pure classes

stainless-em · stainless-em · commit 1da5c820182a · 2025-05-12T19:24:10.000-04:00
diff --git a/README.md b/README.md
@@ -72,14 +72,16 @@ tsc-multi --clean
 
 ### `targets`
 
-Build targets. All options except `extname` and `shareHelpers` will override `compilerOptions` in `tsconfig.json`.
+Build targets. All options except `extname`, `shareHelpers`, and `pureClassAssignment` will override `compilerOptions` in `tsconfig.json`.
 
 ```js
 {
   // Rename the extension of output files
   extname: ".js",
   // Emit all helpers to one file
   shareHelpers: "helpers.js",
+  // Wrap static assignments to a class in @__PURE__ comments
+  pureClassAssignment: true,
   // Skip type-checking (Experimental)
   transpileOnly: false,
   // Compiler options
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "tsc-multi",
-  "version": "1.1.4",
+  "version": "1.1.5",
   "description": "Compile multiple TypeScript projects into multiple targets.",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/src/build.ts b/src/build.ts
@@ -103,24 +103,36 @@ export async function build({
   const reportStyles = getReportStyles();
 
   const codes = await pAll(
-    targets.map(({ extname, transpileOnly, shareHelpers, ...target }, i) => {
-      const prefix = `[${trimPrefix(extname || DEFAULT_EXTNAME, ".")}]: `;
-      const prefixStyle = reportStyles[i % reportStyles.length];
-
-      return () => {
-        return runWorker({
-          ...options,
-          projects,
-          stdout,
-          stderr,
+    targets.map(
+      (
+        {
           extname,
-          shareHelpers,
-          target,
-          reportPrefix: prefixStyle(prefix),
           transpileOnly,
-        });
-      };
-    }),
+          shareHelpers,
+          pureClassAssignment,
+          ...target
+        },
+        i
+      ) => {
+        const prefix = `[${trimPrefix(extname || DEFAULT_EXTNAME, ".")}]: `;
+        const prefixStyle = reportStyles[i % reportStyles.length];
+
+        return () => {
+          return runWorker({
+            ...options,
+            projects,
+            stdout,
+            stderr,
+            extname,
+            shareHelpers,
+            pureClassAssignment,
+            target,
+            reportPrefix: prefixStyle(prefix),
+            transpileOnly,
+          });
+        };
+      }
+    ),
     { concurrency: maxWorkers }
   );
 
diff --git a/src/config.ts b/src/config.ts
@@ -20,6 +20,7 @@ const debug = Debug.extend("config");
 const targetSchema = type({
   extname: optional(string()),
   shareHelpers: optional(string()),
+  pureClassAssignment: optional(boolean()),
   transpileOnly: optional(boolean()),
 });
 
diff --git a/src/transformer.ts b/src/transformer.ts
@@ -1,11 +1,7 @@
 import { resolve, dirname, extname, relative } from "path";
 import type ts from "typescript";
-import { trimSuffix } from "../utils";
+import { trimSuffix } from "./utils";
 import assert from "assert";
-import {
-  isExternalModuleReference,
-  isImportEqualsDeclaration,
-} from "typescript";
 
 const JS_EXT = ".js";
 const JSON_EXT = ".json";
@@ -14,9 +10,10 @@ function isRelativePath(path: string): boolean {
   return path.startsWith("./") || path.startsWith("../");
 }
 
-export interface RewriteImportTransformerOptions {
+export interface TransformerOptions {
   extname: string;
   getResolvedShareHelpers(): string | undefined;
+  pureClassAssignment: boolean;
   helpersNeeded: Set<string>;
   system: ts.System;
   ts: typeof ts;
@@ -32,9 +29,9 @@ function nodeIsSynthesized(range: ts.TextRange): boolean {
   return positionIsSynthesized(range.pos) || positionIsSynthesized(range.end);
 }
 
-export function createRewriteImportTransformer<
-  T extends ts.SourceFile | ts.Bundle
->(options: RewriteImportTransformerOptions): ts.TransformerFactory<T> {
+export function createTransformer<T extends ts.SourceFile | ts.Bundle>(
+  options: TransformerOptions
+): ts.TransformerFactory<T> {
   const {
     sys,
     factory,
@@ -146,8 +143,10 @@ export function createRewriteImportTransformer<
             (isImportDeclaration(original)
               ? isStringLiteral(original.moduleSpecifier) &&
                 original.moduleSpecifier.text === "tslib"
-              : isImportEqualsDeclaration(original) &&
-                isExternalModuleReference(original.moduleReference) &&
+              : options.ts.isImportEqualsDeclaration(original) &&
+                options.ts.isExternalModuleReference(
+                  original.moduleReference
+                ) &&
                 isStringLiteral(original.moduleReference.expression) &&
                 original.moduleReference.expression.text === "tslib")
           ) {
@@ -219,15 +218,114 @@ export function createRewriteImportTransformer<
       return visitEachChild(node, visitor, ctx);
     };
 
+    const pureClassAssignment = (sourceFile: ts.SourceFile) => {
+      if (!options.pureClassAssignment) return sourceFile;
+      const newStatements = [];
+      const classes: Record<
+        string,
+        [
+          ts.ClassDeclaration & { name: ts.Identifier },
+          ...ts.ExpressionStatement[]
+        ]
+      > = Object.create(null);
+      for (const statement of sourceFile.statements) {
+        if (
+          options.ts.isClassDeclaration(statement) &&
+          statement.name &&
+          !classes[statement.name.text]
+        ) {
+          newStatements.push(
+            (classes[statement.name.text] = [
+              statement as typeof statement & { name: ts.Identifier },
+            ])
+          );
+          continue;
+        } else if (
+          options.ts.isExpressionStatement(statement) &&
+          options.ts.isBinaryExpression(statement.expression) &&
+          statement.expression.operatorToken.kind === SyntaxKind.EqualsToken
