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index.js
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index.js
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const createCookieLookup = require('./lookup/cookie');
const createQueryLookup = require('./lookup/query');
const createHostnameLookup = require('./lookup/hostname');
const createDefaultLookup = require('./lookup/default');
const createAcceptLanguageLookup = require('./lookup/accept-language');
const createMapLookup = require('./lookup/map');
const createLocale = require('./locale');
const LOOKUP_CREATORS = {
'cookie': createCookieLookup,
'query': createQueryLookup,
'hostname': createHostnameLookup,
'accept-language': createAcceptLanguageLookup,
'map': createMapLookup,
'default': createDefaultLookup
};
const nonLocaleCharacters = /[^a-z]/ig;
const trailingUnderscores = /^_+|_+$/g;
const languageOrLocale = /^[a-z]{2}(?:_[a-z]{2})?$/i;
function trimLocale (locale) {
return locale
.replace(nonLocaleCharacters, '_')
.replace(trailingUnderscores, '');
}
function isLanguageOrLocale (locale) {
return languageOrLocale.test(locale);
}
function createLocaleMiddleware (options = {}) {
options = {
priority: ['accept-language', 'default'],
requestProperty: 'locale',
...options
};
const lookups = {
...Object.keys(LOOKUP_CREATORS).reduce((result, lookup) => {
result[lookup] = LOOKUP_CREATORS[lookup](options[lookup]);
return result;
}, {}),
...(options.lookups || {})
};
if (typeof options.priority === 'string') {
options.priority = options.priority.split(/ *, */g);
}
if (!options.priority.every(source => source in lookups)) {
const notFound = options.priority.filter(source => !(source in lookups));
throw Error(`Undefined lookup${notFound.length === 1 ? '' : 's'} (${notFound.join(', ')})`);
}
function isAllowed (locale) {
return !options.allowed || options.allowed.indexOf(locale) >= 0;
}
function * lookup (req, all) {
for (let source of options.priority) {
let locales = lookups[source](req, all);
if (typeof locales === 'string') {
locales = [locales];
}
if (Array.isArray(locales) && locales.length > 0) {
locales = locales
.map(trimLocale)
.filter(isLanguageOrLocale)
.filter(isAllowed)
.map(code => createLocale(code, source));
for (let locale of locales) {
yield locale;
}
}
}
}
const middleware = function (req, res, next) {
const locales = [];
let result;
let languageBuffer;
function filterResult (locale) {
if ('region' in locale) {
if (languageBuffer) {
if (languageBuffer.language === locale.language) {
if (languageBuffer.source !== locale.source) {
locale.source = [languageBuffer.source, locale.source];
}
return locale;
}
} else {
return locale;
}
} else {
if (!languageBuffer) {
languageBuffer = locale;
}
}
}
// perform lookups one by one, exiting early
for (let locale of lookup(req, locales)) {
if ((result = filterResult(locale))) {
break;
}
locales.push(locale);
}
// if no early exit was found, eliminate results one by one
while (!result && locales.length > 0) {
languageBuffer = undefined;
locales.shift();
for (let locale of locales) {
if ((result = filterResult(locale))) {
break;
}
}
}
req[options.requestProperty] = result;
next();
};
return middleware;
}
module.exports = createLocaleMiddleware;