Merge branch 'release-boba' into masterupstream/fabian-merge-release-4.0.1-master

# Conflicts:
#	mapbox-gl-js
#	platform/android/CHANGELOG.md
#	platform/android/MapboxGLAndroidSDK/gradle.properties
#	platform/android/gradle/dependencies.gradle
#	platform/darwin/src/MGLVectorTileSource.mm
#	platform/darwin/src/MGLVectorTileSource_Private.h
#	platform/ios/CHANGELOG.md
#	src/mbgl/style/expression/compound_expression.cpp

6 files changed, 433 insertions, 639 deletions

diff --git a/src/mbgl/style/conversion/filter.cpp b/src/mbgl/style/conversion/filter.cpp
index 3c941945fd..386d85e921 100644
--- a/src/mbgl/style/conversion/filter.cpp
+++ b/src/mbgl/style/conversion/filter.cpp
@@ -1,17 +1,39 @@
 #include <mbgl/style/conversion/filter.hpp>
+#include <mbgl/style/expression/literal.hpp>
 #include <mbgl/util/geometry.hpp>
 #include <mbgl/style/expression/expression.hpp>
 #include <mbgl/style/expression/type.hpp>
-#include <mbgl/style/expression/parsing_context.hpp>
+#include <mbgl/style/expression/compound_expression.hpp>
+#include <mbgl/style/expression/boolean_operator.hpp>
 
 namespace mbgl {
 namespace style {
 namespace conversion {
     
-using GeometryValue = mapbox::geometry::value;
+using namespace mbgl::style::expression;
+    
+static bool isExpression(const Convertible& filter);
+std::unique_ptr<Expression> convertLegacyFilter(const Convertible& values, Error& error);
+
+optional<Filter> Converter<Filter>::operator()(const Convertible& value, Error& error) const {
+    if (isExpression(value)) {
+        ParsingContext parsingContext(type::Boolean);
+        ParseResult parseResult = parsingContext.parseExpression(value);
+        if (!parseResult) {
+            error = { parsingContext.getCombinedErrors() };
+            return {};
+        } else {
+            return { Filter(std::move(parseResult)) };
+        }
+    } else {
+        std::unique_ptr<Expression> expression = convertLegacyFilter(value, error);
+        if (!expression) return {};
+        return Filter(optional<std::unique_ptr<Expression>>(std::move(expression)));
+    }
+}
 
 // This is a port from https://github.com/mapbox/mapbox-gl-js/blob/master/src/style-spec/feature_filter/index.js
-static bool isExpressionFilter(const Convertible& filter) {
+bool isExpression(const Convertible& filter) {
     if (!isArray(filter) || arrayLength(filter) == 0) {
         return false;
     }
@@ -20,7 +42,7 @@ static bool isExpressionFilter(const Convertible& filter) {
     
     if (!op) {
         return false;
-
+        
     } else if (*op == "has") {
         if (arrayLength(filter) < 2) return false;
         optional<std::string> operand = toString(arrayMember(filter, 1));
@@ -35,7 +57,7 @@ static bool isExpressionFilter(const Convertible& filter) {
     } else if (*op == "any" || *op == "all") {
         for (std::size_t i = 1; i < arrayLength(filter); i++) {
             Convertible f = arrayMember(filter, i);
-            if (!isExpressionFilter(f) && !toBool(f)) {
+            if (!isExpression(f) && !toBool(f)) {
                 return false;
             }
         }
@@ -46,257 +68,136 @@ static bool isExpressionFilter(const Convertible& filter) {
     }
 }
     
-static optional<GeometryValue> normalizeValue(const optional<GeometryValue>& value, Error& error) {
-    if (!value) {
-        error = { "filter expression value must be a boolean, number, or string" };
-        return {};
-    } else {
-        return *value;
-    }
-}
+std::unique_ptr<Expression> createExpression(std::string op, std::vector<std::unique_ptr<Expression>> args, Error& error) {
+    if (op == "any") {
+        return std::make_unique<Any>(std::move(args));
+        
+    } else if (op == "all") {
+        return std::make_unique<All>(std::move(args));
 
-static optional<FeatureType> toFeatureType(const Convertible& value, Error& error) {
-    optional<std::string> type = toString(value);
-    if (!type) {
-        error = { "value for $type filter must be a string" };
-        return {};
-    } else if (*type == "Point") {
-        return FeatureType::Point;
-    } else if (*type == "LineString") {
-        return FeatureType::LineString;
-    } else if (*type == "Polygon") {
-        return FeatureType::Polygon;
     } else {
-        error = { "value for $type filter must be Point, LineString, or Polygon" };
-        return {};
+        ParsingContext parsingContext(type::Boolean);
+        ParseResult parseResult = createCompoundExpression(op, std::move(args), parsingContext);
+        if (!parseResult) {
+            error = { parsingContext.getCombinedErrors() };
+            return {};
+        } else {
+            return std::move(*parseResult);
+        }
     }
 }
 
-static optional<FeatureIdentifier> toFeatureIdentifier(const Convertible& value, Error& error) {
-    optional<GeometryValue> identifier = toValue(value);
-    if (!identifier) {
-        error = { "filter expression value must be a boolean, number, or string" };
-        return {};
-    } else {
-        return (*identifier).match(
-            [] (uint64_t t) -> optional<FeatureIdentifier> { return { t }; },
-            [] ( int64_t t) -> optional<FeatureIdentifier> { return { t }; },
-            [] (  double t) -> optional<FeatureIdentifier> { return { t }; },
-            [] (const std::string& t) -> optional<FeatureIdentifier> { return { t }; },
-            [&] (const auto&) -> optional<FeatureIdentifier> {
-                error = { "filter expression value must be a boolean, number, or string" };
-                return {};
-            });
-    }
+std::unique_ptr<Expression> createExpression(std::string op, std::unique_ptr<Expression> expression, Error& error) {
+    std::vector<std::unique_ptr<Expression>> args;
+    args.push_back(std::move(expression));
+    return createExpression(op, std::move(args), error);
 }
 
