[core] convert CompoundExpressionRegistry to constexpr hash map

3 files changed, 420 insertions, 110 deletions

diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index 6a4894a478..cc1d58025b 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -12,6 +12,8 @@
 #include <mbgl/util/platform.hpp>
 #include <mbgl/util/variant.hpp>
 
+#include <mapbox/eternal.hpp>
+
 #include <cmath>
 
 namespace mbgl {
@@ -215,14 +217,12 @@ struct SignatureType<Lambda, std::enable_if_t<std::is_class<Lambda>::value>>
 { using Type = typename SignatureType<decltype(&Lambda::operator())>::Type; };
 
 template <typename Fn>
-static std::unique_ptr<detail::SignatureBase> makeSignature(Fn evaluateFunction, std::string name) {
+static std::unique_ptr<detail::SignatureBase> makeSignature(std::string name, Fn evaluateFunction) {
     return std::make_unique<Signature<typename SignatureType<Fn>::Type>>(evaluateFunction, std::move(name));
 }
 
 } // namespace detail
 
-using Definition = CompoundExpressionRegistry::Definition;
-
 Value featureIdAsExpressionValue(EvaluationContext params) {
     assert(params.feature);
     auto id = params.feature->getID();
@@ -295,26 +295,45 @@ optional<std::string> featureIdAsString(EvaluationContext params) {
     );
 };
 
-std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initializeDefinitions() {
-    std::unordered_map<std::string, CompoundExpressionRegistry::Definition> definitions;
-    auto define = [&](std::string name, auto fn) {
-        definitions[name].push_back(detail::makeSignature(fn, name));
-    };
+const auto& eCompoundExpression() {
+    static auto signature = detail::makeSignature("e", []() -> Result<double> { return 2.718281828459045; });
+    return signature;
+}
 
-    define("e", []() -> Result<double> { return 2.718281828459045; });
-    define("pi", []() -> Result<double> { return 3.141592653589793; });
-    define("ln2", []() -> Result<double> { return 0.6931471805599453; });
+const auto& piCompoundExpression() {
+    static auto signature = detail::makeSignature("pi", []() -> Result<double> { return 3.141592653589793; });
+    return signature;
+}
 
-    define("typeof", [](const Value& v) -> Result<std::string> { return toString(typeOf(v)); });
+const auto& ln2CompoundExpression() {
+    static auto signature = detail::makeSignature("ln2", []() -> Result<double> { return 0.6931471805599453; });
+    return signature;
+}
+
+const auto& typeofCompoundExpression() {
+    static auto signature = detail::makeSignature("typeof", [](const Value& v) -> Result<std::string> { return toString(typeOf(v)); });
+    return signature;
+}
 
-    define("to-rgba", [](const Color& color) -> Result<std::array<double, 4>> {
+const auto& toRgbaCompoundExpression() {
+    static auto signature = detail::makeSignature("to-rgba", [](const Color& color) -> Result<std::array<double, 4>> {
         return color.toArray();
     });
+    return signature;
+}
+
+const auto& rgbaCompoundExpression() {
+    static auto signature = detail::makeSignature("rgba", [](double r, double g, double b, double a) { return rgba(r, g, b, a); });
+    return signature;
+}
 
-    define("rgba", [](double r, double g, double b, double a) { return rgba(r, g, b, a); });
-    define("rgb", [](double r, double g, double b) { return rgba(r, g, b, 1.0f); });
+const auto& rgbCompoundExpression() {
+    static auto signature = detail::makeSignature("rgb", [](double r, double g, double b) { return rgba(r, g, b, 1.0f); });
+    return signature;
+}
 
-    define("zoom", [](const EvaluationContext& params) -> Result<double> {
+const auto& zoomCompoundExpression() {
+    static auto signature = detail::makeSignature("zoom", [](const EvaluationContext& params) -> Result<double> {
         if (!params.zoom) {
             return EvaluationError {
                 "The 'zoom' expression is unavailable in the current evaluation context."
@@ -322,8 +341,11 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return *(params.zoom);
     });
+    return signature;
+}
 
