Commit 4d591ff

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perf(@schematics/angular): optimize AST traversal utilities

Improves the performance of AST utility functions by reducing redundant work and memory allocations. - The `findNodes` function is now memoized with a `WeakMap`-based cache. This prevents repeated traversals of the entire source file AST when searching for nodes of the same kind, which is a common pattern. - The `getSourceNodes` function has been refactored to use a single array instead of two, reducing memory overhead and avoiding costly `shift()` operations.

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packages/schematics/angular/utility
- ast-utils.ts

1 file changed

+26

-11

lines changed

`‎packages/schematics/angular/utility/ast-utils.ts`

Lines changed: 26 additions & 11 deletions

Original file line number	Diff line number	Diff line change
`@@ -91,6 +91,11 @@ export function insertImport(`
`91`	`91`	`);`
`92`	`92`	`}`
`93`	`93`
	`94`	`+const findNodesCache = new WeakMap<`
	`95`	`+ ts.SourceFile,`
	`96`	`+ Map<ts.SyntaxKind \| ((node: ts.Node) => boolean), ts.Node[]>`
	`97`	`+>();`
	`98`	`+`
`94`	`99`	`/**`
`95`	`100`	`* Find all nodes from the AST in the subtree of node of SyntaxKind kind.`
`96`	`101`	`* @param node`
`@@ -138,6 +143,14 @@ export function findNodes<T extends ts.Node>(`
`138`	`143`	`? kindOrGuard`
`139`	`144`	`: (node: ts.Node): node is T => node.kind === kindOrGuard;`
`140`	`145`
	`146`	`+ // Caching is only supported for the entire file`
	`147`	`+ if (ts.isSourceFile(node)) {`
	`148`	`+ const sourceFileCache = findNodesCache.get(node);`
	`149`	`+ if (sourceFileCache?.has(kindOrGuard)) {`
	`150`	`+ return sourceFileCache.get(kindOrGuard) as T[];`
	`151`	`+ }`
	`152`	`+ }`
	`153`	`+`
`141`	`154`	`const arr: T[] = [];`
`142`	`155`	`if (test(node)) {`
`143`	`156`	`arr.push(node);`
`@@ -158,6 +171,15 @@ export function findNodes<T extends ts.Node>(`
`158`	`171`	`}`
`159`	`172`	`}`
`160`	`173`
	`174`	`+ if (ts.isSourceFile(node)) {`
	`175`	`+ let sourceFileCache = findNodesCache.get(node);`
	`176`	`+ if (!sourceFileCache) {`
	`177`	`+ sourceFileCache = new Map();`
	`178`	`+ findNodesCache.set(node, sourceFileCache);`
	`179`	`+ }`
	`180`	`+ sourceFileCache.set(kindOrGuard, arr);`
	`181`	`+ }`
	`182`	`+`
`161`	`183`	`return arr;`
`162`	`184`	`}`
`163`	`185`
`@@ -168,20 +190,13 @@ export function findNodes<T extends ts.Node>(`
`168`	`190`	`*/`
`169`	`191`	`export function getSourceNodes(sourceFile: ts.SourceFile): ts.Node[] {`
`170`	`192`	`const nodes: ts.Node[] = [sourceFile];`
`171`		`- const result: ts.Node[] = [];`
`172`		`-`
`173`		`- while (nodes.length > 0) {`
`174`		`- const node = nodes.shift();`
`175`	`193`
`176`		`- if (node) {`
`177`		`- result.push(node);`
`178`		`- if (node.getChildCount(sourceFile) >= 0) {`
`179`		`- nodes.unshift(...node.getChildren());`
`180`		`- }`
`181`		`- }`
	`194`	`+ for (let i = 0; i < nodes.length; i++) {`
	`195`	`+ const node = nodes[i];`
	`196`	`+ nodes.push(...node.getChildren(sourceFile));`
`182`	`197`	`}`
`183`	`198`
`184`		`- return result;`
	`199`	`+ return nodes;`
`185`	`200`	`}`
`186`	`201`
`187`	`202`	`export function findNode(node: ts.Node, kind: ts.SyntaxKind, text: string): ts.Node \| null {`

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`‎packages/schematics/angular/utility/ast-utils.ts`

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