From cedda5ef4f73fccfc795e6bc48b368e48f11ad8d Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Wed, 10 Jan 2018 11:48:06 -0800
Subject: [core] Handle NaN input to interpolate and step

---
 include/mbgl/style/expression/interpolate.hpp | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

(limited to 'include/mbgl')

diff --git a/include/mbgl/style/expression/interpolate.hpp b/include/mbgl/style/expression/interpolate.hpp
index 439122f91c..fd9ec25a2c 100644
--- a/include/mbgl/style/expression/interpolate.hpp
+++ b/include/mbgl/style/expression/interpolate.hpp
@@ -11,7 +11,7 @@
 
 #include <memory>
 #include <map>
-
+#include <cmath>
 
 namespace mbgl {
 namespace style {
@@ -109,9 +109,15 @@ public:
     
     EvaluationResult evaluate(const EvaluationContext& params) const override {
         const EvaluationResult evaluatedInput = input->evaluate(params);
-        if (!evaluatedInput) { return evaluatedInput.error(); }
+        if (!evaluatedInput) {
+            return evaluatedInput.error();
+        }
+
         float x = *fromExpressionValue<float>(*evaluatedInput);
-        
+        if (std::isnan(x)) {
+            return EvaluationError { "Input is not a number." };
+        }
+
         if (stops.empty()) {
             return EvaluationError { "No stops in exponential curve." };
         }
-- 
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