Add support for arbitrary properties (#6161)

* Basic implementation + some failing tests for edge cases

* Use asClass instead of nameClass

* Solve edge cases around content with colons

* Avoid duplicating work when parsing arbitrary properties

* Update changelog

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add `placeholder` variant ([#6106](https://github.com/tailwindlabs/tailwindcss/pull/6106))
 - Add tuple syntax for configuring screens while guaranteeing order ([#5956](https://github.com/tailwindlabs/tailwindcss/pull/5956))
 - Add combinable `touch-action` support ([#6115](https://github.com/tailwindlabs/tailwindcss/pull/6115))
+- Add support for "arbitrary properties" ([#6161](https://github.com/tailwindlabs/tailwindcss/pull/6161))
 
 ## [3.0.0-alpha.2] - 2021-11-08
 

src/lib/expandTailwindAtRules.js

@@ -15,6 +15,8 @@ const PATTERNS = [
   /([^<>"'`\s]*\[\w*\("[^'`\s]*"\)\])/.source, // bg-[url("..."),url("...")]
   /([^<>"'`\s]*\['[^"'`\s]*'\])/.source, // `content-['hello']` but not `content-['hello']']`
   /([^<>"'`\s]*\["[^"'`\s]*"\])/.source, // `content-["hello"]` but not `content-["hello"]"]`
+  /([^<>"'`\s]*\[[^<>"'`\s]*:'[^"'`\s]*'\])/.source, // `[content:'hello']` but not `[content:"hello"]`
+  /([^<>"'`\s]*\[[^<>"'`\s]*:"[^"'`\s]*"\])/.source, // `[content:"hello"]` but not `[content:'hello']`
   /([^<>"'`\s]*\[[^"'`\s]+\][^<>"'`\s]*)/.source, // `fill-[#bada55]`, `fill-[#bada55]/50`
   /([^<>"'`\s]*[^"'`\s:])/.source, //  `px-1.5`, `uppercase` but not `uppercase:`
 ].join('|')

src/lib/generateRules.js

@@ -6,6 +6,9 @@ import prefixSelector from '../util/prefixSelector'
 import { updateAllClasses } from '../util/pluginUtils'
 import log from '../util/log'
 import { formatVariantSelector, finalizeSelector } from '../util/formatVariantSelector'
+import { asClass } from '../util/nameClass'
+import { normalize } from '../util/dataTypes'
+import isValidArbitraryValue from '../util/isValidArbitraryValue'
 
 let classNameParser = selectorParser((selectors) => {
   return selectors.first.filter(({ type }) => type === 'class').pop().value
@@ -245,11 +248,42 @@ function parseRules(rule, cache, options = {}) {
   return [cache.get(rule), options]
 }
 
+function extractArbitraryProperty(classCandidate, context) {
+  let [, property, value] = classCandidate.match(/^\[([a-zA-Z0-9-_]+):(\S+)\]$/) ?? []
+
+  if (value === undefined) {
+    return null
+  }
+
+  let normalized = normalize(value)
+
+  if (!isValidArbitraryValue(normalized)) {
+    return null
+  }
+
+  return [
+    [
+      { sort: context.arbitraryPropertiesSort, layer: 'utilities' },
+      () => ({
+        [asClass(classCandidate)]: {
+          [property]: normalized,
+        },
+      }),
+    ],
+  ]
+}
+
 function* resolveMatchedPlugins(classCandidate, context) {
   if (context.candidateRuleMap.has(classCandidate)) {
     yield [context.candidateRuleMap.get(classCandidate), 'DEFAULT']
   }
 
+  yield* (function* (arbitraryPropertyRule) {
+    if (arbitraryPropertyRule !== null) {
+      yield [arbitraryPropertyRule, 'DEFAULT']
+    }
+  })(extractArbitraryProperty(classCandidate, context))
+
   let candidatePrefix = classCandidate
   let negative = false
 

src/lib/setupContextUtils.js

@@ -18,6 +18,7 @@ import { env } from './sharedState'
 import { toPath } from '../util/toPath'
 import log from '../util/log'
 import negateValue from '../util/negateValue'
+import isValidArbitraryValue from '../util/isValidArbitraryValue'
 
 function parseVariantFormatString(input) {
   if (input.includes('{')) {
@@ -130,64 +131,6 @@ function withIdentifiers(styles) {
   })
 }
 