-template <class FilterType, class IdentifierFilterType>
-optional<Filter> convertUnaryFilter(const Convertible& value, Error& error) {
-    if (arrayLength(value) < 2) {
-        error = { "filter expression must have 2 elements" };
-        return {};
-    }
-
-    optional<std::string> key = toString(arrayMember(value, 1));
-    if (!key) {
-        error = { "filter expression key must be a string" };
-        return {};
-    }
-
-    if (*key == "$id") {
-        return { IdentifierFilterType {} };
+std::unique_ptr<Expression> convertLiteral(const Convertible& convertible, Error& error) {
+    ParsingContext parsingContext;
+    ParseResult parseResult = Literal::parse(convertible, parsingContext);
+    if (parseResult) {
+        return std::move(*parseResult);
     } else {
-        return { FilterType { *key } };
+        error = { parsingContext.getCombinedErrors() };
+        return {};
     }
 }
 
-template <class FilterType, class TypeFilterType, class IdentifierFilterType>
-optional<Filter> convertEqualityFilter(const Convertible& value, Error& error) {
-    if (arrayLength(value) < 3) {
-        error = { "filter expression must have 3 elements" };
-        return {};
+std::vector<std::unique_ptr<Expression>> convertLiteralArray(const Convertible &input, Error& error, std::size_t startIndex = 0) {
+    std::vector<std::unique_ptr<Expression>> output;
+    for (std::size_t i = startIndex; i < arrayLength(input); i++) {
+        output.push_back(convertLiteral(arrayMember(input, i), error));
     }
+    return output;
+}
 
-    optional<std::string> key = toString(arrayMember(value, 1));
-    if (!key) {
-        error = { "filter expression key must be a string" };
+std::unique_ptr<Expression> convertLegacyComparisonFilter(const Convertible& values, Error& error, optional<std::string> opOverride = {}) {
+    optional<std::string> op = opOverride ? opOverride : toString(arrayMember(values, 0));
+    optional<std::string> property = toString(arrayMember(values, 1));
+    
+    if (!property) {
+        error = { "filter property must be a string" };
         return {};
-    }
-
-    if (*key == "$type") {
-        optional<FeatureType> filterValue = toFeatureType(arrayMember(value, 2), error);
-        if (!filterValue) {
-            return {};
-        }
-
-        return { TypeFilterType { *filterValue } };
-
-    } else if (*key == "$id") {
-        optional<FeatureIdentifier> filterValue = toFeatureIdentifier(arrayMember(value, 2), error);
-        if (!filterValue) {
-            return {};
-        }
-
-        return { IdentifierFilterType { *filterValue } };
-
+    } else if (*property == "$type") {
+        return createExpression("filter-type-" + *op, convertLiteralArray(values, error, 2), error);
+    } else if (*property == "$id") {
+        return createExpression("filter-id-" + *op, convertLiteralArray(values, error, 2), error);
     } else {
-        optional<GeometryValue> filterValue = normalizeValue(toValue(arrayMember(value, 2)), error);
-        if (!filterValue) {
-            return {};
-        }
-
-        return { FilterType { *key, *filterValue } };
+        return createExpression("filter-" + *op, convertLiteralArray(values, error, 1), error);
     }
 }
-
-template <class FilterType>
-optional<Filter> convertBinaryFilter(const Convertible& value, Error& error) {
-    if (arrayLength(value) < 3) {
-        error = { "filter expression must have 3 elements" };
-        return {};
-    }
-
-    optional<std::string> key = toString(arrayMember(value, 1));
-    if (!key) {
-        error = { "filter expression key must be a string" };
-        return {};
-    }
-
-    optional<GeometryValue> filterValue = normalizeValue(toValue(arrayMember(value, 2)), error);
-    if (!filterValue) {
+    
+std::unique_ptr<Expression> convertLegacyHasFilter(const Convertible& values, Error& error) {
+    optional<std::string> property = toString(arrayMember(values, 1));
+    
+    if (!property) {
+        error = { "filter property must be a string" };
         return {};
+    } else if (*property == "$type") {
+        return std::make_unique<Literal>(true);
+    } else if (*property == "$id") {
+        return createExpression("filter-has-id", std::vector<std::unique_ptr<Expression>>(), error);
+    } else {
+        return createExpression("filter-has", std::make_unique<Literal>(*property), error);
     }
-
-    return { FilterType { *key, *filterValue } };
 }
 
-template <class FilterType, class TypeFilterType, class IdentifierFilterType>
-optional<Filter> convertSetFilter(const Convertible& value, Error& error) {
-    if (arrayLength(value) < 2) {
-        error = { "filter expression must at least 2 elements" };
-        return {};
-    }
-
-    optional<std::string> key = toString(arrayMember(value, 1));
-    if (!key) {
-        error = { "filter expression key must be a string" };
-        return {};
-    }
-
-    if (*key == "$type") {
-        std::vector<FeatureType> values;
-        for (std::size_t i = 2; i < arrayLength(value); ++i) {
-            optional<FeatureType> filterValue = toFeatureType(arrayMember(value, i), error);
-            if (!filterValue) {
-                return {};
-            }
-            values.push_back(*filterValue);
-        }
-
-        return { TypeFilterType { std::move(values) } };
-
-    } else if (*key == "$id") {
-        std::vector<FeatureIdentifier> values;
-        for (std::size_t i = 2; i < arrayLength(value); ++i) {
-            optional<FeatureIdentifier> filterValue = toFeatureIdentifier(arrayMember(value, i), error);
-            if (!filterValue) {
-                return {};
-            }
-            values.push_back(*filterValue);
-        }
-
-        return { IdentifierFilterType { std::move(values) } };
-
+std::unique_ptr<Expression> convertLegacyInFilter(const Convertible& values, Error& error) {
+    optional<std::string> property = toString(arrayMember(values, 1));
+    
+    if (!property) {
+        error = { "filter property must be a string" };
+        return {};
+    } else if (arrayLength(values) == 0) {
+        return std::make_unique<Literal>(false);
+    } else if (*property == "$type") {
+        return createExpression("filter-type-in", convertLiteralArray(values, error, 2), error);
+    } else if (*property == "$id") {
+        return createExpression("filter-id-in", convertLiteralArray(values, error, 2), error);
     } else {
-        std::vector<GeometryValue> values;
-        for (std::size_t i = 2; i < arrayLength(value); ++i) {
-            optional<GeometryValue> filterValue = normalizeValue(toValue(arrayMember(value, i)), error);
-            if (!filterValue) {
-                return {};
-            }
-            values.push_back(*filterValue);
-        }
-
-        return { FilterType { *key, std::move(values) } };
+        return createExpression("filter-in", convertLiteralArray(values, error, 1), error);
     }
 }
 
