[core] Add possibility of overriding paint properties inside format expression #14062

* [core] Add format override expression and formatted section to evaluation context

* [core] Add textColor to TaggedString's formatted section

* [core] Add FormatSectionOverrides and introduce overridable properties

* [core] Populate symbol layer paint properties for text sections

* [core] Add benchmark for style that uses text-color override

* [core] Add unit test for FormatOverrideExpression

* [core] Add unit test for FormatSectionOverrides

1 files changed, 13 insertions, 4 deletions

diff --git a/include/mbgl/style/expression/expression.hpp b/include/mbgl/style/expression/expression.hpp
index 97b143b3d9..22ae57c2be 100644
--- a/include/mbgl/style/expression/expression.hpp
+++ b/include/mbgl/style/expression/expression.hpp
@@ -25,18 +25,26 @@ public:
 
 class EvaluationContext {
 public:
-    EvaluationContext(float zoom_) : zoom(zoom_), feature(nullptr) {}
-    EvaluationContext(GeometryTileFeature const * feature_) : zoom(optional<float>()), feature(feature_) {}
+    EvaluationContext() = default;
+    explicit EvaluationContext(float zoom_) : zoom(zoom_) {}
+    explicit EvaluationContext(GeometryTileFeature const * feature_) : feature(feature_) {}
     EvaluationContext(float zoom_, GeometryTileFeature const * feature_) :
         zoom(zoom_), feature(feature_)
     {}
     EvaluationContext(optional<float> zoom_, GeometryTileFeature const * feature_, optional<double> colorRampParameter_) :
         zoom(std::move(zoom_)), feature(feature_), colorRampParameter(std::move(colorRampParameter_))
     {}
-    
+
+    EvaluationContext& withFormattedSection(const Value* formattedSection_) noexcept {
+        formattedSection = formattedSection_;
+        return *this;
+    };
+
     optional<float> zoom;
-    GeometryTileFeature const * feature;
+    GeometryTileFeature const * feature = nullptr;
     optional<double> colorRampParameter;
+    // Contains formatted section object, std::unordered_map<std::string, Value>.
+    const Value* formattedSection = nullptr;
 };
 
 template <typename T>
@@ -134,6 +142,7 @@ enum class Kind : int32_t {
     All,
     Comparison,
     FormatExpression,
+    FormatSectionOverride
 };
 
 class Expression {