668 lines
16 KiB
JavaScript
668 lines
16 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Ivan Kopeykin @vankop
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*/
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"use strict";
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/** @typedef {string|(string|ConditionalMapping)[]} DirectMapping */
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/** @typedef {{[k: string]: MappingValue}} ConditionalMapping */
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/** @typedef {ConditionalMapping|DirectMapping|null} MappingValue */
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/** @typedef {Record<string, MappingValue>|ConditionalMapping|DirectMapping} ExportsField */
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/** @typedef {Record<string, MappingValue>} ImportsField */
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/**
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* @typedef {Object} PathTreeNode
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* @property {Map<string, PathTreeNode>|null} children
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* @property {MappingValue} folder
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* @property {Map<string, MappingValue>|null} wildcards
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* @property {Map<string, MappingValue>} files
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*/
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/**
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* Processing exports/imports field
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* @callback FieldProcessor
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* @param {string} request request
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* @param {Set<string>} conditionNames condition names
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* @returns {string[]} resolved paths
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*/
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/*
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Example exports field:
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{
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".": "./main.js",
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"./feature": {
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"browser": "./feature-browser.js",
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"default": "./feature.js"
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}
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}
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Terminology:
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Enhanced-resolve name keys ("." and "./feature") as exports field keys.
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If value is string or string[], mapping is called as a direct mapping
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and value called as a direct export.
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If value is key-value object, mapping is called as a conditional mapping
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and value called as a conditional export.
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Key in conditional mapping is called condition name.
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Conditional mapping nested in another conditional mapping is called nested mapping.
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----------
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Example imports field:
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{
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"#a": "./main.js",
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"#moment": {
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"browser": "./moment/index.js",
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"default": "moment"
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},
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"#moment/": {
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"browser": "./moment/",
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"default": "moment/"
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}
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}
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Terminology:
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Enhanced-resolve name keys ("#a" and "#moment/", "#moment") as imports field keys.
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If value is string or string[], mapping is called as a direct mapping
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and value called as a direct export.
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If value is key-value object, mapping is called as a conditional mapping
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and value called as a conditional export.
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Key in conditional mapping is called condition name.
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Conditional mapping nested in another conditional mapping is called nested mapping.
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*/
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const slashCode = "/".charCodeAt(0);
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const dotCode = ".".charCodeAt(0);
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const hashCode = "#".charCodeAt(0);
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/**
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* @param {ExportsField} exportsField the exports field
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* @returns {FieldProcessor} process callback
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*/
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module.exports.processExportsField = function processExportsField(
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exportsField
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) {
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return createFieldProcessor(
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buildExportsFieldPathTree(exportsField),
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assertExportsFieldRequest,
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assertExportTarget
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);
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};
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/**
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* @param {ImportsField} importsField the exports field
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* @returns {FieldProcessor} process callback
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*/
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module.exports.processImportsField = function processImportsField(
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importsField
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) {
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return createFieldProcessor(
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buildImportsFieldPathTree(importsField),
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assertImportsFieldRequest,
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assertImportTarget
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);
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};
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/**
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* @param {PathTreeNode} treeRoot root
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* @param {(s: string) => string} assertRequest assertRequest
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* @param {(s: string, f: boolean) => void} assertTarget assertTarget
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* @returns {FieldProcessor} field processor
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*/
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function createFieldProcessor(treeRoot, assertRequest, assertTarget) {
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return function fieldProcessor(request, conditionNames) {
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request = assertRequest(request);
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const match = findMatch(request, treeRoot);
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if (match === null) return [];
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const [mapping, remainRequestIndex] = match;
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/** @type {DirectMapping|null} */
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let direct = null;
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if (isConditionalMapping(mapping)) {
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direct = conditionalMapping(
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/** @type {ConditionalMapping} */ (mapping),
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conditionNames
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);
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// matching not found
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if (direct === null) return [];
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} else {
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direct = /** @type {DirectMapping} */ (mapping);
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}
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const remainingRequest =
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remainRequestIndex === request.length + 1
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? undefined
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: remainRequestIndex < 0
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? request.slice(-remainRequestIndex - 1)
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: request.slice(remainRequestIndex);
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return directMapping(
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remainingRequest,
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remainRequestIndex < 0,
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direct,
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conditionNames,