-let matchingBrackets = new Map([
-  ['{', '}'],
-  ['[', ']'],
-  ['(', ')'],
-])
-let inverseMatchingBrackets = new Map(
-  Array.from(matchingBrackets.entries()).map(([k, v]) => [v, k])
-)
-
-let quotes = new Set(['"', "'", '`'])
-
-// Arbitrary values must contain balanced brackets (), [] and {}. Escaped
-// values don't count, and brackets inside quotes also don't count.
-//
-// E.g.: w-[this-is]w-[weird-and-invalid]
-// E.g.: w-[this-is\\]w-\\[weird-but-valid]
-// E.g.: content-['this-is-also-valid]-weirdly-enough']
-function isValidArbitraryValue(value) {
-  let stack = []
-  let inQuotes = false
-
-  for (let i = 0; i < value.length; i++) {
-    let char = value[i]
-
-    // Non-escaped quotes allow us to "allow" anything in between
-    if (quotes.has(char) && value[i - 1] !== '\\') {
-      inQuotes = !inQuotes
-    }
-
-    if (inQuotes) continue
-    if (value[i - 1] === '\\') continue // Escaped
-
-    if (matchingBrackets.has(char)) {
-      stack.push(char)
-    } else if (inverseMatchingBrackets.has(char)) {
-      let inverse = inverseMatchingBrackets.get(char)
-
-      // Nothing to pop from, therefore it is unbalanced
-      if (stack.length <= 0) {
-        return false
-      }
-
-      // Popped value must match the inverse value, otherwise it is unbalanced
-      if (stack.pop() !== inverse) {
-        return false
-      }
-    }
-  }
-
-  // If there is still something on the stack, it is also unbalanced
-  if (stack.length > 0) {
-    return false
-  }
-
-  // All good, totally balanced!
-  return true
-}
-
 function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offsets, classList }) {
   function getConfigValue(path, defaultValue) {
     return path ? dlv(tailwindConfig, path, defaultValue) : tailwindConfig
@@ -617,6 +560,10 @@ function registerPlugins(plugins, context) {
   ])
   let reservedBits = BigInt(highestOffset.toString(2).length)
 
+  // A number one less than the top range of the highest offset area
+  // so arbitrary properties are always sorted at the end.
+  context.arbitraryPropertiesSort = ((1n << reservedBits) << 0n) - 1n
+
   context.layerOrder = {
     base: (1n << reservedBits) << 0n,
     components: (1n << reservedBits) << 1n,

src/util/isValidArbitraryValue.js

@@ -0,0 +1,61 @@
+let matchingBrackets = new Map([
+  ['{', '}'],
+  ['[', ']'],
+  ['(', ')'],
+])
+let inverseMatchingBrackets = new Map(
+  Array.from(matchingBrackets.entries()).map(([k, v]) => [v, k])
+)
+
+let quotes = new Set(['"', "'", '`'])
+
+// Arbitrary values must contain balanced brackets (), [] and {}. Escaped
+// values don't count, and brackets inside quotes also don't count.
+//
+// E.g.: w-[this-is]w-[weird-and-invalid]
+// E.g.: w-[this-is\\]w-\\[weird-but-valid]
+// E.g.: content-['this-is-also-valid]-weirdly-enough']
+export default function isValidArbitraryValue(value) {
+  let stack = []
+  let inQuotes = false
+
+  for (let i = 0; i < value.length; i++) {
+    let char = value[i]
+
+    if (char === ':' && !inQuotes && stack.length === 0) {
+      return false
+    }
+
+    // Non-escaped quotes allow us to "allow" anything in between
+    if (quotes.has(char) && value[i - 1] !== '\\') {
+      inQuotes = !inQuotes
+    }
+
+    if (inQuotes) continue
+    if (value[i - 1] === '\\') continue // Escaped
+
+    if (matchingBrackets.has(char)) {
+      stack.push(char)
+    } else if (inverseMatchingBrackets.has(char)) {
+      let inverse = inverseMatchingBrackets.get(char)
+
+      // Nothing to pop from, therefore it is unbalanced
+      if (stack.length <= 0) {
+        return false
+      }
+
+      // Popped value must match the inverse value, otherwise it is unbalanced
+      if (stack.pop() !== inverse) {
+        return false
+      }
+    }
+  }
+
+  // If there is still something on the stack, it is also unbalanced
+  if (stack.length > 0) {
+    return false
+  }
+
+  // All good, totally balanced!
+  return true
+}

src/util/nameClass.js

@@ -1,7 +1,7 @@
 import escapeClassName from './escapeClassName'
 import escapeCommas from './escapeCommas'
 
-function asClass(name) {
+export function asClass(name) {
   return escapeCommas(`.${escapeClassName(name)}`)
 }