Port negativeMargin module to plugin

src/plugins/negativeMargin.js

@@ -0,0 +1,29 @@
+import _ from 'lodash'
+
+export default function () {
+  return function ({ addUtilities, config, e }) {
+    const generators = [
+      (size, modifier) => ({
+        [`.${e(`-m-${modifier}`)}`]: { margin: `${size}` },
+      }),
+      (size, modifier) => ({
+        [`.${e(`-my-${modifier}`)}`]: { 'margin-top': `${size}`, 'margin-bottom': `${size}` },
+        [`.${e(`-mx-${modifier}`)}`]: { 'margin-left': `${size}`, 'margin-right': `${size}` },
+      }),
+      (size, modifier) => ({
+        [`.${e(`-mt-${modifier}`)}`]: { 'margin-top': `${size}` },
+        [`.${e(`-mr-${modifier}`)}`]: { 'margin-right': `${size}` },
+        [`.${e(`-mb-${modifier}`)}`]: { 'margin-bottom': `${size}` },
+        [`.${e(`-ml-${modifier}`)}`]: { 'margin-left': `${size}` },
+      }),
+    ]
+
+    const utilities = _.flatMap(generators, generator => {
+      return _.flatMap(config('negativeMargin'), (size, modifier) => {
+        return generator(`${size}` === '0' ? `${size}` : `-${size}`, modifier)
+      })
+    })
+
+    addUtilities(utilities, config('modules.negativeMargin'))
+  }
+}