jsdate.c

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
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 *
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/*
 * JS date methods.
 */

/*
 * "For example, OS/360 devotes 26 bytes of the permanently
 *  resident date-turnover routine to the proper handling of
 *  December 31 on leap years (when it is Day 366).  That
 *  might have been left to the operator."
 *
 * Frederick Brooks, 'The Second-System Effect'.
 */

#include "jsstddef.h"
#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsprf.h"
#include "prmjtime.h"
#include "jsutil.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsconfig.h"
#include "jscntxt.h"
#include "jsdate.h"
#include "jsinterp.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsstr.h"

/*
 * The JS 'Date' object is patterned after the Java 'Date' object.
 * Here is an script:
 *
 *    today = new Date();
 *
 *    print(today.toLocaleString());
 *
 *    weekDay = today.getDay();
 *
 *
 * These Java (and ECMA-262) methods are supported:
 *
 *     UTC
 *     getDate (getUTCDate)
 *     getDay (getUTCDay)
 *     getHours (getUTCHours)
 *     getMinutes (getUTCMinutes)
 *     getMonth (getUTCMonth)
 *     getSeconds (getUTCSeconds)
 *     getMilliseconds (getUTCMilliseconds)
 *     getTime
 *     getTimezoneOffset
 *     getYear
 *     getFullYear (getUTCFullYear)
 *     parse
 *     setDate (setUTCDate)
 *     setHours (setUTCHours)
 *     setMinutes (setUTCMinutes)
 *     setMonth (setUTCMonth)
 *     setSeconds (setUTCSeconds)
 *     setMilliseconds (setUTCMilliseconds)
 *     setTime
 *     setYear (setFullYear, setUTCFullYear)
 *     toGMTString (toUTCString)
 *     toLocaleString
 *     toString
 *
 *
 * These Java methods are not supported
 *
 *     setDay
 *     before
 *     after
 *     equals
 *     hashCode
 */

/*
 * 11/97 - jsdate.c has been rewritten to conform to the ECMA-262 language
 * definition and reduce dependence on NSPR.  NSPR is used to get the current
 * time in milliseconds, the time zone offset, and the daylight savings time
 * offset for a given time.  NSPR is also used for Date.toLocaleString(), for
 * locale-specific formatting, and to get a string representing the timezone.
 * (Which turns out to be platform-dependent.)
 *
 * To do:
 * (I did some performance tests by timing how long it took to run what
 *  I had of the js ECMA conformance tests.)
 *
 * - look at saving results across multiple calls to supporting
 * functions; the toString functions compute some of the same values
 * multiple times.  Although - I took a quick stab at this, and I lost
 * rather than gained.  (Fractionally.)  Hard to tell what compilers/processors
 * are doing these days.
 *
 * - look at tweaking function return types to return double instead
 * of int; this seems to make things run slightly faster sometimes.
 * (though it could be architecture-dependent.)  It'd be good to see
 * how this does on win32.  (Tried it on irix.)  Types could use a
 * general going-over.
 */

/*
 * Supporting functions - ECMA 15.9.1.*
 */

#define HalfTimeDomain  8.64e15
#define HoursPerDay     24.0
#define MinutesPerDay   (HoursPerDay * MinutesPerHour)
#define MinutesPerHour  60.0
#define SecondsPerDay   (MinutesPerDay * SecondsPerMinute)
#define SecondsPerHour  (MinutesPerHour * SecondsPerMinute)
#define SecondsPerMinute 60.0

#if defined(XP_WIN) || defined(XP_OS2)
/* Work around msvc double optimization bug by making these runtime values; if
 * they're available at compile time, msvc optimizes division by them by
 * computing the reciprocal and multiplying instead of dividing - this loses
 * when the reciprocal isn't representable in a double.
 */
static jsdouble msPerSecond = 1000.0;
static jsdouble msPerDay = SecondsPerDay * 1000.0;
static jsdouble msPerHour = SecondsPerHour * 1000.0;
static jsdouble msPerMinute = SecondsPerMinute * 1000.0;
#else
#define msPerDay        (SecondsPerDay * msPerSecond)
#define msPerHour       (SecondsPerHour * msPerSecond)
#define msPerMinute     (SecondsPerMinute * msPerSecond)
#define msPerSecond     1000.0
#endif

#define Day(t)          floor((t) / msPerDay)

static jsdouble
TimeWithinDay(jsdouble t)
{
    jsdouble result;
    result = fmod(t, msPerDay);
    if (result < 0)
	result += msPerDay;
    return result;
}

#define DaysInYear(y)   ((y) % 4 == 0 && ((y) % 100 || ((y) % 400 == 0))  \
			 ? 366 : 365)

/* math here has to be f.p, because we need
 *  floor((1968 - 1969) / 4) == -1
 */
#define DayFromYear(y)  (365 * ((y)-1970) + floor(((y)-1969)/4.0)            \
			 - floor(((y)-1901)/100.0) + floor(((y)-1601)/400.0))
#define TimeFromYear(y) (DayFromYear(y) * msPerDay)

static jsint
YearFromTime(jsdouble t)
{
    jsint y = (jsint) floor(t /(msPerDay*365.2425)) + 1970;
    jsdouble t2 = (jsdouble) TimeFromYear(y);

    if (t2 > t) {
        y--;
    } else {
        if (t2 + msPerDay * DaysInYear(y) <= t)
            y++;
    }
    return y;
}

