From 5dab70fab44d71e9a2ecb05ae37c15adbdc1fda8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Greg=20Berg=C3=A9?= <berge.greg@gmail.com>
Date: Tue, 7 Jan 2025 10:23:25 +0100
Subject: [PATCH] Fix "Parser" language syntax highlighting (#2676)

---
 .changeset/three-sloths-taste.md              |  5 +++
 .../DocumentView/CodeBlock/highlight.ts       | 33 ++++++++++++++-----
 2 files changed, 30 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/three-sloths-taste.md

diff --git a/.changeset/three-sloths-taste.md b/.changeset/three-sloths-taste.md
new file mode 100644
index 000000000..7737c04df
--- /dev/null
+++ b/.changeset/three-sloths-taste.md
@@ -0,0 +1,5 @@
+---
+'gitbook': patch
+---
+
+Fix "Parser" language syntax highlighting
diff --git a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
index 3432f56bc..56ada6b4e 100644
--- a/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
+++ b/packages/gitbook/src/components/DocumentView/CodeBlock/highlight.ts
@@ -6,7 +6,7 @@ import {
     HighlighterGeneric,
 } from 'shiki/core';
 import { loadWasm, createOnigurumaEngine } from 'shiki/engine/oniguruma';
-import { bundledLanguages } from 'shiki/langs';
+import { BundledLanguage, bundledLanguages } from 'shiki/langs';
 // @ts-ignore - onigWasm is a Wasm module
 import onigWasm from 'shiki/onig.wasm?module';
 
@@ -81,18 +81,35 @@ export async function highlight(block: DocumentBlockCode): Promise<HighlightLine
     });
 }
 
+const syntaxAliases: Record<string, BundledLanguage> = {
+    // "Parser" language does not exist in Shiki, but it's used in GitBook
+    // The closest language is "Blade"
+    parser: 'blade',
+};
+
+function checkIsBundledLanguage(lang: string): lang is BundledLanguage {
+    return lang in bundledLanguages;
+}
+
 /**
  * Validate a language name.
  */
-function getLanguageForSyntax(syntax: string): keyof typeof bundledLanguages | null {
-    // @ts-ignore
-    const lang = bundledLanguages[syntax];
-    if (!lang) {
-        return null;
+function getLanguageForSyntax(syntax: string): BundledLanguage | null {
+    // Normalize the syntax to lowercase.
+    syntax = syntax.toLowerCase();
+
+    // Check if the syntax is a bundled language.
+    if (checkIsBundledLanguage(syntax)) {
+        return syntax;
     }
 
-    // @ts-ignore
-    return syntax;
+    // Check if there is a valid alias for the syntax.
+    const alias = syntaxAliases[syntax];
+    if (alias && checkIsBundledLanguage(alias)) {
+        return alias;
+    }
+
+    return null;
 }
 
 /**