angular-docs-cn/packages/compiler-cli/linker/src/linker_import_generator.ts

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/**
* @license
* Copyright Google LLC 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 {ImportGenerator, NamedImport} from '../../src/ngtsc/translator';
/**
* A class that is used to generate imports when translating from Angular Output AST to an AST to
* render, such as Babel.
*
* Note that, in the linker, there can only be imports from `@angular/core` and that these imports
* must be achieved by property access on an `ng` namespace identifer, which is passed in via the
* constructor.
*/
export class LinkerImportGenerator<TExpression> implements ImportGenerator<TExpression> {
constructor(private ngImport: TExpression) {}
generateNamespaceImport(moduleName: string): TExpression {
this.assertModuleName(moduleName);
return this.ngImport;
}
generateNamedImport(moduleName: string, originalSymbol: string): NamedImport<TExpression> {
this.assertModuleName(moduleName);
return {moduleImport: this.ngImport, symbol: originalSymbol};
}
private assertModuleName(moduleName: string): void {
if (moduleName !== '@angular/core') {
throw new Error(`Unable to import from anything other than '@angular/core'`);
}
}
}