#define InLeapYear(t)   (JSBool) (DaysInYear(YearFromTime(t)) == 366)

#define DayWithinYear(t, year) ((intN) (Day(t) - DayFromYear(year)))

/*
 * The following array contains the day of year for the first day of
 * each month, where index 0 is January, and day 0 is January 1.
 */
static jsdouble firstDayOfMonth[2][12] = {
    {0.0, 31.0, 59.0, 90.0, 120.0, 151.0, 181.0, 212.0, 243.0, 273.0, 304.0, 334.0},
    {0.0, 31.0, 60.0, 91.0, 121.0, 152.0, 182.0, 213.0, 244.0, 274.0, 305.0, 335.0}
};

#define DayFromMonth(m, leap) firstDayOfMonth[leap][(intN)m];

static intN
MonthFromTime(jsdouble t)
{
    intN d, step;
    jsint year = YearFromTime(t);
    d = DayWithinYear(t, year);

    if (d < (step = 31))
	return 0;
    step += (InLeapYear(t) ? 29 : 28);
    if (d < step)
	return 1;
    if (d < (step += 31))
	return 2;
    if (d < (step += 30))
	return 3;
    if (d < (step += 31))
	return 4;
    if (d < (step += 30))
	return 5;
    if (d < (step += 31))
	return 6;
    if (d < (step += 31))
	return 7;
    if (d < (step += 30))
	return 8;
    if (d < (step += 31))
	return 9;
    if (d < (step += 30))
	return 10;
    return 11;
}

static intN
DateFromTime(jsdouble t)
{
    intN d, step, next;
    jsint year = YearFromTime(t);
    d = DayWithinYear(t, year);

    if (d <= (next = 30))
	return d + 1;
    step = next;
    next += (InLeapYear(t) ? 29 : 28);
    if (d <= next)
	return d - step;
    step = next;
    if (d <= (next += 31))
	return d - step;
    step = next;
    if (d <= (next += 30))
	return d - step;
    step = next;
    if (d <= (next += 31))
	return d - step;
    step = next;
    if (d <= (next += 30))
	return d - step;
    step = next;
    if (d <= (next += 31))
	return d - step;
    step = next;
    if (d <= (next += 31))
	return d - step;
    step = next;
    if (d <= (next += 30))
	return d - step;
    step = next;
    if (d <= (next += 31))
	return d - step;
    step = next;
    if (d <= (next += 30))
	return d - step;
    step = next;
    return d - step;
}

static intN
WeekDay(jsdouble t)
{
    jsint result;
    result = (jsint) Day(t) + 4;
    result = result % 7;
    if (result < 0)
	result += 7;
    return (intN) result;
}

/* LocalTZA gets set by js_InitDateClass() */
static jsdouble LocalTZA;

static jsdouble
DaylightSavingTA(jsdouble t)
{
    volatile int64 PR_t;
    int64 ms2us;
    int64 offset;
    jsdouble result;

    /* abort if NaN */
    if (JSDOUBLE_IS_NaN(t))
	return t;

    /* put our t in an LL, and map it to usec for prtime */
    JSLL_D2L(PR_t, t);
    JSLL_I2L(ms2us, PRMJ_USEC_PER_MSEC);
    JSLL_MUL(PR_t, PR_t, ms2us);

    offset = PRMJ_DSTOffset(PR_t);

    JSLL_DIV(offset, offset, ms2us);
    JSLL_L2D(result, offset);
    return result;
}


#define AdjustTime(t)   fmod(LocalTZA + DaylightSavingTA(t), msPerDay)

#define LocalTime(t)    ((t) + AdjustTime(t))

static jsdouble
UTC(jsdouble t)
{
    return t - AdjustTime(t - LocalTZA);
}

static intN
HourFromTime(jsdouble t)
{
    intN result = (intN) fmod(floor(t/msPerHour), HoursPerDay);
    if (result < 0)
	result += (intN)HoursPerDay;
    return result;
}

static intN
MinFromTime(jsdouble t)
{
    intN result = (intN) fmod(floor(t / msPerMinute), MinutesPerHour);
    if (result < 0)
	result += (intN)MinutesPerHour;
    return result;
}

static intN
SecFromTime(jsdouble t)
{
    intN result = (intN) fmod(floor(t / msPerSecond), SecondsPerMinute);
    if (result < 0)
	result += (intN)SecondsPerMinute;
    return result;
}

static intN
msFromTime(jsdouble t)
{
    intN result = (intN) fmod(t, msPerSecond);
    if (result < 0)
	result += (intN)msPerSecond;
    return result;
}

