Eliminate `Filter` variant

15 files changed, 23 insertions, 135 deletions

diff --git a/benchmark/parse/filter.benchmark.cpp b/benchmark/parse/filter.benchmark.cpp
index e4cf635256..4e39237138 100644
--- a/benchmark/parse/filter.benchmark.cpp
+++ b/benchmark/parse/filter.benchmark.cpp
@@ -1,7 +1,6 @@
 #include <benchmark/benchmark.h>
 
 #include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/style/conversion.hpp>
 #include <mbgl/style/conversion/json.hpp>
 #include <mbgl/style/conversion/filter.hpp>
diff --git a/cmake/core-files.cmake b/cmake/core-files.cmake
index 0853097630..208c598872 100644
--- a/cmake/core-files.cmake
+++ b/cmake/core-files.cmake
@@ -360,7 +360,6 @@ set(MBGL_CORE_FILES
     include/mbgl/style/conversion.hpp
     include/mbgl/style/data_driven_property_value.hpp
     include/mbgl/style/filter.hpp
-    include/mbgl/style/filter_evaluator.hpp
     include/mbgl/style/heatmap_color_property_value.hpp
     include/mbgl/style/image.hpp
     include/mbgl/style/layer.hpp
@@ -377,7 +376,6 @@ set(MBGL_CORE_FILES
     src/mbgl/style/custom_tile_loader.cpp
     src/mbgl/style/custom_tile_loader.hpp
     src/mbgl/style/filter.cpp
-    src/mbgl/style/filter_evaluator.cpp
     src/mbgl/style/image.cpp
     src/mbgl/style/image_impl.cpp
     src/mbgl/style/image_impl.hpp
diff --git a/include/mbgl/style/filter.hpp b/include/mbgl/style/filter.hpp
index 97ce0204b3..b932e06f51 100644
--- a/include/mbgl/style/filter.hpp
+++ b/include/mbgl/style/filter.hpp
@@ -11,28 +11,24 @@
 
 namespace mbgl {
 namespace style {
-
-class Filter;
     
-class ExpressionFilter {
+class Filter {
 public:
     std::shared_ptr<const expression::Expression> expression;
+    
+    bool operator()(const expression::EvaluationContext& context) const;
 
-    friend bool operator==(const ExpressionFilter& lhs, const ExpressionFilter& rhs) {
+    friend bool operator==(const Filter& lhs, const Filter& rhs) {
         if (!lhs.expression || !rhs.expression) {
             return ((bool) lhs.expression) == ((bool) rhs.expression);
         } else {
             return *(lhs.expression) == *(rhs.expression);
         }
     }
-};
-
-using FilterBase = variant<class ExpressionFilter>;
-
-class Filter : public FilterBase {
-public:
-    using FilterBase::FilterBase;
-    bool operator()(const expression::EvaluationContext& context) const;
+    
+    friend bool operator!=(const Filter& lhs, const Filter& rhs) {
+        return !(lhs == rhs);
+    }
 };
 
 } // namespace style
diff --git a/include/mbgl/style/filter_evaluator.hpp b/include/mbgl/style/filter_evaluator.hpp
deleted file mode 100644
index 92403ecfcd..0000000000
--- a/include/mbgl/style/filter_evaluator.hpp
+++ /dev/null
@@ -1,31 +0,0 @@
-#pragma once
-
-#include <mbgl/style/filter.hpp>
-#include <mbgl/util/geometry.hpp>
-
-#include <type_traits>
-
-namespace mbgl {
-namespace style {
-
-/*
-   A visitor that evaluates a `Filter` for a given feature.
-
-   Use via `Filter::operator()`. For example:
-
-       if (filter(feature)) {
-           // matches the filter
-       } else {
-           // does not match
-       }
-*/
-class FilterEvaluator {
-public:
-    const expression::EvaluationContext context;
-
-    bool operator()(const ExpressionFilter&) const;
-
-};
-
-} // namespace style
-} // namespace mbgl
diff --git a/src/mbgl/geometry/feature_index.cpp b/src/mbgl/geometry/feature_index.cpp
index c67786274a..57719de038 100644
--- a/src/mbgl/geometry/feature_index.cpp
+++ b/src/mbgl/geometry/feature_index.cpp
@@ -7,7 +7,6 @@
 #include <mbgl/util/math.hpp>
 #include <mbgl/math/minmax.hpp>
 #include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/tile/tile_id.hpp>
 
 #include <mapbox/geometry/envelope.hpp>
diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index 82a9255824..cd9bcbd585 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -2,7 +2,6 @@
 #include <mbgl/layout/merge_lines.hpp>
 #include <mbgl/layout/clip_lines.hpp>
 #include <mbgl/renderer/buckets/symbol_bucket.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/renderer/bucket_parameters.hpp>
 #include <mbgl/renderer/layers/render_symbol_layer.hpp>
 #include <mbgl/renderer/image_atlas.hpp>
diff --git a/src/mbgl/style/conversion/filter.cpp b/src/mbgl/style/conversion/filter.cpp
index 3000b4fe3b..7b0540dca2 100644
--- a/src/mbgl/style/conversion/filter.cpp
+++ b/src/mbgl/style/conversion/filter.cpp
@@ -119,7 +119,7 @@ optional<Filter> Converter<Filter>::operator()(const Convertible& value, Error&
     
     if (!expression) return {};
     
