Changed from static to 11ty!

13 files changed, 913 insertions, 0 deletions

diff --git a/node_modules/bcp-47/index.d.ts b/node_modules/bcp-47/index.d.ts
new file mode 100644
index 0000000..8b4a602
--- /dev/null
+++ b/node_modules/bcp-47/index.d.ts
@@ -0,0 +1,6 @@
+export {parse} from './lib/parse.js'
+export {stringify} from './lib/stringify.js'
+export type Schema = import('./lib/parse.js').Schema
+export type Extension = import('./lib/parse.js').Extension
+export type Warning = import('./lib/parse.js').Warning
+export type Options = import('./lib/parse.js').Options
diff --git a/node_modules/bcp-47/index.js b/node_modules/bcp-47/index.js
new file mode 100644
index 0000000..a16162c
--- /dev/null
+++ b/node_modules/bcp-47/index.js
@@ -0,0 +1,9 @@
+/**
+ * @typedef {import('./lib/parse.js').Schema} Schema
+ * @typedef {import('./lib/parse.js').Extension} Extension
+ * @typedef {import('./lib/parse.js').Warning} Warning
+ * @typedef {import('./lib/parse.js').Options} Options
+ */
+
+export {parse} from './lib/parse.js'
+export {stringify} from './lib/stringify.js'
diff --git a/node_modules/bcp-47/lib/normal.d.ts b/node_modules/bcp-47/lib/normal.d.ts
new file mode 100644
index 0000000..ca7cd82
--- /dev/null
+++ b/node_modules/bcp-47/lib/normal.d.ts
@@ -0,0 +1,2 @@
+/** @type {Record<string, string|null>} */
+export const normal: Record<string, string | null>
diff --git a/node_modules/bcp-47/lib/normal.js b/node_modules/bcp-47/lib/normal.js
new file mode 100644
index 0000000..20cca11
--- /dev/null
+++ b/node_modules/bcp-47/lib/normal.js
@@ -0,0 +1,29 @@
+/** @type {Record<string, string|null>} */
+export const normal = {
+  'en-gb-oed': 'en-GB-oxendict',
+  'i-ami': 'ami',
+  'i-bnn': 'bnn',
+  'i-default': null,
+  'i-enochian': null,
+  'i-hak': 'hak',
+  'i-klingon': 'tlh',
+  'i-lux': 'lb',
+  'i-mingo': null,
+  'i-navajo': 'nv',
+  'i-pwn': 'pwn',
+  'i-tao': 'tao',
+  'i-tay': 'tay',
+  'i-tsu': 'tsu',
+  'sgn-be-fr': 'sfb',
+  'sgn-be-nl': 'vgt',
+  'sgn-ch-de': 'sgg',
+  'art-lojban': 'jbo',
+  'cel-gaulish': null,
+  'no-bok': 'nb',
+  'no-nyn': 'nn',
+  'zh-guoyu': 'cmn',
+  'zh-hakka': 'hak',
+  'zh-min': null,
+  'zh-min-nan': 'nan',
+  'zh-xiang': 'hsn'
+}
diff --git a/node_modules/bcp-47/lib/parse.d.ts b/node_modules/bcp-47/lib/parse.d.ts
new file mode 100644
index 0000000..ef18cc1
--- /dev/null
+++ b/node_modules/bcp-47/lib/parse.d.ts
@@ -0,0 +1,29 @@
+/**
+ * Parse a BCP 47 language tag.
