Update to PostCSS 8

.eslintrc

@@ -1,4 +1,4 @@
 {
-  "extends": "airbnb-base/legacy",
+  "extends": "airbnb-base",
   "root": true
 }

.travis.yml

@@ -1,7 +1,7 @@
 sudo: false
 language: node_js
 node_js:
-  - stable
-  - "6"
-  - "4"
+  - 14
+  - 12
+  - 10
 after_success: npm run coveralls

lib/__utils__/generateFileUniqueId.js

@@ -1,6 +1,6 @@
-var fs = require('fs');
+const fs = require('fs');
 
 module.exports = function generateFileUniqueId(resolvedPath) {
-  var mtime = fs.statSync(resolvedPath).mtime;
+  const { mtime } = fs.statSync(resolvedPath);
   return mtime.getTime().toString(16);
 };

lib/index.js

@@ -1,15 +1,13 @@
-var Assets = require('assets');
-var dirname = require('path').dirname;
-var functions = require('postcss-functions');
-var postcss = require('postcss');
-var quote = require('./quote');
-var unescapeCss = require('./unescape-css');
-var unquote = require('./unquote');
-var util = require('util');
-var Promise = require('bluebird');
-var generateFileUniqueId = require('./__utils__/generateFileUniqueId');
-
-var cachedDimensions = {};
+const Assets = require('assets');
+const { dirname } = require('path');
+const functions = require('postcss-functions');
+const util = require('util');
+const quote = require('./quote');
+const unescapeCss = require('./unescape-css');
+const unquote = require('./unquote');
+const generateFileUniqueId = require('./__utils__/generateFileUniqueId');
+
+const cachedDimensions = {};
 
 function formatUrl(url) {
   return util.format('url(%s)', quote(url));
@@ -27,22 +25,19 @@ function formatHeight(measurements) {
   return util.format('%dpx', measurements.height);
 }
 
-function plugin(options) {
-  var params = options || {};
-  var resolver;
-
+module.exports = (params = {}) => {
   if (params.relative === undefined) {
-    params.relative = false;
+    params.relative = false; // eslint-disable-line no-param-reassign
   }
 
-  resolver = new Assets(options);
+  const resolver = new Assets(params);
 
   function measure(path, density) {
-    var cached = null;
-    var id = '';
-    var getSizePromise = null;
+    let cached = null;
+    let id = '';
+    let getSizePromise = null;
 
-    return resolver.path(path).then(function measureSize(resolvedPath) {
+    return resolver.path(path).then((resolvedPath) => {
       if (params.cache) {
         cached = cachedDimensions[resolvedPath];
         id = generateFileUniqueId(resolvedPath);
@@ -51,7 +46,7 @@ function plugin(options) {
       if (cached && id && cached[id]) {
         getSizePromise = Promise.resolve(cached[id]);
       } else {
-        getSizePromise = resolver.size(path).then(function cacheSize(size) {
+        getSizePromise = resolver.size(path).then((size) => {
           if (params.cache && id) {
             cachedDimensions[resolvedPath] = {};
             cachedDimensions[resolvedPath][id] = size;
@@ -60,61 +55,64 @@ function plugin(options) {
         });
       }
 
-      return getSizePromise.then(function correctDensity(size) {
+      return getSizePromise.then((size) => {
         if (density !== undefined) {
           return {
             width: Number((size.width / density).toFixed(4)),
-            height: Number((size.height / density).toFixed(4))
+            height: Number((size.height / density).toFixed(4)),
           };
         }
         return size;
       });
     });
   }
 
-  return postcss()
-    .use(function appendInputDir(css) {
-      var inputDir;
-
-      if (css.source.input.file) {
-        inputDir = dirname(css.source.input.file);
-
-        resolver.options.loadPaths = resolver.options.loadPaths || [];
-        resolver.options.loadPaths.unshift(inputDir);
-
-        if (params.relative === true) {
-          resolver.options.relativeTo = inputDir;
-        }
-      }
-
-      if (typeof params.relative === 'string') {
-        resolver.options.relativeTo = params.relative;
-      }
-    })
-    .use(functions({
+  return {
+    // Initialize functions plugin as if it was this plugin
+    ...functions({
       functions: {
         resolve: function resolve(path) {
-          var normalizedPath = unquote(unescapeCss(path));
+          const normalizedPath = unquote(unescapeCss(path));
           return resolver.url(normalizedPath).then(formatUrl);
         },
         inline: function inline(path) {
-          var normalizedPath = unquote(unescapeCss(path));
+          const normalizedPath = unquote(unescapeCss(path));
           return resolver.data(normalizedPath).then(formatUrl);
         },
         size: function size(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          const normalizedPath = unquote(unescapeCss(path));
           return measure(normalizedPath, density).then(formatSize);
         },
         width: function width(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          const normalizedPath = unquote(unescapeCss(path));
           return measure(normalizedPath, density).then(formatWidth);
         },
         height: function height(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          const normalizedPath = unquote(unescapeCss(path));
           return measure(normalizedPath, density).then(formatHeight);
+        },
+      },
+    }),
+    // Override with our own features and name
+    postcssPlugin: 'postcss-assets',
+    Once(root) {
+      let inputDir;
+      if (root.source.input.file) {
+        inputDir = dirname(root.source.input.file);
+
+        resolver.options.loadPaths = resolver.options.loadPaths || [];
+        resolver.options.loadPaths.unshift(inputDir);
+
+        if (params.relative === true) {
+          resolver.options.relativeTo = inputDir;
         }
       }
-    }));
-}
 
-module.exports = postcss.plugin('postcss-assets', plugin);
+      if (typeof params.relative === 'string') {
+        resolver.options.relativeTo = params.relative;
+      }
+    },
+  };
+};
+
+module.exports.postcss = true;

lib/quote.js

@@ -1,14 +1,14 @@
 /* eslint quotes: 0 */
 
-var util = require('util');
+const util = require('util');
 
-var R_QUOTES = /'/g;
+const R_QUOTES = /'/g;
 
 function escapeQuote(match, offset, string) {
   if (string[offset - 1] === '\\') {
     return match;
   }
-  return '\\' + match;
+  return `\\${match}`;
 }
 
 module.exports = function quote(string) {

lib/unescape-css.js

@@ -1,4 +1,4 @@
-var R_ESCAPE = /\\(?:([0-9a-f]{1,6} ?)|(.))/gi;
+const R_ESCAPE = /\\(?:([0-9a-f]{1,6} ?)|(.))/gi;
 
 function unescapeSequence(match, hex, char) {
   if (hex) {