path: root/js/src/builtin/intl/DateTimeFormat.js

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/********** Intl.DateTimeFormat **********/


/**
 * Compute an internal properties object from |lazyDateTimeFormatData|.
 */
function resolveDateTimeFormatInternals(lazyDateTimeFormatData) {
    assert(IsObject(lazyDateTimeFormatData), "lazy data not an object?");

    // Lazy DateTimeFormat data has the following structure:
    //
    //   {
    //     requestedLocales: List of locales,
    //
    //     localeOpt: // *first* opt computed in InitializeDateTimeFormat
    //       {
    //         localeMatcher: "lookup" / "best fit",
    //
    //         hour12: true / false,  // optional
    //       }
    //
    //     timeZone: IANA time zone name,
    //
    //     formatOpt: // *second* opt computed in InitializeDateTimeFormat
    //       {
    //         // all the properties/values listed in Table 3
    //         // (weekday, era, year, month, day, &c.)
    //       }
    //
    //     formatMatcher: "basic" / "best fit",
    //   }
    //
    // Note that lazy data is only installed as a final step of initialization,
    // so every DateTimeFormat lazy data object has *all* these properties,
    // never a subset of them.

    var internalProps = std_Object_create(null);

    // Compute effective locale.
    // Step 8.
    var DateTimeFormat = dateTimeFormatInternalProperties;

    // Step 9.
    var localeData = DateTimeFormat.localeData;

    // Step 10.
    var r = ResolveLocale(callFunction(DateTimeFormat.availableLocales, DateTimeFormat),
                          lazyDateTimeFormatData.requestedLocales,
                          lazyDateTimeFormatData.localeOpt,
                          DateTimeFormat.relevantExtensionKeys,
                          localeData);

    // Steps 11-13.
    internalProps.locale = r.locale;
    internalProps.calendar = r.ca;
    internalProps.numberingSystem = r.nu;

    // Compute formatting options.
    // Step 14.
    var dataLocale = r.dataLocale;

    // Steps 15-17.
    var tz = lazyDateTimeFormatData.timeZone;
    if (tz === undefined) {
        // Step 16.
        tz = DefaultTimeZone();
    }
    internalProps.timeZone = tz;

    // Step 18.
    var formatOpt = lazyDateTimeFormatData.formatOpt;

    // Steps 27-28, more or less - see comment after this function.
    var pattern = toBestICUPattern(dataLocale, formatOpt);

    // Step 29.
    internalProps.pattern = pattern;

    // Step 30.
    internalProps.boundFormat = undefined;

    // The caller is responsible for associating |internalProps| with the right
    // object using |setInternalProperties|.
    return internalProps;
}


/**
 * Returns an object containing the DateTimeFormat internal properties of |obj|,
 * or throws a TypeError if |obj| isn't DateTimeFormat-initialized.
 */
function getDateTimeFormatInternals(obj, methodName) {
    var internals = getIntlObjectInternals(obj, "DateTimeFormat", methodName);
    assert(internals.type === "DateTimeFormat", "bad type escaped getIntlObjectInternals");

    // If internal properties have already been computed, use them.
    var internalProps = maybeInternalProperties(internals);
    if (internalProps)
        return internalProps;

    // Otherwise it's time to fully create them.
    internalProps = resolveDateTimeFormatInternals(internals.lazyData);
    setInternalProperties(internals, internalProps);
    return internalProps;
}

/**
 * Components of date and time formats and their values.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.1.1.
 */
var dateTimeComponentValues = {
    weekday: ["narrow", "short", "long"],
    era: ["narrow", "short", "long"],
    year: ["2-digit", "numeric"],
    month: ["2-digit", "numeric", "narrow", "short", "long"],
    day: ["2-digit", "numeric"],
    hour: ["2-digit", "numeric"],
    minute: ["2-digit", "numeric"],
    second: ["2-digit", "numeric"],
    timeZoneName: ["short", "long"]
};


var dateTimeComponents = std_Object_getOwnPropertyNames(dateTimeComponentValues);

var timeZoneCache = {
    icuDefaultTimeZone: undefined,
    defaultTimeZone: undefined,
};


