fix: Support highlighting language aliases (#1673)

* Fetches language aliases from shiki, fixes #1672
* test cases
* fix formatting with prettier --write .

src/lib/utils/highlighter.ts

@@ -2,16 +2,29 @@ import { ok as assert } from "assert";
 import * as shiki from "shiki";
 import { unique } from "./array";
 
-// This is needed because Shiki includes some "fake" languages
-// ts / js are expected by users to be equivalent to typescript / javascript
-
-const aliases = new Map<string, string>([
-    ["ts", "typescript"],
-    ["js", "javascript"],
-    ["bash", "shellscript"],
-    ["sh", "shellscript"],
-    ["shell", "shellscript"],
-]);
+type MapKey = [string, string[] | undefined];
+type RMapKey = [string, string];
+
+function rM_zipIdWithAliases(bl: shiki.ILanguageRegistration): MapKey {
+    return [bl.id, bl.aliases];
+}
+
+function rM_nonEmptyRow(row: MapKey): boolean {
+    return Boolean(row[1]); // row is empty if second element of a mapkey (aliases) is undefined
+}
+
+function rM_remapAliasToId([base, al]: MapKey): RMapKey[] {
+    return (al || []).map((a) => [a, base]);
+}
+
+const reverseMapping: RMapKey[][] = [
+    [["text", "text"]],
+    ...shiki.BUNDLED_LANGUAGES.map(rM_zipIdWithAliases)
+        .filter(rM_nonEmptyRow)
+        .map(rM_remapAliasToId),
+];
+
+const aliases = new Map<string, string>(reverseMapping.flat());
 
 const supportedLanguages = unique([
     "text",

src/test/utils/languageAliases.test.ts

@@ -0,0 +1,63 @@
+import { deepStrictEqual as equal } from "assert";
+import { isSupportedLanguage } from "../../lib/utils/highlighter";
+
+describe("Language aliases", () => {
+    describe("Original language aliases", () => {
+        it("js is present", () => {
+            equal(isSupportedLanguage("js"), true);
+        });
+        it("ts is present", () => {
+            equal(isSupportedLanguage("ts"), true);
+        });
+        it("sh is present", () => {
+            equal(isSupportedLanguage("sh"), true);
+        });
+        it("bash is present", () => {
+            equal(isSupportedLanguage("bash"), true);
+        });
+        it("zsh is present", () => {
+            equal(isSupportedLanguage("zsh"), true);
+        });
+        it("text is present", () => {
+            equal(isSupportedLanguage("text"), true);
+        });
+    });
+
+    // non-exhaustive, just shows that some of the uncovered ones are now covered
+    describe("Extended language aliases", () => {
+        it("rb is present", () => {
+            equal(isSupportedLanguage("rb"), true);
+        });
+        it("py is present", () => {
+            equal(isSupportedLanguage("py"), true);
+        });
+        it("jssm is present", () => {
+            equal(isSupportedLanguage("jssm"), true);
+        });
+    });
+
+    // non-exhaustive, just shows that the basic names are upheld too
+    describe("Basic ids", () => {
+        it("ruby is present", () => {
+            equal(isSupportedLanguage("ruby"), true);
+        });
+        it("python is present", () => {
+            equal(isSupportedLanguage("python"), true);
+        });
+        it("javascript is present", () => {
+            equal(isSupportedLanguage("javascript"), true);
+        });
+        it("typescript is present", () => {
+            equal(isSupportedLanguage("typescript"), true);
+        });
+        it("fsl is present", () => {
+            equal(isSupportedLanguage("fsl"), true);
+        });
+    });
+
+    describe("Improper language aliases", () => {
+        it("js2 is not present", () => {
+            equal(isSupportedLanguage("js2"), false);
+        });
+    });
+});