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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,193 @@ | ||
| // @ts-check | ||
|
|
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| import path from "node:path"; | ||
| import { access, readFile } from "node:fs/promises"; | ||
| import { parse } from "es-module-lexer"; | ||
| import parseFromString from "./resolve-import-map/parseFromString.mjs"; | ||
| import resolveImportMap from "./resolve-import-map/resolveImportMap.mjs"; | ||
|
|
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| /** | ||
| * @typedef {Map<string, Array<string>>} Cache A cache for resolved imports. | ||
| */ | ||
|
|
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| // The import map parser requries a base url. We don't require one for our purposes, | ||
| // but it allows us to use the parser without modifying the source. One quirk is that it will try map | ||
| // this url to files locally if it's specified, but no one should do that. | ||
| const DUMMY_HOSTNAME = "example.com"; | ||
|
|
||
| /** | ||
| * Reads a file if possible. | ||
| * @param {string} filePath The path to the file. | ||
| * @returns The file contents, or otherwise `undefined`. | ||
| */ | ||
| async function tryReadFile(filePath) { | ||
| try { | ||
| return await readFile(filePath, "utf-8"); | ||
| } catch (error) { | ||
| // Do nothing. | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Checks if a file exists. | ||
| * @param {string} filePath The path to the file. | ||
| * @returns Does the file exist. | ||
| */ | ||
| async function exists(filePath) { | ||
| try { | ||
| await access(filePath); | ||
| return true; | ||
| } catch (error) { | ||
| return false; | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Recursively parses and resolves a module's imports. | ||
| * @param {string} module The path to the module. | ||
| * @param {object} options Options. | ||
| * @param {string} options.url The module URL to resolve. | ||
| * @param {object} [options.parsedImportMap] A parsed import map. | ||
| * @param {boolean} [root] Whether the module is the root module. | ||
| * @returns An array containing paths to modules that can be preloaded. | ||
| */ | ||
| async function resolveImports(module, { url, parsedImportMap }, root = true) { | ||
| /** @type {Array<string>} */ | ||
| let modules = []; | ||
|
|
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| const source = await tryReadFile(module); | ||
|
|
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| if (source === undefined) { | ||
| return modules; | ||
| } | ||
|
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| const [imports] = parse(source); | ||
|
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| await Promise.all( | ||
| imports.map(async ({ n: specifier, d }) => { | ||
| const dynamic = d > -1; | ||
| if (specifier && !dynamic) { | ||
| let importMapResolved = null; | ||
|
|
||
| // If an import map is supplied, everything resolves through it. | ||
| if (parsedImportMap) { | ||
| importMapResolved = resolveImportMap( | ||
| specifier, | ||
| parsedImportMap, | ||
| new URL(url, `https://${DUMMY_HOSTNAME}`), | ||
| ); | ||
| } | ||
|
|
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| let resolvedModule; | ||
|
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| // Are we resolving with an import map? | ||
| if (importMapResolved !== null) { | ||
| // It will match if it's a local module. | ||
| if (importMapResolved.hostname === DUMMY_HOSTNAME) { | ||
| resolvedModule = path.resolve( | ||
| path.dirname(module), | ||
| `.${importMapResolved.pathname}`, | ||
| ); | ||
| } | ||
| } else { | ||
| resolvedModule = path.resolve(path.dirname(module), specifier); | ||
| } | ||
|
|
||
| // If the module has resolved to a local file (and it exists), then it's preloadable. | ||
| if (resolvedModule && (await exists(resolvedModule))) { | ||
| if (!root) { | ||
| modules.push(resolvedModule); | ||
| } | ||
|
|
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| const graph = await resolveImports( | ||
| resolvedModule, | ||
| { parsedImportMap, url }, | ||
| false, | ||
| ); | ||
|
|
||
| if (graph.length > 0) { | ||
| graph.forEach((module) => modules.push(module)); | ||
| } | ||
| } | ||
| } | ||
| }), | ||
| ); | ||
|
|
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| return modules; | ||
| } | ||
|
|
||
| /** | ||
| * Resolves the imports for a given module and caches the result. | ||
| * @param {string} module The path to the module. | ||
| * @param {object} options Options. | ||
| * @param {Cache} options.cache Resolved imports cache. | ||
| * @param {string} options.url The module URL to resolve. | ||
| * @param {object} [options.parsedImportMap] A parsed import map. | ||
| * @returns An array containing paths to modules that can be preloaded, or otherwise `undefined`. | ||
| */ | ||
| async function resolveImportsCached(module, { cache, url, parsedImportMap }) { | ||
| const paths = cache.get(module); | ||
|
|
||
| if (paths !== undefined) { | ||
| return paths; | ||
| } else { | ||
| const graph = await resolveImports(module, { parsedImportMap, url }); | ||
|
|
||
| if (graph.length > 0) { | ||
| cache.set(module, graph); | ||
| return graph; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Creates a function that resolves the link relations for a given module URL. | ||
| * @param {object} [options] Options. | ||
| * @param {string} [options.importMap] An import map. | ||
| * @param {Cache} [options.cache] Specify a cache for resolved imports. | ||
| * @returns A function that resolves the link relations for a given module URL. | ||
| */ | ||
| export default function createResolveLinkRelations({ | ||
| importMap: importMapString, | ||
| cache = new Map(), | ||
| } = {}) { | ||
| /** | ||
| * Resolves link relations for a given URL. | ||
| * @param {object} options Options. | ||
| * @param {string} options.appPath The path to the application root from where files can be read. | ||
| * @param {string} options.url The module URL to resolve. | ||
| * @param {string} [options.importMap] An import map. | ||
| * @returns An array containing relative paths to modules that can be preloaded, or otherwise `undefined`. | ||
| */ | ||
| return async function resolveLinkRelations({ appPath, url }) { | ||
| let parsedImportMap; | ||
|
|
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| if (importMapString !== undefined) { | ||
| parsedImportMap = parseFromString( | ||
| importMapString, | ||
| `https://${DUMMY_HOSTNAME}`, | ||
| ); | ||
| } | ||
|
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| const rootPath = path.resolve(appPath); | ||
| const resolvedFile = path.join(rootPath, url); | ||
|
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| if (resolvedFile.startsWith(rootPath)) { | ||
| const modules = await resolveImportsCached(resolvedFile, { | ||
| cache, | ||
| url, | ||
| parsedImportMap, | ||
| }); | ||
|
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| if (Array.isArray(modules) && modules.length > 0) { | ||
| const resolvedModules = modules.map((module) => { | ||
| return "/" + path.relative(rootPath, module); | ||
| }); | ||
|
|
||
| if (resolvedModules.length > 0) { | ||
| return resolvedModules; | ||
| } | ||
| } | ||
| } | ||
| }; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| // https://url.spec.whatwg.org/#special-scheme | ||
| const specialProtocols = new Set([ | ||
| "ftp:", | ||
| "file:", | ||
| "http:", | ||
| "https:", | ||
| "ws:", | ||
| "wss:", | ||
| ]); | ||
|
|
||
| export default function isSpecial(url) { | ||
| return specialProtocols.has(url.protocol); | ||
| } |
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