Fix: wrap display math like Sphinx (#49)

* Fix: wrap display math like Sphinx

* Package: bump version

package.json

@@ -1,6 +1,6 @@
 {
     "name": "jupyterlab-myst",
-    "version": "0.1.7-a4",
+    "version": "0.1.7-a5",
     "description": "A Myst renderer for JupyterLab",
     "keywords": [
         "jupyter",
@@ -94,4 +94,4 @@
         },
         "outputDir": "jupyterlab_myst/labextension"
     }
-}
+}

src/builtins/docutils/index.ts

@@ -13,6 +13,30 @@ import {
   IOptions
 } from 'markdown-it-docutils';
 
+function splitPart(text: string): string {
+  if (text.includes('\\\\')) {
+    return `\\begin{split}${text}\\end{split}`;
+  } else {
+    return text;
+  }
+}
+
+function wrapDisplayMath(text: string): string {
+  const parts = text.split('\n\n');
+  const split_parts = parts.map(splitPart);
+
+  if (parts.length === 1) {
+    return `\\begin{equation}\\begin{split}${parts[0]}\\end{split}\\end{equation}\n`;
+  } else if (parts.length > 1) {
+    let result = ' \\begin{align}\\begin{aligned}';
+    result += split_parts.join('\\\\');
+    result += ' \\begin{aligned}\\end{align}';
+    return result;
+  } else {
+    return split_parts.join('////');
+  }
+}
+
 /**
  * Provides docutils roles and directives
  */
@@ -33,6 +57,7 @@ export const docutils: JupyterFrontEndPlugin<void> = simpleMarkdownItPlugin(
       const docutilsPlugin = await import(
         /* webpackChunkName: "markdown-it-docutils" */ 'markdown-it-docutils'
       );
+
       function wrappedDocutilsPlugin(md: MarkdownIt, options: IOptions) {
         const roles = {
           ...(options?.roles ?? rolesDefault),
@@ -53,7 +78,7 @@ export const docutils: JupyterFrontEndPlugin<void> = simpleMarkdownItPlugin(
         // Add renderers to MarkdownIt
         md.renderer.rules['math_block'] = (tokens, idx) => {
           const token = tokens[idx];
-          const content = token.content.trim();
+          const content = wrapDisplayMath(token.content.trim());
           const rendered = katex.renderToString(content, {
             displayMode: true,
             throwOnError: false,