#define MakeTime(hour, min, sec, ms) \
(((hour * MinutesPerHour + min) * SecondsPerMinute + sec) * msPerSecond + ms)

static jsdouble
MakeDay(jsdouble year, jsdouble month, jsdouble date)
{
    jsdouble result;
    JSBool leap;
    jsdouble yearday;
    jsdouble monthday;

    year += floor(month / 12);

    month = fmod(month, 12.0);
    if (month < 0)
	month += 12;

    leap = (DaysInYear((jsint) year) == 366);

    yearday = floor(TimeFromYear(year) / msPerDay);
    monthday = DayFromMonth(month, leap);

    result = yearday
	     + monthday
	     + date - 1;
    return result;
}

#define MakeDate(day, time) (day * msPerDay + time)

#define TIMECLIP(d) ((JSDOUBLE_IS_FINITE(d) \
		      && !((d < 0 ? -d : d) > HalfTimeDomain)) \
		     ? js_DoubleToInteger(d + (+0.)) : *cx->runtime->jsNaN)

/**
 * end of ECMA 'support' functions
 */

/*
 * Other Support routines and definitions
 */

static JSClass date_class = {
    js_Date_str,
    JSCLASS_HAS_PRIVATE,
    JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,  JS_PropertyStub,
    JS_EnumerateStub, JS_ResolveStub,   JS_ConvertStub,   JS_FinalizeStub,
    JSCLASS_NO_OPTIONAL_MEMBERS
};

/* for use by date_parse */

static const char* wtb[] = {
    "am", "pm",
    "monday", "tuesday", "wednesday", "thursday", "friday",
    "saturday", "sunday",
    "january", "february", "march", "april", "may", "june",
    "july", "august", "september", "october", "november", "december",
    "gmt", "ut", "utc",
    "est", "edt",
    "cst", "cdt",
    "mst", "mdt",
    "pst", "pdt"
    /* time zone table needs to be expanded */
};

static int ttb[] = {
    -1, -2, 0, 0, 0, 0, 0, 0, 0,       /* AM/PM */
    2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
    10000 + 0, 10000 + 0, 10000 + 0,   /* GMT/UT/UTC */
    10000 + 5 * 60, 10000 + 4 * 60,    /* EST/EDT */
    10000 + 6 * 60, 10000 + 5 * 60,    /* CST/CDT */
    10000 + 7 * 60, 10000 + 6 * 60,    /* MST/MDT */
    10000 + 8 * 60, 10000 + 7 * 60     /* PST/PDT */
};

/* helper for date_parse */
static JSBool
date_regionMatches(const char* s1, int s1off, const jschar* s2, int s2off,
		   int count, int ignoreCase)
{
    JSBool result = JS_FALSE;
    /* return true if matches, otherwise, false */

    while (count > 0 && s1[s1off] && s2[s2off]) {
	if (ignoreCase) {
	    if (JS_TOLOWER((jschar)s1[s1off]) != JS_TOLOWER(s2[s2off])) {
		break;
	    }
	} else {
	    if ((jschar)s1[s1off] != s2[s2off]) {
		break;
	    }
	}
	s1off++;
	s2off++;
	count--;
    }

    if (count == 0) {
	result = JS_TRUE;
    }

    return result;
}

/* find UTC time from given date... no 1900 correction! */
static jsdouble
date_msecFromDate(jsdouble year, jsdouble mon, jsdouble mday, jsdouble hour,
		  jsdouble min, jsdouble sec, jsdouble msec)
{
    jsdouble day;
    jsdouble msec_time;
    jsdouble result;

    day = MakeDay(year, mon, mday);
    msec_time = MakeTime(hour, min, sec, msec);
    result = MakeDate(day, msec_time);
    return result;
}

/*
 * See ECMA 15.9.4.[3-10];
 */
/* XXX this function must be above date_parseString to avoid a
   horrid bug in the Win16 1.52 compiler */
#define MAXARGS        7
static JSBool
date_UTC(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
{
    jsdouble array[MAXARGS];
    uintN loop;
    jsdouble d;

    for (loop = 0; loop < MAXARGS; loop++) {
	if (loop < argc) {
	    if (!js_ValueToNumber(cx, argv[loop], &d))
		return JS_FALSE;
	    /* return NaN if any arg is NaN */
	    if (!JSDOUBLE_IS_FINITE(d)) {
		return js_NewNumberValue(cx, d, rval);
	    }
	    array[loop] = floor(d);
	} else {
	    array[loop] = 0;
	}
    }

    /* adjust 2-digit years into the 20th century */
    if (array[0] >= 0 && array[0] <= 99)
	array[0] += 1900;

    /* if we got a 0 for 'date' (which is out of range)
     * pretend it's a 1.  (So Date.UTC(1972, 5) works) */
    if (array[2] < 1)
	array[2] = 1;

    d = date_msecFromDate(array[0], array[1], array[2],
			      array[3], array[4], array[5], array[6]);
    d = TIMECLIP(d);

    return js_NewNumberValue(cx, d, rval);
}

static JSBool
date_parseString(JSString *str, jsdouble *result)
{
    jsdouble msec;

    const jschar *s = JSSTRING_CHARS(str);
    size_t limit = JSSTRING_LENGTH(str);
    size_t i = 0;
    int year = -1;