-    define("heatmap-density", [](const EvaluationContext& params) -> Result<double> {
+const auto& heatmapDensityCompoundExpression() {
+    static auto signature = detail::makeSignature("heatmap-density", [](const EvaluationContext& params) -> Result<double> {
         if (!params.colorRampParameter) {
             return EvaluationError {
                 "The 'heatmap-density' expression is unavailable in the current evaluation context."
@@ -331,8 +353,11 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return *(params.colorRampParameter);
     });
+    return signature;
+}
 
-    define("line-progress", [](const EvaluationContext& params) -> Result<double> {
+const auto& lineProgressCompoundExpression() {
+    static auto signature = detail::makeSignature("line-progress", [](const EvaluationContext& params) -> Result<double> {
         if (!params.colorRampParameter) {
             return EvaluationError {
                 "The 'line-progress' expression is unavailable in the current evaluation context."
@@ -340,8 +365,11 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return *(params.colorRampParameter);
     });
+    return signature;
+}
 
-    define("has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
+const auto& hasContextCompoundExpression() {
+    static auto signature = detail::makeSignature("has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
@@ -350,11 +378,18 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
 
         return params.feature->getValue(key) ? true : false;
     });
-    define("has", [](const std::string& key, const std::unordered_map<std::string, Value>& object) -> Result<bool> {
+    return signature;
+}
+
+const auto& hasObjectCompoundExpression() {
+    static auto signature = detail::makeSignature("has", [](const std::string& key, const std::unordered_map<std::string, Value>& object) -> Result<bool> {
         return object.find(key) != object.end();
     });
+    return signature;
+}
 
-    define("get", [](const EvaluationContext& params, const std::string& key) -> Result<Value> {
+const auto& getContextCompoundExpression() {
+    static auto signature = detail::makeSignature("get", [](const EvaluationContext& params, const std::string& key) -> Result<Value> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
@@ -367,14 +402,21 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return Value(toExpressionValue(*propertyValue));
     });
-    define("get", [](const std::string& key, const std::unordered_map<std::string, Value>& object) -> Result<Value> {
+    return signature;
+}
+
+const auto& getObjectCompoundExpression() {
+    static auto signature = detail::makeSignature("get", [](const std::string& key, const std::unordered_map<std::string, Value>& object) -> Result<Value> {
         if (object.find(key) == object.end()) {
             return Null;
         }
         return object.at(key);
     });
+    return signature;
+}
 
-    define("properties", [](const EvaluationContext& params) -> Result<std::unordered_map<std::string, Value>> {
+const auto& propertiesCompoundExpression() {
+    static auto signature = detail::makeSignature("properties", [](const EvaluationContext& params) -> Result<std::unordered_map<std::string, Value>> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
@@ -387,8 +429,11 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return result;
     });
+    return signature;
+}
 
-    define("geometry-type", [](const EvaluationContext& params) -> Result<std::string> {
+const auto& geometryTypeCompoundExpression() {
+    static auto signature = detail::makeSignature("geometry-type", [](const EvaluationContext& params) -> Result<std::string> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
@@ -406,8 +451,11 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
             return "Unknown";
         }
     });
+    return signature;
+}
 
-    define("id", [](const EvaluationContext& params) -> Result<Value> {
+const auto& idCompoundExpression() {
+    static auto signature = detail::makeSignature("id", [](const EvaluationContext& params) -> Result<Value> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
@@ -421,219 +469,482 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
             }
         );
     });
+    return signature;
+}
 
