Ignore unknown lang with shiki plugin (#130)

Author: inokawa

fixtures/code.md

@@ -60,3 +60,7 @@ module MyModule {
 declare magicNumber number;
 myArray.forEach(() => { }); // fat arrow syntax
 ```
+
+```unknown
+unknown lang
+```

src/__snapshots__/index.spec.ts.snap

@@ -3307,7 +3307,9 @@ exports[`e2e > code 1`] = `
             w:val="false"
           /><w:color w:val="6A9955" /></w:rPr><w:t
           xml:space="preserve"
-        >// fat arrow syntax</w:t></w:r></w:p><w:sectPr><w:pgSz
+        >// fat arrow syntax</w:t></w:r></w:p><w:r><w:t
+        xml:space="preserve"
+      >unknown lang</w:t></w:r><w:sectPr><w:pgSz
         w:w="11906"
         w:h="16838"
         w:orient="portrait"

src/mdast-util-to-docx.ts

@@ -156,6 +156,31 @@ const createNumberingRegistry = (): NumberingRegistry => {
   };
 };
 
+const composeBuilders = (
+  pluginsBuilders: readonly NodeBuilders[],
+  defaultBuilders: NodeBuilders,
+): NodeBuilders => {
+  return pluginsBuilders.reduceRight<NodeBuilders>((acc, p) => {
+    type Key = keyof typeof p;
+    for (const k of Object.keys(p)) {
+      const cur = p[k as Key]!;
+      const prev = acc[k as Key];
+      acc[k as Key] = (
+        prev
+          ? (n, c) => {
+              const r = cur(n as any, c);
+              if (r) {
+                return r;
+              }
+              return prev(n as any, c);
+            }
+          : cur
+      ) as NodeBuilder<any>;
+    }
+    return acc;
+  }, defaultBuilders);
+};
+
 export interface DocxOptions extends Pick<
   IPropertiesOptions,
   | "title"
@@ -192,16 +217,8 @@ export const mdastToDocx = async (
 
   const pluginCtx = { root: node, definition };
 
-  const builders = (
-    await Promise.all(plugins.map((p) => p(pluginCtx)))
-  ).reduceRight<NodeBuilders>(
-    (acc, p) => {
-      type Key = keyof typeof p;
-      for (const k of Object.keys(p)) {
-        acc[k as Key] = p[k as Key] as any;
-      }
-      return acc;
-    },
+  const builders = composeBuilders(
+    await Promise.all(plugins.map((p) => p(pluginCtx))),
     {
       paragraph: buildParagraph,
       heading: buildHeading,

src/plugins/shiki/index.ts

@@ -7,6 +7,7 @@ import {
 } from "shiki";
 import { visit } from "unist-util-visit";
 import type { FontStyle } from "shiki/textmate";
+import { warnOnce } from "../../utils";
 
 /**
  * Format to 6 disit hex
@@ -41,6 +42,7 @@ export const shikiPlugin = ({
 }: ShikiPluginOptions): RemarkDocxPlugin => {
   let highlighter: Awaited<ReturnType<typeof createHighlighter>> | undefined;
   const langs = new Set<string>();
+  const failedLangs = new Set<string>();
 
   return async ({ root }) => {
     const newLangs: string[] = [];
@@ -57,17 +59,23 @@ export const shikiPlugin = ({
     if (!highlighter) {
       highlighter = await createHighlighter({
         themes: [theme],
-        langs: [...langs],
+        langs: [],
       });
-    } else {
-      await Promise.all(
-        newLangs.map((l) => highlighter!.loadLanguage(l as BundledLanguage)),
-      );
     }
+    await Promise.all(
+      newLangs.map(async (l) => {
+        try {
+          await highlighter!.loadLanguage(l as BundledLanguage);
+        } catch (e) {
+          failedLangs.add(l);
+          warnOnce(String(e));
+        }
+      }),
+    );
 
     return {
       code: ({ value, lang }) => {
-        if (!lang) {
+        if (!lang || failedLangs.has(lang)) {
           return null;
         }
         const res = highlighter!.codeToTokens(value, {