+ *
+ * @param {string} tag
+ * @param {Options} [options]
+ * @returns {Schema}
+ */
+export function parse(tag: string, options?: Options | undefined): Schema
+export type Warning = (reason: string, code: number, offset: number) => void
+export type Options = {
+  normalize?: boolean | undefined
+  forgiving?: boolean | undefined
+  warning?: Warning | undefined
+}
+export type Extension = {
+  singleton: string
+  extensions: Array<string>
+}
+export type Schema = {
+  language: string | null | undefined
+  extendedLanguageSubtags: Array<string>
+  script: string | null | undefined
+  region: string | null | undefined
+  variants: Array<string>
+  extensions: Array<Extension>
+  privateuse: Array<string>
+  irregular: string | null | undefined
+  regular: string | null | undefined
+}
diff --git a/node_modules/bcp-47/lib/parse.js b/node_modules/bcp-47/lib/parse.js
new file mode 100644
index 0000000..7251a71
--- /dev/null
+++ b/node_modules/bcp-47/lib/parse.js
@@ -0,0 +1,310 @@
+/**
+ * @callback Warning
+ * @param {string} reason
+ * @param {number} code
+ * @param {number} offset
+ * @returns {void}
+ *
+ * @typedef Options
+ * @property {boolean} [normalize=true]
+ * @property {boolean} [forgiving=false]
+ * @property {Warning} [warning]
+ *
+ * @typedef Extension
+ * @property {string} singleton
+ * @property {Array<string>} extensions
+ *
+ * @typedef Schema
+ * @property {string|null|undefined} language
+ * @property {Array<string>} extendedLanguageSubtags
+ * @property {string|null|undefined} script
+ * @property {string|null|undefined} region
+ * @property {Array<string>} variants
+ * @property {Array<Extension>} extensions
+ * @property {Array<string>} privateuse
+ * @property {string|null|undefined} irregular
+ * @property {string|null|undefined} regular
+ */
+
+import {isAlphanumerical} from 'is-alphanumerical'
+import {isAlphabetical} from 'is-alphabetical'
+import {isDecimal} from 'is-decimal'
+import {regular} from './regular.js'
+import {normal} from './normal.js'
+
+const own = {}.hasOwnProperty
+
+/**
+ * Parse a BCP 47 language tag.
+ *
+ * @param {string} tag
+ * @param {Options} [options]
+ * @returns {Schema}
+ */
+export function parse(tag, options = {}) {
+  const result = empty()
+  const source = String(tag)
+  const value = source.toLowerCase()
+  let index = 0
+
+  // Check input.
+  if (tag === null || tag === undefined) {
+    throw new Error('Expected string, got `' + tag + '`')
+  }
+
+  // Let’s start.
+  // First: the edge cases.
+  if (own.call(normal, value)) {
+    const replacement = normal[value]
+
+    if (
+      (options.normalize === undefined ||
+        options.normalize === null ||
+        options.normalize) &&
+      typeof replacement === 'string'
+    ) {
+      return parse(replacement)
+    }
+
+    result[regular.includes(value) ? 'regular' : 'irregular'] = source
+
+    return result
+  }
+
+  // Now, to actually parse, eat what could be a language.
+  while (isAlphabetical(value.charCodeAt(index)) && index < 9) index++
+
+  // A language.
+  if (index > 1 /* Min 639. */ && index < 9 /* Max subtag. */) {
+    // 5 and up is a subtag.
+    // 4 is the size of reserved languages.
+    // 3 an ISO 639-2 or ISO 639-3.
+    // 2 is an ISO 639-1.
+    // <https://github.com/wooorm/iso-639-2>
+    // <https://github.com/wooorm/iso-639-3>
+    result.language = source.slice(0, index)
+
+    if (index < 4 /* Max 639. */) {
+      let groups = 0
+
+      while (
+        value.charCodeAt(index) === 45 /* `-` */ &&
+        isAlphabetical(value.charCodeAt(index + 1)) &&
+        isAlphabetical(value.charCodeAt(index + 2)) &&
+        isAlphabetical(value.charCodeAt(index + 3)) &&
+        !isAlphabetical(value.charCodeAt(index + 4))
+      ) {
+        if (groups > 2 /* Max extended language subtag count. */) {
+          return fail(
+            index,
+            3,
+            'Too many extended language subtags, expected at most 3 subtags'
+          )
+        }
+
+        // Extended language subtag.
