angular-docs-cn/dev-infra/ts-circular-dependencies/analyzer.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 {readFileSync} from 'fs';
import {dirname, join, resolve} from 'path';
import * as ts from 'typescript';
import {getFileStatus} from './file_system';
import {getModuleReferences} from './parser';
export type ModuleResolver = (specifier: string) => string|null;
/**
* Reference chains describe a sequence of source files which are connected through imports.
* e.g. `file_a.ts` imports `file_b.ts`, whereas `file_b.ts` imports `file_c.ts`. The reference
* chain data structure could be used to represent this import sequence.
*/
export type ReferenceChain<T = ts.SourceFile> = T[];
/** Default extensions that the analyzer uses for resolving imports. */
const DEFAULT_EXTENSIONS = ['ts', 'js', 'd.ts'];
/**
* Analyzer that can be used to detect import cycles within source files. It supports
* custom module resolution, source file caching and collects unresolved specifiers.
*/
export class Analyzer {
private _sourceFileCache = new Map<string, ts.SourceFile>();
unresolvedModules = new Set<string>();
unresolvedFiles = new Map<string, string[]>();
constructor(
public resolveModuleFn?: ModuleResolver, public extensions: string[] = DEFAULT_EXTENSIONS) {}
/** Finds all cycles in the specified source file. */
findCycles(sf: ts.SourceFile, visited = new WeakSet<ts.SourceFile>(), path: ReferenceChain = []):
ReferenceChain[] {
const previousIndex = path.indexOf(sf);
// If the given node is already part of the current path, then a cycle has
// been found. Add the reference chain which represents the cycle to the results.
if (previousIndex !== -1) {
return [path.slice(previousIndex)];
}
// If the node has already been visited, then it's not necessary to go check its edges
// again. Cycles would have been already detected and collected in the first check.
if (visited.has(sf)) {
return [];
}
path.push(sf);
visited.add(sf);
// Go through all edges, which are determined through import/exports, and collect cycles.
const result: ReferenceChain[] = [];
for (const ref of getModuleReferences(sf)) {
const targetFile = this._resolveImport(ref, sf.fileName);
if (targetFile !== null) {
result.push(...this.findCycles(this.getSourceFile(targetFile), visited, path.slice()));
}
}
return result;
}
/** Gets the TypeScript source file of the specified path. */
getSourceFile(filePath: string): ts.SourceFile {
const resolvedPath = resolve(filePath);
if (this._sourceFileCache.has(resolvedPath)) {
return this._sourceFileCache.get(resolvedPath)!;
}
const fileContent = readFileSync(resolvedPath, 'utf8');
const sourceFile =
ts.createSourceFile(resolvedPath, fileContent, ts.ScriptTarget.Latest, false);
this._sourceFileCache.set(resolvedPath, sourceFile);
return sourceFile;
}
/** Resolves the given import specifier with respect to the specified containing file path. */
private _resolveImport(specifier: string, containingFilePath: string): string|null {
if (specifier.charAt(0) === '.') {
const resolvedPath = this._resolveFileSpecifier(specifier, containingFilePath);
if (resolvedPath === null) {
this._trackUnresolvedFileImport(specifier, containingFilePath);
}
return resolvedPath;
}
if (this.resolveModuleFn) {
const targetFile = this.resolveModuleFn(specifier);
if (targetFile !== null) {
const resolvedPath = this._resolveFileSpecifier(targetFile);
if (resolvedPath !== null) {
return resolvedPath;
}
}
}
this.unresolvedModules.add(specifier);
return null;
}
/** Tracks the given file import as unresolved. */
private _trackUnresolvedFileImport(specifier: string, originFilePath: string) {
if (!this.unresolvedFiles.has(originFilePath)) {
this.unresolvedFiles.set(originFilePath, [specifier]);
}
this.unresolvedFiles.get(originFilePath)!.push(specifier);
}
/** Resolves the given import specifier to the corresponding source file. */
private _resolveFileSpecifier(specifier: string, containingFilePath?: string): string|null {
const importFullPath =
containingFilePath !== undefined ? join(dirname(containingFilePath), specifier) : specifier;
const stat = getFileStatus(importFullPath);
if (stat && stat.isFile()) {
return importFullPath;
}
for (const extension of this.extensions) {
const pathWithExtension = `${importFullPath}.${extension}`;
const stat = getFileStatus(pathWithExtension);
if (stat && stat.isFile()) {
return pathWithExtension;
}
}
// Directories should be considered last. TypeScript first looks for source files, then
// falls back to directories if no file with appropriate extension could be found.
if (stat && stat.isDirectory()) {
return this._resolveFileSpecifier(join(importFullPath, 'index'));
}
return null;
}
}