/**
 * 6.4.2 CanonicalizeTimeZoneName ( timeZone )
 *
 * Canonicalizes the given IANA time zone name.
 *
 * ES2017 Intl draft rev 4a23f407336d382ed5e3471200c690c9b020b5f3
 */
function CanonicalizeTimeZoneName(timeZone) {
    assert(typeof timeZone === "string", "CanonicalizeTimeZoneName");

    // Step 1. (Not applicable, the input is already a valid IANA time zone.)
    assert(timeZone !== "Etc/Unknown", "Invalid time zone");
    assert(timeZone === intl_IsValidTimeZoneName(timeZone), "Time zone name not normalized");

    // Step 2.
    var ianaTimeZone = intl_canonicalizeTimeZone(timeZone);
    assert(ianaTimeZone !== "Etc/Unknown", "Invalid canonical time zone");
    assert(ianaTimeZone === intl_IsValidTimeZoneName(ianaTimeZone), "Unsupported canonical time zone");

    // Step 3.
    if (ianaTimeZone === "Etc/UTC" || ianaTimeZone === "Etc/GMT") {
        // ICU/CLDR canonicalizes Etc/UCT to Etc/GMT, but following IANA and
        // ECMA-402 to the letter means Etc/UCT is a separate time zone.
        if (timeZone === "Etc/UCT" || timeZone === "UCT")
            ianaTimeZone = "Etc/UCT";
        else
            ianaTimeZone = "UTC";
    }

    // Step 4.
    return ianaTimeZone;
}


/**
 * 6.4.3 DefaultTimeZone ()
 *
 * Returns the IANA time zone name for the host environment's current time zone.
 *
 * ES2017 Intl draft rev 4a23f407336d382ed5e3471200c690c9b020b5f3
 */
function DefaultTimeZone() {
    const icuDefaultTimeZone = intl_defaultTimeZone();
    if (timeZoneCache.icuDefaultTimeZone === icuDefaultTimeZone)
        return timeZoneCache.defaultTimeZone;

    // Verify that the current ICU time zone is a valid ECMA-402 time zone.
    var timeZone = intl_IsValidTimeZoneName(icuDefaultTimeZone);
    if (timeZone === null) {
        // Before defaulting to "UTC", try to represent the default time zone
        // using the Etc/GMT + offset format. This format only accepts full
        // hour offsets.
        const msPerHour = 60 * 60 * 1000;
        var offset = intl_defaultTimeZoneOffset();
        assert(offset === (offset | 0),
               "milliseconds offset shouldn't be able to exceed int32_t range");
        var offsetHours = offset / msPerHour, offsetHoursFraction = offset % msPerHour;
        if (offsetHoursFraction === 0) {
            // Etc/GMT + offset uses POSIX-style signs, i.e. a positive offset
            // means a location west of GMT.
            timeZone = "Etc/GMT" + (offsetHours < 0 ? "+" : "-") + std_Math_abs(offsetHours);

            // Check if the fallback is valid.
            timeZone = intl_IsValidTimeZoneName(timeZone);
        }

        // Fallback to "UTC" if everything else fails.
        if (timeZone === null)
            timeZone = "UTC";
    }

    // Canonicalize the ICU time zone, e.g. change Etc/UTC to UTC.
    var defaultTimeZone = CanonicalizeTimeZoneName(timeZone);

    timeZoneCache.defaultTimeZone = defaultTimeZone;
    timeZoneCache.icuDefaultTimeZone = icuDefaultTimeZone;

    return defaultTimeZone;
}

/**
 * Initializes an object as a DateTimeFormat.
 *
 * This method is complicated a moderate bit by its implementing initialization
 * as a *lazy* concept.  Everything that must happen now, does -- but we defer
 * all the work we can until the object is actually used as a DateTimeFormat.
 * This later work occurs in |resolveDateTimeFormatInternals|; steps not noted
 * here occur there.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.1.1.
 */
function InitializeDateTimeFormat(dateTimeFormat, locales, options) {
    assert(IsObject(dateTimeFormat), "InitializeDateTimeFormat");

