Add positional info to attributes

Closes GH-8.
Closes GH-11.
Related-to: mdx-js/mdx#2034.

Reviewed-by: Remco Haszing <remcohaszing@gmail.com>
Reviewed-by: Titus Wormer <tituswormer@gmail.com>

Author: appidea

lib/index.js

@@ -16,6 +16,8 @@
  * @typedef {import('../index.js').MdxJsxExpressionAttribute} MdxJsxExpressionAttribute
  * @typedef {import('../index.js').MdxJsxFlowElement} MdxJsxFlowElement
  * @typedef {import('../index.js').MdxJsxTextElement} MdxJsxTextElement
+ *
+ * @typedef {import('unist').Point} Point
  */
 
 /**
@@ -136,6 +138,18 @@ export function mdxJsxFromMarkdown() {
     this.buffer()
   }
 
+  /**
+   * Copy a point-like value.
+   *
+   * @param {Point} d
+   *   Point-like value.
+   * @returns {Point}
+   *   unist point.
+   */
+  function point(d) {
+    return {line: d.line, column: d.column, offset: d.offset}
+  }
+
   /**
    * @this {CompileContext}
    * @type {FromMarkdownHandle}
@@ -263,7 +277,16 @@ export function mdxJsxFromMarkdown() {
     const tag = this.data.mdxJsxTag
     assert(tag, 'expected `mdxJsxTag`')
     enterMdxJsxTagAnyAttribute.call(this, token)
-    tag.attributes.push({type: 'mdxJsxAttribute', name: '', value: null})
+    tag.attributes.push({
+      type: 'mdxJsxAttribute',
+      name: '',
+      value: null,
+      position: {
+        start: point(token.start),
+        // @ts-expect-error: `end` will be patched later.
+        end: undefined
+      }
+    })
   }
 
   /**
@@ -306,6 +329,8 @@ export function mdxJsxFromMarkdown() {
     const node = tag.attributes[tag.attributes.length - 1]
     assert(node.type === 'mdxJsxAttribute')
     node.name = this.sliceSerialize(token)
+    assert(node.position !== undefined)
+    node.position.end = point(token.end)
   }
 
   /**
@@ -318,19 +343,21 @@ export function mdxJsxFromMarkdown() {
     const node = tag.attributes[tag.attributes.length - 1]
     assert(node.type === 'mdxJsxAttribute')
     node.name += ':' + this.sliceSerialize(token)
+    assert(node.position !== undefined)
+    node.position.end = point(token.end)
   }
 
   /**
    * @this {CompileContext}
    * @type {FromMarkdownHandle}
    */
-  function exitMdxJsxTagAttributeValueLiteral() {
+  function exitMdxJsxTagAttributeValueLiteral(token) {
     const tag = this.data.mdxJsxTag
     assert(tag, 'expected `mdxJsxTag`')
-    tag.attributes[tag.attributes.length - 1].value = parseEntities(
-      this.resume(),
-      {nonTerminated: false}
-    )
+    const node = tag.attributes[tag.attributes.length - 1]
+    node.value = parseEntities(this.resume(), {nonTerminated: false})
+    assert(node.position !== undefined)
+    node.position.end = point(token.end)
   }
 
   /**
@@ -351,6 +378,8 @@ export function mdxJsxFromMarkdown() {
     }
 
     tail.value = node
+    assert(tail.position !== undefined)
+    tail.position.end = point(token.end)
   }
 
   /**