Added new tests for chapters 6 and 9 of ECMAScript Internationalization API Specification.

- Removed a few old test cases that were redundant with new, more comprehensive ones.
- Added testIntl.js as standard include for all console tests in test262.py – see related bug 574.
- Added .jshintrc file for settings for the JSHint tool.

1 files changed, 658 insertions, 0 deletions

diff --git a/console/harness/testIntl.js b/console/harness/testIntl.js
new file mode 100644
index 000000000..251f0a2ca
--- /dev/null
+++ b/console/harness/testIntl.js
@@ -0,0 +1,658 @@
+// Copyright 2011-2012 Norbert Lindenberg. All rights reserved.
+// Copyright 2012  Mozilla Corporation. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/**
+ * This file contains shared functions for the tests in the conformance test
+ * suite for the ECMAScript Internationalization API.
+ * @author Norbert Lindenberg
+ */
+
+
+/**
+ * @description Calls the provided function for every service constructor in
+ * the Intl object, until f returns a falsy value. It returns the result of the
+ * last call to f, mapped to a boolean.
+ * @param {Function} f the function to call for each service constructor in
+ *     the Intl object.
+ *     @param {Function} Constructor the constructor object to test with.
+ * @result {Boolean} whether the test succeeded.
+ */
+function testWithIntlConstructors(f) {
+    var constructors = ["Collator", "NumberFormat", "DateTimeFormat"];
+    return constructors.every(function (constructor) {
+        var Constructor = Intl[constructor];
+        var result;
+        try {
+            result = f(Constructor);
+        } catch (e) {
+            e.message += " (Testing with " + constructor + ".)";
+            throw e;
+        }
+        return result;
+    });
+}
+
+
+/**
+ * Returns the name of the given constructor object, which must be one of
+ * Intl.Collator, Intl.NumberFormat, or Intl.DateTimeFormat.
+ * @param {object} Constructor a constructor
+ * @return {string} the name of the constructor
+ */
+function getConstructorName(Constructor) {
+    switch (Constructor) {
+        case Intl.Collator:
+            return "Collator";
+        case Intl.NumberFormat:
+            return "NumberFormat";
+        case Intl.DateTimeFormat:
+            return "DateTimeFormat";
+        default:
+            $ERROR("test internal error: unknown Constructor");
+    }
+}
+
+
+/**
+ * Taints a named data property of the given object by installing
+ * a setter that throws an exception.
+ * @param {object} obj the object whose data property to taint
+ * @param {string} property the property to taint
+ */
+function taintDataProperty(obj, property) {
+    Object.defineProperty(obj, property, {
+        set: function(value) {
+            $ERROR("Client code can adversely affect behavior: setter for " + property + ".");
+        },
+        enumerable: false,
+        configurable: true
+    });
+}
+
+
+/**
+ * Taints a named method of the given object by replacing it with a function
+ * that throws an exception.
+ * @param {object} obj the object whose method to taint
+ * @param {string} property the name of the method to taint
+ */
+function taintMethod(obj, property) {
+    Object.defineProperty(obj, property, {
+        value: function() {
+            $ERROR("Client code can adversely affect behavior: method " + property + ".");
+        },
+        writable: true,
+        enumerable: false,
+        configurable: true
+    });
+}
+
+
+/**
+ * Taints the given properties (and similarly named properties) by installing
+ * setters on Object.prototype that throw exceptions.
+ * @param {Array} properties an array of property names to taint
+ */
+function taintProperties(properties) {
+    properties.forEach(function (property) {
+        var adaptedProperties = [property, "__" + property, "_" + property, property + "_", property + "__"];
+        adaptedProperties.forEach(function (property) {
+            taintDataProperty(Object.prototype, property);
+        });
+    });
+}
+
+
+/**
+ * Taints the Array object by creating a setter for the property "0" and
+ * replacing some key methods with functions that throw exceptions.
+ */
+function taintArray() {
+    taintDataProperty(Array.prototype, "0");
+    taintMethod(Array.prototype, "indexOf");
+    taintMethod(Array.prototype, "join");
+    taintMethod(Array.prototype, "push");
+    taintMethod(Array.prototype, "slice");
+    taintMethod(Array.prototype, "sort");
+}
+
+
+// auxiliary data for getLocaleSupportInfo
+var languages = ["zh", "es", "en", "hi", "ur", "ar", "ja", "pa"];
+var scripts = ["Latn", "Hans", "Deva", "Arab", "Jpan", "Hant"];
+var countries = ["CN", "IN", "US", "PK", "JP", "TW", "HK", "SG"];
+var localeSupportInfo = {};
+
+
+/**
+ * Gets locale support info for the given constructor object, which must be one
+ * of Intl.Collator, Intl.NumberFormat, Intl.DateTimeFormat.