    // Step 1.
    if (isInitializedIntlObject(dateTimeFormat))
        ThrowTypeError(JSMSG_INTL_OBJECT_REINITED);

    // Step 2.
    var internals = initializeIntlObject(dateTimeFormat);

    // Lazy DateTimeFormat data has the following structure:
    //
    //   {
    //     requestedLocales: List of locales,
    //
    //     localeOpt: // *first* opt computed in InitializeDateTimeFormat
    //       {
    //         localeMatcher: "lookup" / "best fit",
    //       }
    //
    //     timeZone: IANA time zone name,
    //
    //     formatOpt: // *second* opt computed in InitializeDateTimeFormat
    //       {
    //         // all the properties/values listed in Table 3
    //         // (weekday, era, year, month, day, &c.)
    //
    //         hour12: true / false  // optional
    //       }
    //
    //     formatMatcher: "basic" / "best fit",
    //   }
    //
    // Note that lazy data is only installed as a final step of initialization,
    // so every DateTimeFormat lazy data object has *all* these properties,
    // never a subset of them.
    var lazyDateTimeFormatData = std_Object_create(null);

    // Step 3.
    var requestedLocales = CanonicalizeLocaleList(locales);
    lazyDateTimeFormatData.requestedLocales = requestedLocales;

    // Step 4.
    options = ToDateTimeOptions(options, "any", "date");

    // Compute options that impact interpretation of locale.
    // Step 5.
    var localeOpt = new Record();
    lazyDateTimeFormatData.localeOpt = localeOpt;

    // Steps 6-7.
    var localeMatcher =
        GetOption(options, "localeMatcher", "string", ["lookup", "best fit"],
                  "best fit");
    localeOpt.localeMatcher = localeMatcher;

    // Steps 15-17.
    var tz = options.timeZone;
    if (tz !== undefined) {
        // Step 15.a.
        tz = ToString(tz);

        // Step 15.b.
        var timeZone = intl_IsValidTimeZoneName(tz);
        if (timeZone === null)
            ThrowRangeError(JSMSG_INVALID_TIME_ZONE, tz);

        // Step 15.c.
        tz = CanonicalizeTimeZoneName(timeZone);
    }
    lazyDateTimeFormatData.timeZone = tz;

    // Step 18.
    var formatOpt = new Record();
    lazyDateTimeFormatData.formatOpt = formatOpt;

    // Step 19.
    var i, prop;
    for (i = 0; i < dateTimeComponents.length; i++) {
        prop = dateTimeComponents[i];
        var value = GetOption(options, prop, "string", dateTimeComponentValues[prop], undefined);
        formatOpt[prop] = value;
    }

    // Steps 20-21 provided by ICU - see comment after this function.

    // Step 22.
    //
    // For some reason (ICU not exposing enough interface?) we drop the
    // requested format matcher on the floor after this.  In any case, even if
    // doing so is justified, we have to do this work here in case it triggers
    // getters or similar. (bug 852837)
    var formatMatcher =
        GetOption(options, "formatMatcher", "string", ["basic", "best fit"],
                  "best fit");

    // Steps 23-25 provided by ICU, more or less - see comment after this function.

    // Step 26.
    var hr12  = GetOption(options, "hour12", "boolean", undefined, undefined);

    // Pass hr12 on to ICU.
    if (hr12 !== undefined)
        formatOpt.hour12 = hr12;

    // Step 31.
    //
    // We've done everything that must be done now: mark the lazy data as fully
    // computed and install it.
    setLazyData(internals, "DateTimeFormat", lazyDateTimeFormatData);
}


