[core] Add expression filter support (#11251)

* WIP

* WIP

* WIP

* Remove Filter::operator()(const Feature&)

* WIP

* WIP

* WIP

* WIP

* Hook up expression filter evaluator

* Replace `shared_ptr` with &reference

* Fill in implementation of `void operator()(const ExpressionFilter&)`

* Fix failing tests

* Switch back to a shared_ptr per chat with @anandthakker

* Fix benchmark compilation

* Shot in the dark to fix CI

* Shot in the dark to fix CI (part 2)

* Shot in the dark to fix CI (part 3)

* In src/mbgl/style/conversion/filter.cpp, add a port of isExpressionFilter and use it to decide in Converter<Filter>::operator() whether to parse the incoming JSON as an ExpressionFilter or one of the legacy filter types

* Remove bool Filter::operator()(const GeometryTileFeature&) const

*  Ensure the map zoom is passed into filtering operations wherever applicable

* Add expression filter tests

* Addressed PR feedback

* Implement `NSPredicate *operator()(mbgl::style::ExpressionFilter filter)`

* Fix formatting& nit

1 files changed, 6 insertions, 0 deletions

diff --git a/platform/darwin/src/NSPredicate+MGLAdditions.mm b/platform/darwin/src/NSPredicate+MGLAdditions.mm
index 3ffe200d01..63c8307803 100644
--- a/platform/darwin/src/NSPredicate+MGLAdditions.mm
+++ b/platform/darwin/src/NSPredicate+MGLAdditions.mm
@@ -1,6 +1,7 @@
 #import "NSPredicate+MGLAdditions.h"
 
 #import "MGLValueEvaluator.h"
+#import "MGLStyleValue_Private.h"
 
 class FilterEvaluator {
 public:
@@ -194,6 +195,11 @@ public:
     NSPredicate *operator()(mbgl::style::NotHasIdentifierFilter filter) {
         return [NSPredicate predicateWithFormat:@"%K == nil", @"$id"];
     }
+    
+    NSPredicate *operator()(mbgl::style::ExpressionFilter filter) {
+        id jsonObject = MGLJSONObjectFromMBGLExpression(*filter.expression);
+        return [NSPredicate mgl_predicateWithJSONObject:jsonObject];
+    }
 };
 
 @implementation NSPredicate (MGLAdditions)