+        result.extendedLanguageSubtags.push(source.slice(index + 1, index + 4))
+        index += 4
+        groups++
+      }
+    }
+
+    // ISO 15924 script.
+    // <https://github.com/wooorm/iso-15924>
+    if (
+      value.charCodeAt(index) === 45 /* `-` */ &&
+      isAlphabetical(value.charCodeAt(index + 1)) &&
+      isAlphabetical(value.charCodeAt(index + 2)) &&
+      isAlphabetical(value.charCodeAt(index + 3)) &&
+      isAlphabetical(value.charCodeAt(index + 4)) &&
+      !isAlphabetical(value.charCodeAt(index + 5))
+    ) {
+      result.script = source.slice(index + 1, index + 5)
+      index += 5
+    }
+
+    if (value.charCodeAt(index) === 45 /* `-` */) {
+      // ISO 3166-1 region.
+      // <https://github.com/wooorm/iso-3166>
+      if (
+        isAlphabetical(value.charCodeAt(index + 1)) &&
+        isAlphabetical(value.charCodeAt(index + 2)) &&
+        !isAlphabetical(value.charCodeAt(index + 3))
+      ) {
+        result.region = source.slice(index + 1, index + 3)
+        index += 3
+      }
+      // UN M49 region.
+      // <https://github.com/wooorm/un-m49>
+      else if (
+        isDecimal(value.charCodeAt(index + 1)) &&
+        isDecimal(value.charCodeAt(index + 2)) &&
+        isDecimal(value.charCodeAt(index + 3)) &&
+        !isDecimal(value.charCodeAt(index + 4))
+      ) {
+        result.region = source.slice(index + 1, index + 4)
+        index += 4
+      }
+    }
+
+    while (value.charCodeAt(index) === 45 /* `-` */) {
+      const start = index + 1
+      let offset = start
+
+      while (isAlphanumerical(value.charCodeAt(offset))) {
+        if (offset - start > 7 /* Max variant. */) {
+          return fail(
+            offset,
+            1,
+            'Too long variant, expected at most 8 characters'
+          )
+        }
+
+        offset++
+      }
+
+      if (
+        // Long variant.
+        offset - start > 4 /* Min alpha numeric variant. */ ||
+        // Short variant.
+        (offset - start > 3 /* Min variant. */ &&
+          isDecimal(value.charCodeAt(start)))
+      ) {
+        result.variants.push(source.slice(start, offset))
+        index = offset
+      }
+      // Something else.
+      else {
+        break
+      }
+    }
+
+    // Extensions.
+    while (value.charCodeAt(index) === 45 /* `-` */) {
+      // Exit if this isn’t an extension.
+      if (
+        value.charCodeAt(index + 1) === 120 /* `x` */ ||
+        !isAlphanumerical(value.charCodeAt(index + 1)) ||
+        value.charCodeAt(index + 2) !== 45 /* `-` */ ||
+        !isAlphanumerical(value.charCodeAt(index + 3))
+      ) {
+        break
+      }
+
+      let offset = index + 2
+      let groups = 0
+
+      while (
+        value.charCodeAt(offset) === 45 /* `-` */ &&
+        isAlphanumerical(value.charCodeAt(offset + 1)) &&
+        isAlphanumerical(value.charCodeAt(offset + 2))
+      ) {
+        const start = offset + 1
+        offset = start + 2
+        groups++
+
+        while (isAlphanumerical(value.charCodeAt(offset))) {
+          if (offset - start > 7 /* Max extension. */) {
+            return fail(
+              offset,
+              2,
+              'Too long extension, expected at most 8 characters'
+            )
+          }
+
+          offset++
+        }
+      }
+
+      if (!groups) {
+        return fail(
+          offset,
+          4,
+          'Empty extension, extensions must have at least 2 characters of content'
+        )
+      }
+
+      result.extensions.push({
+        singleton: source.charAt(index + 1),
+        extensions: source.slice(index + 3, offset).split('-')
+      })
+
+      index = offset
+    }
+  }
+  // Not a language.
