perf: improves performance by avoiding the emit-phase of TSC in the CLI

wessberg · Sep 17, 2019 · f0e3923 · f0e3923
1 parent 358f336
commit f0e3923
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Showing 4 changed files with 32 additions and 30 deletions.
diff --git a/src/cli/task/transform/transform-task.ts b/src/cli/task/transform/transform-task.ts
@@ -2,9 +2,9 @@ import {TransformTaskOptions} from "./transform-task-options";
 import {CONSTANT} from "../../constant/constant";
 import {inspect} from "util";
 import {sync} from "glob";
-import {CompilerOptions, createPrinter, createProgram, NewLineKind, ScriptTarget, sys} from "typescript";
-import {cjsToEsm} from "../../../transformer/cjs-to-esm";
+import {CompilerOptions, createEmptyStatement, createPrinter, createProgram, NewLineKind, ScriptTarget, sys, TransformationContext} from "typescript";
 import {dirname, isAbsolute, join, relative} from "path";
+import {cjsToEsmTransformerFactory} from "../../../transformer/cjs-to-esm-transformer-factory";
 
 /**
  * Executes the 'generate' task
@@ -54,25 +54,36 @@ export async function transformTask({logger, input, outDir, root, fs}: Transform
 			rootDir: root
 		}
 	});
-	program.emit(
-		undefined,
-		(_fileName, _data) => {
-			// Noop
-		},
-		undefined,
-		false,
-		cjsToEsm({
-			sourceFileHook: async sourceFile => {
-				if (!matchedFiles.has(sourceFile.fileName)) return;
 
-				const destinationFile = join(absoluteOutDir, relative(root, sourceFile.fileName));
+	// Prepare a noop TransformationContext
+	const context: TransformationContext = {
+		enableEmitNotification: () => {},
+		endLexicalEnvironment: () => [],
+		enableSubstitution: () => {},
+		getCompilerOptions: () => options,
+		startLexicalEnvironment: () => {},
+		hoistFunctionDeclaration: () => {},
+		hoistVariableDeclaration: () => {},
+		isEmitNotificationEnabled: () => false,
+		isSubstitutionEnabled: () => false,
+		onEmitNode: () => {},
+		onSubstituteNode: () => createEmptyStatement(),
+		readEmitHelpers: () => [],
+		requestEmitHelper: () => {},
+		resumeLexicalEnvironment: () => {},
+		suspendLexicalEnvironment: () => {}
+	};
+
+	const transformer = cjsToEsmTransformerFactory()(context);
+
+	for (const sourceFile of program.getSourceFiles()) {
+		if (!matchedFiles.has(sourceFile.fileName)) continue;
+		const transformedSourceFile = transformer(sourceFile);
 
-				if (!fs.existsSync(destinationFile)) {
-					fs.mkdirSync(dirname(destinationFile), {recursive: true});
-					fs.writeFileSync(destinationFile, printer.printFile(sourceFile));
-					logger.info(`${relative(root, sourceFile.fileName)} => ${relative(root, destinationFile)}`);
-				}
-			}
-		})
-	);
+		const destinationFile = join(absoluteOutDir, relative(root, transformedSourceFile.fileName));
+
+		fs.mkdirSync(dirname(destinationFile), {recursive: true});
+		fs.writeFileSync(destinationFile, printer.printFile(transformedSourceFile));
+		logger.info(`${relative(root, transformedSourceFile.fileName)} => ${relative(root, destinationFile)}`);
+	}
 }
diff --git a/src/transformer/before/transform-source-file.ts b/src/transformer/before/transform-source-file.ts
@@ -41,7 +41,6 @@ export function transformSourceFile(
 ): BeforeTransformerSourceFileStepResult {
 	// Take a fast path of the text of the SourceFile doesn't contain anything that can be transformed
 	if (!baseVisitorContext.onlyExports && !sourceFile.text.includes("require") && !sourceFile.text.includes("exports")) {
-		baseVisitorContext.sourceFileHook(sourceFile);
 		return {sourceFile, exports: {namedExports: new Set(), hasDefaultExport: false}};
 	}
 
@@ -339,10 +338,6 @@ export function transformSourceFile(
 		console.log("EXPORTS:", visitorContext.exportedLocals);
 	}
 
-	if (!visitorContext.onlyExports) {
-		baseVisitorContext.sourceFileHook(updatedSourceFile);
-	}
-
 	return {
 		sourceFile: updatedSourceFile,
 		exports: moduleExports

diff --git a/src/transformer/cjs-to-esm-options.ts b/src/transformer/cjs-to-esm-options.ts
@@ -1,9 +1,7 @@
 import {ResolveOptions} from "./util/resolve-path";
-import {SourceFile} from "typescript";
 
 export interface CjsToEsmOptions {
 	debug?: boolean;
 	readFile?: ResolveOptions["readFile"];
 	fileExists?: ResolveOptions["fileExists"];
-	sourceFileHook?(sourceFile: SourceFile): void;
 }
diff --git a/src/transformer/cjs-to-esm-transformer-factory.ts b/src/transformer/cjs-to-esm-transformer-factory.ts
@@ -12,7 +12,6 @@ import {existsSync, readFileSync, statSync} from "fs";
 export function cjsToEsmTransformerFactory({
 	fileExists = file => existsSync(file) && !statSync(file).isDirectory(),
 	readFile = (file: string, encoding?: string) => (existsSync(file) ? readFileSync(file, encoding).toString() : undefined),
-	sourceFileHook = () => {},
 	debug = false,
 	...rest
 }: CjsToEsmOptions = {}): TransformerFactory<SourceFile> {
@@ -24,7 +23,6 @@ export function cjsToEsmTransformerFactory({
 			printer: debug ? createPrinter() : undefined,
 			fileExists,
 			readFile,
-			sourceFileHook,
 			onlyExports: false
 		};
 	})();