Fix ContainerWithChildren to allow discriminating the node type by comparing its type property (#2049)

Goodwine · web-flow · commit ecd20eb7f958 · 2025-06-16T15:55:49.000+02:00
* Fix ContainerWithChildren to allow discriminating the node type by comparing its type property

* add more description to the test

* Revert version changes

* move tests to test/types.ts
diff --git a/lib/container.d.ts b/lib/container.d.ts
@@ -2,14 +2,17 @@ import AtRule from './at-rule.js'
 import Comment from './comment.js'
 import Declaration from './declaration.js'
 import Node, { ChildNode, ChildProps, NodeProps } from './node.js'
+import { Root } from './postcss.js'
 import Rule from './rule.js'
 
 declare namespace Container {
-  export class ContainerWithChildren<
-    Child extends Node = ChildNode
-  > extends Container_<Child> {
+  export type ContainerWithChildren<Child extends Node = ChildNode> = {
     nodes: Child[]
-  }
+  } & (
+    | AtRule
+    | Root
+    | Rule
+  )
 
   export interface ValueOptions {
     /**
diff --git a/test/types.ts b/test/types.ts
@@ -1,4 +1,5 @@
 import postcss, { Document, PluginCreator } from '../lib/postcss.js'
+import { RootRaws } from '../lib/root.js'
 
 const plugin: PluginCreator<string> = prop => {
   return {
@@ -30,4 +31,34 @@ function parseMarkdown(): Document {
 let doc = postcss().process('a{}', { parser: parseMarkdown }).root
 console.log(doc.toString())
 
+function parentCanNarrowType(): never | void {
+  let atRule = postcss.parse('@a{b{}}').first
+  if (atRule?.type !== 'atrule') return
+  let rule = atRule.first
+  if (rule?.type !== 'rule') return
+  let parent = rule.parent
+  switch (parent?.type) {
+    case undefined:
+      console.log('ok')
+      break
+    case 'atrule':
+      console.log(parent.params)
+      break
+    case 'root':
+      {
+        let raws: RootRaws = parent.raws
+        console.log(raws)
+      }
+      break
+    case 'rule':
+      console.log(rule.selector)
+      break
+    default: {
+      let exhaustiveCheck: never = parent
+      return exhaustiveCheck
+    }
+  }
+}
+parentCanNarrowType()
+
 export default plugin
