feat: improve transpiler infrastructure

src/lib/transpiler/_entry.ts

@@ -0,0 +1,4 @@
+import coffeescript from "./coffeescript.ts";
+import babel from "./babel.ts";
+
+register(v => coffeescript(babel(v)));

src/lib/transpiler/babel.ts

@@ -0,0 +1,25 @@
+import { SourceMap } from "./map.ts";
+import { transform } from "@babel/standalone";
+// import presetEnv from "@babel/preset-env";
+
+export default function babel(next: Compiler): Compiler {
+	print("Loaded babel!");
+	
+	return (filename, code, prevMap) => {
+		const res = transform(code, {
+			filename,
+			sourceMaps: true,
+		});
+
+		const map = SourceMap.parse({
+			file: "babel-internal://" + filename,
+			mappings: res.map!.mappings,
+			sources: [filename],
+		});
+
+		const compiled = next("babel-internal://" + filename, res.code!, SourceMap.chain(map, prevMap));
+		registerSource(filename, code);
+		return compiled;
+	};
+}
+

src/lib/transpiler/coffeescript.ts

@@ -0,0 +1,28 @@
+import { compile } from "coffeescript";
+import { SourceMap } from "./map.ts";
+
+export default function coffee(next: Compiler): Compiler {
+	print("Loaded coffeescript!");
+	
+	return (filename, code, prevMap) => {
+		const {
+			js: result,
+			v3SourceMap: rawMap,
+		} = compile(code, {
+			filename,
+			sourceMap: true,
+			bare: true,
+		});
+
+		const map = SourceMap.parse({
+			file: "coffee-internal://" + filename,
+			mappings: JSON.parse(rawMap).mappings,
+			sources: [filename],
+		});
+
+		const compiled = next("coffee-internal://" + filename, result, SourceMap.chain(map, prevMap));
+		registerSource(filename, code);
+		return compiled;
+	};
+}
+

src/lib/transpiler/map.ts

@@ -123,13 +123,16 @@ export class VLQSourceMap {
 
 	public static parseVLQ(compiled: string, filenames: string[], raw: string): VLQSourceMap {
 		const mapping = decodeVLQ(raw);
-		const res = new Map<string, [start: number, dst: Location][][]>();
+		const file: [start: number, dst: Location][][] = [];
+		const res = new Map<string, [start: number, dst: Location][][]>([[compiled, file]]);
 
 		let originalRow = 0;
 		let originalCol = 0;
 		let originalFile = 0;
+		const lastCols = new Set<number>();
 
 		for (let compiledRow = 0; compiledRow < mapping.length; compiledRow++) {
+			const line = file[compiledRow] ??= [];
 			let compiledCol = 0;
 
 			for (const rawSeg of mapping[compiledRow]) {
@@ -138,12 +141,13 @@ export class VLQSourceMap {
 				originalRow += rawSeg.length > 2 ? rawSeg[2] : 0;
 				originalCol += rawSeg.length > 3 ? rawSeg[3] : 0;
 
-				let file = res.get(compiled);
-				if (file == null) res.set(compiled, file = []);
-
-				const line = file[compiledRow] ??= [];
-				line[line.length] = [compiledCol, [filenames[originalFile], originalRow, originalCol]];
+				if (!lastCols.has(compiledCol)) {
+					line[line.length] = [compiledCol, [filenames[originalFile], originalRow, originalCol]];
+				}
+				lastCols.add(compiledCol);
 			}
+
+			line.sort((a, b) => a[0] - b[0]);
 		}
 
 		return new VLQSourceMap(res);

src/lib/transpiler/types.ts

@@ -0,0 +1,10 @@
+import { type SourceMap } from "./map.ts";
+
+declare global {
+	type CompilerFactory = (next: Compiler) => Compiler;
+	type Compiler = (filename: string, src: string, mapper: SourceMap) => Function;
+
+	function print(...args: any[]): void;
+	function register(factory: CompilerFactory): void;
+	function registerSource(filename: string, src: string): void;
+}

src/lib/transpiler/typescript.ts

@@ -17,7 +17,7 @@ function resource(name: string) {
 	else return resources[name] = getResource(name);
 }
 
-register(next => {
+export default function typescript(next: Compiler): Compiler {
 	const files: Record<string, IScriptSnapshot> = {};
 	const versions: Record<string, number> = {};
 	let declI = 0;
@@ -34,6 +34,7 @@ register(next => {
 		forceConsistentCasingInFileNames: true,
 		declaration: true,
 		sourceMap: true,
+		downlevelIteration: true,
 	};
 
 	let service: LanguageService;
@@ -114,7 +115,7 @@ register(next => {
 		const result = outputs["/src.js"];
 		const declaration = outputs["/src.d.ts"];
 
-		const compiled = next("ts-internal://" + filename, result, SourceMap.chain(prevMap, map));
+		const compiled = next("ts-internal://" + filename, result, SourceMap.chain(map, prevMap));
 		registerSource(filename, code);
 
 		return function (this: any) {
@@ -123,4 +124,4 @@ register(next => {
 			return res;
 		};
 	};
-});
+}