+ * @param {object} Constructor the constructor for which to get locale support info
+ * @return {object} locale support info with the following properties:
+ *     supported: array of fully supported language tags
+ *     byFallback: array of language tags that are supported through fallbacks
+ *     unsupported: array of unsupported language tags
+ */
+function getLocaleSupportInfo(Constructor) {
+    var constructorName = getConstructorName(Constructor);
+    if (localeSupportInfo[constructorName] !== undefined) {
+        return localeSupportInfo[constructorName];
+    }
+
+    var allTags = [];
+    var i, j, k;
+    var language, script, country;
+    for (i = 0; i < languages.length; i++) {
+        language = languages[i];
+        allTags.push(language);
+        for (j = 0; j < scripts.length; j++) {
+            script = scripts[j];
+            allTags.push(language + "-" + script);
+            for (k = 0; k < countries.length; k++) {
+                country = countries[k];
+                allTags.push(language + "-" + script + "-" + country);
+            }
+        }
+        for (k = 0; k < countries.length; k++) {
+            country = countries[k];
+            allTags.push(language + "-" + country);
+        }
+    }
+    
+    var supported = [];
+    var byFallback = [];
+    var unsupported = [];
+    for (i = 0; i < allTags.length; i++) {
+        var request = allTags[i];
+        var result = new Constructor([request], {localeMatcher: "lookup"}).resolvedOptions().locale;
+         if (request === result) {
+            supported.push(request);
+        } else if (request.indexOf(result) === 0) {
+            byFallback.push(request);
+        } else {
+            unsupported.push(request);
+        }
+    }
+    
+    localeSupportInfo[constructorName] = {
+        supported: supported,
+        byFallback: byFallback,
+        unsupported: unsupported
+    };
+    
+    return localeSupportInfo[constructorName];
+}
+        
+
+/**
+ * @description Tests whether locale is a String value representing a
+ * structurally valid and canonicalized BCP 47 language tag, as defined in
+ * sections 6.2.2 and 6.2.3 of the ECMAScript Internationalization API
+ * Specification.
+ * @param {String} locale the string to be tested.
+ * @result {Boolean} whether the test succeeded.
+ */
+function isCanonicalizedStructurallyValidLanguageTag(locale) {
+
+    /**
+     * Regular expression defining BCP 47 language tags.
+     *
+     * Spec: RFC 5646 section 2.1.
+     */
+    var alpha = "[a-zA-Z]",
+        digit = "[0-9]",
+        alphanum = "(" + alpha + "|" + digit + ")",
+        regular = "(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang)",
+        irregular = "(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)",
+        grandfathered = "(" + irregular + "|" + regular + ")",
+        privateuse = "(x(-[a-z0-9]{1,8})+)",
+        singleton = "(" + digit + "|[A-WY-Za-wy-z])",
+        extension = "(" + singleton + "(-" + alphanum + "{2,8})+)",
+        variant = "(" + alphanum + "{5,8}|(" + digit + alphanum + "{3}))",
+        region = "(" + alpha + "{2}|" + digit + "{3})",
+        script = "(" + alpha + "{4})",
+        extlang = "(" + alpha + "{3}(-" + alpha + "{3}){0,2})",
+        language = "(" + alpha + "{2,3}(-" + extlang + ")?|" + alpha + "{4}|" + alpha + "{5,8})",
+        langtag = language + "(-" + script + ")?(-" + region + ")?(-" + variant + ")*(-" + extension + ")*(-" + privateuse + ")?",
+        languageTag = "^(" + langtag + "|" + privateuse + "|" + grandfathered + ")$",
+        languageTagRE = new RegExp(languageTag, "i");
+    var duplicateSingleton = "-" + singleton + "-(.*-)?\\1(?!" + alphanum + ")",
+        duplicateSingletonRE = new RegExp(duplicateSingleton, "i"),
+        duplicateVariant = "(" + alphanum + "{2,8}-)+" + variant + "-(" + alphanum + "{2,8}-)*\\3(?!" + alphanum + ")",
+        duplicateVariantRE = new RegExp(duplicateVariant, "i");
+
+
+    /**
+     * Verifies that the given string is a well-formed BCP 47 language tag
+     * with no duplicate variant or singleton subtags.
