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perf(@angular/build): use iterative post-order AST traversal for OXC transforms #33951

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Merged
alan-agius4 merged 1 commit into from
Aug 28, 2026
+445 −181
Merged

perf(@angular/build): use iterative post-order AST traversal for OXC transforms #33951

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54 changes: 3 additions & 51 deletions packages/angular/build/src/tools/esbuild/i18n-inliner-worker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,8 @@ import { MagicString } from 'magic-string';
import assert from 'node:assert';
import { deserialize } from 'node:v8';
import { workerData } from 'node:worker_threads';
import { parseSync, visitorKeys } from 'oxc-parser';
import { parseSync } from 'oxc-parser';
import { traversePostOrder } from '../oxc/traversal';
import { loadLocaleData } from './i18n-locale-plugin';
import { createSharedTranslationProxy } from './i18n-translation-reader';

Expand Down Expand Up @@ -284,55 +285,6 @@ async function loadLocalizeTools(): Promise<LocalizeUtilityModule> {
return localizeToolsModule;
}

/**
* Traverses ESTree AST nodes in post-order (bottom-up) without recursion.
* Bottom-up traversal ensures that nested `$localize` expressions are transformed and
* written to MagicString before outer containing templates are evaluated.
*
* @param root The root AST node to traverse.
* @param onExit Callback invoked on each AST node in post-order.
*/
function walkAstPostOrder(root: Node, onExit: (node: Node) => void): void {
const traverseStack: Node[] = [root];
const postOrderNodes: Node[] = [];

while (traverseStack.length > 0) {
const current = traverseStack.pop();
if (!current) {
continue;
}

postOrderNodes.push(current);

const keys = visitorKeys[current.type];
if (!keys) {
continue;
}

for (let i = 0; i < keys.length; i++) {
const child = (current as unknown as Record<string, Node | Node[]>)[keys[i]];
if (!child) {
continue;
}

if (Array.isArray(child)) {
for (const item of child) {
if (item) {
traverseStack.push(item);
}
}
} else {
traverseStack.push(child);
}
}
}

// Process collected nodes in reverse order to achieve bottom-up (post-order) traversal
for (let i = postOrderNodes.length - 1; i >= 0; i--) {
onExit(postOrderNodes[i]);
}
}

/**
* Metadata for a `$localize` tagged template expression extracted from the AST.
*/
Expand Down Expand Up @@ -372,7 +324,7 @@ function extractLocalizeMetadata(filename: string, code: string): FileLocalizeMe
const localeInsertSites: { start: number; end: number }[] = [];
let diagnostics: string[] | undefined;

walkAstPostOrder(program, (node) => {
traversePostOrder(program, (node) => {
if (node.type === 'Literal') {
if (typeof node.value === 'string' && node.value === '___NG_LOCALE_INSERT___') {
localeInsertSites.push({ start: node.start, end: node.end });
Expand Down
218 changes: 88 additions & 130 deletions packages/angular/build/src/tools/oxc/oxc-transform.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -10,8 +10,9 @@ import type { DecodedSourceMap } from '@ampproject/remapping';
import { needsLinking } from '@angular/compiler-cli/linker';
import type { BindingIdentifier, Class, Node } from '@oxc-project/types';
import { MagicString } from 'magic-string';
import { Visitor, parseSync } from 'oxc-parser';
import { parseSync } from 'oxc-parser';
import { OxcLinker } from '../angular/linker/oxc-linker';
import { traversePostOrder } from './traversal';

export interface OxcTransformOptions {
sourcemap?: boolean;
Expand Down Expand Up @@ -320,11 +321,6 @@ export function transform(filename: string, code: string, options: OxcTransformO
return editedRanges.some((r) => start >= r.start && end <= r.end);
}

// Track function nesting depth and closest function expression wrapper
let functionDepth = 0;
let classDepth = 0;
const functionStack: Node[] = [];

/**
* Scans and rewrites TypeScript emitted enum declarations in the statement block.
* Wraps enum statements inside a pure IIFE assignable directly to the enum variable.
Expand Down Expand Up @@ -630,153 +626,115 @@ export function transform(filename: string, code: string, options: OxcTransformO
}
}

