Couple more cleanupsupstream/expressions

3 files changed, 15 insertions, 25 deletions

diff --git a/cmake/test-files.cmake b/cmake/test-files.cmake
index 5df5fb38d1..31747e1d45 100644
--- a/cmake/test-files.cmake
+++ b/cmake/test-files.cmake
@@ -88,7 +88,7 @@ set(MBGL_TEST_FILES
     test/style/conversion/stringify.test.cpp
 
     # style/expression
-    test/style/expression/is_expression.test.cpp
+    test/style/expression/expression.test.cpp
     test/style/expression/util.test.cpp
 
     # style
diff --git a/include/mbgl/style/expression/interpolate.hpp b/include/mbgl/style/expression/interpolate.hpp
index cb3bfe8b4a..2dcb5a32a4 100644
--- a/include/mbgl/style/expression/interpolate.hpp
+++ b/include/mbgl/style/expression/interpolate.hpp
@@ -140,7 +140,20 @@ public:
                 return upper.error();
             }
 
-            return interpolate({*lower, *upper}, t);
+            if (!lower->is<T>()) {
+                return EvaluationError {
+                    "Expected value to be of type " + toString(valueTypeToExpressionType<T>()) +
+                    ", but found " + toString(typeOf(*lower)) + " instead."
+                };
+            }
+            
+            if (!upper->is<T>()) {
+                return EvaluationError {
+                    "Expected value to be of type " + toString(valueTypeToExpressionType<T>()) +
+                    ", but found " + toString(typeOf(*upper)) + " instead."
+                };
+            }
+            return util::interpolate(lower->get<T>(), upper->get<T>(), t);
         }
     }
     
@@ -157,29 +170,6 @@ public:
         }
         return false;
     }
-
-    
-private:
-    static EvaluationResult interpolate(const Range<Value>& outputs, const double t) {
-        optional<T> lower = fromExpressionValue<T>(outputs.min);
-        if (!lower) {
-            // TODO - refactor fromExpressionValue to return EvaluationResult<T> so as to
-            // consolidate DRY up producing this error message.
-            return EvaluationError {
-                "Expected value to be of type " + toString(valueTypeToExpressionType<T>()) +
-                ", but found " + toString(typeOf(outputs.min)) + " instead."
-            };
-        }
-        const optional<T> upper = fromExpressionValue<T>(outputs.max);
-        if (!upper) {
-            return EvaluationError {
-                "Expected value to be of type " + toString(valueTypeToExpressionType<T>()) +
-                ", but found " + toString(typeOf(outputs.min)) + " instead."
-            };
-        }
-        T result = util::interpolate(*lower, *upper, t);
-        return toExpressionValue(result);
-    }
 };
 
 } // namespace expression
diff --git a/test/style/expression/is_expression.test.cpp b/test/style/expression/expression.test.cpp
index 694569695c..694569695c 100644
--- a/test/style/expression/is_expression.test.cpp
+++ b/test/style/expression/expression.test.cpp