From e058a470b19d659d3dc686bb3f4bfbdb375a0b8b Mon Sep 17 00:00:00 2001
From: Brandon Bloom <brandon@brandonbloom.name>
Date: Tue, 13 Jun 2017 18:15:59 -0700
Subject: [PATCH] Eval hack until arbitrary expressions are supported.

Ideally this will no longer be necessary after this happens:
https://github.com/mapbox/mapbox-gl-js/pull/4777
---
 src/style-spec/function/index.js | 25 ++++++++++++++++++-------
 src/style-spec/reference/v8.json |  4 ++++
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/style-spec/function/index.js b/src/style-spec/function/index.js
index 7a22b919cbe..ae11f614541 100644
--- a/src/style-spec/function/index.js
+++ b/src/style-spec/function/index.js
@@ -136,13 +136,24 @@ function createFunction(parameters, propertySpec) {
             fun.isFeatureConstant = true;
             fun.isZoomConstant = false;
         } else {
-            fun = function(zoom, feature) {
-                const value = feature[parameters.property];
-                if (value === undefined) {
-                    return coalesce(parameters.default, propertySpec.default);
-                }
-                return outputFunction(innerFun(parameters, propertySpec, value, hashedStops, categoricalKeyType));
-            };
+            if (parameters.mdory) {
+                const fn = new Function(['feature'], `return (${parameters.mdory});`);
+                fun = function(zoom, feature) {
+                    const value = fn(feature);
+                    if (value === undefined || Number.isNaN(value)) {
+                        return coalesce(parameters.default, propertySpec.default);
+                    }
+                    return outputFunction(innerFun(parameters, propertySpec, value, hashedStops, categoricalKeyType));
+                };
+            } else {
+                fun = function(zoom, feature) {
+                    const value = feature[parameters.property];
+                    if (value === undefined) {
+                        return coalesce(parameters.default, propertySpec.default);
+                    }
+                    return outputFunction(innerFun(parameters, propertySpec, value, hashedStops, categoricalKeyType));
+                };
+            }
             fun.isFeatureConstant = false;
             fun.isZoomConstant = true;
         }
diff --git a/src/style-spec/reference/v8.json b/src/style-spec/reference/v8.json
index 74da0b212f0..6b99e676984 100644
--- a/src/style-spec/reference/v8.json
+++ b/src/style-spec/reference/v8.json
@@ -1624,6 +1624,10 @@
     "doc": "The geometry type for the filter to select."
   },
   "function": {
+    "mdory": {
+      "type": "string",
+      "doc": "a eval hack for mdory until https://github.com/mapbox/mapbox-gl-js/pull/4777"
+    },
     "stops": {
       "type": "array",
       "doc": "An array of stops.",