Remove dependency on postcss-functions (#4317)

* Write postcss-functions ourselves

* Add test for nested theme calls

* Remove unused import

package.json

@@ -79,7 +79,6 @@
     "normalize-path": "^3.0.0",
     "object-hash": "^2.1.1",
     "parse-glob": "^3.0.4",
-    "postcss-functions": "^3",
     "postcss-js": "^3.0.3",
     "postcss-nested": "5.0.5",
     "postcss-selector-parser": "^6.0.5",

src/lib/evaluateTailwindFunctions.js

@@ -1,7 +1,7 @@
 import _ from 'lodash'
-import functions from 'postcss-functions'
 import didYouMean from 'didyoumean'
 import transformThemeValue from '../util/transformThemeValue'
+import parseValue from 'postcss-value-parser'
 
 function findClosestExistingPath(theme, path) {
   const parts = _.toPath(path)
@@ -109,23 +109,70 @@ function validatePath(config, path, defaultValue) {
   }
 }
 
+function extractArgs(node, vNodes, functions) {
+  vNodes = vNodes.map((vNode) => resolveVNode(node, vNode, functions))
+
+  let args = ['']
+
+  for (let vNode of vNodes) {
+    if (vNode.type === 'div' && vNode.value === ',') {
+      args.push('')
+    } else {
+      args[args.length - 1] += parseValue.stringify(vNode)
+    }
+  }
+
+  return args
+}
+
+function resolveVNode(node, vNode, functions) {
+  if (vNode.type === 'function' && functions[vNode.value] !== undefined) {
+    let args = extractArgs(node, vNode.nodes, functions)
+    vNode.type = 'word'
+    vNode.value = functions[vNode.value](node, ...args)
+  }
+
+  return vNode
+}
+
+function resolveFunctions(node, input, functions) {
+  return parseValue(input)
+    .walk((vNode) => {
+      resolveVNode(node, vNode, functions)
+    })
+    .toString()
+}
+
+let nodeTypePropertyMap = {
+  atrule: 'params',
+  decl: 'value',
+}
+
 export default function (config) {
-  return (root) =>
-    functions({
-      functions: {
-        theme: (path, ...defaultValue) => {
-          const { isValid, value, error } = validatePath(
-            config,
-            path,
-            defaultValue.length ? defaultValue : undefined
-          )
-
-          if (!isValid) {
-            throw root.error(error)
-          }
-
-          return value
-        },
-      },
-    })(root)
+  let functions = {
+    theme: (node, path, ...defaultValue) => {
+      const { isValid, value, error } = validatePath(
+        config,
+        path,
+        defaultValue.length ? defaultValue : undefined
+      )
+
+      if (!isValid) {
+        throw node.error(error)
+      }
+
+      return value
+    },
+  }
+  return (root) => {
+    root.walk((node) => {
+      let property = nodeTypePropertyMap[node.type]
+
+      if (property === undefined) {
+        return
+      }
+
+      node[property] = resolveFunctions(node, node[property], functions)
+    })
+  }
 }

tests/themeFunction.test.js

@@ -68,6 +68,27 @@ test('a default value can be provided', () => {
   })
 })
 
+test('the default value can use the theme function', () => {
+  const input = `
+    .cookieMonster { color: theme('colors.blue', theme('colors.yellow')); }
+  `
+
+  const output = `
+    .cookieMonster { color: #f7cc50; }
+  `
+
+  return run(input, {
+    theme: {
+      colors: {
+        yellow: '#f7cc50',
+      },
+    },
+  }).then((result) => {
+    expect(result.css).toEqual(output)
+    expect(result.warnings().length).toBe(0)
+  })
+})
+
 test('quotes are preserved around default values', () => {
   const input = `
     .heading { font-family: theme('fontFamily.sans', "Helvetica Neue"); }