-    define("+", [](const Varargs<double>& args) -> Result<double> {
+const auto& plusCompoundExpression() {
+    static auto signature = detail::makeSignature("+", [](const Varargs<double>& args) -> Result<double> {
         double sum = 0.0f;
         for (auto arg : args) {
             sum += arg;
         }
         return sum;
     });
-    define("-", [](double a, double b) -> Result<double> { return a - b; });
-    define("-", [](double a) -> Result<double> { return -a; });
-    define("*", [](const Varargs<double>& args) -> Result<double> {
+    return signature;
+}
+
+const auto& minusCompoundExpression() {
+    static auto signature = detail::makeSignature("-", [](double a, double b) -> Result<double> { return a - b; });
+    return signature;
+}
+
+const auto& negateCompoundExpression() {
+    static auto signature = detail::makeSignature("-", [](double a) -> Result<double> { return -a; });
+    return signature;
+}
+
+const auto& multiplyCompoundExpression() {
+    static auto signature = detail::makeSignature("*", [](const Varargs<double>& args) -> Result<double> {
         double prod = 1.0f;
         for (auto arg : args) {
             prod *= arg;
         }
         return prod;
     });
-    define("/", [](double a, double b) -> Result<double> { return a / b; });
-    define("%", [](double a, double b) -> Result<double> { return fmod(a, b); });
-    define("^", [](double a, double b) -> Result<double> { return pow(a, b); });
-    define("sqrt", [](double x) -> Result<double> { return sqrt(x); });
-    define("log10", [](double x) -> Result<double> { return log10(x); });
-    define("ln", [](double x) -> Result<double> { return log(x); });
-    define("log2", [](double x) -> Result<double> { return util::log2(x); });
-    define("sin", [](double x) -> Result<double> { return sin(x); });
-    define("cos", [](double x) -> Result<double> { return cos(x); });
-    define("tan", [](double x) -> Result<double> { return tan(x); });
-    define("asin", [](double x) -> Result<double> { return asin(x); });
-    define("acos", [](double x) -> Result<double> { return acos(x); });
-    define("atan", [](double x) -> Result<double> { return atan(x); });
-
-    define("min", [](const Varargs<double>& args) -> Result<double> {
+    return signature;
+}
+
+const auto& divideCompoundExpression() {
+    static auto signature = detail::makeSignature("/", [](double a, double b) -> Result<double> { return a / b; });
+    return signature;
+}
+
+const auto& modCompoundExpression() {
+    static auto signature = detail::makeSignature("%", [](double a, double b) -> Result<double> { return fmod(a, b); });
+    return signature;
+}
+
+const auto& powCompoundExpression() {
+    static auto signature = detail::makeSignature("^", [](double a, double b) -> Result<double> { return pow(a, b); });
+    return signature;
+}
+
+const auto& sqrtCompoundExpression() {
+    static auto signature = detail::makeSignature("sqrt", [](double x) -> Result<double> { return sqrt(x); });
+    return signature;
+}
+
+const auto& log10CompoundExpression() {
+    static auto signature = detail::makeSignature("log10", [](double x) -> Result<double> { return log10(x); });
+    return signature;
+}
+
+const auto& lnCompoundExpression() {
+    static auto signature = detail::makeSignature("ln", [](double x) -> Result<double> { return log(x); });
+    return signature;
+}
+
+const auto& log2CompoundExpression() {
+    static auto signature = detail::makeSignature("log2", [](double x) -> Result<double> { return util::log2(x); });
+    return signature;
+}
+
+const auto& sinCompoundExpression() {
+    static auto signature = detail::makeSignature("sin", [](double x) -> Result<double> { return sin(x); });
+    return signature;
+}
+
+const auto& cosCompoundExpression() {
+    static auto signature = detail::makeSignature("cos", [](double x) -> Result<double> { return cos(x); });
+    return signature;
+}
+
+const auto& tanCompoundExpression() {
+    static auto signature = detail::makeSignature("tan", [](double x) -> Result<double> { return tan(x); });
+    return signature;
+}
+
+const auto& asinCompoundExpression() {
+    static auto signature = detail::makeSignature("asin", [](double x) -> Result<double> { return asin(x); });
+    return signature;
+}
+
+const auto& acosCompoundExpression() {
+    static auto signature = detail::makeSignature("acos", [](double x) -> Result<double> { return acos(x); });
+    return signature;
+}
+
+const auto& atanCompoundExpression() {
+    static auto signature = detail::makeSignature("atan", [](double x) -> Result<double> { return atan(x); });
+    return signature;
+}
+
+const auto& minCompoundExpression() {
+    static auto signature = detail::makeSignature("min", [](const Varargs<double>& args) -> Result<double> {
         double result = std::numeric_limits<double>::infinity();
         for (double arg : args) {
             result = fmin(arg, result);
         }
         return result;
     });
-    define("max", [](const Varargs<double>& args) -> Result<double> {
+    return signature;
+}
+
+const auto& maxCompoundExpression() {
+    static auto signature = detail::makeSignature("max", [](const Varargs<double>& args) -> Result<double> {
         double result = -std::numeric_limits<double>::infinity();
         for (double arg : args) {
             result = fmax(arg, result);
         }
         return result;
     });
+    return signature;
+}
+
+const auto& roundCompoundExpression() {
+    static auto signature = detail::makeSignature("round", [](double x) -> Result<double> { return ::round(x); });
+    return signature;
+}
 