+  else {
+    index = 0
+  }
+
+  // Private use.
+  if (
+    (index === 0 && value.charCodeAt(index) === 120) /* `x` */ ||
+    (value.charCodeAt(index) === 45 /* `-` */ &&
+      value.charCodeAt(index + 1) === 120) /* `x` */
+  ) {
+    index = index ? index + 2 : 1
+    let offset = index
+
+    while (
+      value.charCodeAt(offset) === 45 /* `-` */ &&
+      isAlphanumerical(value.charCodeAt(offset + 1))
+    ) {
+      const start = index + 1
+      offset = start
+
+      while (isAlphanumerical(value.charCodeAt(offset))) {
+        if (offset - start > 7 /* Max private use. */) {
+          return fail(
+            offset,
+            5,
+            'Too long private-use area, expected at most 8 characters'
+          )
+        }
+
+        offset++
+      }
+
+      result.privateuse.push(source.slice(index + 1, offset))
+      index = offset
+    }
+  }
+
+  if (index !== source.length) {
+    return fail(index, 6, 'Found superfluous content after tag')
+  }
+
+  return result
+
+  /**
+   * Create an empty results object.
+   *
+   * @param {number} offset
+   * @param {number} code
+   * @param {string} reason
+   * @returns {Schema}
+   */
+  function fail(offset, code, reason) {
+    if (options.warning) options.warning(reason, code, offset)
+    return options.forgiving ? result : empty()
+  }
+}
+
+/**
+ * Create an empty results object.
+ *
+ * @returns {Schema}
+ */
+function empty() {
+  return {
+    language: null,
+    extendedLanguageSubtags: [],
+    script: null,
+    region: null,
+    variants: [],
+    extensions: [],
+    privateuse: [],
+    irregular: null,
+    regular: null
+  }
+}
diff --git a/node_modules/bcp-47/lib/regular.d.ts b/node_modules/bcp-47/lib/regular.d.ts
new file mode 100644
index 0000000..1818fbd
--- /dev/null
+++ b/node_modules/bcp-47/lib/regular.d.ts
@@ -0,0 +1,2 @@
+/** @type {Array<string>} */
+export const regular: Array<string>
diff --git a/node_modules/bcp-47/lib/regular.js b/node_modules/bcp-47/lib/regular.js
new file mode 100644
index 0000000..0aa5fab
--- /dev/null
+++ b/node_modules/bcp-47/lib/regular.js
@@ -0,0 +1,12 @@
+/** @type {Array<string>} */
+export const regular = [
+  'art-lojban',
+  'cel-gaulish',
+  'no-bok',
+  'no-nyn',
+  'zh-guoyu',
+  'zh-hakka',
+  'zh-min',
+  'zh-min-nan',
+  'zh-xiang'
+]
diff --git a/node_modules/bcp-47/lib/stringify.d.ts b/node_modules/bcp-47/lib/stringify.d.ts
new file mode 100644
index 0000000..14942c4
--- /dev/null
+++ b/node_modules/bcp-47/lib/stringify.d.ts
@@ -0,0 +1,13 @@
+/**
+ * @typedef {Partial<import('./parse.js').Schema>} Schema
+ * @typedef {Partial<import('./parse.js').Extension>} Extension
+ */
+/**
+ * Compile a language schema to a BCP 47 language tag.
+ *
+ * @param {Schema} schema
+ * @returns {string}
+ */
+export function stringify(schema?: Schema): string
+export type Schema = Partial<import('./parse.js').Schema>
+export type Extension = Partial<import('./parse.js').Extension>
diff --git a/node_modules/bcp-47/lib/stringify.js b/node_modules/bcp-47/lib/stringify.js
new file mode 100644
index 0000000..e5b367a
--- /dev/null
+++ b/node_modules/bcp-47/lib/stringify.js
@@ -0,0 +1,50 @@
+/**
+ * @typedef {Partial<import('./parse.js').Schema>} Schema
+ * @typedef {Partial<import('./parse.js').Extension>} Extension
+ */
+
+/**
+ * Compile a language schema to a BCP 47 language tag.
