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ICU-3790 reduce time taken by format() by 25%

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X-SVN-Rev: 15622
This commit is contained in:
Alan Liu 2004-05-28 20:37:11 +00:00
parent a1298b23eb
commit ddb79422d6
1 changed files with 264 additions and 6 deletions
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270
icu4j/src/com/ibm/icu/text/SimpleDateFormat.java
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@ -272,6 +272,12 @@ public class SimpleDateFormat extends DateFormat {
*/
private static Hashtable cachedLocaleData = new Hashtable(3);
/**
* If true, this object supports fast formatting using
* the subFormat variant that takes a StringBuffer.
*/
private transient boolean fastFormat;
/**
* Construct a SimpleDateFormat using the default pattern for the default
* locale. <b>Note:</b> Not all locales support SimpleDateFormat; for full
@ -416,6 +422,11 @@ public class SimpleDateFormat extends DateFormat {
numberFormat.setMinimumFractionDigits(0); // To prevent "Jan 1.00, 1997.00"
initializeDefaultCentury();
// Currently, we only support fast formatting in SimpleDateFormat
// itself. TODO add constructor parameters to allow subclasses
// to say that they implement fast formatting.
fastFormat = (getClass() == SimpleDateFormat.class);
}
/* Initialize the fields we use to disambiguate ambiguous years. Separate
@ -473,8 +484,75 @@ public class SimpleDateFormat extends DateFormat {
* @stable ICU 2.0
*/
public StringBuffer format(Calendar cal, StringBuffer toAppendTo,
FieldPosition pos)
{
FieldPosition pos) {
if (!fastFormat) {
return slowFormat(cal, toAppendTo, pos);
}
// Initialize
pos.setBeginIndex(0);
pos.setEndIndex(0);
// Careful: For best performance, minimize the number of calls
// to StringBuffer.append() by consolidating appends when
// possible.
int j, n = pattern.length();
for (int i=0; i<n; ) {
char ch = pattern.charAt(i);
if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
// ch is a date-time pattern character to be interpreted
// by subFormat(); count the number of times it is repeated
for (j=i+1; j<n && pattern.charAt(j)==ch; ++j) {}
subFormat(toAppendTo, ch, j-i, pos, formatData, cal);
i = j;
} else if (ch == '\'') {
// Handle an entire quoted string, included embedded
// doubled apostrophes (as in 'o''clock').
int start = i+1;
for (;;) {
++i; // i points after '
if (i==n) { // trailing ' (pathological)
break;
}
for (j=i; j<n && pattern.charAt(j)!='\''; ++j) {}
// j points to next ' or EOS
if (j==start) { // '' outside of quotes
toAppendTo.append('\'');
++i;
break;
}
// look ahead to detect '' within quotes
int k = j, jj = j+1;
if (jj<n && pattern.charAt(jj)=='\'') {
++k;
}
// append this run, and if there is '' within
// quotes, append a trailing ' as well
toAppendTo.append(pattern.substring(i, k));
i = jj;
if (k==j) {
break;
}
}
} else {
// Append unquoted literal characters
toAppendTo.append(ch);
++i;
}
}
return toAppendTo;
}
private StringBuffer slowFormat(Calendar cal, StringBuffer toAppendTo,
FieldPosition pos) {
// Initialize
pos.setBeginIndex(0);
pos.setEndIndex(0);
@ -732,6 +810,186 @@ public class SimpleDateFormat extends DateFormat {
return current;
}
/**
* Internal high-speed method. Reuses a StringBuffer for results
* instead of creating a String on the heap for each call.
*/
private void subFormat(StringBuffer buf,
char ch, int count,
FieldPosition pos, DateFormatSymbols formatData,
Calendar cal) {
final int maxIntCount = Integer.MAX_VALUE;
final int bufstart = buf.length();
final int patternCharIndex = DateFormatSymbols.patternChars.indexOf(ch);
if (patternCharIndex == -1) {
throw new IllegalArgumentException("Illegal pattern character " +
"'" + ch + "' in \"" +
new String(pattern) + '"');
}
final int field = PATTERN_INDEX_TO_CALENDAR_FIELD[patternCharIndex];
int value = cal.get(field);
switch (patternCharIndex) {
case 0: // 'G' - ERA
buf.append(formatData.eras[value]);
break;
case 1: // 'y' - YEAR
/* According to the specification, if the number of pattern letters ('y') is 2,
* the year is truncated to 2 digits; otherwise it is interpreted as a number.
* But the original code process 'y', 'yy', 'yyy' in the same way. and process
* patterns with 4 or more than 4 'y' characters in the same way.
