refactor(@angular/build): simplify watch-mode asset precedence and ignore normalization

Simplify incremental asset precedence checks in `collectAssetsToEmit` by relying on in-memory `emittedAssets` state rather than redundant filesystem `statSync` calls, and index emitted asset sources by output path in `BuilderState` for O(1) eviction. Also expand wildcard-suffixed ignore patterns so both direct files and nested directory contents are ignored in watch mode.

Author: alan-agius4

packages/angular/build/src/builders/library/builder-state.ts

@@ -37,6 +37,7 @@ export class BuilderState {
   #emittedBundleFiles = new Set<string>();
   #emittedManifestFiles = new Set<string>();
   readonly #emittedAssets = new Map<string, Set<string>>();
+  readonly #emittedAssetSources = new Map<string, string>();
   #hasEmittedAssets = false;
 
   #executionResult = new ExecutionResult();
@@ -421,13 +422,13 @@ export class BuilderState {
         continue;
       }
 
-      if (this.#hasEmittedAssets) {
-        for (const [source, prevOutputs] of this.#emittedAssets) {
-          if (prevOutputs.delete(emittedAsset.path)) {
-            if (prevOutputs.size === 0) {
-              this.#emittedAssets.delete(source);
-            }
-            break;
+      const prevSource = this.#emittedAssetSources.get(emittedAsset.path);
+      if (prevSource !== undefined) {
+        const prevOutputs = this.#emittedAssets.get(prevSource);
+        if (prevOutputs) {
+          prevOutputs.delete(emittedAsset.path);
+          if (prevOutputs.size === 0) {
+            this.#emittedAssets.delete(prevSource);
           }
         }
       }
@@ -437,12 +438,14 @@ export class BuilderState {
         this.#emittedAssets.set(emittedAsset.source, outputs);
       }
       outputs.add(emittedAsset.path);
+      this.#emittedAssetSources.set(emittedAsset.path, emittedAsset.source);
     }
 
     for (const source of toDelete) {
       const outputs = this.#emittedAssets.get(source);
       if (outputs) {
         for (const output of outputs) {
+          this.#emittedAssetSources.delete(output);
           filesToDelete.add(output);
         }
         this.#emittedAssets.delete(source);
@@ -481,6 +484,7 @@ export class BuilderState {
     this.#emittedBundleFiles.clear();
     this.#emittedManifestFiles.clear();
     this.#emittedAssets.clear();
+    this.#emittedAssetSources.clear();
     this.#hasUpdatedBundles = false;
   }
 }

packages/angular/build/src/builders/library/pipeline/assets.ts

@@ -39,19 +39,27 @@ export interface AssetMatcher {
 }
 
 /**
- * Normalizes a glob pattern to match `tinyglobby` semantics by stripping trailing slashes,
- * expanding directory patterns with `/**`, and normalizing POSIX segments.
+ * Normalizes an ignore glob pattern for `picomatch` to match `tinyglobby` directory-exclusion
+ * semantics by stripping trailing slashes, normalizing POSIX segments, and expanding patterns
+ * with `/**` (returning both `normalized` and `${normalized}/**` for single-wildcard suffixes
+ * because `picomatch` does not make trailing `/**` optional after `*`).
  *
- * @param pattern The raw glob pattern string.
- * @returns The normalized POSIX glob pattern.
+ * @param pattern The raw ignore glob pattern string.
+ * @returns The normalized POSIX glob patterns.
  */
-function normalizeGlobPattern(pattern: string): string {
-  let result = pattern.endsWith('/') ? pattern.slice(0, -1) : pattern;
-  if (pattern.endsWith('/') || !result.endsWith('*')) {
-    result += '/**';
+function normalizeGlobPattern(pattern: string): string[] {
+  const trimmed = pattern.endsWith('/') ? pattern.slice(0, -1) : pattern;
+  const normalized = path.posix.normalize(trimmed);
+
+  if (!normalized.endsWith('*')) {
+    return [`${normalized}/**`];
+  }
+
+  if (normalized.endsWith('/**')) {
+    return [normalized];
   }
 
-  return path.posix.normalize(result);
+  return [normalized, `${normalized}/**`];
 }
 