-template <class FilterType>
-optional<Filter> convertCompoundFilter(const Convertible& value, Error& error) {
-    std::vector<Filter> filters;
-    for (std::size_t i = 1; i < arrayLength(value); ++i) {
-        optional<Filter> element = convert<Filter>(arrayMember(value, i), error);
-        if (!element) {
-            return {};
-        }
-        filters.push_back(*element);
+std::vector<std::unique_ptr<Expression>> convertLegacyFilterArray(const Convertible &input, Error& error, std::size_t startIndex = 0) {
+    std::vector<std::unique_ptr<Expression>> output;
+    for (std::size_t i = startIndex; i < arrayLength(input); i++) {
+        output.push_back(convertLegacyFilter(arrayMember(input, i), error));
     }
-
-    return { FilterType { std::move(filters) } };
+    return output;
 }
     
-optional<Filter> convertExpressionFilter(const Convertible& value, Error& error) {
-    expression::ParsingContext ctx(expression::type::Boolean);
-    expression::ParseResult expression = ctx.parseExpression(value);
-    if (!expression) {
-        error = { ctx.getCombinedErrors() };
-        return {};
-    }
-
-    return { ExpressionFilter { std::move(*expression) } };
-}
-
-optional<Filter> Converter<Filter>::operator()(const Convertible& value, Error& error) const {
-    if (isExpressionFilter(value)) {
-        return convertExpressionFilter(value, error);
+std::unique_ptr<Expression> convertLegacyFilter(const Convertible& values, Error& error) {
+    if (isUndefined(values)) {
+        return std::make_unique<Literal>(true);
     }
     
-    if (!isArray(value)) {
-        error = { "filter expression must be an array" };
-        return {};
-    }
-
-    if (arrayLength(value) < 1) {
-        error = { "filter expression must have at least 1 element" };
-        return {};
-    }
+    optional<std::string> op = toString(arrayMember(values, 0));
 
-    optional<std::string> op = toString(arrayMember(value, 0));
     if (!op) {
         error = { "filter operator must be a string" };
         return {};
+    } else if (arrayLength(values) <= 1) {
+        return std::make_unique<Literal>(*op != "any");
+    } else {
+        return (
+            *op == "==" ||
+            *op == "<" ||
+            *op == ">" ||
+            *op == "<=" ||
+            *op == ">=" ? convertLegacyComparisonFilter(values, error) :
+            *op == "!=" ? createExpression("!", convertLegacyComparisonFilter(values, error, {"=="}), error) :
+            *op == "any" ? createExpression("any", convertLegacyFilterArray(values, error, 1), error) :
+            *op == "all" ? createExpression("all", convertLegacyFilterArray(values, error, 1), error) :
+            *op == "none" ? createExpression("!", createExpression("any", convertLegacyFilterArray(values, error, 1), error), error) :
+            *op == "in" ? convertLegacyInFilter(values, error) :
+            *op == "!in" ? createExpression("!", convertLegacyInFilter(values, error), error) :
+            *op == "has" ? convertLegacyHasFilter(values, error) :
+            *op == "!has" ? createExpression("!", convertLegacyHasFilter(values, error), error) :
+            std::make_unique<Literal>(true)
+        );
     }
-
-    if (*op == "==") {
-        return convertEqualityFilter<EqualsFilter, TypeEqualsFilter, IdentifierEqualsFilter>(value, error);
-    } else if (*op == "!=") {
-        return convertEqualityFilter<NotEqualsFilter, TypeNotEqualsFilter, IdentifierNotEqualsFilter>(value, error);
-    } else if (*op == ">") {
-        return convertBinaryFilter<GreaterThanFilter>(value, error);
-    } else if (*op == ">=") {
-        return convertBinaryFilter<GreaterThanEqualsFilter>(value, error);
-    } else if (*op == "<") {
-        return convertBinaryFilter<LessThanFilter>(value, error);
-    } else if (*op == "<=") {
-        return convertBinaryFilter<LessThanEqualsFilter>(value, error);
-    } else if (*op == "in") {
-        return convertSetFilter<InFilter, TypeInFilter, IdentifierInFilter>(value, error);
-    } else if (*op == "!in") {
-        return convertSetFilter<NotInFilter, TypeNotInFilter, IdentifierNotInFilter>(value, error);
-    } else if (*op == "all") {
-        return convertCompoundFilter<AllFilter>(value, error);
-    } else if (*op == "any") {
-        return convertCompoundFilter<AnyFilter>(value, error);
-    } else if (*op == "none") {
-        return convertCompoundFilter<NoneFilter>(value, error);
-    } else if (*op == "has") {
-        return convertUnaryFilter<HasFilter, HasIdentifierFilter>(value, error);
-    } else if (*op == "!has") {
-       return convertUnaryFilter<NotHasFilter, NotHasIdentifierFilter>(value, error);
-    }
-
-    error = { R"(filter operator must be one of "==", "!=", ">", ">=", "<", "<=", "in", "!in", "all", "any", "none", "has", or "!has")" };
-    return {};
 }
 
 } // namespace conversion
diff --git a/src/mbgl/style/conversion/stringify.hpp b/src/mbgl/style/conversion/stringify.hpp
index 7b7727d7c4..74171763a0 100644
--- a/src/mbgl/style/conversion/stringify.hpp
+++ b/src/mbgl/style/conversion/stringify.hpp
@@ -126,162 +126,9 @@ void stringify(Writer& writer, const FeatureIdentifier& id) {
 }
 