* So I change the codes to meet the specification. [Richard/GCl]
*/
if (count == 2)
zeroPaddingNumber(buf, value, 2, 2); // clip 1996 to 96
else //count = 1 or count > 2
zeroPaddingNumber(buf, value, count, maxIntCount);
break;
case 2: // 'M' - MONTH
if (count >= 4)
buf.append(formatData.months[value]);
else if (count == 3)
buf.append(formatData.shortMonths[value]);
else
zeroPaddingNumber(buf, value+1, count, maxIntCount);
break;
case 4: // 'k' - HOUR_OF_DAY (1..24)
if (value == 0)
zeroPaddingNumber(buf,
cal.getMaximum(Calendar.HOUR_OF_DAY)+1,
count, maxIntCount);
else
zeroPaddingNumber(buf, value, count, maxIntCount);
break;
case 8: // 'S' - FRACTIONAL_SECOND
// Fractional seconds left-justify
{
numberFormat.setMinimumIntegerDigits(Math.min(3, count));
numberFormat.setMaximumIntegerDigits(maxIntCount);
if (count == 1) {
value = (value + 50) / 100;
} else if (count == 2) {
value = (value + 5) / 10;
}
FieldPosition p = new FieldPosition(-1);
numberFormat.format((long) value, buf, p);
if (count > 3) {
numberFormat.setMinimumIntegerDigits(count - 3);
numberFormat.format(0L, buf, p);
}
}
break;
case 9: // 'E' - DAY_OF_WEEK
if (count >= 4)
buf.append(formatData.weekdays[value]);
else // count < 4, use abbreviated form if exists
buf.append(formatData.shortWeekdays[value]);
break;
case 14: // 'a' - AM_PM
buf.append(formatData.ampms[value]);
break;
case 15: // 'h' - HOUR (1..12)
if (value == 0)
zeroPaddingNumber(buf,
cal.getLeastMaximum(Calendar.HOUR)+1,
count, maxIntCount);
else
zeroPaddingNumber(buf, value, count, maxIntCount);
break;
case 17: // 'z' - ZONE_OFFSET
int zoneIndex
= formatData.getZoneIndex (cal.getTimeZone().getID());
if (zoneIndex == -1)
{
// For time zones that have no names, use strings
// GMT+hours:minutes and GMT-hours:minutes.
// For instance, France time zone uses GMT+01:00.
value = cal.get(Calendar.ZONE_OFFSET) +
cal.get(Calendar.DST_OFFSET);
if (value < 0)
{
buf.append(GMT_MINUS);
value = -value; // suppress the '-' sign for text display.
}
else
buf.append(GMT_PLUS);
zeroPaddingNumber(buf, (int)(value/millisPerHour), 2, 2);
buf.append(':');
zeroPaddingNumber(buf, (int)((value%millisPerHour)/millisPerMinute), 2, 2);
}
else if (cal.get(Calendar.DST_OFFSET) != 0)
{
if (count >= 4)
buf.append(formatData.zoneStrings[zoneIndex][3]);
else
// count < 4, use abbreviated form if exists
buf.append(formatData.zoneStrings[zoneIndex][4]);
}
else
{
if (count >= 4)
buf.append(formatData.zoneStrings[zoneIndex][1]);
else
buf.append(formatData.zoneStrings[zoneIndex][2]);
}
break;
case 23: // 'Z' - TIMEZONE_RFC
{
char sign = '+';
value = (cal.get(Calendar.ZONE_OFFSET) +
cal.get(Calendar.DST_OFFSET)) / millisPerMinute;
if (value < 0) {
value = -value;
sign = '-';
}
value = (value / 3) * 5 + (value % 60); // minutes => KKmm
buf.append(sign);
zeroPaddingNumber(buf, value, 4, 4);
}
break;
default:
// case 3: // 'd' - DATE
// case 5: // 'H' - HOUR_OF_DAY (0..23)
// case 6: // 'm' - MINUTE
// case 7: // 's' - SECOND
// case 10: // 'D' - DAY_OF_YEAR
// case 11: // 'F' - DAY_OF_WEEK_IN_MONTH
// case 12: // 'w' - WEEK_OF_YEAR
// case 13: // 'W' - WEEK_OF_MONTH
// case 16: // 'K' - HOUR (0..11)
// case 18: // 'Y' - YEAR_WOY
// case 19: // 'e' - DOW_LOCAL
// case 20: // 'u' - EXTENDED_YEAR
// case 21: // 'g' - JULIAN_DAY
// case 22: // 'A' - MILLISECONDS_IN_DAY
zeroPaddingNumber(buf, value, count, maxIntCount);
break;
} // switch (patternCharIndex)
// Set the FieldPosition (for the first occurence only)
if (pos.getBeginIndex() == pos.getEndIndex() &&
pos.getField() == PATTERN_INDEX_TO_DATE_FORMAT_FIELD[patternCharIndex]) {
pos.setBeginIndex(bufstart);
pos.setEndIndex(buf.length());
}
}
/**
* Internal high-speed method. Reuses a StringBuffer for results
* instead of creating a String on the heap for each call.
*/
private void zeroPaddingNumber(StringBuffer buf, int value,
int minDigits, int maxDigits) {
FieldPosition pos = new FieldPosition(-1);
numberFormat.setMinimumIntegerDigits(minDigits);
numberFormat.setMaximumIntegerDigits(maxDigits);
numberFormat.format(value, buf, pos);
}
/**
* Formats a number with the specified minimum and maximum number of digits.
* @stable ICU 2.0
@ -1488,8 +1746,8 @@ public class SimpleDateFormat extends DateFormat {
*/
public String toLocalizedPattern() {
return translatePattern(pattern,
DateFormatSymbols.patternChars,
formatData.localPatternChars);
DateFormatSymbols.patternChars,
formatData.localPatternChars);
}
/**
@ -1508,8 +1766,8 @@ public class SimpleDateFormat extends DateFormat {
*/
public void applyLocalizedPattern(String pattern) {
this.pattern = translatePattern(pattern,
formatData.localPatternChars,
DateFormatSymbols.patternChars);
formatData.localPatternChars,
DateFormatSymbols.patternChars);
setLocale(null, null);
}