-    define("round", [](double x) -> Result<double> { return ::round(x); });
-    define("floor", [](double x) -> Result<double> { return std::floor(x); });
-    define("ceil", [](double x) -> Result<double> { return std::ceil(x); });
-    define("abs", [](double x) -> Result<double> { return std::abs(x); });
+const auto& floorCompoundExpression() {
+    static auto signature = detail::makeSignature("floor", [](double x) -> Result<double> { return std::floor(x); });
+    return signature;
+}
+
+const auto& ceilCompoundExpression() {
+    static auto signature = detail::makeSignature("ceil", [](double x) -> Result<double> { return std::ceil(x); });
+    return signature;
+}
 
-    define("!", [](bool e) -> Result<bool> { return !e; });
+const auto& absCompoundExpression() {
+    static auto signature = detail::makeSignature("abs", [](double x) -> Result<double> { return std::abs(x); });
+    return signature;
+}
 
-    define("is-supported-script", [](const std::string& x) -> Result<bool> {
+const auto& notCompoundExpression() {
+    static auto signature = detail::makeSignature("!", [](bool e) -> Result<bool> { return !e; });
+    return signature;
+}
+
+const auto& isSupportedScriptCompoundExpression() {
+    static auto signature = detail::makeSignature("is-supported-script", [](const std::string& x) -> Result<bool> {
         return util::i18n::isStringInSupportedScript(x);
     });
+    return signature;
+}
 
-    define("upcase", [](const std::string& input) -> Result<std::string> {
+const auto& upcaseCompoundExpression() {
+    static auto signature = detail::makeSignature("upcase", [](const std::string& input) -> Result<std::string> {
         return platform::uppercase(input);
     });
-    define("downcase", [](const std::string& input) -> Result<std::string> {
+    return signature;
+}
+
+const auto& downcaseCompoundExpression() {
+    static auto signature = detail::makeSignature("downcase", [](const std::string& input) -> Result<std::string> {
         return platform::lowercase(input);
     });
-    define("concat", [](const Varargs<Value>& args) -> Result<std::string> {
+    return signature;
+}
+
+const auto& concatCompoundExpression() {
+    static auto signature = detail::makeSignature("concat", [](const Varargs<Value>& args) -> Result<std::string> {
         std::string s;
         for (const Value& arg : args) {
             s += toString(arg);
         }
         return s;
     });
-    define("resolved-locale", [](const Collator& collator) -> Result<std::string> {
+    return signature;
+}
+
+const auto& resolvedLocaleCompoundExpression() {
+    static auto signature = detail::makeSignature("resolved-locale", [](const Collator& collator) -> Result<std::string> {
         return collator.resolvedLocale();
     });
+    return signature;
+}
 
-    define("error", [](const std::string& input) -> Result<type::ErrorType> {
+const auto& errorCompoundExpression() {
+    static auto signature = detail::makeSignature("error", [](const std::string& input) -> Result<type::ErrorType> {
         return EvaluationError { input };
     });
+    return signature;
+}
 
-    // Legacy Filters
-    define("filter-==", [](const EvaluationContext& params, const std::string& key, const Value &lhs) -> Result<bool> {
+// Legacy Filters
+const auto& filterEqualsCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-==", [](const EvaluationContext& params, const std::string& key, const Value &lhs) -> Result<bool> {
         const auto rhs = featurePropertyAsExpressionValue(params, key);
         return rhs ? lhs == *rhs : false;
     });
+    return signature;
+}
 
-    define("filter-id-==", [](const EvaluationContext& params, const Value &lhs) -> Result<bool> {
+const auto& filterIdEqualsCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-==", [](const EvaluationContext& params, const Value &lhs) -> Result<bool> {
         return lhs == featureIdAsExpressionValue(params);
     });
+    return signature;
+}
 
-    define("filter-type-==", [](const EvaluationContext& params, const std::string &lhs) -> Result<bool> {
+const auto& filterTypeEqualsCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-type-==", [](const EvaluationContext& params, const std::string &lhs) -> Result<bool> {
         if (!params.feature) return false;
         return featureTypeAsString(params.feature->getType()) == lhs;
     });
+    return signature;
+}
 