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assertTarget
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);
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};
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}
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/**
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* @param {string} request request
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* @returns {string} updated request
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*/
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function assertExportsFieldRequest(request) {
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if (request.charCodeAt(0) !== dotCode) {
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throw new Error('Request should be relative path and start with "."');
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}
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if (request.length === 1) return "";
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if (request.charCodeAt(1) !== slashCode) {
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throw new Error('Request should be relative path and start with "./"');
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}
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if (request.charCodeAt(request.length - 1) === slashCode) {
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throw new Error("Only requesting file allowed");
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}
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return request.slice(2);
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}
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/**
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* @param {string} request request
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* @returns {string} updated request
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*/
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function assertImportsFieldRequest(request) {
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if (request.charCodeAt(0) !== hashCode) {
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throw new Error('Request should start with "#"');
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}
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if (request.length === 1) {
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throw new Error("Request should have at least 2 characters");
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}
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if (request.charCodeAt(1) === slashCode) {
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throw new Error('Request should not start with "#/"');
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}
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if (request.charCodeAt(request.length - 1) === slashCode) {
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throw new Error("Only requesting file allowed");
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}
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return request.slice(1);
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}
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/**
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* @param {string} exp export target
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* @param {boolean} expectFolder is folder expected
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*/
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function assertExportTarget(exp, expectFolder) {
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if (
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exp.charCodeAt(0) === slashCode ||
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(exp.charCodeAt(0) === dotCode && exp.charCodeAt(1) !== slashCode)
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) {
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throw new Error(
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`Export should be relative path and start with "./", got ${JSON.stringify(
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exp
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)}.`
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);
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}
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const isFolder = exp.charCodeAt(exp.length - 1) === slashCode;
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if (isFolder !== expectFolder) {
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throw new Error(
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expectFolder
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? `Expecting folder to folder mapping. ${JSON.stringify(
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exp
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)} should end with "/"`
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: `Expecting file to file mapping. ${JSON.stringify(
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exp
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)} should not end with "/"`
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);
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}
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}
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/**
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* @param {string} imp import target
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* @param {boolean} expectFolder is folder expected
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*/
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function assertImportTarget(imp, expectFolder) {
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const isFolder = imp.charCodeAt(imp.length - 1) === slashCode;
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if (isFolder !== expectFolder) {
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throw new Error(
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expectFolder
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? `Expecting folder to folder mapping. ${JSON.stringify(
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imp
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)} should end with "/"`
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: `Expecting file to file mapping. ${JSON.stringify(
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imp
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)} should not end with "/"`
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);
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}
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}
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/**
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* Trying to match request to field
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* @param {string} request request
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* @param {PathTreeNode} treeRoot path tree root
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* @returns {[MappingValue, number]|null} match or null, number is negative and one less when it's a folder mapping, number is request.length + 1 for direct mappings
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*/
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function findMatch(request, treeRoot) {
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if (request.length === 0) {
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const value = treeRoot.files.get("");
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return value ? [value, 1] : null;
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}
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if (
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treeRoot.children === null &&
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treeRoot.folder === null &&
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treeRoot.wildcards === null
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) {
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const value = treeRoot.files.get(request);
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return value ? [value, request.length + 1] : null;
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}
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let node = treeRoot;
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let lastNonSlashIndex = 0;
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let slashIndex = request.indexOf("/", 0);
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/** @type {[MappingValue, number]|null} */
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let lastFolderMatch = null;
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const applyFolderMapping = () => {
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const folderMapping = node.folder;
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if (folderMapping) {
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if (lastFolderMatch) {
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lastFolderMatch[0] = folderMapping;
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lastFolderMatch[1] = -lastNonSlashIndex - 1;
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} else {
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lastFolderMatch = [folderMapping, -lastNonSlashIndex - 1];
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}
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}
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};
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const applyWildcardMappings = (wildcardMappings, remainingRequest) => {
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if (wildcardMappings) {
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for (const [key, target] of wildcardMappings) {
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if (remainingRequest.startsWith(key)) {
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if (!lastFolderMatch) {
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lastFolderMatch = [target, lastNonSlashIndex + key.length];
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} else if (lastFolderMatch[1] < lastNonSlashIndex + key.length) {
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lastFolderMatch[0] = target;
