refactor(ivy): implement ngcc `SwitchMarkerAnalyzer` (#26082)

PR Close #26082

packages/compiler-cli/src/ngcc/src/analysis/switch_marker_analyzer.ts

@@ -0,0 +1,43 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import * as ts from 'typescript';
+import {NgccReflectionHost, SwitchableVariableDeclaration} from '../host/ngcc_host';
+
+export interface SwitchMarkerAnalysis {
+  sourceFile: ts.SourceFile;
+  declarations: SwitchableVariableDeclaration[];
+}
+
+export type SwitchMarkerAnalyses = Map<ts.SourceFile, SwitchMarkerAnalysis>;
+export const SwitchMarkerAnalyses = Map;
+
+/**
+ * This Analyzer will analyse the files that have an NGCC switch marker in them
+ * that will be replaced.
+ */
+export class SwitchMarkerAnalyzer {
+  constructor(private host: NgccReflectionHost) {}
+  /**
+   * Analyze the files in the program to identify declarations that contain NGCC
+   * switch markers.
+   * @param program The program to analyze.
+   * @return A map of source files to analysis objects. The map will contain only the
+   * source files that had switch markers, and the analysis will contain an array of
+   * the declarations in that source file that contain the marker.
+   */
+  analyzeProgram(program: ts.Program): SwitchMarkerAnalyses {
+    const analyzedFiles = new SwitchMarkerAnalyses();
+    program.getSourceFiles().forEach(sourceFile => {
+      const declarations = this.host.getSwitchableDeclarations(sourceFile);
+      if (declarations.length) {
+        analyzedFiles.set(sourceFile, {sourceFile, declarations});
+      }
+    });
+    return analyzedFiles;
+  }
+}

packages/compiler-cli/src/ngcc/test/analysis/switch_marker_analyzer_spec.ts

@@ -0,0 +1,76 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import * as ts from 'typescript';
+
+import {SwitchMarkerAnalyzer} from '../../src/analysis/switch_marker_analyzer';
+import {Fesm2015ReflectionHost} from '../../src/host/fesm2015_host';
+import {makeProgram} from '../helpers/utils';
+
+const TEST_PROGRAM = [
+  {
+    name: 'entrypoint.js',
+    contents: `
+    import {a} from './a';
+    import {b} from './b';
+    `
+  },
+  {
+    name: 'a.js',
+    contents: `
+    import {c} from './c';
+    export const a = 1;
+    `
+  },
+  {
+    name: 'b.js',
+    contents: `
+    export const b = 42;
+    var factoryB = factory__PRE_NGCC__;
+    `
+  },
+  {
+    name: 'c.js',
+    contents: `
+    export const c = 'So long, and thanks for all the fish!';
+    var factoryC = factory__PRE_NGCC__;
+    var factoryD = factory__PRE_NGCC__;
+    `
+  },
+];
+
+describe('SwitchMarkerAnalyzer', () => {
+  describe('analyzeProgram()', () => {
+    it('should check for switchable markers in all the files of the program', () => {
+      const program = makeProgram(...TEST_PROGRAM);
+      const host = new Fesm2015ReflectionHost(program.getTypeChecker());
+      const analyzer = new SwitchMarkerAnalyzer(host);
+      const analysis = analyzer.analyzeProgram(program);
+
+      const entrypoint = program.getSourceFile('entrypoint.js') !;
+      const a = program.getSourceFile('a.js') !;
+      const b = program.getSourceFile('b.js') !;
+      const c = program.getSourceFile('c.js') !;
+
+      expect(analysis.size).toEqual(2);
+      expect(analysis.has(entrypoint)).toBe(false);
+      expect(analysis.has(a)).toBe(false);
+      expect(analysis.has(b)).toBe(true);
+      expect(analysis.get(b) !.sourceFile).toBe(b);
+      expect(analysis.get(b) !.declarations.map(decl => decl.getText())).toEqual([
+        'factoryB = factory__PRE_NGCC__'
+      ]);
+
+      expect(analysis.has(c)).toBe(true);
+      expect(analysis.get(c) !.sourceFile).toBe(c);
+      expect(analysis.get(c) !.declarations.map(decl => decl.getText())).toEqual([
+        'factoryC = factory__PRE_NGCC__',
+        'factoryD = factory__PRE_NGCC__',
+      ]);
+    });
+  });
+});