+     *
+     * Spec: ECMAScript Internationalization API Specification, draft, 6.2.2.
+     */
+    function isStructurallyValidLanguageTag(locale) {
+        if (!languageTagRE.test(locale)) {
+            return false;
+        }
+        locale = locale.split(/-x-/)[0];
+        return !duplicateSingletonRE.test(locale) && !duplicateVariantRE.test(locale);
+    }
+
+
+    /**
+     * Mappings from complete tags to preferred values.
+     *
+     * Spec: IANA Language Subtag Registry.
+     */
+    var __tagMappings = {
+        // property names must be in lower case; values in canonical form
+
+        // grandfathered tags from IANA language subtag registry, file date 2011-08-25
+        "art-lojban": "jbo",
+        "cel-gaulish": "cel-gaulish",
+        "en-gb-oed": "en-GB-oed",
+        "i-ami": "ami",
+        "i-bnn": "bnn",
+        "i-default": "i-default",
+        "i-enochian": "i-enochian",
+        "i-hak": "hak",
+        "i-klingon": "tlh",
+        "i-lux": "lb",
+        "i-mingo": "i-mingo",
+        "i-navajo": "nv",
+        "i-pwn": "pwn",
+        "i-tao": "tao",
+        "i-tay": "tay",
+        "i-tsu": "tsu",
+        "no-bok": "nb",
+        "no-nyn": "nn",
+        "sgn-be-fr": "sfb",
+        "sgn-be-nl": "vgt",
+        "sgn-ch-de": "sgg",
+        "zh-guoyu": "cmn",
+        "zh-hakka": "hak",
+        "zh-min": "zh-min",
+        "zh-min-nan": "nan",
+        "zh-xiang": "hsn",
+        // deprecated redundant tags from IANA language subtag registry, file date 2011-08-25
+        "sgn-br": "bzs",
+        "sgn-co": "csn",
+        "sgn-de": "gsg",
+        "sgn-dk": "dsl",
+        "sgn-es": "ssp",
+        "sgn-fr": "fsl",
+        "sgn-gb": "bfi",
+        "sgn-gr": "gss",
+        "sgn-ie": "isg",
+        "sgn-it": "ise",
+        "sgn-jp": "jsl",
+        "sgn-mx": "mfs",
+        "sgn-ni": "ncs",
+        "sgn-nl": "dse",
+        "sgn-no": "nsl",
+        "sgn-pt": "psr",
+        "sgn-se": "swl",
+        "sgn-us": "ase",
+        "sgn-za": "sfs",
+        "zh-cmn": "cmn",
+        "zh-cmn-hans": "cmn-Hans",
+        "zh-cmn-hant": "cmn-Hant",
+        "zh-gan": "gan",
+        "zh-wuu": "wuu",
+        "zh-yue": "yue",
+        // deprecated variant with prefix from IANA language subtag registry, file date 2011-08-25
+        "ja-latn-hepburn-heploc": "ja-Latn-alalc97"
+    };
+
+
+    /**
+     * Mappings from non-extlang subtags to preferred values.
+     *
+     * Spec: IANA Language Subtag Registry.
+     */
+    var __subtagMappings = {
+        // property names and values must be in canonical case
+        // language subtags with Preferred-Value mappings from IANA language subtag registry, file date 2011-08-25
+        "in": "id",
+        "iw": "he",
+        "ji": "yi",
+        "jw": "jv",
+        "mo": "ro",
+        "ayx": "nun",
+        "cjr": "mom",
+        "cmk": "xch",
+        "drh": "khk",
+        "drw": "prs",
+        "gav": "dev",
+        "mst": "mry",
+        "myt": "mry",
+        "tie": "ras",
+        "tkk": "twm",
+        "tnf": "prs",
+        // region subtags with Preferred-Value mappings from IANA language subtag registry, file date 2011-08-25
+        "BU": "MM",
+        "DD": "DE",
+        "FX": "FR",
+        "TP": "TL",
+        "YD": "YE",
+        "ZR": "CD"
+    };
+
+
+    /**
+     * Mappings from extlang subtags to preferred values.
+     *
+     * Spec: IANA Language Subtag Registry.
