remove fast-stable-stringify (#5154)

closes #5152

src/style-spec/group_by_layout.js

@@ -1,12 +1,35 @@
 'use strict';
 
-const refProperties = require('./util/ref_properties'),
-    stringify = require('fast-stable-stringify');
+const refProperties = require('./util/ref_properties');
 
-function key(layer) {
-    return stringify(refProperties.map((k) => {
-        return layer[k];
-    }));
+function stringify(obj) {
+    const type = typeof obj;
+    if (type === 'number' || type === 'string' || obj === undefined || obj === null)
+        return JSON.stringify(obj);
+
+    if (Array.isArray(obj)) {
+        let str = '[';
+        for (const val of obj) {
+            str += `${stringify(val)},`;
+        }
+        return `${str}]`;
+    }
+
+    const keys = Object.keys(obj).sort();
+
+    let str = '{';
+    for (let i = 0; i < keys.length; i++) {
+        str += `${JSON.stringify(keys[i])}:${stringify(obj[keys[i]])},`;
+    }
+    return `${str}}`;
+}
+
+function getKey(layer) {
+    let key = '';
+    for (const k of refProperties) {
+        key += `/${stringify(layer[k])}`;
+    }
+    return key;
 }
 
 module.exports = groupByLayout;
@@ -29,7 +52,7 @@ function groupByLayout(layers) {
     const groups = {};
 
     for (let i = 0; i < layers.length; i++) {
-        const k = key(layers[i]);
+        const k = getKey(layers[i]);
         let group = groups[k];
         if (!group) {
             group = groups[k] = [];

src/style-spec/package.json

@@ -22,7 +22,6 @@
   },
   "dependencies": {
     "csscolorparser": "~1.0.2",
-    "fast-stable-stringify": "^0.1.1",
     "jsonlint-lines-primitives": "~1.6.0",
     "lodash.isequal": "^3.0.4",
     "minimist": "0.0.8",

yarn.lock

@@ -2682,7 +2682,7 @@ glob-stream@^5.3.2:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
-glob@^5.0.3:
+glob@^5.0.14, glob@^5.0.3:
   version "5.0.15"
   resolved "https://registry.yarnpkg.com/glob/-/glob-5.0.15.tgz#1bc936b9e02f4a603fcc222ecf7633d30b8b93b1"
   dependencies: