Implement getClassOrder instead of sortClassList

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Remove opacity variables from `:visited` pseudo class ([#7458](https://github.com/tailwindlabs/tailwindcss/pull/7458))
 - Support arbitrary values + calc + theme with quotes ([#7462](https://github.com/tailwindlabs/tailwindcss/pull/7462))
 - Don't duplicate layer output when scanning content with variants + wildcards ([#7478](https://github.com/tailwindlabs/tailwindcss/pull/7478))
+- Implement `getClassOrder` instead of `sortClassList` ([#7459](https://github.com/tailwindlabs/tailwindcss/pull/7459))
 
 ## [3.0.22] - 2022-02-11
 

src/lib/setupContextUtils.js

@@ -744,33 +744,25 @@ function registerPlugins(plugins, context) {
   // sorting could be weird since you still require them in order to make the
   // host utitlies work properly. (Thanks Biology)
   let parasiteUtilities = new Set([prefix(context, 'group'), prefix(context, 'peer')])
-  context.sortClassList = function sortClassList(classes) {
+  context.getClassOrder = function getClassOrder(classes) {
     let sortedClassNames = new Map()
     for (let [sort, rule] of generateRules(new Set(classes), context)) {
       if (sortedClassNames.has(rule.raws.tailwind.candidate)) continue
       sortedClassNames.set(rule.raws.tailwind.candidate, sort)
     }
 
-    return classes
-      .map((className) => {
-        let order = sortedClassNames.get(className) ?? null
+    return classes.map((className) => {
+      let order = sortedClassNames.get(className) ?? null
 
-        if (order === null && parasiteUtilities.has(className)) {
-          // This will make sure that it is at the very beginning of the
-          // `components` layer which technically means 'before any
-          // components'.
-          order = context.layerOrder.components
-        }
+      if (order === null && parasiteUtilities.has(className)) {
+        // This will make sure that it is at the very beginning of the
+        // `components` layer which technically means 'before any
+        // components'.
+        order = context.layerOrder.components
+      }
 
-        return [className, order]
-      })
-      .sort(([, a], [, z]) => {
-        if (a === z) return 0
-        if (a === null) return -1
-        if (z === null) return 1
-        return bigSign(a - z)
-      })
-      .map(([className]) => className)
+      return [className, order]
+    })
   }
 
   // Generate a list of strings for autocompletion purposes, e.g.

tests/sortClassList.test.js → tests/getSortOrder.test.js

@@ -1,5 +1,42 @@
 import resolveConfig from '../src/public/resolve-config'
 import { createContext } from '../src/lib/setupContextUtils'
+import bigSign from '../src/util/bigSign'
+
+/**
+ * This is a function that the prettier-plugin-tailwindcss would use. It would
+ * do the actual sorting based on the classes and order we return from `getClassOrder`.
+ *
+ * This way the actual sorting logic is done in the plugin which allows you to
+ * put unknown classes at the end for example.
+ *
+ * @param {Array<[string, bigint]>} arrayOfTuples
+ * @returns {string}
+ */
+function defaultSort(arrayOfTuples) {
+  return arrayOfTuples
+    .sort(([, a], [, z]) => {
+      if (a === z) return 0
+      if (a === null) return -1
+      if (z === null) return 1
+      return bigSign(a - z)
+    })
+    .map(([className]) => className)
+    .join(' ')
+}
+
+it('should return a list of tuples with the sort order', () => {
+  let input = 'font-bold underline hover:font-medium unknown'
+  let config = {}
+  let context = createContext(resolveConfig(config))
+  expect(context.getClassOrder(input.split(' '))).toEqual([
+    ['font-bold', expect.any(BigInt)],
+    ['underline', expect.any(BigInt)],
+    ['hover:font-medium', expect.any(BigInt)],
+
+    // Unknown values receive `null`
+    ['unknown', null],
+  ])
+})
 
 it.each([
   // Utitlies
@@ -33,7 +70,7 @@ it.each([
 ])('should sort "%s" based on the order we generate them in to "%s"', (input, output) => {
   let config = {}
   let context = createContext(resolveConfig(config))
-  expect(context.sortClassList(input.split(' ')).join(' ')).toEqual(output)
+  expect(defaultSort(context.getClassOrder(input.split(' ')))).toEqual(output)
 })
 
 it.each([
@@ -73,6 +110,6 @@ it.each([
   (input, output) => {
     let config = { prefix: 'tw-' }
     let context = createContext(resolveConfig(config))
-    expect(context.sortClassList(input.split(' ')).join(' ')).toEqual(output)
+    expect(defaultSort(context.getClassOrder(input.split(' ')))).toEqual(output)
   }
 )