322951af49
Our approach for handling cyclic imports results in code that is not easy to tree-shake, so it is not suitable for publishing in a library. When compiling in partial compilation mode, we are targeting such library publication, so we now create a fatal diagnostic error instead of trying to handle the cyclic import situation. Closes #40678 PR Close #40782
75 lines
2.1 KiB
TypeScript
75 lines
2.1 KiB
TypeScript
/**
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* @license
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* Copyright Google LLC All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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import * as ts from 'typescript';
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import {ImportGraph} from './imports';
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/**
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* Analyzes a `ts.Program` for cycles.
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*/
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export class CycleAnalyzer {
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constructor(private importGraph: ImportGraph) {}
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/**
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* Check for a cycle to be created in the `ts.Program` by adding an import between `from` and
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* `to`.
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*
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* @returns a `Cycle` object if an import between `from` and `to` would create a cycle; `null`
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* otherwise.
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*/
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wouldCreateCycle(from: ts.SourceFile, to: ts.SourceFile): Cycle|null {
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// Import of 'from' -> 'to' is illegal if an edge 'to' -> 'from' already exists.
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return this.importGraph.transitiveImportsOf(to).has(from) ?
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new Cycle(this.importGraph, from, to) :
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null;
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}
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/**
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* Record a synthetic import from `from` to `to`.
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*
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* This is an import that doesn't exist in the `ts.Program` but will be considered as part of the
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* import graph for cycle creation.
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*/
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recordSyntheticImport(from: ts.SourceFile, to: ts.SourceFile): void {
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this.importGraph.addSyntheticImport(from, to);
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}
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}
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/**
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* Represents an import cycle between `from` and `to` in the program.
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*
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* This class allows us to do the work to compute the cyclic path between `from` and `to` only if
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* needed.
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*/
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export class Cycle {
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constructor(
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private importGraph: ImportGraph, readonly from: ts.SourceFile, readonly to: ts.SourceFile) {}
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/**
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* Compute an array of source-files that illustrates the cyclic path between `from` and `to`.
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*
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* Note that a `Cycle` will not be created unless a path is available between `to` and `from`,
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* so `findPath()` will never return `null`.
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*/
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getPath(): ts.SourceFile[] {
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return [this.from, ...this.importGraph.findPath(this.to, this.from)!];
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}
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}
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/**
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* What to do if a cycle is detected.
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*/
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export const enum CycleHandlingStrategy {
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/** Add "remote scoping" code to avoid creating a cycle. */
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UseRemoteScoping,
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/** Fail the compilation with an error. */
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Error,
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}
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