+     */
+    var __extlangMappings = {
+        // extlang subtags with Preferred-Value mappings from IANA language subtag registry, file date 2011-08-25
+        // values are arrays with [0] the replacement value, [1] (if present) the prefix to be removed
+        "aao": ["aao", "ar"],
+        "abh": ["abh", "ar"],
+        "abv": ["abv", "ar"],
+        "acm": ["acm", "ar"],
+        "acq": ["acq", "ar"],
+        "acw": ["acw", "ar"],
+        "acx": ["acx", "ar"],
+        "acy": ["acy", "ar"],
+        "adf": ["adf", "ar"],
+        "ads": ["ads", "sgn"],
+        "aeb": ["aeb", "ar"],
+        "aec": ["aec", "ar"],
+        "aed": ["aed", "sgn"],
+        "aen": ["aen", "sgn"],
+        "afb": ["afb", "ar"],
+        "afg": ["afg", "sgn"],
+        "ajp": ["ajp", "ar"],
+        "apc": ["apc", "ar"],
+        "apd": ["apd", "ar"],
+        "arb": ["arb", "ar"],
+        "arq": ["arq", "ar"],
+        "ars": ["ars", "ar"],
+        "ary": ["ary", "ar"],
+        "arz": ["arz", "ar"],
+        "ase": ["ase", "sgn"],
+        "asf": ["asf", "sgn"],
+        "asp": ["asp", "sgn"],
+        "asq": ["asq", "sgn"],
+        "asw": ["asw", "sgn"],
+        "auz": ["auz", "ar"],
+        "avl": ["avl", "ar"],
+        "ayh": ["ayh", "ar"],
+        "ayl": ["ayl", "ar"],
+        "ayn": ["ayn", "ar"],
+        "ayp": ["ayp", "ar"],
+        "bbz": ["bbz", "ar"],
+        "bfi": ["bfi", "sgn"],
+        "bfk": ["bfk", "sgn"],
+        "bjn": ["bjn", "ms"],
+        "bog": ["bog", "sgn"],
+        "bqn": ["bqn", "sgn"],
+        "bqy": ["bqy", "sgn"],
+        "btj": ["btj", "ms"],
+        "bve": ["bve", "ms"],
+        "bvl": ["bvl", "sgn"],
+        "bvu": ["bvu", "ms"],
+        "bzs": ["bzs", "sgn"],
+        "cdo": ["cdo", "zh"],
+        "cds": ["cds", "sgn"],
+        "cjy": ["cjy", "zh"],
+        "cmn": ["cmn", "zh"],
+        "coa": ["coa", "ms"],
+        "cpx": ["cpx", "zh"],
+        "csc": ["csc", "sgn"],
+        "csd": ["csd", "sgn"],
+        "cse": ["cse", "sgn"],
+        "csf": ["csf", "sgn"],
+        "csg": ["csg", "sgn"],
+        "csl": ["csl", "sgn"],
+        "csn": ["csn", "sgn"],
+        "csq": ["csq", "sgn"],
+        "csr": ["csr", "sgn"],
+        "czh": ["czh", "zh"],
+        "czo": ["czo", "zh"],
+        "doq": ["doq", "sgn"],
+        "dse": ["dse", "sgn"],
+        "dsl": ["dsl", "sgn"],
+        "dup": ["dup", "ms"],
+        "ecs": ["ecs", "sgn"],
+        "esl": ["esl", "sgn"],
+        "esn": ["esn", "sgn"],
+        "eso": ["eso", "sgn"],
+        "eth": ["eth", "sgn"],
+        "fcs": ["fcs", "sgn"],
+        "fse": ["fse", "sgn"],
+        "fsl": ["fsl", "sgn"],
+        "fss": ["fss", "sgn"],
+        "gan": ["gan", "zh"],
+        "gom": ["gom", "kok"],
+        "gse": ["gse", "sgn"],
+        "gsg": ["gsg", "sgn"],
+        "gsm": ["gsm", "sgn"],
+        "gss": ["gss", "sgn"],
+        "gus": ["gus", "sgn"],
+        "hab": ["hab", "sgn"],
+        "haf": ["haf", "sgn"],
+        "hak": ["hak", "zh"],
+        "hds": ["hds", "sgn"],
+        "hji": ["hji", "ms"],
+        "hks": ["hks", "sgn"],
+        "hos": ["hos", "sgn"],
+        "hps": ["hps", "sgn"],
+        "hsh": ["hsh", "sgn"],
+        "hsl": ["hsl", "sgn"],
+        "hsn": ["hsn", "zh"],
+        "icl": ["icl", "sgn"],
+        "ils": ["ils", "sgn"],
+        "inl": ["inl", "sgn"],
+        "ins": ["ins", "sgn"],
+        "ise": ["ise", "sgn"],