// Intl.DateTimeFormat and ICU skeletons and patterns
// ==================================================
//
// Different locales have different ways to display dates using the same
// basic components. For example, en-US might use "Sept. 24, 2012" while
// fr-FR might use "24 Sept. 2012". The intent of Intl.DateTimeFormat is to
// permit production of a format for the locale that best matches the
// set of date-time components and their desired representation as specified
// by the API client.
//
// ICU supports specification of date and time formats in three ways:
//
// 1) A style is just one of the identifiers FULL, LONG, MEDIUM, or SHORT.
//    The date-time components included in each style and their representation
//    are defined by ICU using CLDR locale data (CLDR is the Unicode
//    Consortium's Common Locale Data Repository).
//
// 2) A skeleton is a string specifying which date-time components to include,
//    and which representations to use for them. For example, "yyyyMMMMdd"
//    specifies a year with at least four digits, a full month name, and a
//    two-digit day. It does not specify in which order the components appear,
//    how they are separated, the localized strings for textual components
//    (such as weekday or month), whether the month is in format or
//    stand-alone form¹, or the numbering system used for numeric components.
//    All that information is filled in by ICU using CLDR locale data.
//    ¹ The format form is the one used in formatted strings that include a
//    day; the stand-alone form is used when not including days, e.g., in
//    calendar headers. The two forms differ at least in some Slavic languages,
//    e.g. Russian: "22 марта 2013 г." vs. "Март 2013".
//
// 3) A pattern is a string specifying which date-time components to include,
//    in which order, with which separators, in which grammatical case. For
//    example, "EEEE, d MMMM y" specifies the full localized weekday name,
//    followed by comma and space, followed by the day, followed by space,
//    followed by the full month name in format form, followed by space,
//    followed by the full year. It
//    still does not specify localized strings for textual components and the
//    numbering system - these are determined by ICU using CLDR locale data or
//    possibly API parameters.
//
// All actual formatting in ICU is done with patterns; styles and skeletons
// have to be mapped to patterns before processing.
//
// The options of DateTimeFormat most closely correspond to ICU skeletons. This
// implementation therefore, in the toBestICUPattern function, converts
// DateTimeFormat options to ICU skeletons, and then lets ICU map skeletons to
// actual ICU patterns. The pattern may not directly correspond to what the
// skeleton requests, as the mapper (UDateTimePatternGenerator) is constrained
// by the available locale data for the locale. The resulting ICU pattern is
// kept as the DateTimeFormat's [[pattern]] internal property and passed to ICU
// in the format method.
//
// An ICU pattern represents the information of the following DateTimeFormat
// internal properties described in the specification, which therefore don't
// exist separately in the implementation:
// - [[weekday]], [[era]], [[year]], [[month]], [[day]], [[hour]], [[minute]],
//   [[second]], [[timeZoneName]]
// - [[hour12]]
// - [[hourNo0]]
// When needed for the resolvedOptions method, the resolveICUPattern function
// maps the instance's ICU pattern back to the specified properties of the
// object returned by resolvedOptions.
//
// ICU date-time skeletons and patterns aren't fully documented in the ICU
// documentation (see http://bugs.icu-project.org/trac/ticket/9627). The best
// documentation at this point is in UTR 35:
// http://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns


