Brackets in link text (#551)

* Add brackets in link text tests

* Update LINK_R to handle link texts with brackets inside

Supports links like [[this]](https://example.com), which is perfectly valid markdown by most parsers.

index.compiler.spec.tsx

@@ -4067,3 +4067,26 @@ it('handles a holistic example', () => {
 
   expect(root.innerHTML).toMatchSnapshot()
 })
+
+
+it('handles <code> brackets in link text', () => {
+  render(compiler('[`[text]`](https://example.com)'))
+
+  expect(root.innerHTML).toMatchInlineSnapshot(`
+    <a href="https://example.com">
+      <code>
+        [text]
+      </code>
+    </a>
+  `)
+})
+
+it('handles naked brackets in link text', () => {
+  render(compiler('[[text]](https://example.com)'))
+
+  expect(root.innerHTML).toMatchInlineSnapshot(`
+    <a href="https://example.com">
+      [text]
+    </a>
+  `)
+})

index.tsx

@@ -482,8 +482,13 @@ function generateListRule(
   }
 }
 
-const LINK_R = /^\[([^\]]*)]\( *((?:\([^)]*\)|[^() ])*) *"?([^)"]*)?"?\)/
-const IMAGE_R = /^!\[([^\]]*)]\( *((?:\([^)]*\)|[^() ])*) *"?([^)"]*)?"?\)/
+const LINK_INSIDE = "(?:\\[[^\\]]*\\]|[^\\[\\]]|\\](?=[^\\[]*\\]))*";
+const LINK_HREF_AND_TITLE =
+    "\\s*<?((?:\\([^)]*\\)|[^\\s\\\\]|\\\\.)*?)>?(?:\\s+['\"]([\\s\\S]*?)['\"])?\\s*";
+const LINK_R = new RegExp(
+      "^\\[(" + LINK_INSIDE + ")\\]\\(" + LINK_HREF_AND_TITLE + "\\)",
+  )
+const IMAGE_R = /^!\[(.*?)\]\( *((?:\([^)]*\)|[^() ])*) *"?([^)"]*)?"?\)/
 
 const NON_PARAGRAPH_BLOCK_SYNTAXES = [
   BLOCKQUOTE_R,