+ *
+ * @param {Schema} schema
+ * @returns {string}
+ */
+export function stringify(schema = {}) {
+  /** @type {Array<string>} */
+  let result = []
+
+  if (schema.irregular) {
+    return schema.irregular
+  }
+
+  if (schema.regular) {
+    return schema.regular
+  }
+
+  if (schema.language) {
+    result = result.concat(
+      schema.language,
+      schema.extendedLanguageSubtags || [],
+      schema.script || [],
+      schema.region || [],
+      schema.variants || []
+    )
+
+    const values = schema.extensions || []
+    let index = -1
+
+    while (++index < values.length) {
+      const value = values[index]
+
+      if (value.singleton && value.extensions && value.extensions.length > 0) {
+        result.push(value.singleton, ...value.extensions)
+      }
+    }
+  }
+
+  if (schema.privateuse && schema.privateuse.length > 0) {
+    result.push('x', ...schema.privateuse)
+  }
+
+  return result.join('-')
+}
diff --git a/node_modules/bcp-47/license b/node_modules/bcp-47/license
new file mode 100644
index 0000000..8d8660d
--- /dev/null
+++ b/node_modules/bcp-47/license
@@ -0,0 +1,22 @@
+(The MIT License)
+
+Copyright (c) 2016 Titus Wormer <tituswormer@gmail.com>
+
+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.
diff --git a/node_modules/bcp-47/package.json b/node_modules/bcp-47/package.json
new file mode 100644
index 0000000..8a12183
--- /dev/null
+++ b/node_modules/bcp-47/package.json
@@ -0,0 +1,85 @@
+{
+  "name": "bcp-47",
+  "version": "2.1.0",
+  "description": "Parse and stringify BCP 47 language tags",
+  "license": "MIT",
+  "keywords": [
+    "bcp",
+    "47",
+    "bcp47",
+    "bcp-47",
+    "language",
+    "tag",
+    "parse"
+  ],
+  "repository": "wooorm/bcp-47",
+  "bugs": "https://github.com/wooorm/bcp-47/issues",
+  "funding": {
+    "type": "github",
+    "url": "https://github.com/sponsors/wooorm"
+  },
+  "author": "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)",
+  "contributors": [
+    "Titus Wormer <tituswormer@gmail.com> (https://wooorm.com)"
+  ],
+  "sideEffects": false,
+  "type": "module",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "files": [
+    "index.d.ts",
+    "index.js",
+    "lib/"
+  ],
+  "dependencies": {
+    "is-alphabetical": "^2.0.0",
+    "is-alphanumerical": "^2.0.0",
+    "is-decimal": "^2.0.0"
+  },
+  "devDependencies": {
+    "@types/tape": "^4.0.0",
+    "c8": "^7.0.0",
+    "is-hidden": "^2.0.0",
+    "prettier": "^2.0.0",
+    "remark-cli": "^10.0.0",
+    "remark-preset-wooorm": "^9.0.0",
+    "rimraf": "^3.0.0",
+    "tape": "^5.0.0",
+    "type-coverage": "^2.0.0",
+    "typescript": "^4.0.0",
+    "xo": "^0.46.0"
+  },
+  "scripts": {
+    "prepublishOnly": "npm run build && npm run format",
+    "build": "rimraf \"{lib,test}/**/*.d.ts\" \"*.d.ts\" && tsc && type-coverage",
+    "format": "remark . -qfo && prettier . -w --loglevel warn && xo --fix",
+    "test-api": "node --conditions development test/index.js",
+    "test-coverage": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 --reporter lcov npm run test-api",
+    "test": "npm run build && npm run format && npm run test-coverage"
+  },
+  "prettier": {
+    "tabWidth": 2,
+    "useTabs": false,
+    "singleQuote": true,
+    "bracketSpacing": false,
+    "semi": false,
+    "trailingComma": "none"
+  },
+  "xo": {
+    "prettier": true,
+    "rules": {
+      "complexity": "off"
+    }
+  },
+  "remarkConfig": {
+    "plugins": [
+      "preset-wooorm"
+    ]
+  },
+  "typeCoverage": {
+    "atLeast": 100,
+    "detail": true,
+    "strict": true,
+    "ignoreCatch": true
+  }
+}
diff --git a/node_modules/bcp-47/readme.md b/node_modules/bcp-47/readme.md
new file mode 100644
index 0000000..3e96ac6
--- /dev/null
+++ b/node_modules/bcp-47/readme.md
@@ -0,0 +1,344 @@
+# bcp-47
+
+[![Build][build-badge]][build]
+[![Coverage][coverage-badge]][coverage]
+[![Downloads][downloads-badge]][downloads]
+[![Size][size-badge]][size]
+
+Parse and stringify [BCP 47][spec] language tags.