/**
 * Returns an ICU pattern string for the given locale and representing the
 * specified options as closely as possible given available locale data.
 */
function toBestICUPattern(locale, options) {
    // Create an ICU skeleton representing the specified options. See
    // http://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
    var skeleton = "";
    switch (options.weekday) {
    case "narrow":
        skeleton += "EEEEE";
        break;
    case "short":
        skeleton += "E";
        break;
    case "long":
        skeleton += "EEEE";
    }
    switch (options.era) {
    case "narrow":
        skeleton += "GGGGG";
        break;
    case "short":
        skeleton += "G";
        break;
    case "long":
        skeleton += "GGGG";
        break;
    }
    switch (options.year) {
    case "2-digit":
        skeleton += "yy";
        break;
    case "numeric":
        skeleton += "y";
        break;
    }
    switch (options.month) {
    case "2-digit":
        skeleton += "MM";
        break;
    case "numeric":
        skeleton += "M";
        break;
    case "narrow":
        skeleton += "MMMMM";
        break;
    case "short":
        skeleton += "MMM";
        break;
    case "long":
        skeleton += "MMMM";
        break;
    }
    switch (options.day) {
    case "2-digit":
        skeleton += "dd";
        break;
    case "numeric":
        skeleton += "d";
        break;
    }
    var hourSkeletonChar = "j";
    if (options.hour12 !== undefined) {
        if (options.hour12)
            hourSkeletonChar = "h";
        else
            hourSkeletonChar = "H";
    }
    switch (options.hour) {
    case "2-digit":
        skeleton += hourSkeletonChar + hourSkeletonChar;
        break;
    case "numeric":
        skeleton += hourSkeletonChar;
        break;
    }
    switch (options.minute) {
    case "2-digit":
        skeleton += "mm";
        break;
    case "numeric":
        skeleton += "m";
        break;
    }
    switch (options.second) {
    case "2-digit":
        skeleton += "ss";
        break;
    case "numeric":
        skeleton += "s";
        break;
    }
    switch (options.timeZoneName) {
    case "short":
        skeleton += "z";
        break;
    case "long":
        skeleton += "zzzz";
        break;
    }

    // Let ICU convert the ICU skeleton to an ICU pattern for the given locale.
    return intl_patternForSkeleton(locale, skeleton);
}


/**
 * Returns a new options object that includes the provided options (if any)
 * and fills in default components if required components are not defined.
 * Required can be "date", "time", or "any".
 * Defaults can be "date", "time", or "all".
 *
 * Spec: ECMAScript Internationalization API Specification, 12.1.1.
 */
function ToDateTimeOptions(options, required, defaults) {
    assert(typeof required === "string", "ToDateTimeOptions");
    assert(typeof defaults === "string", "ToDateTimeOptions");

    // Steps 1-3.
    if (options === undefined)
        options = null;
    else
        options = ToObject(options);
    options = std_Object_create(options);

    // Step 4.
    var needDefaults = true;

    // Step 5.
    if ((required === "date" || required === "any") &&
        (options.weekday !== undefined || options.year !== undefined ||
         options.month !== undefined || options.day !== undefined))
    {
        needDefaults = false;
    }

    // Step 6.
    if ((required === "time" || required === "any") &&
        (options.hour !== undefined || options.minute !== undefined ||
         options.second !== undefined))
    {
        needDefaults = false;
    }

    // Step 7.
    if (needDefaults && (defaults === "date" || defaults === "all")) {
        // The specification says to call [[DefineOwnProperty]] with false for
        // the Throw parameter, while Object.defineProperty uses true. For the
        // calls here, the difference doesn't matter because we're adding
        // properties to a new object.
        _DefineDataProperty(options, "year", "numeric");
        _DefineDataProperty(options, "month", "numeric");
        _DefineDataProperty(options, "day", "numeric");
    }

    // Step 8.
    if (needDefaults && (defaults === "time" || defaults === "all")) {
        // See comment for step 7.
        _DefineDataProperty(options, "hour", "numeric");
        _DefineDataProperty(options, "minute", "numeric");
        _DefineDataProperty(options, "second", "numeric");
    }

    // Step 9.
    return options;
}


/**
 * Compares the date and time components requested by options with the available
 * date and time formats in formats, and selects the best match according
 * to a specified basic matching algorithm.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.1.1.
 */
function BasicFormatMatcher(options, formats) {
    // Steps 1-6.
    var removalPenalty = 120,
        additionPenalty = 20,
        longLessPenalty = 8,
        longMorePenalty = 6,
        shortLessPenalty = 6,
        shortMorePenalty = 3;

    // Table 3.
    var properties = ["weekday", "era", "year", "month", "day",
        "hour", "minute", "second", "timeZoneName"];

    // Step 11.c.vi.1.
    var values = ["2-digit", "numeric", "narrow", "short", "long"];