 template <class Writer>
-class StringifyFilter {
-public:
-    Writer& writer;
-
-    void operator()(const NullFilter&) {
-        writer.Null();
-    }
-
-    void operator()(const EqualsFilter& f) {
-        stringifyBinaryFilter(f, "==");
-    }
-
-    void operator()(const NotEqualsFilter& f) {
-        stringifyBinaryFilter(f, "!=");
-    }
-
-    void operator()(const LessThanFilter& f) {
-        stringifyBinaryFilter(f, "<");
-    }
-
-    void operator()(const LessThanEqualsFilter& f) {
-        stringifyBinaryFilter(f, "<=");
-    }
-
-    void operator()(const GreaterThanFilter& f) {
-        stringifyBinaryFilter(f, ">");
-    }
-
-    void operator()(const GreaterThanEqualsFilter& f) {
-        stringifyBinaryFilter(f, ">=");
-    }
-
-    void operator()(const InFilter& f) {
-        stringifySetFilter(f, "in");
-    }
-
-    void operator()(const NotInFilter& f) {
-        stringifySetFilter(f, "!in");
-    }
-
-    void operator()(const AllFilter& f) {
-        stringifyCompoundFilter(f, "all");
-    }
-
-    void operator()(const AnyFilter& f) {
-        stringifyCompoundFilter(f, "any");
-    }
-
-    void operator()(const NoneFilter& f) {
-        stringifyCompoundFilter(f, "none");
-    }
-
-    void operator()(const HasFilter& f) {
-        stringifyUnaryFilter("has", f.key);
-    }
-
-    void operator()(const NotHasFilter& f) {
-        stringifyUnaryFilter("!has", f.key);
-    }
-
-    void operator()(const TypeEqualsFilter& f) {
-        stringifyBinaryFilter(f, "==", "$type");
-    }
-
-    void operator()(const TypeNotEqualsFilter& f) {
-        stringifyBinaryFilter(f, "!=", "$type");
-    }
-
-    void operator()(const TypeInFilter& f) {
-        stringifySetFilter(f, "in", "$type");
-    }
-
-    void operator()(const TypeNotInFilter& f) {
-        stringifySetFilter(f, "!in", "$type");
-    }
-
-    void operator()(const IdentifierEqualsFilter& f) {
-        stringifyBinaryFilter(f, "==", "$id");
-    }
-
-    void operator()(const IdentifierNotEqualsFilter& f) {
-        stringifyBinaryFilter(f, "!=", "$id");
-    }
-
-    void operator()(const IdentifierInFilter& f) {
-        stringifySetFilter(f, "in", "$id");
-    }
-
-    void operator()(const IdentifierNotInFilter& f) {
-        stringifySetFilter(f, "!in", "$id");
-    }
-
-    void operator()(const HasIdentifierFilter&) {
-        stringifyUnaryFilter("has", "$id");
-    }
-
-    void operator()(const NotHasIdentifierFilter&) {
-        stringifyUnaryFilter("!has", "$id");
-    }
-    
-    void operator()(const ExpressionFilter& filter) {
-        stringify(writer, filter.expression->serialize());
-    }
-
-private:
-    template <class F>
-    void stringifyBinaryFilter(const F& f, const char * op) {
-        stringifyBinaryFilter(f, op, f.key);
-    }
-
-    template <class F>
-    void stringifyBinaryFilter(const F& f, const char * op, const std::string& key) {
-        writer.StartArray();
-        writer.String(op);
-        writer.String(key);
-        stringify(writer, f.value);
-        writer.EndArray();
-    }
-
-    template <class F>
-    void stringifySetFilter(const F& f, const char * op) {
-        stringifySetFilter(f, op, f.key);
-    }
-
-    template <class F>
-    void stringifySetFilter(const F& f, const char * op, const std::string& key) {
-        writer.StartArray();
-        writer.String(op);
-        writer.String(key);
-        for (const auto& value : f.values) {
-            stringify(writer, value);
-        }
-        writer.EndArray();
-    }
-
-    template <class F>
-    void stringifyCompoundFilter(const F& f, const char * op) {
-        writer.StartArray();
-        writer.String(op);
-        for (const auto& filter : f.filters) {
-            Filter::visit(filter, *this);
-        }
-        writer.EndArray();
-    }
-
-    void stringifyUnaryFilter(const char * op, const std::string& key) {
-        writer.StartArray();
-        writer.String(op);
-        writer.String(key);
-        writer.EndArray();
-    }
-};
-
-template <class Writer>
-void stringify(Writer& writer, const Filter& f) {
-    Filter::visit(f, StringifyFilter<Writer> { writer });
+void stringify(Writer& writer, const Filter& filter) {
+    if (!filter.expression) writer.Null();
+    else stringify(writer, (*filter.expression)->serialize());
 }
 
 template <class Writer>
diff --git a/src/mbgl/style/expression/compound_expression.cpp b/src/mbgl/style/expression/compound_expression.cpp
index bcde09e1b6..4226756fe4 100644
--- a/src/mbgl/style/expression/compound_expression.cpp
+++ b/src/mbgl/style/expression/compound_expression.cpp
@@ -19,7 +19,7 @@ namespace detail {
     The Signature<Fn> structs are wrappers around an "evaluate()" function whose
     purpose is to extract the necessary Type data from the evaluate function's
     type.  There are three key (partial) specializations:
-    
+ 
     Signature<R (Params...)>:
     Wraps a simple evaluate function (const T0&, const T1&, ...) -> Result<U>
  