+
+## Contents
+
+*   [What is this?](#what-is-this)
+*   [When should I use this?](#when-should-i-use-this)
+*   [Install](#install)
+*   [Use](#use)
+*   [API](#api)
+    *   [`parse(tag[, options])`](#parsetag-options)
+    *   [`stringify(schema)`](#stringifyschema)
+    *   [`Schema`](#schema)
+    *   [`function warning(reason, code, offset)`](#function-warningreason-code-offset)
+*   [Types](#types)
+*   [Compatibility](#compatibility)
+*   [Security](#security)
+*   [Related](#related)
+*   [Contribute](#contribute)
+*   [License](#license)
+
+## What is this?
+
+This is a package that can parse BCP 47 language tags to an object representing
+them, and serialize those objects back into language tags.
+It supports a forgiving mode to handle incorrect BCP 47 tags and can emit
+warnings about problems in incorrect tags.
+
+## When should I use this?
+
+You can use this package if you need to access the data stored in BCP 47
+language tags.
+You can also use this package if you want to check (lint) or manipulate tags.
+
+## Install
+
+This package is [ESM only][esm].
+In Node.js (version 12.20+, 14.14+, or 16.0+), install with [npm][]:
+
+```sh
+npm install bcp-47
+```
+
+In Deno with [Skypack][]:
+
+```js
+import * as bcp47 from 'https://cdn.skypack.dev/bcp-47@2?dts'
+```
+
+In browsers with [Skypack][]:
+
+```html
+<script type="module">
+  import * as bcp47 from 'https://cdn.skypack.dev/bcp-47@2?min'
+</script>
+```
+
+## Use
+
+```js
+import {parse, stringify} from 'bcp-47'
+
+const schema = parse('hy-Latn-IT-arevela')
+
+console.log(schema)
+console.log(stringify(schema))
+```
+
+Yields:
+
+```js
+{ language: 'hy',
+  extendedLanguageSubtags: [],
+  script: 'Latn',
+  region: 'IT',
+  variants: ['arevela'],
+  extensions: [],
+  privateuse: [],
+  irregular: null,
+  regular: null }
+'hy-Latn-IT-arevela'
+```
+
+## API
+
+This package exports the following identifiers: `parse` and `stringify`.
+There is no default export.
+
+### `parse(tag[, options])`
+
+Parse a BCP 47 tag into a language schema.
+Note that the algorithm is case insensitive.
+
+###### `options.normalize`
+
+Whether to normalize legacy tags when possible (`boolean`, default:
+`true`).
+For example, `i-klingon` does not match the BCP 47 language algorithm but is
+considered valid by BCP 47 nonetheless.
+It is suggested to use `tlh` instead (the ISO 639-3 code for Klingon).
+When `normalize` is `true`, passing `i-klingon` or other deprecated tags, is
+handled as if their suggested valid tag was given instead.
+
+###### `options.forgiving`
+
+By default, when an error is encountered, an empty object is returned.