    // Steps 7-8.
    var bestScore = -Infinity;
    var bestFormat;

    // Steps 9-11.
    var i = 0;
    var len = formats.length;
    while (i < len) {
        // Steps 11.a-b.
        var format = formats[i];
        var score = 0;

        // Step 11.c.
        var formatProp;
        for (var j = 0; j < properties.length; j++) {
            var property = properties[j];

            // Step 11.c.i.
            var optionsProp = options[property];
            // Step missing from spec.
            // https://bugs.ecmascript.org/show_bug.cgi?id=1254
            formatProp = undefined;

            // Steps 11.c.ii-iii.
            if (callFunction(std_Object_hasOwnProperty, format, property))
                formatProp = format[property];

            if (optionsProp === undefined && formatProp !== undefined) {
                // Step 11.c.iv.
                score -= additionPenalty;
            } else if (optionsProp !== undefined && formatProp === undefined) {
                // Step 11.c.v.
                score -= removalPenalty;
            } else {
                // Step 11.c.vi.
                var optionsPropIndex = callFunction(ArrayIndexOf, values, optionsProp);
                var formatPropIndex = callFunction(ArrayIndexOf, values, formatProp);
                var delta = std_Math_max(std_Math_min(formatPropIndex - optionsPropIndex, 2), -2);
                if (delta === 2)
                    score -= longMorePenalty;
                else if (delta === 1)
                    score -= shortMorePenalty;
                else if (delta === -1)
                    score -= shortLessPenalty;
                else if (delta === -2)
                    score -= longLessPenalty;
            }
        }

        // Step 11.d.
        if (score > bestScore) {
            bestScore = score;
            bestFormat = format;
        }

        // Step 11.e.
        i++;
    }

    // Step 12.
    return bestFormat;
}


/**
 * Compares the date and time components requested by options with the available
 * date and time formats in formats, and selects the best match according
 * to an unspecified best-fit matching algorithm.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.1.1.
 */
function BestFitFormatMatcher(options, formats) {
    // this implementation doesn't have anything better
    return BasicFormatMatcher(options, formats);
}


/**
 * Returns the subset of the given locale list for which this locale list has a
 * matching (possibly fallback) locale. Locales appear in the same order in the
 * returned list as in the input list.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.2.2.
 */
function Intl_DateTimeFormat_supportedLocalesOf(locales /*, options*/) {
    var options = arguments.length > 1 ? arguments[1] : undefined;

    var availableLocales = callFunction(dateTimeFormatInternalProperties.availableLocales,
                                        dateTimeFormatInternalProperties);
    var requestedLocales = CanonicalizeLocaleList(locales);
    return SupportedLocales(availableLocales, requestedLocales, options);
}


/**
 * DateTimeFormat internal properties.
 *
 * Spec: ECMAScript Internationalization API Specification, 9.1 and 12.2.3.
 */
var dateTimeFormatInternalProperties = {
    localeData: dateTimeFormatLocaleData,
    _availableLocales: null,
    availableLocales: function()
    {
        var locales = this._availableLocales;
        if (locales)
            return locales;

        locales = intl_DateTimeFormat_availableLocales();
        addSpecialMissingLanguageTags(locales);
        return (this._availableLocales = locales);
    },
    relevantExtensionKeys: ["ca", "nu"]
};


function dateTimeFormatLocaleData(locale) {
    return {
        ca: intl_availableCalendars(locale),
        nu: getNumberingSystems(locale)
    };
}


/**
 * Function to be bound and returned by Intl.DateTimeFormat.prototype.format.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.3.2.
 */
function dateTimeFormatFormatToBind() {
    // Steps 1.a.i-ii
    var date = arguments.length > 0 ? arguments[0] : undefined;
    var x = (date === undefined) ? std_Date_now() : ToNumber(date);

