[core] Split Interpolator into a separate file

5 files changed, 53 insertions, 46 deletions

diff --git a/cmake/core-files.cmake b/cmake/core-files.cmake
index 7e48b336b4..714d6d5c8f 100644
--- a/cmake/core-files.cmake
+++ b/cmake/core-files.cmake
@@ -453,6 +453,7 @@ set(MBGL_CORE_FILES
     include/mbgl/style/expression/find_zoom_curve.hpp
     include/mbgl/style/expression/get_covering_stops.hpp
     include/mbgl/style/expression/interpolate.hpp
+    include/mbgl/style/expression/interpolator.hpp
     include/mbgl/style/expression/is_constant.hpp
     include/mbgl/style/expression/is_expression.hpp
     include/mbgl/style/expression/length.hpp
diff --git a/include/mbgl/style/expression/interpolate.hpp b/include/mbgl/style/expression/interpolate.hpp
index cc744ac7b7..1f73fc14b4 100644
--- a/include/mbgl/style/expression/interpolate.hpp
+++ b/include/mbgl/style/expression/interpolate.hpp
@@ -3,12 +3,9 @@
 #include <mbgl/style/expression/expression.hpp>
 #include <mbgl/style/expression/parsing_context.hpp>
 #include <mbgl/style/expression/get_covering_stops.hpp>
+#include <mbgl/style/expression/interpolator.hpp>
 #include <mbgl/style/conversion.hpp>
 
-#include <mbgl/util/interpolate.hpp>
-#include <mbgl/util/range.hpp>
-#include <mbgl/util/unitbezier.hpp>
-
 #include <memory>
 #include <map>
 #include <cmath>
@@ -17,48 +14,10 @@ namespace mbgl {
 namespace style {
 namespace expression {
 
-class ExponentialInterpolator {
-public:
-    ExponentialInterpolator(double base_) : base(base_) {}
-
-    double base;
-    
-    double interpolationFactor(const Range<double>& inputLevels, const double input) const {
-        return util::interpolationFactor(base,
-                                         Range<float> {
-                                            static_cast<float>(inputLevels.min),
-                                            static_cast<float>(inputLevels.max)
-                                         },
-                                         input);
-    }
-    
-    bool operator==(const ExponentialInterpolator& rhs) const {
-        return base == rhs.base;
-    }
-};
-
-class CubicBezierInterpolator {
-public:
-    CubicBezierInterpolator(double x1_, double y1_, double x2_, double y2_) : ub(x1_, y1_, x2_, y2_) {}
-    
-    double interpolationFactor(const Range<double>& inputLevels, const double input) const {
-        return ub.solve(input / (inputLevels.max - inputLevels.min), 1e-6);
-    }
-    
-    bool operator==(const CubicBezierInterpolator& rhs) const {
-        return ub == rhs.ub;
-    }
-    
-    util::UnitBezier ub;
-};
-
-
 ParseResult parseInterpolate(const mbgl::style::conversion::Convertible& value, ParsingContext& ctx);
 
 class InterpolateBase : public Expression {
 public:
-    using Interpolator = variant<ExponentialInterpolator, CubicBezierInterpolator>;
-
     InterpolateBase(const type::Type& type_,
           Interpolator interpolator_,
           std::unique_ptr<Expression> input_,
diff --git a/include/mbgl/style/expression/interpolator.hpp b/include/mbgl/style/expression/interpolator.hpp
new file mode 100644
index 0000000000..f37fb2c9cd
--- /dev/null
+++ b/include/mbgl/style/expression/interpolator.hpp
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <mbgl/util/interpolate.hpp>
+#include <mbgl/util/range.hpp>
+#include <mbgl/util/unitbezier.hpp>
+
+namespace mbgl {
+namespace style {
+namespace expression {
+
+class ExponentialInterpolator {
+public:
+    ExponentialInterpolator(double base_) : base(base_) {}
+
+    double base;
+    
+    double interpolationFactor(const Range<double>& inputLevels, const double input) const {
+        return util::interpolationFactor(base,
+                                         Range<float> {
+                                            static_cast<float>(inputLevels.min),
+                                            static_cast<float>(inputLevels.max)
+                                         },
+                                         input);
+    }
+    
+    bool operator==(const ExponentialInterpolator& rhs) const {
+        return base == rhs.base;
+    }
+};
+
+class CubicBezierInterpolator {
+public:
+    CubicBezierInterpolator(double x1_, double y1_, double x2_, double y2_) : ub(x1_, y1_, x2_, y2_) {}
+    
+    double interpolationFactor(const Range<double>& inputLevels, const double input) const {
+        return ub.solve(input / (inputLevels.max - inputLevels.min), 1e-6);
+    }
+    
+    bool operator==(const CubicBezierInterpolator& rhs) const {
+        return ub == rhs.ub;
+    }
+    
+    util::UnitBezier ub;
+};
+
+using Interpolator = variant<ExponentialInterpolator, CubicBezierInterpolator>;
+
+} // namespace expression
+} // namespace style
+} // namespace mbgl
diff --git a/include/mbgl/style/function/convert.hpp b/include/mbgl/style/function/convert.hpp
index 401a81d52e..b34071d219 100644
--- a/include/mbgl/style/function/convert.hpp
+++ b/include/mbgl/style/function/convert.hpp
@@ -95,7 +95,7 @@ struct Convert {
     static ParseResult makeInterpolate(type::Type type,
                                  std::unique_ptr<Expression> input,
                                  std::map<double, std::unique_ptr<Expression>> convertedStops,
-                                 typename Interpolate<OutputType>::Interpolator interpolator)
+                                 Interpolator interpolator)
     {
         ParseResult curve = ParseResult(std::make_unique<Interpolate<OutputType>>(
             std::move(type),
diff --git a/src/mbgl/style/expression/interpolate.cpp b/src/mbgl/style/expression/interpolate.cpp
index 75f4ce828e..051f2cf9f5 100644
--- a/src/mbgl/style/expression/interpolate.cpp
+++ b/src/mbgl/style/expression/interpolate.cpp
@@ -5,9 +5,6 @@ namespace mbgl {
 namespace style {
 namespace expression {
 
-using Interpolator = variant<ExponentialInterpolator,
-                             CubicBezierInterpolator>;
-
 using namespace mbgl::style::conversion;
 
 ParseResult parseInterpolate(const Convertible& value, ParsingContext& ctx) {