+When in forgiving mode, all found values up to the point of the error
+are included (`boolean`, default: `false`).
+So, for example, where by default `en-GB-abcdefghi` an empty object is returned
+(as the language variant is too long), in `forgiving` mode the `language` of
+`schema` is populated with `en` and the `region` is populated with `GB`.
+
+###### `options.warning`
+
+When given, `warning` is called when an error is encountered
+([`Function`][warning]).
+
+###### Returns
+
+Parsed BCP 47 language tag ([`Schema`][schema]).
+
+###### Throws
+
+When `tag` is `null` or `undefined`.
+
+### `stringify(schema)`
+
+Compile a [`schema`][schema] to a BCP 47 language tag.
+
+###### Returns
+
+BCP 47 language tag (`string`).
+
+### `Schema`
+
+A schema represents a language tag.
+A schema is deemed empty when it has neither `language`, `irregular`, `regular`,
+nor `privateuse` (where an empty `privateuse` array is handled as no
+`privateuse` as well).
+
+###### `schema.language`
+
+Two or three character [ISO 639][iso-639] language code, four character reserved
+language code, or 5 to 8 (inclusive) characters registered language subtag
+(`string`).
+For example, `en` (English) or `cmn` (Mandarin Chinese).
+
+###### `schema.extendedLanguageSubtags`
+
+Selected three-character [ISO 639][iso-639] codes(`Array<string>`), such as
+`yue` in `zh-yue-HK` (Chinese, Cantonese, as used in Hong Kong SAR).
+
+###### `schema.script`
+
+Four character [ISO 15924][iso-15924] script code (`string`), such as `Latn` in
+`hy-Latn-IT-arevela` (Eastern Armenian written in Latin script, as used in
+Italy).
+
+###### `schema.region`
+
+Two alphabetical character [ISO 3166-1][iso-3166-1] code or three digit
+[UN M49][un-m49] code (`string`).
+For example, `CN` in `cmn-Hans-CN` (Mandarin Chinese, Simplified script, as used
+in China) or `419` in `es-419` (Spanish as used in Latin America and the
+Caribbean).
+
+###### `schema.variants`
+
+5 to 8 (inclusive) character language variants (`Array<string>`), such as
+`rozaj` and `biske` in `sl-rozaj-biske` (San Giorgio dialect of Resian dialect
+of Slovenian).
+
+###### `schema.extensions`
+
+List of extensions (`Array<Object>`), each an object containing a one character
+`singleton`, and a list of `extensions` (`string`).
+`singleton` cannot be `x` (case insensitive) and `extensions` must be between
+two and eight (inclusive) characters.
+For example, an extension would be `u-co-phonebk` in `de-DE-u-co-phonebk`
+(German, as used in Germany, using German phonebook sort order), where `u` is
+the `singleton` and `co` and `phonebk` are its extensions.
+
+###### `schema.privateuse`
+
+List of private-use subtags (`Array<string>`), where each subtag must be between
+one and eight (inclusive) characters.
+
+###### `schema.regular`
+
+One of the `regular` tags (`string`): tags that are seen as something different
+by the algorithm.
+Valid values are:
+
+*   `art-lojban`
+*   `cel-gaulish`
+*   `no-bok`
+*   `no-nyn`
+*   `zh-guoyu`
+*   `zh-hakka`
+*   `zh-min`
+*   `zh-min-nan`
+*   `zh-xiang`
+
+###### `schema.irregular`
+
+One of the `irregular` tags (`string`): tags that are seen as invalid by the
+algorithm).
+Valid values are:
+
+*   `en-GB-oed`
+*   `i-ami`
+*   `i-bnn`
+*   `i-default`
+*   `i-enochian`
+*   `i-hak`
+*   `i-klingon`
+*   `i-lux`
+*   `i-mingo`
+*   `i-navajo`
+*   `i-pwn`
+*   `i-tao`
+*   `i-tay`
+*   `i-tsu`
+*   `sgn-BE-FR`
+*   `sgn-BE-NL`
+*   `sgn-CH-DE`
+
+### `function warning(reason, code, offset)`
+
+Called when an error occurs.