-    return { ExpressionFilter { std::move(*expression) } };
+    return { Filter { std::move(*expression) } };
 }
 
     std::unique_ptr<Expression> convertComparisonOp(const Convertible& values, Error& error, optional<std::string> opOverride = {}) {
diff --git a/src/mbgl/style/conversion/stringify.hpp b/src/mbgl/style/conversion/stringify.hpp
index 19031ad7fc..dc19caff5d 100644
--- a/src/mbgl/style/conversion/stringify.hpp
+++ b/src/mbgl/style/conversion/stringify.hpp
@@ -126,19 +126,9 @@ void stringify(Writer& writer, const FeatureIdentifier& id) {
 }
 
 template <class Writer>
-class StringifyFilter {
-public:
-    Writer& writer;
-    
-    void operator()(const ExpressionFilter& filter) {
-        if (!filter.expression) writer.Null();
-        else stringify(writer, filter.expression->serialize());
-    }
-};
-
-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/filter.cpp b/src/mbgl/style/filter.cpp
index 51aa6bcf82..0da7229e3c 100644
--- a/src/mbgl/style/filter.cpp
+++ b/src/mbgl/style/filter.cpp
@@ -1,12 +1,21 @@
 #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 });
+    
+    // TODO What is our fallback behvaiour?
+    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;
+    }
+    return false;
+    
 }
 
 } // namespace style
diff --git a/src/mbgl/style/filter_evaluator.cpp b/src/mbgl/style/filter_evaluator.cpp
deleted file mode 100644
index 172c84a628..0000000000
--- a/src/mbgl/style/filter_evaluator.cpp
+++ /dev/null
@@ -1,66 +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;
-    }
-};
-
-bool FilterEvaluator::operator()(const ExpressionFilter& filter) const {
-    // TODO What is our fallback behvaiour?
-    if (!filter.expression) return true;
-    
-    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
diff --git a/src/mbgl/tile/custom_geometry_tile.cpp b/src/mbgl/tile/custom_geometry_tile.cpp
index a2fefcfa9f..272a1594d4 100644
--- a/src/mbgl/tile/custom_geometry_tile.cpp
+++ b/src/mbgl/tile/custom_geometry_tile.cpp
@@ -3,7 +3,6 @@
 #include <mbgl/renderer/query.hpp>
 #include <mbgl/renderer/tile_parameters.hpp>
 #include <mbgl/actor/scheduler.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/tile/tile_observer.hpp>
 #include <mbgl/style/custom_tile_loader.hpp>
diff --git a/src/mbgl/tile/geojson_tile.cpp b/src/mbgl/tile/geojson_tile.cpp
index f211c03569..7a83da2267 100644
--- a/src/mbgl/tile/geojson_tile.cpp
+++ b/src/mbgl/tile/geojson_tile.cpp
@@ -2,7 +2,6 @@
 #include <mbgl/tile/geojson_tile_data.hpp>
 #include <mbgl/renderer/query.hpp>
 #include <mbgl/renderer/tile_parameters.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 
 namespace mbgl {
 
diff --git a/src/mbgl/tile/geometry_tile.cpp b/src/mbgl/tile/geometry_tile.cpp
index a99cb91d26..28f46f6f54 100644
--- a/src/mbgl/tile/geometry_tile.cpp
+++ b/src/mbgl/tile/geometry_tile.cpp
@@ -16,7 +16,6 @@
 #include <mbgl/storage/file_source.hpp>
 #include <mbgl/geometry/feature_index.hpp>
 #include <mbgl/map/transform_state.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/util/logging.hpp>
 #include <mbgl/actor/scheduler.hpp>
 
diff --git a/src/mbgl/tile/geometry_tile_worker.cpp b/src/mbgl/tile/geometry_tile_worker.cpp
index 1378ad5d3a..61bc0cb597 100644
--- a/src/mbgl/tile/geometry_tile_worker.cpp
+++ b/src/mbgl/tile/geometry_tile_worker.cpp
@@ -5,7 +5,6 @@
 #include <mbgl/renderer/bucket_parameters.hpp>
 #include <mbgl/renderer/group_by_layout.hpp>
 #include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/style/layers/symbol_layer_impl.hpp>
 #include <mbgl/renderer/layers/render_symbol_layer.hpp>
 #include <mbgl/renderer/buckets/symbol_bucket.hpp>
diff --git a/test/style/filter.test.cpp b/test/style/filter.test.cpp
index 49edcaef45..ed8973e21c 100644
--- a/test/style/filter.test.cpp
+++ b/test/style/filter.test.cpp
@@ -4,7 +4,6 @@
 #include <mbgl/test/stub_geometry_tile_feature.hpp>
 
 #include <mbgl/style/filter.hpp>
-#include <mbgl/style/filter_evaluator.hpp>
 #include <mbgl/style/conversion/json.hpp>
 #include <mbgl/style/conversion/filter.hpp>