Address issue 1004 ("\n in mo.md literally interperted in markdown mode")

frontend/package.json

@@ -80,7 +80,7 @@
     "compassql": "^0.21.2",
     "cssnano": "^6.0.4",
     "date-fns": "^3.3.1",
-    "dedent": "^1.5.1",
+    "string-dedent": "^3.0.1",
     "dequal": "^2.0.3",
     "eslint-plugin-header": "^3.1.1",
     "htm": "^3.1.1",

frontend/src/core/codemirror/language/__tests__/markdown.test.ts

@@ -105,7 +105,7 @@ describe("MarkdownLanguageAdapter", () => {
       expect(innerCode).toBe(
         `# Hello, Markdown!\nmo.md(\n    '''\n    # Hello, Markdown!\n    Use marimo's "md" function to embed rich text into your marimo\n    '''\n)`,
       );
-      expect(offset).toBe(18);
+      expect(offset).toBe(9);
     });
 
     it("simple markdown", () => {
@@ -119,28 +119,36 @@ describe("MarkdownLanguageAdapter", () => {
       const pythonCode = 'mo.md("""   \n# Title\nContent\n   """)';
       const [innerCode, offset] = adapter.transformIn(pythonCode);
       expect(innerCode).toBe("# Title\nContent");
-      expect(offset).toBe(13);
+      expect(offset).toBe(9);
     });
 
-    it("should handle space around the f=strings", () => {
-      const pythonCode = 'mo.md(\n\t"""\n# Title\nContent\n"""\n)';
+    it("should handle space around the f-strings", () => {
+      const pythonCode = 'mo.md(\n\t"""\n# Title\n{  Content  }\n"""\n)';
       const [innerCode, offset] = adapter.transformIn(pythonCode);
-      expect(innerCode).toBe("# Title\nContent");
-      expect(offset).toBe(12);
+      expect(innerCode).toBe("# Title\n{  Content  }");
+      expect(offset).toBe(11);
     });
 
     it("should dedent indented strings", () => {
       const pythonCode =
         'mo.md(\n\t"""\n\t- item 1\n\t-item 2\n\t-item3\n\t"""\n)';
       const [innerCode, offset] = adapter.transformIn(pythonCode);
       expect(innerCode).toBe("- item 1\n-item 2\n-item3");
-      expect(offset).toBe(13);
+      expect(offset).toBe(11);
+    });
+
+    it("should preserve escaped characters", () => {
+      const pythonCode = `mo.md(r"$\\nu = \\mathllap{}\\cdot\\mathllap{\\alpha}$")`;
+      const [innerCode, offset] = adapter.transformIn(pythonCode);
+      expect(innerCode).toBe("$\\nu = \\mathllap{}\\cdot\\mathllap{\\alpha}$");
+      expect(offset).toBe(8);
     });
   });
 
   describe("transformOut", () => {
     it("should wrap Markdown code with triple double-quoted string format", () => {
       const code = "# Markdown Title\n\nSome content here.";
+      adapter.lastQuotePrefix = "";
       const [wrappedCode, offset] = adapter.transformOut(code);
       expect(wrappedCode).toMatchInlineSnapshot(`
         "mo.md(
@@ -156,6 +164,7 @@ describe("MarkdownLanguageAdapter", () => {
 
     it("should escape triple quotes in the Markdown code", () => {
       const code = 'Markdown with an escaped """quote"""!!';
+      adapter.lastQuotePrefix = "";
       const [wrappedCode, offset] = adapter.transformOut(code);
       expect(wrappedCode).toBe(
         `mo.md("Markdown with an escaped \\"\\"\\"quote\\"\\"\\"!!")`,
@@ -193,6 +202,15 @@ describe("MarkdownLanguageAdapter", () => {
       expect(wrappedCode).toBe('mo.md(rf"Normal markdown")');
       expect(offset).toBe(9);
     });
+
+    it("should preserve r strings", () => {
+      const code = "$\\nu = \\mathllap{}\\cdot\\mathllap{\\alpha}$";
+      adapter.lastQuotePrefix = "r";
+      const [wrappedCode, offset] = adapter.transformOut(code);
+      const pythonCode = `mo.md(r"$\\nu = \\mathllap{}\\cdot\\mathllap{\\alpha}$")`;
+      expect(wrappedCode).toBe(pythonCode);
+      expect(offset).toBe(8);
+    });
   });
 
   describe("isSupported", () => {

frontend/src/core/codemirror/language/markdown.ts

@@ -5,7 +5,7 @@ import { markdown } from "@codemirror/lang-markdown";
 import { languages } from "@codemirror/language-data";
 import { parseMixed } from "@lezer/common";
 import { python, pythonLanguage } from "@codemirror/lang-python";
-import dedent from "dedent";
+import dedent from "string-dedent";
 import { logNever } from "@/utils/assertNever";
 import {
   Completion,
@@ -53,15 +53,16 @@ export class MarkdownLanguageAdapter implements LanguageAdapter {
     for (const [start, regex] of regexes) {
       const match = pythonCode.match(regex);
       if (match) {
-        const innerCode = match[1].trim();
+        const innerCode = match[1];
 
         const [quotePrefix, quoteType] = splitQuotePrefix(start);
         // store the quote prefix for later when we transform out
         this.lastQuotePrefix = quotePrefix;
         const unescapedCode = innerCode.replaceAll(`\\${quoteType}`, quoteType);
 
         const offset = pythonCode.indexOf(innerCode);
-        return [dedent(unescapedCode), offset];
+        // string-dedent expects the first and last line to be empty / contain only whitespace, so we pad with \n
+        return [dedent(`\n${unescapedCode}\n`).trim(), offset];
       }
     }