+        "isg": ["isg", "sgn"],
+        "isr": ["isr", "sgn"],
+        "jak": ["jak", "ms"],
+        "jax": ["jax", "ms"],
+        "jcs": ["jcs", "sgn"],
+        "jhs": ["jhs", "sgn"],
+        "jls": ["jls", "sgn"],
+        "jos": ["jos", "sgn"],
+        "jsl": ["jsl", "sgn"],
+        "jus": ["jus", "sgn"],
+        "kgi": ["kgi", "sgn"],
+        "knn": ["knn", "kok"],
+        "kvb": ["kvb", "ms"],
+        "kvk": ["kvk", "sgn"],
+        "kvr": ["kvr", "ms"],
+        "kxd": ["kxd", "ms"],
+        "lbs": ["lbs", "sgn"],
+        "lce": ["lce", "ms"],
+        "lcf": ["lcf", "ms"],
+        "liw": ["liw", "ms"],
+        "lls": ["lls", "sgn"],
+        "lsg": ["lsg", "sgn"],
+        "lsl": ["lsl", "sgn"],
+        "lso": ["lso", "sgn"],
+        "lsp": ["lsp", "sgn"],
+        "lst": ["lst", "sgn"],
+        "lsy": ["lsy", "sgn"],
+        "ltg": ["ltg", "lv"],
+        "lvs": ["lvs", "lv"],
+        "lzh": ["lzh", "zh"],
+        "max": ["max", "ms"],
+        "mdl": ["mdl", "sgn"],
+        "meo": ["meo", "ms"],
+        "mfa": ["mfa", "ms"],
+        "mfb": ["mfb", "ms"],
+        "mfs": ["mfs", "sgn"],
+        "min": ["min", "ms"],
+        "mnp": ["mnp", "zh"],
+        "mqg": ["mqg", "ms"],
+        "mre": ["mre", "sgn"],
+        "msd": ["msd", "sgn"],
+        "msi": ["msi", "ms"],
+        "msr": ["msr", "sgn"],
+        "mui": ["mui", "ms"],
+        "mzc": ["mzc", "sgn"],
+        "mzg": ["mzg", "sgn"],
+        "mzy": ["mzy", "sgn"],
+        "nan": ["nan", "zh"],
+        "nbs": ["nbs", "sgn"],
+        "ncs": ["ncs", "sgn"],
+        "nsi": ["nsi", "sgn"],
+        "nsl": ["nsl", "sgn"],
+        "nsp": ["nsp", "sgn"],
+        "nsr": ["nsr", "sgn"],
+        "nzs": ["nzs", "sgn"],
+        "okl": ["okl", "sgn"],
+        "orn": ["orn", "ms"],
+        "ors": ["ors", "ms"],
+        "pel": ["pel", "ms"],
+        "pga": ["pga", "ar"],
+        "pks": ["pks", "sgn"],
+        "prl": ["prl", "sgn"],
+        "prz": ["prz", "sgn"],
+        "psc": ["psc", "sgn"],
+        "psd": ["psd", "sgn"],
+        "pse": ["pse", "ms"],
+        "psg": ["psg", "sgn"],
+        "psl": ["psl", "sgn"],
+        "pso": ["pso", "sgn"],
+        "psp": ["psp", "sgn"],
+        "psr": ["psr", "sgn"],
+        "pys": ["pys", "sgn"],
+        "rms": ["rms", "sgn"],
+        "rsi": ["rsi", "sgn"],
+        "rsl": ["rsl", "sgn"],
+        "sdl": ["sdl", "sgn"],
+        "sfb": ["sfb", "sgn"],
+        "sfs": ["sfs", "sgn"],
+        "sgg": ["sgg", "sgn"],
+        "sgx": ["sgx", "sgn"],
+        "shu": ["shu", "ar"],
+        "slf": ["slf", "sgn"],
+        "sls": ["sls", "sgn"],
+        "sqs": ["sqs", "sgn"],
+        "ssh": ["ssh", "ar"],
+        "ssp": ["ssp", "sgn"],
+        "ssr": ["ssr", "sgn"],
+        "svk": ["svk", "sgn"],
+        "swc": ["swc", "sw"],
+        "swh": ["swh", "sw"],
+        "swl": ["swl", "sgn"],
+        "syy": ["syy", "sgn"],
+        "tmw": ["tmw", "ms"],
+        "tse": ["tse", "sgn"],
+        "tsm": ["tsm", "sgn"],
+        "tsq": ["tsq", "sgn"],
+        "tss": ["tss", "sgn"],
+        "tsy": ["tsy", "sgn"],
+        "tza": ["tza", "sgn"],
+        "ugn": ["ugn", "sgn"],
+        "ugy": ["ugy", "sgn"],
+        "ukl": ["ukl", "sgn"],
+        "uks": ["uks", "sgn"],
+        "urk": ["urk", "ms"],
+        "uzn": ["uzn", "uz"],
+        "uzs": ["uzs", "uz"],
+        "vgt": ["vgt", "sgn"],
+        "vkk": ["vkk", "ms"],
