first commit

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: main
+  pull_request:
+    branches: main
+
+jobs:
+  test-node:
+    name: Node.js Tests
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node: [14.x, 16.x]
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js ${{ matrix.node }}
+      uses: actions/setup-node@v2
+      with:
+        node: ${{ matrix.node }}
+    - run: npm install
+    - run: npm run build
+    - run: npm run test
+

.gitignore

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+node_modules
+package-lock.json
+lib
+dist
+

LICENSE

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+MIT License
+-----------
+
+Copyright (C) 2020-2021 Guy Bedford
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Import Map Utility
+
+Generic ImportMap class utility for the manipulation and resolution of import maps, used by JSPM.
+
+## Getting Started
+
+### Installation
+
+Node.js:
+```
+npm install @jspm/import-map
+```
+
+Browser:
+
+```js
+const { ImportMap } = await import('https://jspm.dev/@jspm/import-map');
+```
+
+`@jspm/import-map` only ships as an ES module, so to use it in Node.js add `"type": "module"` to your package.json file or write an `.mjs` to load it.
+
+### Usage
+
+example.mjs
+```js
+import { ImportMap } from '@jspm/import-map';
+
+// Must pass a full URL as a base URL for the map
+const mapBase = new URL('.', import.meta.url);
+
+const map = new ImportMap(mapBase, {
+  imports: {
+    react: 'https://cdn.com/react.js'
+  },
+  scopes: {
+    'https://site.com/': {
+      react: 'https://cdn.com/react2.js'
+    }
+  }
+});
+
+// Use the map resolver
+map.resolve('react', mapBase) === 'https://cdn.com/react.js';
+map.resolve('react', 'https://site.com/') === 'https://cdn.com/react2.js';
+
+// Supports normal URL resolution behaving a browser-compatible ES module resolver
+map.resolve('./hello.js', 'https://site.com/') === 'https://site.com/hello.js';
+
+// Mutate the map
+map.set('react', './custom-react.js');
+map.resolve('react') === new URL('./custom-react.js', mapBase).href;
+
+// Mutate the map inside a custom scope
+map.set('react', './custom-react2.js', 'https://another.com/');
+map.resolve('react', 'https://another.com/') === new URL('./custom-react2.js', mapBase).href;
+
+// Get the map JSON
+console.log(JSON.stringify(map.toJSON(), null, 2));
+// {
+//   "imports": {
+//     "react": "./custom-react.js"
+//   },
+//   "scopes": {
+//     "https://site.com/": {
+//       "react": "https://cdn.com/react2.js"
+//     },
+//     "https://another.com/": {
+//       "react": "./custom-react2.js"
+//     }
+//   }
+// }
+
+// Rebase the map
+map.rebase('./map/');
+console.log(JSON.stringify(map.toJSON(), null, 2));
+// {
+//   "imports": {
+//     "react": "../custom-react.js"
+//   },
+//   "scopes": {
+//     "https://site.com/": {
+//       "react": "https://cdn.com/react2.js"
+//     },
+//     "https://another.com/": {
+//       "react": "../custom-react2.js"
+//     }
+//   }
+// }
+
+// Flatten the import map (removes unnecessary scope redundancy)
+map.set('react', '../custom-react.js', 'https://site.com/');
+map.flatten();
+console.log(JSON.stringify(map.toJSON(), null, 2));
+// {
+//   "imports": {
+//     "react": "../custom-react.js"
+//   },
+//   "scopes": {
+//     "https://another.com/": {
+//       "react": "../custom-react2.js"
+//     }
+//   }
+// }
+
+// Replace URLs in the map
+map.replace('https://cdn.com/', 'https://cdn-mirror.com/');
+map.replace('https://another.com/', 'https://another-site.com/');
+console.log(JSON.stringify(map.toJSON(), null, 2));
+// {
+//   "imports": {
+//     "react": "../custom-react.js"
+//   },
+//   "scopes": {
+//     "https://another-site.com/": {
+//       "react": "../custom-react2.js"
+//     }
+//   }
+// }
+```
+
+## API
+
+See [map.d.ts](blob/main/map.d.ts).
+
+Support is also provided for conditional maps supporting a way to manage generic maps for multiple environment targets, before serializing or resolving for exact environment targets.
+
+## Contributing
+
+**All pull requests welcome!**
+
+### License
+
+MIT

map.d.ts

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+export interface ConditionalTarget {
+    [env: string]: ConditionalTarget | string | null;
+}
+export interface IImportMap {
+    imports?: Record<string, string | null>;
+    scopes?: {
+        [scope: string]: Record<string, string | null>;
+    };
+}
+export interface IConditionalImportMap {
+    imports?: Record<string, string | ConditionalTarget | null>;
+    scopes?: {
+        [scope: string]: Record<string, string | ConditionalTarget | null>;
+    };
+}
+export declare class ImportMap {
+    #private;
+    constructor(mapBaseUrl: string | URL, initialMap?: IConditionalImportMap);
+    clone(): ImportMap;
+    extend(map: IImportMap | IConditionalImportMap, overrideScopes?: boolean): this;
+    sort(): void;
+    set(name: string, target: string | null | ConditionalTarget, parent?: string): void;
+    replace(url: string, newUrl: string): this;
+    combineSubpaths(): void;
+    flatten(): this;
+    rebase(newBaseUrl?: string, abs?: boolean): this;
+    /**
+     * Narrow all mappings to the given conditional environment constraints
+     */
+    setEnv(env: string[] | EnvConstraints): this;
+    resolve(specifier: string, parentUrl?: URL | string, env?: string[] | EnvConstraints): string | ConditionalTarget | null;
+    toJSON(): any;
+}
+export declare type EnvConstraints = {
+    include?: string[];
+    exclude?: string[];
+    covers?: string[][];
+};
+export declare function resolveConditional(target: string | ConditionalTarget | null, env?: string[] | EnvConstraints): string | ConditionalTarget;