+
+###### Parameters
+
+*   `reason` (`string`)
+    — English reason for failure
+*   `code` (`number`)
+    — code for failure
+*   `offset` (`number`)
+    — index-based place where the error occurred in the tag
+
+###### Warnings
+
+| code | reason                                                                 |
+| :--- | :--------------------------------------------------------------------- |
+| 1    | Too long variant, expected at most 8 characters                        |
+| 2    | Too long extension, expected at most 8 characters                      |
+| 3    | Too many extended language subtags, expected at most 3 subtags         |
+| 4    | Empty extension, extensions must have at least 2 characters of content |
+| 5    | Too long private-use area, expected at most 8 characters               |
+| 6    | Found superfluous content after tag                                    |
+
+## Types
+
+This package is fully typed with [TypeScript][].
+It exports additional `Schema`, `Extension`, `Warning`, and `Options` types that
+model their respective interfaces.
+
+## Compatibility
+
+This package is at least compatible with all maintained versions of Node.js.
+As of now, that is Node.js 12.20+, 14.14+, and 16.0+.
+It also works in Deno and modern browsers.
+
+## Security
+
+This package is safe.
+
+## Related
+
+*   [`wooorm/bcp-47-match`](https://github.com/wooorm/bcp-47-match)
+    — match BCP 47 language tags with language ranges per RFC 4647
+*   [`wooorm/bcp-47-normalize`](https://github.com/wooorm/bcp-47-normalize)
+    — normalize, canonicalize, and format BCP 47 tags
+*   [`wooorm/iso-3166`](https://github.com/wooorm/iso-3166)
+    — ISO 3166 codes
+*   [`wooorm/iso-639-2`](https://github.com/wooorm/iso-639-2)
+    — ISO 639-2 codes
+*   [`wooorm/iso-639-3`](https://github.com/wooorm/iso-639-3)
+    — ISO 639-3 codes
+*   [`wooorm/iso-15924`](https://github.com/wooorm/iso-15924)
+    — ISO 15924 codes
+*   [`wooorm/un-m49`](https://github.com/wooorm/un-m49)
+    — UN M49 codes
+
+## Contribute
+
+Yes please!
+See [How to Contribute to Open Source][contribute].
+
+## License
+
+[MIT][license] © [Titus Wormer][author]
+
+<!-- Definitions -->
+
+[build-badge]: https://github.com/wooorm/bcp-47/workflows/main/badge.svg
+
+[build]: https://github.com/wooorm/bcp-47/actions
+
+[coverage-badge]: https://img.shields.io/codecov/c/github/wooorm/bcp-47.svg
+
+[coverage]: https://codecov.io/github/wooorm/bcp-47
+
+[downloads-badge]: https://img.shields.io/npm/dm/bcp-47.svg
+
+[downloads]: https://www.npmjs.com/package/bcp-47
+
+[size-badge]: https://img.shields.io/bundlephobia/minzip/bcp-47.svg
+
+[size]: https://bundlephobia.com/result?p=bcp-47
+
+[npm]: https://docs.npmjs.com/cli/install
+
+[skypack]: https://www.skypack.dev
+
+[license]: license
+
+[author]: https://wooorm.com
+
+[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
+
+[typescript]: https://www.typescriptlang.org
+
+[contribute]: https://opensource.guide/how-to-contribute/
+
+[spec]: https://tools.ietf.org/rfc/bcp/bcp47.html
+
+[warning]: #function-warningreason-code-offset
+
+[schema]: #schema
+
+[iso-639]: https://en.wikipedia.org/wiki/ISO_639
+
+[iso-15924]: https://en.wikipedia.org/wiki/ISO_15924
+
+[iso-3166-1]: https://en.wikipedia.org/wiki/ISO_3166-1
+
+[un-m49]: https://en.wikipedia.org/wiki/UN_M.49