+        ) {
+          if (
+            options.ts.isPropertyAccessExpression(statement.expression.left) &&
+            options.ts.isIdentifier(statement.expression.left.expression) &&
+            classes[statement.expression.left.expression.text]
+          ) {
+            classes[statement.expression.left.expression.text].push(statement);
+            continue;
+          } else if (
+            options.ts.isIdentifier(statement.expression.left) &&
+            options.ts.isIdentifier(statement.expression.right) &&
+            classes[statement.expression.right.text] &&
+            (statement.expression.left as any)?.emitNode?.autoGenerate
+          ) {
+            // _a = Cloudflare;
+            // Cloudflare.Cloudflare = _a;
+            classes[statement.expression.right.text].push(statement);
+            continue;
+          } else if (options.ts.isIdentifier(statement.expression.left)) {
+            // _BaseCloudflare_encoder = new WeakMap();
+            const cls = (statement.expression.left as any)?.emitNode
+              ?.autoGenerate?.prefix?.node?.text;
+            if (classes[cls]) {
+              classes[cls].push(statement);
+            }
+            continue;
+          }
+        }
+        newStatements.push(statement);
+      }
+      return ctx.factory.updateSourceFile(
+        sourceFile,
+        newStatements.map((group) =>
+          Array.isArray(group)
+            ? group.length === 1 &&
+              !group[0].members.some(
+                (member) =>
+                  member.name?.kind === SyntaxKind.ComputedPropertyName
+              )
+              ? group[0]
+              : ctx.factory.createVariableStatement(group[0].modifiers, [
+                  ctx.factory.createVariableDeclaration(
+                    group[0].name.text,
+                    undefined,
+                    undefined,
+                    options.ts.addSyntheticLeadingComment(
+                      ctx.factory.createImmediatelyInvokedArrowFunction([
+                        ctx.factory.updateClassDeclaration(
+                          group[0],
+                          [],
+                          group[0].name,
+                          group[0].typeParameters,
+                          group[0].heritageClauses,
+                          group[0].members
+                        ),
+                        ...group.slice(1),
+                        ctx.factory.createReturnStatement(
+                          ctx.factory.createIdentifier(group[0].name.text)
+                        ),
+                      ]),
+                      SyntaxKind.MultiLineCommentTrivia,
+                      " @__PURE__ ",
+                      false
+                    )
+                  ),
+                ])
+            : group
+        )
+      );
+    };
+
     return (file) => {
       if (options.ts.isSourceFile(file)) {
         sourceFile = file;
-        return visitNode(file, visitor) as any;
+        return pureClassAssignment(visitNode(file, visitor) as ts.SourceFile);
       } else if (options.ts.isBundle(file)) {
         return ctx.factory.createBundle(
           file.sourceFiles.map((file) => {
             sourceFile = file;
-            return visitNode(file, visitor) as ts.SourceFile;
+            return pureClassAssignment(
+              visitNode(file, visitor) as ts.SourceFile
+            );
           })
         ) as any;
       } else {
diff --git a/src/worker/types.ts b/src/worker/types.ts
@@ -4,6 +4,7 @@ export interface WorkerOptions {
   target: Omit<Target, "extname">;
   extname?: string;
   shareHelpers?: string;
+  pureClassAssignment?: boolean;
   verbose?: boolean;
   dry?: boolean;
   force?: boolean;
diff --git a/src/worker/worker.ts b/src/worker/worker.ts
@@ -6,7 +6,7 @@ import {
   trimSuffix,
   isIncrementalCompilation,
 } from "../utils";
-import { createRewriteImportTransformer } from "../transformers/rewriteImport";
+import { createTransformer } from "../transformer";
 import { WorkerOptions } from "./types";
 import { dirname, extname, join, resolve } from "path";
 import assert from "assert";
@@ -252,17 +252,19 @@ export class Worker {
 
     const transformers: ts.CustomTransformers = {
       after: [
-        createRewriteImportTransformer({
+        createTransformer({
           extname: this.data.extname || JS_EXT,
+          pureClassAssignment: this.data.pureClassAssignment || false,
           getResolvedShareHelpers: () => resolvedShareHelpers,
           helpersNeeded,
           system: this.system,
           ts: this.ts,
         }),
       ],
       afterDeclarations: [
-        createRewriteImportTransformer({
+        createTransformer({
           extname: this.data.extname || JS_EXT,
+          pureClassAssignment: this.data.pureClassAssignment || false,
           getResolvedShareHelpers: () => resolvedShareHelpers,
           helpersNeeded,
           system: this.system,
@@ -427,12 +429,13 @@ export class Worker {
     // TODO: Merge custom transformers
     const transformers: ts.CustomTransformers = {
       after: [
-        createRewriteImportTransformer({
+        createTransformer({
           extname: this.data.extname || JS_EXT,
           getResolvedShareHelpers: () => resolvedShareHelpers,
           helpersNeeded,
           system: this.system,
           ts: this.ts,
+          pureClassAssignment: this.data.pureClassAssignment || false,
         }),
       ],
     };

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "tsc-multi",`
`3`		`- "version": "1.1.4",`
	`3`	`+ "version": "1.1.5",`
`4`	`4`	`"description": "Compile multiple TypeScript projects into multiple targets.",`
`5`	`5`	`"main": "dist/index.js",`
`6`	`6`	`"types": "dist/index.d.ts",`