+        "vkt": ["vkt", "ms"],
+        "vsi": ["vsi", "sgn"],
+        "vsl": ["vsl", "sgn"],
+        "vsv": ["vsv", "sgn"],
+        "wuu": ["wuu", "zh"],
+        "xki": ["xki", "sgn"],
+        "xml": ["xml", "sgn"],
+        "xmm": ["xmm", "ms"],
+        "xms": ["xms", "sgn"],
+        "yds": ["yds", "sgn"],
+        "ysl": ["ysl", "sgn"],
+        "yue": ["yue", "zh"],
+        "zib": ["zib", "sgn"],
+        "zlm": ["zlm", "ms"],
+        "zmi": ["zmi", "ms"],
+        "zsl": ["zsl", "sgn"],
+        "zsm": ["zsm", "ms"]
+    };
+
+
+    /**
+     * Canonicalizes the given well-formed BCP 47 language tag, including regularized case of subtags.
+     *
+     * Spec: ECMAScript Internationalization API Specification, draft, 6.2.3.
+     * Spec: RFC 5646, section 4.5.
+     */
+    function canonicalizeLanguageTag(locale) {
+
+        // start with lower case for easier processing, and because most subtags will need to be lower case anyway
+        locale = locale.toLowerCase();
+
+        // handle mappings for complete tags
+        if (__tagMappings.hasOwnProperty(locale)) {
+            return __tagMappings[locale];
+        }
+
+        var subtags = locale.split("-");
+        var i = 0;
+
+        // handle standard part: all subtags before first singleton or "x"
+        while (i < subtags.length) {
+            var subtag = subtags[i];
+            if (subtag.length === 1 && (i > 0 || subtag === "x")) {
+                break;
+            } else if (i !== 0 && subtag.length === 2) {
+                subtag = subtag.toUpperCase();
+            } else if (subtag.length === 4) {
+                subtag = subtag[0].toUpperCase() + subtag.substring(1).toLowerCase();
+            }
+            if (__subtagMappings.hasOwnProperty(subtag)) {
+                subtag = __subtagMappings[subtag];
+            } else if (__extlangMappings.hasOwnProperty(subtag)) {
+                subtag = __extlangMappings[subtag][0];
+                if (i === 1 && __extlangMappings[subtag][1] === subtags[0]) {
+                    subtags.shift();
+                    i--;
+                }
+            }
+            subtags[i] = subtag;
+            i++;
+        }
+        var normal = subtags.slice(0, i).join("-");
+
+        // handle extensions
+        var extensions = [];
+        while (i < subtags.length && subtags[i] !== "x") {
+            var extensionStart = i;
+            i++;
+            while (i < subtags.length && subtags[i].length > 1) {
+                i++;
+            }
+            var extension = subtags.slice(extensionStart, i).join("-");
+            extensions.push(extension);
+        }
+        extensions.sort();
+
+        // handle private use
+        var privateUse;
+        if (i < subtags.length) {
+            privateUse = subtags.slice(i).join("-");
+        }
+
+        // put everything back together
+        var canonical = normal;
+        if (extensions.length > 0) {
+            canonical += "-" + extensions.join("-");
+        }
+        if (privateUse !== undefined) {
+            if (canonical.length > 0) {
+                canonical += "-" + privateUse;
+            } else {
+                canonical = privateUse;
+            }
+        }
+
+        return canonical;
+    }
+
+    return typeof locale === "string" && isStructurallyValidLanguageTag(locale) &&
+            canonicalizeLanguageTag(locale) === locale;
+}
+