const visitor = new Visitor({
ClassDeclaration(node) {
classDepth++;
},
'ClassDeclaration:exit'() {
classDepth--;
},
ClassExpression(node) {
classDepth++;
},
'ClassExpression:exit'() {
classDepth--;
},
FunctionDeclaration(node) {
functionDepth++;
functionStack.push(node);
},
'FunctionDeclaration:exit'() {
functionDepth--;
functionStack.pop();
},
FunctionExpression(node) {
functionDepth++;
functionStack.push(node);
},
'FunctionExpression:exit'() {
functionDepth--;
functionStack.pop();
},
ArrowFunctionExpression(node) {
functionDepth++;
functionStack.push(node);
},
'ArrowFunctionExpression:exit'() {
functionDepth--;
functionStack.pop();
},
'Program:exit'(node) {
if (advancedOptimizations) {
adjustTypeScriptEnumsInStatements(node.body);
adjustStaticMembersInStatements(node.body);
}
},
'BlockStatement:exit'(node) {
if (advancedOptimizations) {
adjustTypeScriptEnumsInStatements(node.body);
adjustStaticMembersInStatements(node.body);
}
},
CallExpression(node) {
if (isAlreadyEdited(node.start, node.end)) {
return;
}
traversePostOrder(program, (node, { functionDepth, classDepth, parentFunc }) => {
switch (node.type) {
case 'Program':
case 'BlockStatement':
if (advancedOptimizations) {
adjustTypeScriptEnumsInStatements(node.body);
adjustStaticMembersInStatements(node.body);
}
break;

case 'CallExpression': {
if (isAlreadyEdited(node.start, node.end)) {
return;
}

if (linker) {
const linkedCode = linker.linkCallExpression(node);
if (linkedCode !== undefined) {
source.overwrite(node.start, node.end, linkedCode);
markEdited(node.start, node.end);

if (linker) {
const linkedCode = linker.linkCallExpression(node);
if (linkedCode !== undefined) {
source.overwrite(node.start, node.end, linkedCode);
markEdited(node.start, node.end);
return;
}
}

if (!advancedOptimizations) {
return;
}
}

if (!advancedOptimizations) {
return;
}
// 1. Elide Angular Metadata check
let calleeName: string | undefined;
if (node.callee.type === 'Identifier') {
calleeName = node.callee.name;
} else if (
node.callee.type === 'MemberExpression' &&
node.callee.property.type === 'Identifier'
) {
calleeName = node.callee.property.name;
}

// 1. Elide Angular Metadata check
let calleeName: string | undefined;
if (node.callee.type === 'Identifier') {
calleeName = node.callee.name;
} else if (
node.callee.type === 'MemberExpression' &&
node.callee.property.type === 'Identifier'
) {
calleeName = node.callee.property.name;
}
if (calleeName && angularMetadataFunctions.has(calleeName)) {
if (
parentFunc &&
(parentFunc.type === 'FunctionExpression' ||
parentFunc.type === 'ArrowFunctionExpression')
) {
source.overwrite(node.start, node.end, 'void 0');
markEdited(node.start, node.end);

return;
}
}

if (calleeName && angularMetadataFunctions.has(calleeName)) {
const parentFunc = functionStack[functionStack.length - 1];
// 2. Mark Top-Level Pure Functions check
if (!pureAnnotate || functionDepth > 0 || classDepth > 0 || topLevelSafeMode) {
return;
}

const callee = unwrapParentheses(node.callee);
if (
parentFunc &&
(parentFunc.type === 'FunctionExpression' ||
parentFunc.type === 'ArrowFunctionExpression')
(callee.type === 'FunctionExpression' || callee.type === 'ArrowFunctionExpression') &&
node.arguments.length !== 0
) {
source.overwrite(node.start, node.end, 'void 0');
markEdited(node.start, node.end);

return;
}
}

// 2. Mark Top-Level Pure Functions check
if (!pureAnnotate || functionDepth > 0 || classDepth > 0 || topLevelSafeMode) {
return;
}
if (
callee.type === 'Identifier' &&
(isTslibHelperName(callee.name) || isBabelHelperName(callee.name))
) {
return;
}

const callee = unwrapParentheses(node.callee);
if (
(callee.type === 'FunctionExpression' || callee.type === 'ArrowFunctionExpression') &&
node.arguments.length !== 0
) {
return;
if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
}
break;
}

if (
callee.type === 'Identifier' &&
(isTslibHelperName(callee.name) || isBabelHelperName(callee.name))
) {
return;
}
case 'NewExpression': {
if (
!advancedOptimizations ||
!pureAnnotate ||
functionDepth > 0 ||
classDepth > 0 ||
isAlreadyEdited(node.start, node.end)
) {
return;
}

if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
}
},
NewExpression(node) {
if (
!advancedOptimizations ||
!pureAnnotate ||
functionDepth > 0 ||
classDepth > 0 ||
isAlreadyEdited(node.start, node.end)
) {
return;
}
if (!topLevelSafeMode) {
if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
}

if (!topLevelSafeMode) {
if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
return;
}

return;
}

const callee = node.callee;
if (callee.type === 'Identifier' && sideEffectFreeConstructors.has(callee.name)) {
if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
const newCallee = node.callee;
if (newCallee.type === 'Identifier' && sideEffectFreeConstructors.has(newCallee.name)) {
if (!hasPureComment(node.start)) {
source.appendLeft(node.start, '/*#__PURE__*/ ');
}
}
break;
}
},
}
});

visitor.visit(program);

let map: DecodedSourceMap | undefined;
if (options.sourcemap) {
const rawMap = source.generateDecodedMap({ hires: true, source: filename });
Expand Down
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