feat(ivy): generator of setClassMetadata statements for Angular types (#26860)

This commit introduces generateSetClassMetadataCall(), an API in ngtsc
for generating calls to setClassMetadata() for a given declaration. The
reflection API is used to enumerate Angular decorators on the declaration,
which are converted to a format that ReflectionCapabilities can understand.
The reflection metadata is then patched onto the declared type via a call
to setClassMetadata().

This is simply a utility, a future commit invokes this utility for
each DecoratorHandler.

Testing strategy: tests are included which exercise generateSetClassMetadata
in isolation.

PR Close #26860

packages/compiler-cli/src/ngtsc/annotations/src/metadata.ts

@@ -0,0 +1,133 @@
+/**
+ * @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 {ExternalExpr, Identifiers, InvokeFunctionExpr, Statement, WrappedNodeExpr} from '@angular/compiler';
+import * as ts from 'typescript';
+
+import {CtorParameter, Decorator, ReflectionHost} from '../../host';
+
+/**
+ * Given a class declaration, generate a call to `setClassMetadata` with the Angular metadata
+ * present on the class or its member fields.
+ *
+ * If no such metadata is present, this function returns `null`. Otherwise, the call is returned
+ * as a `Statement` for inclusion along with the class.
+ */
+export function generateSetClassMetadataCall(
+    clazz: ts.Declaration, reflection: ReflectionHost, isCore: boolean): Statement|null {
+  // Classes come in two flavors, class declarations (ES2015) and variable declarations (ES5).
+  // Both must have a declared name to have metadata set on them.
+  if ((!ts.isClassDeclaration(clazz) && !ts.isVariableDeclaration(clazz)) ||
+      clazz.name === undefined || !ts.isIdentifier(clazz.name)) {
+    return null;
+  }
+  const id = ts.updateIdentifier(clazz.name);
+
+  // Reflect over the class decorators. If none are present, or those that are aren't from
+  // Angular, then return null. Otherwise, turn them into metadata.
+  const classDecorators = reflection.getDecoratorsOfDeclaration(clazz);
+  if (classDecorators === null) {
+    return null;
+  }
+  const ngClassDecorators =
+      classDecorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
+  if (ngClassDecorators.length === 0) {
+    return null;
+  }
+  const metaDecorators = ts.createArrayLiteral(ngClassDecorators);
+
+  // Convert the constructor parameters to metadata, passing null if none are present.
+  let metaCtorParameters: ts.Expression = ts.createNull();
+  const classCtorParameters = reflection.getConstructorParameters(clazz);
+  if (classCtorParameters !== null) {
+    metaCtorParameters = ts.createArrayLiteral(
+        classCtorParameters.map(param => ctorParameterToMetadata(param, isCore)));
+  }
+
+  // Do the same for property decorators.
+  let metaPropDecorators: ts.Expression = ts.createNull();
+  const decoratedMembers =
+      reflection.getMembersOfClass(clazz)
+          .filter(member => !member.isStatic && member.decorators !== null)
+          .map(member => classMemberToMetadata(member.name, member.decorators !, isCore));
+  if (decoratedMembers.length > 0) {
+    metaPropDecorators = ts.createObjectLiteral(decoratedMembers);
+  }
+
+  // Generate a pure call to setClassMetadata with the class identifier and its metadata.
+  const setClassMetadata = new ExternalExpr(Identifiers.setClassMetadata);
+  const fnCall = new InvokeFunctionExpr(
+      /* fn */ setClassMetadata,
+      /* args */
+      [
+        new WrappedNodeExpr(id),
+        new WrappedNodeExpr(metaDecorators),
+        new WrappedNodeExpr(metaCtorParameters),
+        new WrappedNodeExpr(metaPropDecorators),
+      ],
+      /* type */ undefined,
+      /* sourceSpan */ undefined,
+      /* pure */ true);
+  return fnCall.toStmt();
+}
+
+/**
+ * Convert a reflected constructor parameter to metadata.
+ */
+function ctorParameterToMetadata(param: CtorParameter, isCore: boolean): ts.Expression {
+  // Parameters sometimes have a type that can be referenced. If so, then use it, otherwise
+  // its type is undefined.
+  const type = param.type !== null ? param.type : ts.createIdentifier('undefined');
+  const properties: ts.ObjectLiteralElementLike[] = [
+    ts.createPropertyAssignment('type', type),
+  ];
+
+  // If the parameter has decorators, include the ones from Angular.
+  if (param.decorators !== null) {
+    const ngDecorators =
+        param.decorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
+    properties.push(ts.createPropertyAssignment('decorators', ts.createArrayLiteral(ngDecorators)));
+  }
+  return ts.createObjectLiteral(properties, true);
+}
+
+/**
+ * Convert a reflected class member to metadata.
+ */
+function classMemberToMetadata(
+    name: string, decorators: Decorator[], isCore: boolean): ts.PropertyAssignment {
+  const ngDecorators =
+      decorators.filter(dec => isAngularDecorator(dec, isCore)).map(decoratorToMetadata);
+  const decoratorMeta = ts.createArrayLiteral(ngDecorators);
+  return ts.createPropertyAssignment(name, decoratorMeta);
+}
+
+/**
+ * Convert a reflected decorator to metadata.
+ */
+function decoratorToMetadata(decorator: Decorator): ts.ObjectLiteralExpression {
+  // Decorators have a type.
+  const properties: ts.ObjectLiteralElementLike[] = [
+    ts.createPropertyAssignment('type', ts.updateIdentifier(decorator.identifier)),
+  ];
+  // Sometimes they have arguments.
+  if (decorator.args !== null && decorator.args.length > 0) {
+    const args = decorator.args.map(arg => ts.getMutableClone(arg));
+    properties.push(ts.createPropertyAssignment('args', ts.createArrayLiteral(args)));
+  }
+  return ts.createObjectLiteral(properties, true);
+}
+
+/**
+ * Whether a given decorator should be treated as an Angular decorator.
+ *
+ * Either it's used in @angular/core, or it's imported from there.
+ */
+function isAngularDecorator(decorator: Decorator, isCore: boolean): boolean {
+  return isCore || (decorator.import !== null && decorator.import.from === '@angular/core');
+}

