258 lines
8.8 KiB
JavaScript
258 lines
8.8 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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const forEachBail = require("./forEachBail");
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const { PathType, getType } = require("./util/path");
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/** @typedef {import("./Resolver")} Resolver */
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/** @typedef {import("./Resolver").ResolveRequest} ResolveRequest */
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/** @typedef {import("./Resolver").ResolveContext} ResolveContext */
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/** @typedef {import("./Resolver").ResolveStepHook} ResolveStepHook */
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/** @typedef {import("./Resolver").ResolveCallback} ResolveCallback */
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/** @typedef {string | string[] | false} Alias */
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/** @typedef {{ alias: Alias, name: string, onlyModule?: boolean }} AliasOption */
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/**
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* @typedef {object} CompiledAliasOption
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* @property {string} name original alias name
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* @property {string} nameWithSlash name + "/" — precomputed to avoid per-resolve concat
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* @property {Alias} alias alias target(s)
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* @property {boolean} onlyModule normalized onlyModule flag
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* @property {string | null} absolutePath absolute form of `name` (with slash ending), null when not absolute
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* @property {string | null} wildcardPrefix substring before the single "*" in `name`, null when no wildcard
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* @property {string | null} wildcardSuffix substring after the single "*" in `name`, null when no wildcard
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* @property {number} firstCharCode first character code of `name` — used as a cheap screen on the hot path. `-1` indicates "matches any first char" (empty wildcard prefix).
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* @property {boolean} arrayAlias true when `alias` is an array — precomputed so the hot path skips `Array.isArray`
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*/
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const EMPTY_COMPILED_OPTIONS = /** @type {CompiledAliasOption[]} */ ([]);
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/**
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* Precompute per-option strings used on every resolve so the hot path in
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* `aliasResolveHandler` does no string concatenation / split work per entry.
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* Called once per plugin apply — the returned array is stable for the
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* lifetime of the resolver.
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* @param {Resolver} resolver resolver
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* @param {AliasOption[]} options options
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* @returns {CompiledAliasOption[]} compiled options
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*/
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function compileAliasOptions(resolver, options) {
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if (options.length === 0) return EMPTY_COMPILED_OPTIONS;
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const result = Array.from({ length: options.length });
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for (let i = 0; i < options.length; i++) {
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const item = options[i];
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const { name } = item;
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let absolutePath = null;
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const type = getType(name);
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if (type === PathType.AbsolutePosix || type === PathType.AbsoluteWin) {
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absolutePath = resolver.join(name, "_").slice(0, -1);
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}
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const firstStar = name.indexOf("*");
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let wildcardPrefix = null;
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let wildcardSuffix = null;
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if (firstStar !== -1 && !name.includes("*", firstStar + 1)) {
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wildcardPrefix = name.slice(0, firstStar);
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wildcardSuffix = name.slice(firstStar + 1);
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}
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// firstCharCode: used by `aliasResolveHandler` to quickly skip aliases
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// whose name can't possibly match the current innerRequest. For a plain
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// alias (no wildcard) the first char of the name is also the first char
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// of `nameWithSlash` and of `absolutePath` (since the latter is derived
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// from name via `resolver.join(name, "_")`, which only appends). For a
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// wildcard with a non-empty prefix, the first char of that prefix is
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// also the first char of name. Only the `name === "*"` case (empty
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// wildcard prefix) can match arbitrary first chars — encode that as -1.
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let firstCharCode;
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if (wildcardPrefix !== null && wildcardPrefix.length === 0) {
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firstCharCode = -1;
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} else {
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firstCharCode = name.length > 0 ? name.charCodeAt(0) : -1;
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}
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result[i] = {
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name,
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nameWithSlash: `${name}/`,
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alias: item.alias,
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onlyModule: Boolean(item.onlyModule),
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absolutePath,
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wildcardPrefix,
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wildcardSuffix,
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firstCharCode,
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arrayAlias: Array.isArray(item.alias),
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};
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}
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return result;
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}
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/** @typedef {(err?: null | Error, result?: null | ResolveRequest) => void} InnerCallback */
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/**
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* @param {Resolver} resolver resolver
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* @param {CompiledAliasOption[]} options compiled options
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* @param {ResolveStepHook} target target
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* @param {ResolveRequest} request request
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* @param {ResolveContext} resolveContext resolve context
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* @param {InnerCallback} callback callback
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* @returns {void}
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*/
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function aliasResolveHandler(
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resolver,
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options,
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target,
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request,
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resolveContext,
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callback,
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) {
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if (options.length === 0) return callback();
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const innerRequest = request.request || request.path;
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if (!innerRequest) return callback();
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// Precompute values used in the inner scan loop so we don't recompute
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// them per option. This is meaningful when `options` has hundreds of
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// entries (e.g. monorepos with generated alias lists) — see the
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// `huge-alias-list` / `huge-alias-miss` benchmarks.