-    define("filter-<", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+const auto& filterLessThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-<", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
         auto rhs = featurePropertyAsDouble(params, key);
         return rhs ? rhs < lhs : false;
     });
+    return signature;
+}
 
-    define("filter-<", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+const auto& filterLessThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-<", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
         auto rhs = featurePropertyAsString(params, key);
         return rhs ? rhs < lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id-<", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+const auto& filterIdLessThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-<", [](const EvaluationContext& params, double lhs) -> Result<bool> {
         auto rhs = featureIdAsDouble(params);
         return rhs ? rhs < lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id-<", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+const auto& filterIdLessThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-<", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
         auto rhs = featureIdAsString(params);
         return rhs ? rhs < lhs : false;
     });
+    return signature;
+}
 
-    define("filter->", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+const auto& filterMoreThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter->", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
         auto rhs = featurePropertyAsDouble(params, key);
         return rhs ? rhs > lhs : false;
     });
+    return signature;
+}
 
-    define("filter->", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+const auto& filterMoreThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter->", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
         auto rhs = featurePropertyAsString(params, key);
         return rhs ? rhs > lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id->", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+const auto& filterIdMoreThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id->", [](const EvaluationContext& params, double lhs) -> Result<bool> {
         auto rhs = featureIdAsDouble(params);
         return rhs ? rhs > lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id->", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+const auto& filterIdMoreThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id->", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
         auto rhs = featureIdAsString(params);
         return rhs ? rhs > lhs : false;
     });
+    return signature;
+}
 
-    define("filter-<=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+const auto& filterLessOrEqualThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-<=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
         auto rhs = featurePropertyAsDouble(params, key);
         return rhs ? rhs <= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-<=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+const auto& filterLessOrEqualThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-<=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
         auto rhs = featurePropertyAsString(params, key);
         return rhs ? rhs <= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id-<=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+const auto& filterIdLessOrEqualThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-<=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
         auto rhs = featureIdAsDouble(params);
         return rhs ? rhs <= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id-<=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+const auto& filterIdLessOrEqualThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-<=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
         auto rhs = featureIdAsString(params);
         return rhs ? rhs <= lhs : false;
     });
+    return signature;
+}
 
-    define("filter->=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+const auto& filterGreaterOrEqualThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter->=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
         auto rhs = featurePropertyAsDouble(params, key);
         return rhs ? rhs >= lhs : false;
     });
+    return signature;
+}
 
-    define("filter->=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+const auto& filterGreaterOrEqualThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter->=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
         auto rhs = featurePropertyAsString(params, key);
         return rhs ? rhs >= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id->=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+const auto& filterIdGreaterOrEqualThanNumberCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id->=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
         auto rhs = featureIdAsDouble(params);
         return rhs ? rhs >= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-id->=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+const auto& filterIdGreaterOrEqualThanStringCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id->=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
         auto rhs = featureIdAsString(params);
         return rhs ? rhs >= lhs : false;
     });
+    return signature;
+}
 
-    define("filter-has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
+const auto& filterHasCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
         assert(params.feature);
         return bool(params.feature->getValue(key));
     });
+    return signature;
+}
 
-    define("filter-has-id", [](const EvaluationContext& params) -> Result<bool> {
+const auto& filterHasIdCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-has-id", [](const EvaluationContext& params) -> Result<bool> {
         assert(params.feature);
         return !params.feature->getID().is<NullValue>();
     });
+    return signature;
+}
 
-    define("filter-type-in", [](const EvaluationContext& params, const Varargs<std::string>& types) -> Result<bool> {
+const auto& filterTypeInCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-type-in", [](const EvaluationContext& params, const Varargs<std::string>& types) -> Result<bool> {
         assert(params.feature);
         optional<std::string> type = featureTypeAsString(params.feature->getType());
         return std::find(types.begin(), types.end(), type) != types.end();
     });
+    return signature;
+}
 
-    define("filter-id-in", [](const EvaluationContext& params, const Varargs<Value>& ids) -> Result<bool> {
+const auto& filterIdInCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-id-in", [](const EvaluationContext& params, const Varargs<Value>& ids) -> Result<bool> {
         auto id = featureIdAsExpressionValue(params);
         return std::find(ids.begin(), ids.end(), id) != ids.end();
     });
+    return signature;
+}
+
 