packages/compiler-cli/src/ngtsc/annotations/test/BUILD.bazel

@@ -15,6 +15,7 @@ ts_library(
         "//packages/compiler-cli/src/ngtsc/diagnostics",
         "//packages/compiler-cli/src/ngtsc/metadata",
         "//packages/compiler-cli/src/ngtsc/testing",
+        "//packages/compiler-cli/src/ngtsc/translator",
         "@ngdeps//typescript",
     ],
 )

packages/compiler-cli/src/ngtsc/annotations/test/metadata_spec.ts

@@ -0,0 +1,94 @@
+/**
+ * @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 {Statement} from '@angular/compiler';
+import * as ts from 'typescript';
+
+import {TypeScriptReflectionHost} from '../../metadata';
+import {getDeclaration, makeProgram} from '../../testing/in_memory_typescript';
+import {ImportManager, translateStatement} from '../../translator';
+import {generateSetClassMetadataCall} from '../src/metadata';
+
+const CORE = {
+  name: 'node_modules/@angular/core/index.d.ts',
+  contents: `
+    export declare function Input(...args: any[]): any;
+    export declare function Inject(...args: any[]): any;
+    export declare function Component(...args: any[]): any;
+    export declare class Injector {}
+  `
+};
+
+describe('ngtsc setClassMetadata converter', () => {
+  it('should convert decorated class metadata', () => {
+    const res = compileAndPrint(`
+    import {Component} from '@angular/core';
+    
+    @Component('metadata') class Target {}
+    `);
+    expect(res).toEqual(
+        `/*@__PURE__*/ i0.ɵsetClassMetadata(Target, [{ type: Component, args: ['metadata'] }], null, null);`);
+  });
+
+  it('should convert decorated class construtor parameter metadata', () => {
+    const res = compileAndPrint(`
+    import {Component, Inject, Injector} from '@angular/core';
+    const FOO = 'foo';
+    
+    @Component('metadata') class Target {
+      constructor(@Inject(FOO) foo: any, bar: Injector) {}
+    }
+    `);
+    expect(res).toContain(
+        `[{ type: undefined, decorators: [{ type: Inject, args: [FOO] }] }, { type: Injector }], null);`);
+  });
+
+  it('should convert decorated field metadata', () => {
+    const res = compileAndPrint(`
+    import {Component, Input} from '@angular/core';
+    
+    @Component('metadata') class Target {
+      @Input() foo: string;
+
+      @Input('value') bar: string;
+
+      notDecorated: string;
+    }
+    `);
+    expect(res).toContain(`{ foo: [{ type: Input }], bar: [{ type: Input, args: ['value'] }] })`);
+  });
+
+  it('should not convert non-angular decorators to metadata', () => {
+    const res = compileAndPrint(`
+    declare function NotAComponent(...args: any[]): any;
+    
+    @NotAComponent('metadata') class Target {}
+    `);
+    expect(res).toBe('');
+  });
+});
+
+function compileAndPrint(contents: string): string {
+  const {program} = makeProgram([
+    CORE, {
+      name: 'index.ts',
+      contents,
+    }
+  ]);
+  const host = new TypeScriptReflectionHost(program.getTypeChecker());
+  const target = getDeclaration(program, 'index.ts', 'Target', ts.isClassDeclaration);
+  const call = generateSetClassMetadataCall(target, host, false);
+  if (call === null) {
+    return '';
+  }
+  const sf = program.getSourceFile('index.ts') !;
+  const im = new ImportManager(false, 'i');
+  const tsStatement = translateStatement(call, im);
+  const res = ts.createPrinter().printNode(ts.EmitHint.Unspecified, tsStatement, sf);
+  return res.replace(/\s+/g, ' ');
+}