@@ -30,9 +30,9 @@ namespace detail {
     Signature<R (const EvaluationContext&, Params...)>:
     Wraps an evaluate function that needs to access the expression evaluation
     parameters in addition to its subexpressions, i.e.,
-    (const EvaluationParams& const T0&, const T1&, ...) -> Result<U>.  Needed
+    (const EvaluationParams&, const T0&, const T1&, ...) -> Result<U>.  Needed
     for expressions like ["zoom"], ["get", key], etc.
-    
+ 
     In each of the above evaluate signatures, T0, T1, etc. are the types of
     the successfully evaluated subexpressions.
 */
@@ -43,7 +43,7 @@ struct Signature;
 template <class R, class... Params>
 struct Signature<R (Params...)> : SignatureBase {
     using Args = std::array<std::unique_ptr<Expression>, sizeof...(Params)>;
-    
+
     Signature(R (*evaluate_)(Params...), std::string name_) :
         SignatureBase(
             valueTypeToExpressionType<std::decay_t<typename R::Value>>(),
@@ -55,7 +55,7 @@ struct Signature<R (Params...)> : SignatureBase {
     EvaluationResult apply(const EvaluationContext& evaluationParameters, const Args& args) const {
         return applyImpl(evaluationParameters, args, std::index_sequence_for<Params...>{});
     }
-    
+
     std::unique_ptr<Expression> makeExpression(std::vector<std::unique_ptr<Expression>> args) const override {
         typename Signature::Args argsArray;
         std::copy_n(std::make_move_iterator(args.begin()), sizeof...(Params), argsArray.begin());
@@ -80,7 +80,7 @@ private:
 template <class R, typename T>
 struct Signature<R (const Varargs<T>&)> : SignatureBase {
     using Args = std::vector<std::unique_ptr<Expression>>;
-    
+
     Signature(R (*evaluate_)(const Varargs<T>&), std::string name_) :
         SignatureBase(
             valueTypeToExpressionType<std::decay_t<typename R::Value>>(),
@@ -89,11 +89,11 @@ struct Signature<R (const Varargs<T>&)> : SignatureBase {
         ),
         evaluate(evaluate_)
     {}
-    
+
     std::unique_ptr<Expression> makeExpression(std::vector<std::unique_ptr<Expression>> args) const override  {
         return std::make_unique<CompoundExpression<Signature>>(name, *this, std::move(args));
     };
-    
+
     EvaluationResult apply(const EvaluationContext& evaluationParameters, const Args& args) const {
         Varargs<T> evaluated;
         evaluated.reserve(args.size());
@@ -115,7 +115,7 @@ struct Signature<R (const Varargs<T>&)> : SignatureBase {
 template <class R, class... Params>
 struct Signature<R (const EvaluationContext&, Params...)> : SignatureBase {
     using Args = std::array<std::unique_ptr<Expression>, sizeof...(Params)>;
-    
+
     Signature(R (*evaluate_)(const EvaluationContext&, Params...), std::string name_) :
         SignatureBase(
             valueTypeToExpressionType<std::decay_t<typename R::Value>>(),
@@ -124,17 +124,17 @@ struct Signature<R (const EvaluationContext&, Params...)> : SignatureBase {
         ),
         evaluate(evaluate_)
     {}
-    
+
     std::unique_ptr<Expression> makeExpression(std::vector<std::unique_ptr<Expression>> args) const override {
         typename Signature::Args argsArray;
         std::copy_n(std::make_move_iterator(args.begin()), sizeof...(Params), argsArray.begin());
         return std::make_unique<CompoundExpression<Signature>>(name, *this, std::move(argsArray));
     }
-    
+
     EvaluationResult apply(const EvaluationContext& evaluationParameters, const Args& args) const {
         return applyImpl(evaluationParameters, args, std::index_sequence_for<Params...>{});
     }
-    
+
 private:
     template <std::size_t ...I>
     EvaluationResult applyImpl(const EvaluationContext& evaluationParameters, const Args& args, std::index_sequence<I...>) const {
@@ -150,6 +150,41 @@ private:
     
     R (*evaluate)(const EvaluationContext&, Params...);
 };
+    
+// Evaluate function needing EvaluationContext and Varargs
+// (const EvaluationContext&, const Varargs<T>&) -> Result<U>
+template <class R, typename T>
+struct Signature<R (const EvaluationContext&, const Varargs<T>&)> : SignatureBase {
+    using Args = std::vector<std::unique_ptr<Expression>>;
+    
+    Signature(R (*evaluate_)(const EvaluationContext&, const Varargs<T>&), std::string name_) :
+    SignatureBase(
+                  valueTypeToExpressionType<std::decay_t<typename R::Value>>(),
+                  VarargsType { valueTypeToExpressionType<T>() },
+                  std::move(name_)
+                  ),
+    evaluate(evaluate_)
+    {}
+    
+    std::unique_ptr<Expression> makeExpression(std::vector<std::unique_ptr<Expression>> args) const override  {
+        return std::make_unique<CompoundExpression<Signature>>(name, *this, std::move(args));
+    };
+    
+    EvaluationResult apply(const EvaluationContext& evaluationParameters, const Args& args) const {
+        Varargs<T> evaluated;
+        evaluated.reserve(args.size());
+        for (const auto& arg : args) {
+            const EvaluationResult evaluatedArg = arg->evaluate(evaluationParameters);
+            if(!evaluatedArg) return evaluatedArg.error();
+            evaluated.push_back(*fromExpressionValue<std::decay_t<T>>(*evaluatedArg));
+        }
+        const R value = evaluate(evaluationParameters, evaluated);
+        if (!value) return value.error();
+        return *value;
+    }
+    
+    R (*evaluate)(const EvaluationContext&, const Varargs<T>&);
+};
 
 // Machinery to pull out function types from class methods, lambdas, etc.
 template <class R, class... Params>
@@ -181,29 +216,104 @@ static std::unique_ptr<detail::SignatureBase> makeSignature(Fn evaluateFunction,
     return std::make_unique<detail::Signature<Fn>>(evaluateFunction, std::move(name));
 }
 
+Value featureIdAsExpressionValue(EvaluationContext params) {
+    assert(params.feature);
+    auto id = params.feature->getID();
+    if (!id) return Null;
+    return id->match([](const auto& idid) {
+        return toExpressionValue(mbgl::Value(idid));
+    });
+};
+
+optional<Value> featurePropertyAsExpressionValue(EvaluationContext params, const std::string& key) {
+    assert(params.feature);
+    auto property = params.feature->getValue(key);
+    return property ? toExpressionValue(*property) : optional<Value>();
+};
+
+optional<std::string> featureTypeAsString(FeatureType type) {
+    switch(type) {
+    case FeatureType::Point:
+        return optional<std::string>("Point");
+    case FeatureType::LineString:
+        return optional<std::string>("LineString");
+    case FeatureType::Polygon:
+        return optional<std::string>("Polygon");
+    case FeatureType::Unknown:
+        return optional<std::string>("Unknown");
+    default:
+        return {};
+    }
+};
+
+optional<double> featurePropertyAsDouble(EvaluationContext params, const std::string& key) {
+    assert(params.feature);
+    auto property = params.feature->getValue(key);
+    if (!property) return {};
+    return property->match(
+        [](double value) { return value; },
+        [](uint64_t value) { return optional<double>(static_cast<double>(value)); },
+        [](int64_t value) { return optional<double>(static_cast<double>(value)); },
+        [](auto) { return optional<double>(); }
+    );
+};
+
+optional<std::string> featurePropertyAsString(EvaluationContext params, const std::string& key) {
+    assert(params.feature);
+    auto property = params.feature->getValue(key);
+    if (!property) return {};
+    return property->match(
+        [](std::string value) { return value; },
+        [](auto) { return optional<std::string>(); }
+    );
+};
+
+optional<double> featureIdAsDouble(EvaluationContext params) {
+    assert(params.feature);
+    auto id = params.feature->getID();
+    if (!id) return optional<double>();
+    return id->match(
+        [](double value) { return value; },
+        [](uint64_t value) { return optional<double>(static_cast<double>(value)); },
+        [](int64_t value) { return optional<double>(static_cast<double>(value)); },
+        [](auto) { return optional<double>(); }
+    );
+};
+
+optional<std::string> featureIdAsString(EvaluationContext params) {
+    assert(params.feature);
+    auto id = params.feature->getID();
+    if (!id) return optional<std::string>();
+    return id->match(
+        [](std::string value) { return value; },
+        [](auto) { return optional<std::string>(); }
+    );
+};
+
 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(makeSignature(fn, name));
     };
-    
+
     define("e", []() -> Result<double> { return 2.718281828459045; });
     define("pi", []() -> Result<double> { return 3.141592653589793; });
     define("ln2", []() -> Result<double> { return 0.6931471805599453; });
 