-    define("filter-in", [](const EvaluationContext& params, const Varargs<Value>& varargs) -> Result<bool> {
+const auto& filterInCompoundExpression() {
+    static auto signature = detail::makeSignature("filter-in", [](const EvaluationContext& params, const Varargs<Value>& varargs) -> Result<bool> {
         if (varargs.size() < 2) return false;
         assert(varargs[0].is<std::string>());
         auto value = featurePropertyAsExpressionValue(params, varargs[0].get<std::string>());
         return value ? std::find(varargs.begin() + 1, varargs.end(), *value) != varargs.end() : false;
     });
-
-    return definitions;
+    return signature;
 }
 
-std::unordered_map<std::string, Definition> CompoundExpressionRegistry::definitions = initializeDefinitions();
+using ParseCompoundFunction = const std::unique_ptr<detail::SignatureBase>& (*)();
+MAPBOX_ETERNAL_CONSTEXPR const auto compoundExpressionRegistry = mapbox::eternal::hash_map<mapbox::eternal::string, ParseCompoundFunction>({
+    { "e", eCompoundExpression },
+    { "pi", piCompoundExpression },
+    { "ln2", ln2CompoundExpression },
+    { "typeof", typeofCompoundExpression },
+    { "to-rgba", toRgbaCompoundExpression },
+    { "rgba", rgbaCompoundExpression },
+    { "rgb", rgbCompoundExpression },
+    { "zoom", zoomCompoundExpression },
+    { "heatmap-density", heatmapDensityCompoundExpression },
+    { "line-progress", lineProgressCompoundExpression },
+    { "has", hasContextCompoundExpression },
+    { "has", hasObjectCompoundExpression },
+    { "get", getContextCompoundExpression },
+    { "get", getObjectCompoundExpression },
+    { "properties", propertiesCompoundExpression },
+    { "geometry-type", geometryTypeCompoundExpression },
+    { "id", idCompoundExpression },
+    { "+", plusCompoundExpression },
+    { "-", minusCompoundExpression },
+    { "-", negateCompoundExpression },
+    { "*", multiplyCompoundExpression },
+    { "/", divideCompoundExpression },
+    { "%", modCompoundExpression },
+    { "^", powCompoundExpression },
+    { "sqrt", sqrtCompoundExpression },
+    { "log10", log10CompoundExpression },
+    { "ln", lnCompoundExpression },
+    { "log2", log2CompoundExpression },
+    { "sin", sinCompoundExpression },
+    { "cos", cosCompoundExpression },
+    { "tan", tanCompoundExpression },
+    { "asin", asinCompoundExpression },
+    { "acos", acosCompoundExpression },
+    { "atan", atanCompoundExpression },
+    { "min", minCompoundExpression },
+    { "max", maxCompoundExpression },
+    { "round", roundCompoundExpression },
+    { "floor", floorCompoundExpression },
+    { "ceil", ceilCompoundExpression },
+    { "abs", absCompoundExpression },
+    { "!", notCompoundExpression },
+    { "is-supported-script", isSupportedScriptCompoundExpression },
+    { "upcase", upcaseCompoundExpression },
+    { "downcase", downcaseCompoundExpression },
+    { "concat", concatCompoundExpression },
+    { "resolved-locale", resolvedLocaleCompoundExpression },
+    { "error", errorCompoundExpression },
+    // Legacy Filters
+    { "filter-==", filterEqualsCompoundExpression },
+    { "filter-id-==", filterIdEqualsCompoundExpression },
+    { "filter-type-==", filterTypeEqualsCompoundExpression },
+    { "filter-<", filterLessThanNumberCompoundExpression },
+    { "filter-<", filterLessThanStringCompoundExpression },
+    { "filter-id-<", filterIdLessThanNumberCompoundExpression },
+    { "filter-id-<", filterIdLessThanStringCompoundExpression },
+    { "filter->", filterMoreThanNumberCompoundExpression },
+    { "filter->", filterMoreThanStringCompoundExpression },
+    { "filter-id->", filterIdMoreThanNumberCompoundExpression },
+    { "filter-id->", filterIdMoreThanStringCompoundExpression },
+    { "filter-<=", filterLessOrEqualThanNumberCompoundExpression },
+    { "filter-<=", filterLessOrEqualThanStringCompoundExpression },
+    { "filter-id-<=", filterIdLessOrEqualThanNumberCompoundExpression },
+    { "filter-id-<=", filterIdLessOrEqualThanStringCompoundExpression },
+    { "filter->=", filterGreaterOrEqualThanNumberCompoundExpression },
+    { "filter->=", filterGreaterOrEqualThanStringCompoundExpression },
+    { "filter-id->=", filterIdGreaterOrEqualThanNumberCompoundExpression },
+    { "filter-id->=", filterIdGreaterOrEqualThanStringCompoundExpression },
+    { "filter-has", filterHasCompoundExpression },
+    { "filter-has-id", filterHasIdCompoundExpression },
+    { "filter-type-in", filterTypeInCompoundExpression },
+    { "filter-id-in", filterIdInCompoundExpression },
+    { "filter-in", filterInCompoundExpression },
+});
 
