /* EnumMap.hpp in Headers */ = {isa = PBXBuildFile; fileRef = BA2317BF6FB54E328DEB7055 /* EnumMap.hpp */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -1836,6 +1837,7 @@
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 		9D3DD6CD73F5421880280D9D /* Litter.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = Litter.cpp; path = src/openrct2/world/Litter.cpp; sourceTree = SOURCE_ROOT; };
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+		BA2317BF6FB54E328DEB7055 /* EnumMap.hpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.h; name = EnumMap.hpp; path = src/openrct2/core/EnumMap.hpp; sourceTree = SOURCE_ROOT; };
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@@ -2503,6 +2505,7 @@
 				4C8BB67F25533D64005C8830 /* StringReader.h */,
 				F76C83991EC4E7CC00FA49E2 /* Zip.cpp */,
 				F76C839A1EC4E7CC00FA49E2 /* Zip.h */,
+				BA2317BF6FB54E328DEB7055 /* EnumMap.hpp */,
 			);
 			path = core;
 			sourceTree = "<group>";
@@ -3468,6 +3471,7 @@
 				2ADE2F342244191E002598AF /* VirtualFloor.h in Headers */,
 				66A10F8B257F1E1800DD651A /* LandSmoothAction.h in Headers */,
 				F42186C5840D4196981ADD16 /* EntityTweener.h in Headers */,
+				317B766A750D4365B22A1682 /* EnumMap.hpp in Headers */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

src/openrct2/core/EnumMap.hpp

@@ -0,0 +1,157 @@
+/*****************************************************************************
+ * Copyright (c) 2014-2021 OpenRCT2 developers
+ *
+ * For a complete list of all authors, please refer to contributors.md
+ * Interested in contributing? Visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is licensed under the GNU General Public License version 3.
+ *****************************************************************************/
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <string_view>
+#include <vector>
+
+/**
+ * Bi-directional map for converting between strings and enums / numbers.
+ */
+template<typename T> class EnumMap
+{
+private:
+    std::vector<std::pair<std::string_view, T>> _map;
+    bool _continiousValueIndex{ false };
+
+    static constexpr size_t BucketSize = 43;
+    std::array<std::vector<int32_t>, BucketSize> _buckets;
+
+    static constexpr bool ValueIndexable()
+    {
+        if constexpr (std::is_enum_v<T>)
+            return true;
+        else if constexpr (std::is_integral_v<T>)
+            return true;
+        return false;
+    }
+
+    static constexpr auto ValueDistance(T a, T b)
+    {
+        if constexpr (std::is_enum_v<T>)
+            return static_cast<std::underlying_type_t<T>>(b) - static_cast<std::underlying_type_t<T>>(a);
+        else if constexpr (std::is_integral_v<T>)
+            return (b - a);
+    }
+
+    static constexpr uint32_t MakeHash(const std::string_view str)
+    {
+        uint32_t res = 0x811c9dc5;
+        for (auto chr : str)
+        {
+            res ^= chr;
+            res *= 0x01000193;
+        }
+        return res;
+    }
+
+public:
+    EnumMap(const std::initializer_list<std::pair<std::string_view, T>>&& items)
+        : _map{ items }
+    {
+        std::sort(_map.begin(), _map.end(), [](const auto& a, const auto& b) { return a.second < b.second; });
+
+        if constexpr (ValueIndexable())
+        {
+            _continiousValueIndex = true;
+            T cur{};
+            for (size_t i = 1; i < _map.size(); i++)
+            {
+                auto nextVal = _map[i].second;
+                auto dist = ValueDistance(cur, _map[i].second);
+                if (dist != 1)
+                {
+                    _continiousValueIndex = false;
+                    break;
+                }
+                cur = nextVal;
+            }
+        }
+
+        int32_t index = 0;
+        for (auto& kv : _map)
+        {
+            auto hash = MakeHash(kv.first);
+            auto bucketIndex = hash % BucketSize;
+            auto& bucket = _buckets[bucketIndex];
+            bucket.push_back(index);
+            index++;
+        }
+    }
+
+    std::string_view operator[](T k) const
+    {
+        auto it = find(k);
+        return it->first;
+    }
+
+    T operator[](std::string_view k) const
+    {
+        auto it = find(k);
+        return it->second;
+    }
+
+    auto find(const std::string_view k) const
+    {
+        const auto hash = MakeHash(k);
+        const auto bucketIndex = hash % BucketSize;
+        const auto& bucket = _buckets[bucketIndex];
+
+        for (auto index : bucket)
+        {
+            auto& entry = _map[index];
+            if (entry.first == k)
+            {
+                return _map.begin() + index;
+            }
+        }
+
+        return end();
+    }
+
+    auto find(const T k) const
+    {
+        const auto binarySearchValue = [&]() {
+            auto it = std::lower_bound(_map.begin(), _map.end(), k, [](const auto& a, const auto& b) { return a.second < b; });
+            if (it == _map.end() || it->second != k)
+                return end();
+
+            return it;
+        };
+
+        if constexpr (ValueIndexable())
+        {
+            if (_continiousValueIndex)
+            {
+                auto index = static_cast<size_t>(k);
+                return _map.begin() + index;
+            }
+            else
+            {
+                return binarySearchValue();
+            }
+        }
+        else
+        {
+            return binarySearchValue();
+        }
+    }
+
+    auto begin() const
+    {
+        return _map.begin();
+    }
+
+    auto end() const
+    {
+        return _map.end();
+    }
+};

src/openrct2/libopenrct2.vcxproj

@@ -157,6 +157,7 @@
     <ClInclude Include="core\DataSerialiserTraits.h" />
     <ClInclude Include="core\Diagnostics.hpp" />
     <ClInclude Include="core\Endianness.h" />
+    <ClInclude Include="core\EnumMap.hpp" />
     <ClInclude Include="core\File.h" />
     <ClInclude Include="core\FileIndex.hpp" />
     <ClInclude Include="core\FileScanner.h" />