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lastFolderMatch[1] = lastNonSlashIndex + key.length;
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}
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}
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}
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}
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};
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while (slashIndex !== -1) {
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applyFolderMapping();
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const wildcardMappings = node.wildcards;
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if (!wildcardMappings && node.children === null) return lastFolderMatch;
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const folder = request.slice(lastNonSlashIndex, slashIndex);
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applyWildcardMappings(wildcardMappings, folder);
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if (node.children === null) return lastFolderMatch;
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const newNode = node.children.get(folder);
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if (!newNode) {
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return lastFolderMatch;
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}
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node = newNode;
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lastNonSlashIndex = slashIndex + 1;
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slashIndex = request.indexOf("/", lastNonSlashIndex);
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}
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const remainingRequest =
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lastNonSlashIndex > 0 ? request.slice(lastNonSlashIndex) : request;
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const value = node.files.get(remainingRequest);
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if (value) {
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return [value, request.length + 1];
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}
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applyFolderMapping();
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applyWildcardMappings(node.wildcards, remainingRequest);
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return lastFolderMatch;
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}
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/**
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* @param {ConditionalMapping|DirectMapping|null} mapping mapping
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* @returns {boolean} is conditional mapping
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*/
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function isConditionalMapping(mapping) {
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return (
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mapping !== null && typeof mapping === "object" && !Array.isArray(mapping)
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);
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}
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/**
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* @param {string|undefined} remainingRequest remaining request when folder mapping, undefined for file mappings
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* @param {boolean} subpathMapping true, for subpath mappings
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* @param {DirectMapping|null} mappingTarget direct export
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* @param {Set<string>} conditionNames condition names
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* @param {(d: string, f: boolean) => void} assert asserting direct value
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* @returns {string[]} mapping result
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*/
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function directMapping(
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remainingRequest,
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subpathMapping,
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mappingTarget,
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conditionNames,
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assert
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) {
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if (mappingTarget === null) return [];
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if (typeof mappingTarget === "string") {
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return [
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targetMapping(remainingRequest, subpathMapping, mappingTarget, assert)
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];
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}
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const targets = [];
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for (const exp of mappingTarget) {
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if (typeof exp === "string") {
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targets.push(
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targetMapping(remainingRequest, subpathMapping, exp, assert)
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);
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continue;
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}
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const mapping = conditionalMapping(exp, conditionNames);
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if (!mapping) continue;
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const innerExports = directMapping(
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remainingRequest,
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subpathMapping,
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mapping,
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conditionNames,
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assert
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);
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for (const innerExport of innerExports) {
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targets.push(innerExport);
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}
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}
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return targets;
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}
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/**
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* @param {string|undefined} remainingRequest remaining request when folder mapping, undefined for file mappings
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* @param {boolean} subpathMapping true, for subpath mappings
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* @param {string} mappingTarget direct export
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* @param {(d: string, f: boolean) => void} assert asserting direct value
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* @returns {string} mapping result
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*/
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function targetMapping(
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remainingRequest,
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subpathMapping,
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mappingTarget,
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assert
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) {
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if (remainingRequest === undefined) {
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assert(mappingTarget, false);
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return mappingTarget;
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}
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if (subpathMapping) {
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assert(mappingTarget, true);
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return mappingTarget + remainingRequest;
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}
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assert(mappingTarget, false);
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return mappingTarget.replace(/\*/g, remainingRequest.replace(/\$/g, "$$"));
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}
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/**
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* @param {ConditionalMapping} conditionalMapping_ conditional mapping
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* @param {Set<string>} conditionNames condition names
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* @returns {DirectMapping|null} direct mapping if found
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*/
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function conditionalMapping(conditionalMapping_, conditionNames) {
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/** @type {[ConditionalMapping, string[], number][]} */
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let lookup = [[conditionalMapping_, Object.keys(conditionalMapping_), 0]];
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loop: while (lookup.length > 0) {
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const [mapping, conditions, j] = lookup[lookup.length - 1];
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const last = conditions.length - 1;
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for (let i = j; i < conditions.length; i++) {
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const condition = conditions[i];
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// assert default. Could be last only
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if (i !== last) {
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if (condition === "default") {
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throw new Error("Default condition should be last one");
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}
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} else if (condition === "default") {