 using namespace mbgl::style::conversion;
-    
-std::string expectedTypesError(const Definition& definition,
+
+using DefinitionIterator = decltype(compoundExpressionRegistry)::const_iterator;
+using Definitions = std::pair<DefinitionIterator, DefinitionIterator>;
+
+std::string expectedTypesError(const Definitions& definitions,
                                const std::vector<std::unique_ptr<Expression>>& args) {
     std::vector<std::string> availableOverloads; // Only used if there are no overloads with matching number of args
     std::vector<std::string> overloads;
-    for (const auto& signature : definition) {
+    for (auto it = definitions.first; it != definitions.second; ++it) {
+        const auto& signature = it->second();
         signature->params.match(
         [&](const VarargsType& varargs) {
             std::string overload = "(" + toString(varargs.type) + ")";
@@ -671,13 +982,14 @@ std::string expectedTypesError(const Definition& definition,
     return "Expected arguments of type " + signatures + ", but found (" + actualTypes + ") instead.";
 }
 
-static ParseResult createCompoundExpression(const Definition& definition,
+static ParseResult createCompoundExpression(const Definitions& definitions,
                                             std::vector<std::unique_ptr<Expression>> args,
                                             ParsingContext& ctx)
 {
     ParsingContext signatureContext(ctx.getKey());
 
-    for (const std::unique_ptr<detail::SignatureBase>& signature : definition) {
+    for (auto it = definitions.first; it != definitions.second; ++it) {
+        const auto& signature = it->second();
         signatureContext.clearErrors();
 
         if (signature->params.is<std::vector<type::Type>>()) {
@@ -713,10 +1025,10 @@ static ParseResult createCompoundExpression(const Definition& definition,
         }
     }
 
-    if (definition.size() == 1) {
+    if (definitions.second - definitions.first == 1) {
         ctx.appendErrors(std::move(signatureContext));
     } else {
-        ctx.error(expectedTypesError(definition, args));
+        ctx.error(expectedTypesError(definitions, args));
     }
 
     return ParseResult();
@@ -725,20 +1037,19 @@ static ParseResult createCompoundExpression(const Definition& definition,
 ParseResult parseCompoundExpression(const std::string name, const Convertible& value, ParsingContext& ctx) {
     assert(isArray(value) && arrayLength(value) > 0);
 
-    auto it = CompoundExpressionRegistry::definitions.find(name);
-    if (it == CompoundExpressionRegistry::definitions.end()) {
+    const auto definitions = compoundExpressionRegistry.equal_range(name.c_str());
+    if (definitions.first == definitions.second) {
         ctx.error(
              R"(Unknown expression ")" + name + R"(". If you wanted a literal array, use ["literal", [...]].)",
             0
         );
         return ParseResult();
     }
-    const CompoundExpressionRegistry::Definition& definition = it->second;
 
     auto length = arrayLength(value);
     