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const innerFirstCharCode = innerRequest.charCodeAt(0);
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const hasRequestString = Boolean(request.request);
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forEachBail(
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options,
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(item, callback) => {
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// Cheap char-code screen: when the compiled option's first char
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// doesn't match the request's first char (and it isn't an
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// "empty-prefix wildcard" — encoded as -1), this option cannot
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// possibly match, so skip straight away and avoid the
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// `startsWith` / `===` work below.
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const { firstCharCode } = item;
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if (firstCharCode !== -1 && firstCharCode !== innerFirstCharCode) {
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return callback();
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}
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/** @type {boolean} */
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let shouldStop = false;
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// For absolute-name aliases, accept the normalized
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// `absolutePath` form as well as the raw `nameWithSlash`.
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// `nameWithSlash` unconditionally appends `/`, so a raw
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// windows request with native backslashes
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// (e.g. `C:\\abs\\foo\\baz` against `name: "C:\\abs\\foo"`)
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// otherwise fails `startsWith("C:\\abs\\foo/")` and is
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// silently skipped. The `!hasRequestString` branch already
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// uses `absolutePath`; mirroring it here closes the gap
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// without changing any existing matches.
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const matchRequest =
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innerRequest === item.name ||
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(!item.onlyModule &&
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(hasRequestString
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? innerRequest.startsWith(item.nameWithSlash) ||
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(item.absolutePath !== null &&
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innerRequest.startsWith(item.absolutePath))
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: item.absolutePath !== null &&
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innerRequest.startsWith(item.absolutePath)));
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const matchWildcard = !item.onlyModule && item.wildcardPrefix !== null;
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if (matchRequest || matchWildcard) {
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/**
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* @param {Alias} alias alias
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* @param {(err?: null | Error, result?: null | ResolveRequest) => void} callback callback
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* @returns {void}
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*/
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const resolveWithAlias = (alias, callback) => {
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if (alias === false) {
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/** @type {ResolveRequest} */
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const ignoreObj = {
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...request,
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path: false,
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};
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if (typeof resolveContext.yield === "function") {
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resolveContext.yield(ignoreObj);
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return callback(null, null);
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}
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return callback(null, ignoreObj);
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}
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let newRequestStr;
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if (
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matchWildcard &&
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innerRequest.startsWith(
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/** @type {string} */ (item.wildcardPrefix),
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) &&
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innerRequest.endsWith(/** @type {string} */ (item.wildcardSuffix))
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) {
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const match = innerRequest.slice(
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/** @type {string} */ (item.wildcardPrefix).length,
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innerRequest.length -
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/** @type {string} */ (item.wildcardSuffix).length,
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);
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newRequestStr = alias.toString().replace("*", match);
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}
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if (
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matchRequest &&
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innerRequest !== alias &&
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!innerRequest.startsWith(`${alias}/`)
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) {
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/** @type {string} */
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const remainingRequest = innerRequest.slice(item.name.length);
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newRequestStr = alias + remainingRequest;
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}
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if (newRequestStr !== undefined) {
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shouldStop = true;
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/** @type {ResolveRequest} */
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const obj = {
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...request,
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request: newRequestStr,
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fullySpecified: false,
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};
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return resolver.doResolve(
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target,
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obj,
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`aliased with mapping '${item.name}': '${alias}' to '${newRequestStr}'`,
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resolveContext,
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(err, result) => {
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if (err) return callback(err);
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if (result) return callback(null, result);
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return callback();
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},
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);
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}
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return callback();
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};
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/**
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* @param {(null | Error)=} err error
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* @param {(null | ResolveRequest)=} result result
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* @returns {void}
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*/
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const stoppingCallback = (err, result) => {
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if (err) return callback(err);
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if (result) return callback(null, result);
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// Don't allow other aliasing or raw request
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if (shouldStop) return callback(null, null);
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return callback();
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};
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if (item.arrayAlias) {
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return forEachBail(
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/** @type {string[]} */ (item.alias),
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resolveWithAlias,
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stoppingCallback,
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);
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}
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return resolveWithAlias(item.alias, stoppingCallback);
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}
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return callback();
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},
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callback,
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);
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}
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module.exports.aliasResolveHandler = aliasResolveHandler;
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module.exports.compileAliasOptions = compileAliasOptions;
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