    // Step 1.a.iii.
    return intl_FormatDateTime(this, x, false);
}

/**
 * Returns a function bound to this DateTimeFormat that returns a String value
 * representing the result of calling ToNumber(date) according to the
 * effective locale and the formatting options of this DateTimeFormat.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.3.2.
 */
function Intl_DateTimeFormat_format_get() {
    // Check "this DateTimeFormat object" per introduction of section 12.3.
    var internals = getDateTimeFormatInternals(this, "format");

    // Step 1.
    if (internals.boundFormat === undefined) {
        // Step 1.a.
        var F = dateTimeFormatFormatToBind;

        // Step 1.b-d.
        var bf = callFunction(FunctionBind, F, this);
        internals.boundFormat = bf;
    }

    // Step 2.
    return internals.boundFormat;
}


function Intl_DateTimeFormat_formatToParts() {
    // Check "this DateTimeFormat object" per introduction of section 12.3.
    getDateTimeFormatInternals(this, "formatToParts");

    // Steps 1.a.i-ii
    var date = arguments.length > 0 ? arguments[0] : undefined;
    var x = (date === undefined) ? std_Date_now() : ToNumber(date);

    // Step 1.a.iii.
    return intl_FormatDateTime(this, x, true);
}


/**
 * Returns the resolved options for a DateTimeFormat object.
 *
 * Spec: ECMAScript Internationalization API Specification, 12.3.3 and 12.4.
 */
function Intl_DateTimeFormat_resolvedOptions() {
    // Check "this DateTimeFormat object" per introduction of section 12.3.
    var internals = getDateTimeFormatInternals(this, "resolvedOptions");

    var result = {
        locale: internals.locale,
        calendar: internals.calendar,
        numberingSystem: internals.numberingSystem,
        timeZone: internals.timeZone
    };
    resolveICUPattern(internals.pattern, result);
    return result;
}


// Table mapping ICU pattern characters back to the corresponding date-time
// components of DateTimeFormat. See
// http://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
var icuPatternCharToComponent = {
    E: "weekday",
    G: "era",
    y: "year",
    M: "month",
    L: "month",
    d: "day",
    h: "hour",
    H: "hour",
    k: "hour",
    K: "hour",
    m: "minute",
    s: "second",
    z: "timeZoneName",
    v: "timeZoneName",
    V: "timeZoneName"
};


/**
 * Maps an ICU pattern string to a corresponding set of date-time components
 * and their values, and adds properties for these components to the result
 * object, which will be returned by the resolvedOptions method. For the
 * interpretation of ICU pattern characters, see
 * http://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
 */
function resolveICUPattern(pattern, result) {
    assert(IsObject(result), "resolveICUPattern");
    var i = 0;
    while (i < pattern.length) {
        var c = pattern[i++];
        if (c === "'") {
            while (i < pattern.length && pattern[i] !== "'")
                i++;
            i++;
        } else {
            var count = 1;
            while (i < pattern.length && pattern[i] === c) {
                i++;
                count++;
            }
            var value;
            switch (c) {
            // "text" cases
            case "G":
            case "E":
            case "z":
            case "v":
            case "V":
                if (count <= 3)
                    value = "short";
                else if (count === 4)
                    value = "long";
                else
                    value = "narrow";
                break;
            // "number" cases
            case "y":
            case "d":
            case "h":
            case "H":
            case "m":
            case "s":
            case "k":
            case "K":
                if (count === 2)
                    value = "2-digit";
                else
                    value = "numeric";
                break;
            // "text & number" cases
            case "M":
            case "L":
                if (count === 1)
                    value = "numeric";
                else if (count === 2)
                    value = "2-digit";
                else if (count === 3)
                    value = "short";
                else if (count === 4)
                    value = "long";
                else
                    value = "narrow";
                break;
            default:
                // skip other pattern characters and literal text
            }
            if (callFunction(std_Object_hasOwnProperty, icuPatternCharToComponent, c))
                _DefineDataProperty(result, icuPatternCharToComponent[c], value);
            if (c === "h" || c === "K")
                _DefineDataProperty(result, "hour12", true);
            else if (c === "H" || c === "k")
                _DefineDataProperty(result, "hour12", false);
        }
    }
}