-    for (std::size_t j = 0; j < definition.size(); j++) {
-        const std::unique_ptr<detail::SignatureBase>& signature = definition[j];
+    for (auto it = definitions.first; it != definitions.second; ++it) {
+        const auto& signature = it->second();
 
         if (
             signature->params.is<VarargsType>() ||
@@ -752,7 +1063,7 @@ ParseResult parseCompoundExpression(const std::string name, const Convertible& v
             args.reserve(length - 1);
 
             for (std::size_t i = 1; i < length; i++) {
-                optional<type::Type> expected = definition[j]->params.match(
+                optional<type::Type> expected = signature->params.match(
                     [](const VarargsType& varargs) { return varargs.type; },
                     [&](const std::vector<type::Type>& params_) { return params_[i - 1]; }
                 );
@@ -769,7 +1080,7 @@ ParseResult parseCompoundExpression(const std::string name, const Convertible& v
                 // on to next one.
                 continue;
             } else {
-                ParseResult parseWithArgs = createCompoundExpression(definition, std::move(args), ctx);
+                ParseResult parseWithArgs = createCompoundExpression(definitions, std::move(args), ctx);
                 if (parseWithArgs) {
                     return parseWithArgs;
                 }
@@ -790,7 +1101,7 @@ ParseResult parseCompoundExpression(const std::string name, const Convertible& v
         args.push_back(std::move(*parsed));
     }
 
-    ctx.error(expectedTypesError(definition, args));
+    ctx.error(expectedTypesError(definitions, args));
 
     return ParseResult();
 }
@@ -799,7 +1110,7 @@ ParseResult createCompoundExpression(const std::string& name,
                                      std::vector<std::unique_ptr<Expression>> args,
                                      ParsingContext& ctx)
 {
-    return createCompoundExpression(CompoundExpressionRegistry::definitions.at(name), std::move(args), ctx);
+    return createCompoundExpression(compoundExpressionRegistry.equal_range(name.c_str()), std::move(args), ctx);
 }
 
 CompoundExpression::CompoundExpression(const detail::SignatureBase& signature_, std::vector<std::unique_ptr<Expression>> args_) :
@@ -844,6 +1155,10 @@ bool CompoundExpression::operator==(const Expression& e) const {
     return false;
 }
 
+bool CompoundExpression::exists(const std::string& name) {
+    return compoundExpressionRegistry.contains(name.c_str());
+}
+
 } // namespace expression
 } // namespace style
 } // namespace mbgl
diff --git a/src/mbgl/style/expression/is_expression.cpp b/src/mbgl/style/expression/is_expression.cpp
index 34f0fec7a3..cf26182164 100644
--- a/src/mbgl/style/expression/is_expression.cpp
+++ b/src/mbgl/style/expression/is_expression.cpp
@@ -16,8 +16,7 @@ bool isExpression(const Convertible& value) {
     optional<std::string> name = toString(arrayMember(value, 0));
     if (!name) return false;
     
-    return getExpression(*name) ||
-        (CompoundExpressionRegistry::definitions.find(*name) != CompoundExpressionRegistry::definitions.end());
+    return isExpression(*name) || CompoundExpression::exists(*name);
 }
 
 
diff --git a/src/mbgl/style/expression/parsing_context.cpp b/src/mbgl/style/expression/parsing_context.cpp
index 79a2f251e2..411aa660e8 100644
--- a/src/mbgl/style/expression/parsing_context.cpp
+++ b/src/mbgl/style/expression/parsing_context.cpp
@@ -97,6 +97,7 @@ ParseResult ParsingContext::parse(const Convertible& value, std::size_t index_,
     return child.parse(value);
 }
 
+using ParseFunction = ParseResult (*)(const conversion::Convertible&, ParsingContext&);
 MAPBOX_ETERNAL_CONSTEXPR const auto expressionRegistry = mapbox::eternal::hash_map<mapbox::eternal::string, ParseFunction>({
     {"==", parseComparison},
     {"!=", parseComparison},
@@ -126,16 +127,11 @@ MAPBOX_ETERNAL_CONSTEXPR const auto expressionRegistry = mapbox::eternal::hash_m
     {"to-color", Coercion::parse},
     {"to-number", Coercion::parse},
     {"to-string", Coercion::parse},
-    {"var", Var::parse}
+    {"var", Var::parse},
 });
 
-ParseFunction getExpression(const std::string& name) {
-    auto parseFunction = expressionRegistry.find(name.c_str());
-    if (parseFunction != expressionRegistry.end()) {
-        return parseFunction->second;
-    } else {
-        return nullptr;
-    }
+bool isExpression(const std::string& name) {
+    return expressionRegistry.contains(name.c_str());
 }
 
 ParseResult ParsingContext::parse(const Convertible& value, optional<TypeAnnotationOption> typeAnnotationOption) {