     define("typeof", [](const Value& v) -> Result<std::string> { return toString(typeOf(v)); });
-    
+
     define("to-string", [](const Value& value) -> Result<std::string> {
         return value.match(
+            [](const NullValue&) -> Result<std::string> { return std::string(); },
             [](const Color& c) -> Result<std::string> { return c.stringify(); }, // avoid quoting
             [](const std::string& s) -> Result<std::string> { return s; }, // avoid quoting
             [](const auto& v) -> Result<std::string> { return stringify(v); }
         );
     });
-    
+
     define("to-boolean", [](const Value& v) -> Result<bool> {
         return v.match(
-            [&] (double f) { return (bool)f; },
+            [&] (double f) { return static_cast<bool>(f); },
             [&] (const std::string& s) { return s.length() > 0; },
             [&] (bool b) { return b; },
             [&] (const NullValue&) { return false; },
@@ -213,10 +323,10 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
     define("to-rgba", [](const Color& color) -> Result<std::array<double, 4>> {
         return color.toArray();
     });
-    
+
     define("rgba", rgba);
     define("rgb", [](double r, double g, double b) { return rgba(r, g, b, 1.0f); });
-    
+
     define("zoom", [](const EvaluationContext& params) -> Result<double> {
         if (!params.zoom) {
             return EvaluationError {
@@ -225,7 +335,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return *(params.zoom);
     });
-    
+
     define("heatmap-density", [](const EvaluationContext& params) -> Result<double> {
         if (!params.heatmapDensity) {
             return EvaluationError {
@@ -241,7 +351,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
                 "Feature data is unavailable in the current evaluation context."
             };
         }
-        
+
         return params.feature->getValue(key) ? true : false;
     });
     define("has", [](const std::string& key, const std::unordered_map<std::string, Value>& object) -> Result<bool> {
@@ -267,7 +377,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return object.at(key);
     });
-    
+
     define("properties", [](const EvaluationContext& params) -> Result<std::unordered_map<std::string, Value>> {
         if (!params.feature) {
             return EvaluationError {
@@ -281,14 +391,14 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
         }
         return result;
     });
-    
+
     define("geometry-type", [](const EvaluationContext& params) -> Result<std::string> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
             };
         }
-    
+
         auto type = params.feature->getType();
         if (type == FeatureType::Point) {
             return "Point";
@@ -300,14 +410,14 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
             return "Unknown";
         }
     });
-    
+
     define("id", [](const EvaluationContext& params) -> Result<Value> {
         if (!params.feature) {
             return EvaluationError {
                 "Feature data is unavailable in the current evaluation context."
             };
         }
-    
+
         auto id = params.feature->getID();
         if (!id) {
             return Null;
@@ -318,7 +428,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
             }
         );
     });
-    
+
     define("+", [](const Varargs<double>& args) -> Result<double> {
         double sum = 0.0f;
         for (auto arg : args) {
@@ -348,7 +458,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
     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> {
         double result = std::numeric_limits<double>::infinity();
         for (double arg : args) {
@@ -377,7 +487,7 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
     define("<", [](const std::string& lhs, const std::string& rhs) -> Result<bool> { return lhs < rhs; });
     define("<=", [](double lhs, double rhs) -> Result<bool> { return lhs <= rhs; });
     define("<=", [](const std::string& lhs, const std::string& rhs) -> Result<bool> { return lhs <= rhs; });
-    
+
     define("!", [](bool e) -> Result<bool> { return !e; });
     
     define("is-supported-script", [](const std::string& x) -> Result<bool> {
@@ -400,7 +510,130 @@ std::unordered_map<std::string, CompoundExpressionRegistry::Definition> initiali
     define("error", [](const std::string& input) -> Result<type::ErrorType> {
         return EvaluationError { input };
     });
+
+    // Legacy Filters
+    define("filter-==", [](const EvaluationContext& params, const std::string& key, const Value &lhs) -> Result<bool> {
+        const auto rhs = featurePropertyAsExpressionValue(params, key);
+        return rhs ? lhs == *rhs : false;
+    });
+
+    define("filter-id-==", [](const EvaluationContext& params, const Value &lhs) -> Result<bool> {
+        return lhs == featureIdAsExpressionValue(params);
+    });
+
+    define("filter-type-==", [](const EvaluationContext& params, const std::string &lhs) -> Result<bool> {
+        if (!params.feature) return false;
+        return featureTypeAsString(params.feature->getType()) == lhs;
+    });
+
+    define("filter-<", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsDouble(params, key);
+        return rhs ? rhs < lhs : false;
+    });
+
+    define("filter-<", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsString(params, key);
+        return rhs ? rhs < lhs : false;
+    });
+
+    define("filter-id-<", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+        auto rhs = featureIdAsDouble(params);
+        return rhs ? rhs < lhs : false;
+    });
+
+    define("filter-id-<", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+        auto rhs = featureIdAsString(params);
+        return rhs ? rhs < lhs : false;
+    });
+
+    define("filter->", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsDouble(params, key);
+        return rhs ? rhs > lhs : false;
+    });
+
+    define("filter->", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsString(params, key);
+        return rhs ? rhs > lhs : false;
+    });
+
+    define("filter-id->", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+        auto rhs = featureIdAsDouble(params);
+        return rhs ? rhs > lhs : false;
+    });
+
+    define("filter-id->", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+        auto rhs = featureIdAsString(params);
+        return rhs ? rhs > lhs : false;
+    });
+
+    define("filter-<=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsDouble(params, key);
+        return rhs ? rhs <= lhs : false;
+    });
+    
+    define("filter-<=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsString(params, key);
+        return rhs ? rhs <= lhs : false;
+    });
+
+    define("filter-id-<=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+        auto rhs = featureIdAsDouble(params);
+        return rhs ? rhs <= lhs : false;
+    });
     