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const innerMapping = mapping[condition];
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// is nested
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if (isConditionalMapping(innerMapping)) {
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const conditionalMapping = /** @type {ConditionalMapping} */ (innerMapping);
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lookup[lookup.length - 1][2] = i + 1;
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lookup.push([conditionalMapping, Object.keys(conditionalMapping), 0]);
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continue loop;
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}
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return /** @type {DirectMapping} */ (innerMapping);
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}
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if (conditionNames.has(condition)) {
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const innerMapping = mapping[condition];
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// is nested
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if (isConditionalMapping(innerMapping)) {
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const conditionalMapping = /** @type {ConditionalMapping} */ (innerMapping);
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lookup[lookup.length - 1][2] = i + 1;
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lookup.push([conditionalMapping, Object.keys(conditionalMapping), 0]);
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continue loop;
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}
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return /** @type {DirectMapping} */ (innerMapping);
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}
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}
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lookup.pop();
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}
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return null;
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}
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/**
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* Internal helper to create path tree node
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* to ensure that each node gets the same hidden class
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* @returns {PathTreeNode} node
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*/
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function createNode() {
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return {
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children: null,
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folder: null,
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wildcards: null,
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files: new Map()
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};
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}
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/**
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* Internal helper for building path tree
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* @param {PathTreeNode} root root
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* @param {string} path path
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* @param {MappingValue} target target
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*/
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function walkPath(root, path, target) {
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if (path.length === 0) {
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root.folder = target;
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return;
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}
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let node = root;
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// Typical path tree can looks like
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// root
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// - files: ["a.js", "b.js"]
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// - children:
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// node1:
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// - files: ["a.js", "b.js"]
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let lastNonSlashIndex = 0;
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let slashIndex = path.indexOf("/", 0);
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while (slashIndex !== -1) {
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const folder = path.slice(lastNonSlashIndex, slashIndex);
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let newNode;
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if (node.children === null) {
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newNode = createNode();
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node.children = new Map();
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node.children.set(folder, newNode);
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} else {
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newNode = node.children.get(folder);
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if (!newNode) {
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newNode = createNode();
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node.children.set(folder, newNode);
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}
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}
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node = newNode;
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lastNonSlashIndex = slashIndex + 1;
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slashIndex = path.indexOf("/", lastNonSlashIndex);
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}
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if (lastNonSlashIndex >= path.length) {
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node.folder = target;
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} else {
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const file = lastNonSlashIndex > 0 ? path.slice(lastNonSlashIndex) : path;
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if (file.endsWith("*")) {
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if (node.wildcards === null) node.wildcards = new Map();
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node.wildcards.set(file.slice(0, -1), target);
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} else {
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node.files.set(file, target);
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}
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}
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}
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/**
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* @param {ExportsField} field exports field
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* @returns {PathTreeNode} tree root
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*/
|
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function buildExportsFieldPathTree(field) {
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const root = createNode();
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|
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// handle syntax sugar, if exports field is direct mapping for "."
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if (typeof field === "string") {
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root.files.set("", field);
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return root;
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} else if (Array.isArray(field)) {
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root.files.set("", field.slice());
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return root;
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}
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const keys = Object.keys(field);
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|
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for (let i = 0; i < keys.length; i++) {
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const key = keys[i];
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if (key.charCodeAt(0) !== dotCode) {
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// handle syntax sugar, if exports field is conditional mapping for "."
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if (i === 0) {
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while (i < keys.length) {
|
|
const charCode = keys[i].charCodeAt(0);
|
|
if (charCode === dotCode || charCode === slashCode) {
|
|
throw new Error(
|
|
`Exports field key should be relative path and start with "." (key: ${JSON.stringify(
|
|
key
|
|
)})`
|
|
);
|
|
}
|
|
i++;
|
|
}
|
|
|
|
root.files.set("", field);
|
|
return root;
|
|
}
|
|
|
|
throw new Error(
|
|
`Exports field key should be relative path and start with "." (key: ${JSON.stringify(
|
|
key
|
|
)})`
|
|
);
|
|
}
|
|
|
|
if (key.length === 1) {
|
|
root.files.set("", field[key]);
|
|
continue;
|
|
}
|
|
|
|
if (key.charCodeAt(1) !== slashCode) {
|
|
throw new Error(
|
|
`Exports field key should be relative path and start with "./" (key: ${JSON.stringify(
|
|
key
|
|
)})`
|
|
);
|
|
}
|
|
|
|
walkPath(root, key.slice(2), field[key]);
|
|
}
|
|
|
|
return root;
|
|
}
|
|
|
|
/**
|
|
* @param {ImportsField} field imports field
|
|
* @returns {PathTreeNode} root
|
|
*/
|
|
function buildImportsFieldPathTree(field) {
|
|
const root = createNode();
|
|
|
|
const keys = Object.keys(field);
|
|
|
|
for (let i = 0; i < keys.length; i++) {
|
|
const key = keys[i];
|
|
|
|
if (key.charCodeAt(0) !== hashCode) {
|
|
throw new Error(
|
|
`Imports field key should start with "#" (key: ${JSON.stringify(key)})`
|
|
);
|
|
}
|
|
|
|
if (key.length === 1) {
|
|
throw new Error(
|
|
`Imports field key should have at least 2 characters (key: ${JSON.stringify(
|
|
key
|
|
)})`
|
|
);
|
|
}
|
|
|
|
if (key.charCodeAt(1) === slashCode) {
|
|
throw new Error(
|
|
`Imports field key should not start with "#/" (key: ${JSON.stringify(
|
|
key
|
|
)})`
|
|
);
|
|
}
|
|
|
|
walkPath(root, key.slice(1), field[key]);
|
|
}
|
|
|
|
return root;
|
|
}
|