 /**
@@ -90,7 +98,7 @@ export function createAssetMatchers(assets: NormalizedAssetsPattern[]): readonly
     const { glob: rawGlob, ignore: rawIgnore, input } = asset;
     const ignore = [...DEFAULT_ASSET_IGNORE, ...(rawIgnore ?? [])]
       .filter((pattern) => pattern.length > 0)
-      .map(normalizeGlobPattern);
+      .flatMap(normalizeGlobPattern);
     const isMatch = picomatch(rawGlob ? path.posix.normalize(rawGlob) : [], {
       dot: true,
       windows: false,
@@ -186,77 +194,48 @@ export async function collectAssetsToEmit(
     }
 
     if (matchers.length > 1) {
-      // Ensure lower-priority modified assets do not overwrite existing higher-priority assets on disk.
+      // Ensure lower-priority modified assets do not overwrite existing higher-priority assets.
       for (const [outputPath, { file, matcherIndex }] of filesToEmit) {
         for (let laterIndex = matchers.length - 1; laterIndex > matcherIndex; laterIndex--) {
-          const laterMatcher = matchers[laterIndex];
-          const candidateFile = getCandidateSourceForOutput(laterMatcher, outputPath);
-          if (!candidateFile || candidateFile === file.source) {
-            continue;
-          }
-
-          if (isMatchingAssetFile(candidateFile, laterMatcher.asset.followSymlinks)) {
-            if (emittedAssets.get(candidateFile)?.has(outputPath)) {
-              filesToEmit.delete(outputPath);
-            } else {
-              filesToEmit.set(outputPath, {
-                file: createDiskOutputFile(candidateFile, outputPath),
-                matcherIndex: laterIndex,
-              });
-            }
+          const candidateFile = getCandidateSourceForOutput(matchers[laterIndex], outputPath);
+          if (
+            candidateFile &&
+            candidateFile !== file.source &&
+            !filesToDelete.has(candidateFile) &&
+            emittedAssets.get(candidateFile)?.has(outputPath)
+          ) {
+            filesToEmit.delete(outputPath);
             break;
-          } else if (emittedAssets.get(candidateFile)?.has(outputPath)) {
-            filesToDelete.add(candidateFile);
           }
         }
       }
 
       // Restore lower-priority fallback assets when a higher-priority overriding asset is deleted.
       for (const deletedFile of filesToDelete) {
-        for (
-          let deletedMatcherIndex = 0;
-          deletedMatcherIndex < matchers.length;
-          deletedMatcherIndex++
-        ) {
-          const { asset, prefix, isMatch } = matchers[deletedMatcherIndex];
-          if (!deletedFile.startsWith(prefix)) {
-            continue;
-          }
-
-          const relative = deletedFile.slice(prefix.length);
-          if (!isMatch(relative)) {
-            continue;
-          }
-
-          const outputPath = path.posix.join(asset.output, relative);
-          if (filesToEmit.has(outputPath)) {
-            continue;
-          }
-
-          for (let candidateIndex = matchers.length - 1; candidateIndex >= 0; candidateIndex--) {
-            if (candidateIndex === deletedMatcherIndex) {
-              continue;
-            }
+        const deletedOutputs = emittedAssets.get(deletedFile);
+        if (!deletedOutputs) {
+          continue;
+        }
 
+        for (const outputPath of deletedOutputs) {
+          const minCandidateIndex = (filesToEmit.get(outputPath)?.matcherIndex ?? -1) + 1;
+          for (
+            let candidateIndex = matchers.length - 1;
+            candidateIndex >= minCandidateIndex;
+            candidateIndex--
+          ) {
             const candidateMatcher = matchers[candidateIndex];
             const candidateFile = getCandidateSourceForOutput(candidateMatcher, outputPath);
             if (!candidateFile || filesToDelete.has(candidateFile)) {
               continue;
             }
 
             if (isMatchingAssetFile(candidateFile, candidateMatcher.asset.followSymlinks)) {
-              if (
-                candidateIndex < deletedMatcherIndex ||
-                !emittedAssets.get(candidateFile)?.has(outputPath)
-              ) {
-                filesToEmit.set(outputPath, {
-                  file: createDiskOutputFile(candidateFile, outputPath),
-                  matcherIndex: candidateIndex,
-                });
-              }
+              filesToEmit.set(outputPath, {
+                file: createDiskOutputFile(candidateFile, outputPath),
+                matcherIndex: candidateIndex,
+              });
               break;
-            } else if (emittedAssets.get(candidateFile)?.has(outputPath)) {
-              filesToDelete.add(candidateFile);
             }
           }
         }