+    define("filter-id-<=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+        auto rhs = featureIdAsString(params);
+        return rhs ? rhs <= lhs : false;
+    });
+
+    define("filter->=", [](const EvaluationContext& params, const std::string& key, double lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsDouble(params, key);
+        return rhs ? rhs >= lhs : false;
+    });
+    
+    define("filter->=", [](const EvaluationContext& params, const std::string& key, std::string lhs) -> Result<bool> {
+        auto rhs = featurePropertyAsString(params, key);
+        return rhs ? rhs >= lhs : false;
+    });
+
+    define("filter-id->=", [](const EvaluationContext& params, double lhs) -> Result<bool> {
+        auto rhs = featureIdAsDouble(params);
+        return rhs ? rhs >= lhs : false;
+    });
+
+    define("filter-id->=", [](const EvaluationContext& params, std::string lhs) -> Result<bool> {
+        auto rhs = featureIdAsString(params);
+        return rhs ? rhs >= lhs : false;
+    });
+
+    define("filter-has", [](const EvaluationContext& params, const std::string& key) -> Result<bool> {
+        assert(params.feature);
+        return bool(params.feature->getValue(key));
+    });
+
+    define("filter-has-id", [](const EvaluationContext& params) -> Result<bool> {
+        assert(params.feature);
+        return bool(params.feature->getID());
+    });
+
+    define("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();
+    });
+    
+    define("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();
+    });
+
+    define("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;
 }
 
@@ -419,7 +652,7 @@ ParseResult parseCompoundExpression(const std::string name, const Convertible& v
         return ParseResult();
     }
     const CompoundExpressionRegistry::Definition& definition = it->second;
-    
+
     auto length = arrayLength(value);
 
     // Check if we have a single signature with the correct number of
@@ -445,14 +678,14 @@ 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;
-        
+
         if (singleMatchingSignature) {
             expected = definition[*singleMatchingSignature]->params.match(
                 [](const VarargsType& varargs) { return varargs.type; },
                 [&](const std::vector<type::Type>& params_) { return params_[i - 1]; }
             );
         }
-    
+
         auto parsed = ctx.parse(arrayMember(value, i), i, expected);
         if (!parsed) {
             return parsed;
@@ -479,7 +712,7 @@ ParseResult createCompoundExpression(const Definition& definition,
     
     for (const std::unique_ptr<detail::SignatureBase>& signature : definition) {
         signatureContext.clearErrors();
-        
+
         if (signature->params.is<std::vector<type::Type>>()) {
             const std::vector<type::Type>& params = signature->params.get<std::vector<type::Type>>();
             if (params.size() != args.size()) {
@@ -507,12 +740,12 @@ ParseResult createCompoundExpression(const Definition& definition,
                 }
             }
         }
-        
+
         if (signatureContext.getErrors().size() == 0) {
             return ParseResult(signature->makeExpression(std::move(args)));
         }
     }
-    
+
     if (definition.size() == 1) {
         ctx.appendErrors(std::move(signatureContext));
     } else {
@@ -545,10 +778,32 @@ ParseResult createCompoundExpression(const Definition& definition,
         }
         ctx.error("Expected arguments of type " + signatures + ", but found (" + actualTypes + ") instead.");
     }
-    
+
     return ParseResult();
 }
 
+ParseResult createCompoundExpression(const std::string& name, ParsingContext& ctx) {
+    return createCompoundExpression(name, std::vector<std::unique_ptr<Expression>>(), ctx);
+}
+
+ParseResult createCompoundExpression(const std::string& name,
+                                     std::unique_ptr<Expression> arg1,
+                                     ParsingContext& ctx) {
+    std::vector<std::unique_ptr<Expression>> args;
+    args.push_back(std::move(arg1));
+    return createCompoundExpression(name, std::move(args), ctx);
+}
+
+ParseResult createCompoundExpression(const std::string& name,
+                                     std::unique_ptr<Expression> arg1,
+                                     std::unique_ptr<Expression> arg2,
+                                     ParsingContext& ctx) {
+    std::vector<std::unique_ptr<Expression>> args;
+    args.push_back(std::move(arg1));
+    args.push_back(std::move(arg2));
+    return createCompoundExpression(name, std::move(args), ctx);
+}
+
 } // namespace expression
 } // namespace style
 } // namespace mbgl
diff --git a/src/mbgl/style/expression/literal.cpp b/src/mbgl/style/expression/literal.cpp
index 8a63980dba..f68cfd5cf5 100644
--- a/src/mbgl/style/expression/literal.cpp
+++ b/src/mbgl/style/expression/literal.cpp
@@ -109,6 +109,14 @@ mbgl::Value Literal::serialize() const {
         return *fromExpressionValue<mbgl::Value>(value);
     }
 }
+    
+std::unique_ptr<Literal> createLiteral(const char* value) {
+    return createLiteral(std::string(value));
+}
+
+std::unique_ptr<Literal> createLiteral(Value value) {
+    return std::make_unique<Literal>(value);
+}
 
 } // namespace expression
 } // namespace style
diff --git a/src/mbgl/style/filter.cpp b/src/mbgl/style/filter.cpp
index 51aa6bcf82..2559eb4816 100644
--- a/src/mbgl/style/filter.cpp
+++ b/src/mbgl/style/filter.cpp
@@ -1,12 +1,20 @@
 #include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/tile/geometry_tile_data.hpp>
 
 namespace mbgl {
 namespace style {
 
 bool Filter::operator()(const expression::EvaluationContext &context) const {
-    return FilterBase::visit(*this, FilterEvaluator { context });
+    
+    if (!this->expression) return true;
+    
+    const expression::EvaluationResult result = (*this->expression)->evaluate(context);
+    if (result) {
+        const optional<bool> typed = expression::fromExpressionValue<bool>(*result);
+        return typed ? *typed : false;
+    } else {
+        return true;
+    }
 }
 