package.json

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+{
+  "name": "@jspm/import-map",
+  "description": "Package Import Map Utility",
+  "license": "MIT",
+  "version": "0.1.0",
+  "types": "map.d.ts",
+  "scripts": {
+    "tsc": "tsc -p .",
+    "tsc:watch": "tsc -p . --watch",
+    "rollup": "rollup -c",
+    "build": "npm run tsc && npm run rollup && cp lib/map.d.ts .",
+    "test": "node --conditions test --enable-source-maps test/test.js",
+    "test:build": "node --enable-source-maps test/test.js"
+  },
+  "type": "module",
+  "exports": {
+    "test": "./lib/map.js",
+    "default": "./dist/map.js"
+  },
+  "files": [
+    "dist"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/jspm/map.git"
+  },
+  "keywords": [
+    "jspm",
+    "import maps",
+    "es modules"
+  ],
+  "author": "Guy Bedford",
+  "bugs": {
+    "url": "https://github.com/jspm/map/issues"
+  },
+  "homepage": "https://github.com/jspm/map#readme",
+  "devDependencies": {
+    "typescript": "^4.3.5"
+  }
+}

rollup.config.js

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+import { pathToFileURL, fileURLToPath } from 'url';
+
+export default {
+  input: {
+    'map': 'lib/map.js',
+  },
+  output: {
+    dir: 'dist',
+    format: 'esm'
+  },
+  plugins: [{
+    resolveId (specifier, parent) {
+      if (parent && !specifier.startsWith('./') && !specifier.startsWith('../') && !specifier.startsWith('/'))
+        return { id: specifier, external: true };
+      return fileURLToPath(new URL(specifier, parent ? pathToFileURL(parent) : import.meta.url));
+    }
+  }],
+  // disable external module warnings
+  // (JSPM / the import map handles these for us instead)
+  onwarn (warning, warn) {
+    if (warning.code === 'UNRESOLVED_IMPORT')
+      return;
+    warn(warning);
+  }
+};

src/common/alphabetize.ts

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+export function alphabetize<T> (obj: Record<string, T>): Record<string, T> {
+  const out: Record<string, T> = {};
+  for (const key of Object.keys(obj).sort())
+    out[key] = obj[key];
+  return out;
+}

src/common/url.ts

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+declare global {
+  // @ts-ignore
+  var document: any;
+  // @ts-ignore
+  var location: any;
+  // @ts-ignore
+  var process: any;
+}
+
+export let baseUrl: URL;
+// @ts-ignore
+if (typeof Deno !== 'undefined') {
+  // @ts-ignore
+  baseUrl = new URL('file://' + Deno.cwd() + '/');
+}
+else if (typeof process !== 'undefined' && process.versions.node) {
+  baseUrl = new URL('file://' + process.cwd() + '/');
+}
+else if (typeof document as any !== 'undefined') {
+  const baseEl: any | null = document.querySelector('base[href]');
+  if (baseEl)
+    baseUrl = new URL(baseEl.href + (baseEl.href.endsWith('/') ? '' : '/'));
+  else if (typeof location !== 'undefined')
+    baseUrl = new URL('../', new URL(location.href));
+}
+
+export function importedFrom (parentUrl?: string | URL) {
+  if (!parentUrl) return '';
+  return ` imported from ${parentUrl}`;
+}
+
+function matchesRoot (url: URL, baseUrl: URL) {
+  return url.protocol === baseUrl.protocol && url.host === baseUrl.host && url.port === baseUrl.port && url.username === baseUrl.username && url.password === baseUrl.password;
+}
+
+export function relativeUrl (url: URL, baseUrl: URL, absolute = false) {
+  const href = url.href;
+  const baseUrlHref = baseUrl.href;
+  if (href.startsWith(baseUrlHref))
+    return (absolute ? '/' : './') + href.slice(baseUrlHref.length);
+  if (!matchesRoot(url, baseUrl))
+    return url.href;
+  if (absolute)
+    return url.href;
+  const baseUrlPath = baseUrl.pathname;
+  const urlPath = url.pathname;
+  const minLen = Math.min(baseUrlPath.length, urlPath.length);
+  let sharedBaseIndex = -1;
+  for (let i = 0; i < minLen; i++) {
+    if (baseUrlPath[i] !== urlPath[i]) break;
+    if (urlPath[i] === '/') sharedBaseIndex = i;
+  }
+  return '../'.repeat(baseUrlPath.slice(sharedBaseIndex + 1).split('/').length - 1) + urlPath.slice(sharedBaseIndex + 1) + url.search + url.hash;
+}
+
+export function isURL (specifier: string) {
+  try {
+    if (specifier[0] === '#')
+      return false;
+    new URL(specifier);
+  }
+  catch {
+    return false;
+  }
+  return true;
+}
+
+export function isPlain (specifier: string) {
+  return !isRelative(specifier) && !isURL(specifier);
+}
+
+export function isRelative (specifier: string) {
+  return specifier.startsWith('./') || specifier.startsWith('../') || specifier.startsWith('/');
+}
+
+export function urlToNiceStr (url: string) {
+  if (url.startsWith(baseUrl.href))
+    return './' + url.slice(baseUrl.href.length);
+}