packages/angular/build/src/builders/library/pipeline/assets_spec.ts

@@ -38,6 +38,9 @@ describe('library pipeline assets', () => {
             './ignored-dir-2/',
             '**/ignored-subdir',
             '{brace-dir-a,brace-dir-b}',
+            'wildcard-parent/*/',
+            'wildcard-rel/*/sub/..',
+            'explicit-globstar/**',
             'specific.txt',
           ],
         },
@@ -58,6 +61,13 @@ describe('library pipeline assets', () => {
       expect(matcher.isMatch('nested/ignored-subdir/deep/file.txt')).toBeFalse();
       expect(matcher.isMatch('brace-dir-a/file.txt')).toBeFalse();
       expect(matcher.isMatch('brace-dir-b/sub/file.txt')).toBeFalse();
+      expect(matcher.isMatch('wildcard-parent/file.txt')).toBeFalse();
+      expect(matcher.isMatch('wildcard-parent/sub/file.txt')).toBeFalse();
+      expect(matcher.isMatch('wildcard-parent/sub/deep/file.txt')).toBeFalse();
+      expect(matcher.isMatch('wildcard-rel/file.txt')).toBeFalse();
+      expect(matcher.isMatch('wildcard-rel/sub/file.txt')).toBeFalse();
+      expect(matcher.isMatch('explicit-globstar/file.txt')).toBeFalse();
+      expect(matcher.isMatch('explicit-globstar/sub/file.txt')).toBeFalse();
       expect(matcher.isMatch('.gitkeep')).toBeFalse();
       expect(matcher.isMatch('nested/.DS_Store')).toBeFalse();
     });
@@ -121,17 +131,22 @@ describe('library pipeline assets', () => {
 
     it('should not overwrite a higher-priority emitted asset when only a lower-priority asset is modified in watch mode', async () => {
       const defaultDir = `${tempRoot}/lib`;
+      const fallbackDir = `${tempRoot}/fallback`;
       const customDir = `${tempRoot}/docs`;
       await mkdir(defaultDir, { recursive: true });
+      await mkdir(fallbackDir, { recursive: true });
       await mkdir(customDir, { recursive: true });
 
       const defaultReadme = `${defaultDir}/README.md`;
+      const fallbackReadme = `${fallbackDir}/README.md`;
       const customReadme = `${customDir}/README.md`;
       await writeFile(defaultReadme, '# Default updated');
+      await writeFile(fallbackReadme, '# Fallback');
       await writeFile(customReadme, '# Custom');
 
       const assets = [
         { glob: 'README.md', input: defaultDir, output: '.' },
+        { glob: 'README.md', input: fallbackDir, output: '.' },
         { glob: 'README.md', input: customDir, output: '.' },
       ];
 
@@ -146,35 +161,20 @@ describe('library pipeline assets', () => {
       expect(resultWithEmitted.filesToEmit).toEqual([]);
       expect(resultWithEmitted.filesToDelete).toEqual([]);
 
-      // When customReadme was not yet recorded in emittedAssets, modifying defaultReadme should emit customReadme.
-      const resultWithoutEmitted = await collectAssetsToEmit(
-        assets,
-        tempRoot,
-        new Map(),
-        new Set([defaultReadme]),
-      );
-      expect(resultWithoutEmitted.filesToEmit).toEqual([
-        {
-          origin: 'disk',
-          source: customReadme,
-          path: 'README.md',
-        },
-      ]);
-
-      // When customReadme was recorded in emittedAssets but no longer exists on disk,
-      // modifying defaultReadme should queue customReadme for deletion and emit defaultReadme.
+      // When customReadme is deleted in the same watch iteration while defaultReadme is modified,
+      // customReadme should be queued for deletion and higher-priority fallbackReadme should be emitted.
       await rm(customReadme);
-      const resultWithMissingHigherPriority = await collectAssetsToEmit(
+      const resultWithDeletedHigherPriority = await collectAssetsToEmit(
         assets,
         tempRoot,
         emittedAssets,
-        new Set([defaultReadme]),
+        new Set([defaultReadme, customReadme]),
       );
-      expect(resultWithMissingHigherPriority.filesToDelete).toEqual([customReadme]);
-      expect(resultWithMissingHigherPriority.filesToEmit).toEqual([
+      expect(resultWithDeletedHigherPriority.filesToDelete).toEqual([customReadme]);
+      expect(resultWithDeletedHigherPriority.filesToEmit).toEqual([
         {
           origin: 'disk',
-          source: defaultReadme,
+          source: fallbackReadme,
           path: 'README.md',
         },
       ]);