 } // namespace style
diff --git a/src/mbgl/style/filter_evaluator.cpp b/src/mbgl/style/filter_evaluator.cpp
deleted file mode 100644
index 72022172f4..0000000000
--- a/src/mbgl/style/filter_evaluator.cpp
+++ /dev/null
@@ -1,225 +0,0 @@
-#include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
-#include <mbgl/tile/geometry_tile_data.hpp>
-
-namespace mbgl {
-namespace style {
-    
-template <class Op>
-struct Comparator {
-    const Op& op;
-    
-    template <class T>
-    bool operator()(const T& lhs, const T& rhs) const {
-        return op(lhs, rhs);
-    }
-    
-    template <class T0, class T1>
-    auto operator()(const T0& lhs, const T1& rhs) const
-    -> typename std::enable_if_t<std::is_arithmetic<T0>::value && !std::is_same<T0, bool>::value &&
-    std::is_arithmetic<T1>::value && !std::is_same<T1, bool>::value, bool> {
-        return op(double(lhs), double(rhs));
-    }
-    
-    template <class T0, class T1>
-    auto operator()(const T0&, const T1&) const
-    -> typename std::enable_if_t<!std::is_arithmetic<T0>::value || std::is_same<T0, bool>::value ||
-    !std::is_arithmetic<T1>::value || std::is_same<T1, bool>::value, bool> {
-        return false;
-    }
-    
-    bool operator()(const NullValue&,
-                    const NullValue&) const {
-        // Should be unreachable; null is not currently allowed by the style specification.
-        assert(false);
-        return false;
-    }
-    
-    bool operator()(const std::vector<Value>&,
-                    const std::vector<Value>&) const {
-        // Should be unreachable; nested values are not currently allowed by the style specification.
-        assert(false);
-        return false;
-    }
-    
-    bool operator()(const PropertyMap&,
-                    const PropertyMap&) const {
-        // Should be unreachable; nested values are not currently allowed by the style specification.
-        assert(false);
-        return false;
-    }
-};
-
-template <class Op>
-bool compare(const Value& lhs, const Value& rhs, const Op& op) {
-    return Value::binary_visit(lhs, rhs, Comparator<Op> { op });
-}
-
-bool equal(const Value& lhs, const Value& rhs) {
-    return compare(lhs, rhs, [] (const auto& lhs_, const auto& rhs_) { return lhs_ == rhs_; });
-}
-
-bool FilterEvaluator::operator()(const NullFilter&) const {
-    return true;
-}
-
-bool FilterEvaluator::operator()(const EqualsFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return actual && equal(*actual, filter.value);
-}
-
-bool FilterEvaluator::operator()(const NotEqualsFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return !actual || !equal(*actual, filter.value);
-}
-
-bool FilterEvaluator::operator()(const LessThanFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return actual && compare(*actual, filter.value, [] (const auto& lhs_, const auto& rhs_) { return lhs_ < rhs_; });
-}
-
-bool FilterEvaluator::operator()(const LessThanEqualsFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return actual && compare(*actual, filter.value, [] (const auto& lhs_, const auto& rhs_) { return lhs_ <= rhs_; });
-}
-
-bool FilterEvaluator::operator()(const GreaterThanFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return actual && compare(*actual, filter.value, [] (const auto& lhs_, const auto& rhs_) { return lhs_ > rhs_; });
-}
-
-bool FilterEvaluator::operator()(const GreaterThanEqualsFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    return actual && compare(*actual, filter.value, [] (const auto& lhs_, const auto& rhs_) { return lhs_ >= rhs_; });
-}
-
-bool FilterEvaluator::operator()(const InFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    if (!actual)
-        return false;
-    for (const auto& v: filter.values) {
-        if (equal(*actual, v)) {
-            return true;
-        }
-    }
-    return false;
-}
-
-bool FilterEvaluator::operator()(const NotInFilter& filter) const {
-    optional<Value> actual = context.feature->getValue(filter.key);
-    if (!actual)
-        return true;
-    for (const auto& v: filter.values) {
-        if (equal(*actual, v)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-bool FilterEvaluator::operator()(const AnyFilter& filter) const {
-    for (const auto& f: filter.filters) {
-        if (Filter::visit(f, *this)) {
-            return true;
-        }
-    }
-    return false;
-}
-
-bool FilterEvaluator::operator()(const AllFilter& filter) const {
-    for (const auto& f: filter.filters) {
-        if (!Filter::visit(f, *this)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-bool FilterEvaluator::operator()(const NoneFilter& filter) const {
-    for (const auto& f: filter.filters) {
-        if (Filter::visit(f, *this)) {
-            return false;
-        }
-    }
-    return true;
-}
-
-bool FilterEvaluator::operator()(const HasFilter& filter) const {
-    return bool(context.feature->getValue(filter.key));
-}
-
-bool FilterEvaluator::operator()(const NotHasFilter& filter) const {
-    return !context.feature->getValue(filter.key);
-}
-
-bool FilterEvaluator::operator()(const TypeEqualsFilter& filter) const {
-    return context.feature->getType() == filter.value;
-}
-
-bool FilterEvaluator::operator()(const TypeNotEqualsFilter& filter) const {
-    return context.feature->getType() != filter.value;
-}
-
-bool FilterEvaluator::operator()(const TypeInFilter& filter) const {
-    for (const auto& v: filter.values) {
-        if (context.feature->getType() == v) {
-            return true;
-        }
-    }
-    return false;
-}
-
-bool FilterEvaluator::operator()(const TypeNotInFilter& filter) const {
-    for (const auto& v: filter.values) {
-        if (context.feature->getType() == v) {
-            return false;
-        }
-    }
-    return true;
-}
-
-bool FilterEvaluator::operator()(const IdentifierEqualsFilter& filter) const {
-    return context.feature->getID() == filter.value;
-}
-
-bool FilterEvaluator::operator()(const IdentifierNotEqualsFilter& filter) const {
-    return context.feature->getID() != filter.value;
-}
-
-bool FilterEvaluator::operator()(const IdentifierInFilter& filter) const {
-    for (const auto& v: filter.values) {
-        if (context.feature->getID() == v) {
-            return true;
-        }
-    }
-    return false;
-}
-
-bool FilterEvaluator::operator()(const IdentifierNotInFilter& filter) const {
-    for (const auto& v: filter.values) {
-        if (context.feature->getID() == v) {
-            return false;
-        }
-    }
-    return true;
-}
-
-bool FilterEvaluator::operator()(const HasIdentifierFilter&) const {
-    return bool(context.feature->getID());
-}
-
-bool FilterEvaluator::operator()(const NotHasIdentifierFilter&) const {
-    return !context.feature->getID();
-}
-
-bool FilterEvaluator::operator()(const ExpressionFilter& filter) const {
-    const expression::EvaluationResult result = filter.expression->evaluate(context);
-    if (result) {
-        const optional<bool> typed = expression::fromExpressionValue<bool>(*result);
-        return typed ? *typed : false;
-    }
-    return false;
-}
-    
-} // namespace style
-} // namespace mbgl