Add expressions to mdast node type registry

When using this utility, the expression types will automatically be
added to mdast in the correct places.
See DefinitelyTyped/DefinitelyTyped#54421 for more information.

Author: wooorm

.gitignore

@@ -1,6 +1,7 @@
 coverage/
 node_modules/
-*.d.ts
+index.d.ts
+test.d.ts
 *.log
 .DS_Store
 yarn.lock

complex-types.d.ts

@@ -0,0 +1,26 @@
+import {Literal} from 'mdast'
+import {Program} from 'estree-jsx'
+
+export interface MDXFlowExpression extends Literal {
+  type: 'mdxFlowExpression'
+  data?: {
+    estree?: Program
+  } & Literal['data']
+}
+
+export interface MDXTextExpression extends Literal {
+  type: 'mdxTextExpression'
+  data?: {
+    estree?: Program
+  } & Literal['data']
+}
+
+declare module 'mdast' {
+  interface StaticPhrasingContentMap {
+    mdxTextExpression: MDXTextExpression
+  }
+
+  interface BlockContentMap {
+    mdxFlowExpression: MDXFlowExpression
+  }
+}

index.js

@@ -1,13 +1,11 @@
 /**
- * @typedef {import('mdast').Literal} Literal
  * @typedef {import('mdast-util-from-markdown').Extension} FromMarkdownExtension
  * @typedef {import('mdast-util-from-markdown').Handle} FromMarkdownHandle
  * @typedef {import('mdast-util-to-markdown').Options} ToMarkdownExtension
  * @typedef {import('mdast-util-to-markdown').Handle} ToMarkdownHandle
- * @typedef {import('estree-jsx').Program} Estree
- *
- * @typedef {Literal & {type: 'mdxFlowExpression', data: {estree?: Estree}}} MDXFlowExpression
- * @typedef {Literal & {type: 'mdxSpanExpression', data: {estree?: Estree}}} MDXSpanExpression
+ * @typedef {import('estree-jsx').Program} Program
+ * @typedef {import('./complex-types').MDXFlowExpression} MDXFlowExpression
+ * @typedef {import('./complex-types').MDXTextExpression} MDXTextExpression
  */
 
 import stripIndent from 'strip-indent'
@@ -42,29 +40,29 @@ export const mdxExpressionToMarkdown = {
 
 /** @type {FromMarkdownHandle} */
 function enterMdxFlowExpression(token) {
-  // @ts-expect-error: fine.
   this.enter({type: 'mdxFlowExpression', value: ''}, token)
   this.buffer()
 }
 
 /** @type {FromMarkdownHandle} */
 function enterMdxTextExpression(token) {
-  // @ts-expect-error: fine.
   this.enter({type: 'mdxTextExpression', value: ''}, token)
   this.buffer()
 }
 
 /** @type {FromMarkdownHandle} */
 function exitMdxExpression(token) {
   const value = this.resume()
-  const node = this.exit(token)
-
+  /** @type {Program|undefined} */
+  // @ts-expect-error: estree.
+  const estree = token.estree
+  const node = /** @type {MDXFlowExpression|MDXTextExpression} */ (
+    this.exit(token)
+  )
   node.value = token.type === 'mdxFlowExpression' ? dedent(value) : value
 
-  // @ts-expect-error: estree.
-  if (token.estree) {
-    // @ts-expect-error: estree.
-    node.data = {estree: token.estree}
+  if (estree) {
+    node.data = {estree}
   }
 }
 
@@ -76,7 +74,7 @@ function exitMdxExpressionData(token) {
 
 /**
  * @type {ToMarkdownHandle}
- * @param {MDXFlowExpression|MDXSpanExpression} node
+ * @param {MDXFlowExpression|MDXTextExpression} node
  */
 function handleMdxExpression(node) {
   const value = node.value || ''

package.json

@@ -31,6 +31,7 @@
   "main": "index.js",
   "types": "index.d.ts",
   "files": [
+    "complex-types.d.ts",
     "index.d.ts",
     "index.js"
   ],
@@ -39,7 +40,7 @@
     "strip-indent": "^4.0.0"
   },
   "devDependencies": {
-    "@types/acorn": "^4.0.5",
+    "@types/acorn": "^4.0.0",
     "@types/tape": "^4.0.0",
     "acorn": "^8.0.0",
     "c8": "^7.0.0",
@@ -57,7 +58,7 @@
     "xo": "^0.39.0"
   },
   "scripts": {
-    "build": "rimraf \"*.d.ts\" && tsc && type-coverage",
+    "build": "rimraf \"{index,test}.d.ts\" && tsc && type-coverage",
     "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
     "test-api": "node --conditions development test.js",
     "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov node --conditions development test.js",

test.js

@@ -419,6 +419,7 @@ test('mdast -> markdown', (t) => {
         children: [
           {type: 'mdxFlowExpression', value: 'a + b'},
           {type: 'mdxFlowExpression', value: '\nc +\n1\n'},
+          // @ts-expect-error: `value` missing.
           {type: 'mdxFlowExpression'},
           {type: 'paragraph', children: [{type: 'text', value: 'd'}]}
         ]
@@ -439,6 +440,7 @@ test('mdast -> markdown', (t) => {
           {type: 'text', value: ', d '},
           {type: 'mdxTextExpression', value: 'e + 1'},
           {type: 'text', value: ', f '},
+          // @ts-expect-error: `value` missing.
           {type: 'mdxTextExpression'},
           {type: 'text', value: '.'}
         ]
@@ -460,10 +462,10 @@ test('mdast -> markdown', (t) => {
 
   t.deepEqual(
     toMarkdown(
-      {type: 'definition', url: 'x', title: 'a\n{\nb'},
+      {type: 'definition', identifier: 'a', url: 'x', title: 'a\n{\nb'},
       {extensions: [mdxExpressionToMarkdown]}
     ),
-    '[]: x "a\n\\{\nb"\n',
+    '[a]: x "a\n\\{\nb"\n',
     'should escape `{` at the start of a line'
   )