/*
* Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package javax.xml.bind;
import javax.xml.namespace.QName;
import javax.xml.namespace.NamespaceContext;
import javax.xml.datatype.DatatypeFactory;
import javax.xml.datatype.DatatypeConfigurationException;
import java.math.BigInteger;
import java.math.BigDecimal;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
/**
* This class is the JAXB RI's default implementation of the
* {@link DatatypeConverterInterface}.
*
* <p>
* When client apps specify the use of the static print/parse
* methods in {@link DatatypeConverter}, it will delegate
* to this class.
*
* <p>
* This class is responsible for whitespace normalization.
*
* @author <ul><li>Ryan Shoemaker, Sun Microsystems, Inc.</li></ul>
* @version $Revision$
* @since JAXB2.1
*/
final class DatatypeConverterImpl implements DatatypeConverterInterface {
/**
* To avoid re-creating instances, we cache one instance.
*/
public static final DatatypeConverterInterface theInstance = new DatatypeConverterImpl();
protected DatatypeConverterImpl() {
}
public String parseString(String lexicalXSDString) {
return lexicalXSDString;
}
public BigInteger parseInteger(String lexicalXSDInteger) {
return _parseInteger(lexicalXSDInteger);
}
public static BigInteger _parseInteger(CharSequence s) {
return new BigInteger(removeOptionalPlus(WhiteSpaceProcessor.trim(s)).toString());
}
public String printInteger(BigInteger val) {
return _printInteger(val);
}
public static String _printInteger(BigInteger val) {
return val.toString();
}
public int parseInt(String s) {
return _parseInt(s);
}
/**
* Faster but less robust String->int conversion.
*
* Note that:
* <ol>
* <li>XML Schema allows '+', but {@link Integer#valueOf(String)} is not.
* <li>XML Schema allows leading and trailing (but not in-between) whitespaces..
* {@link Integer#valueOf(String)} doesn't allow any.
* </ol>
*/
public static int _parseInt(CharSequence s) {
int len = s.length();
int sign = 1;
int r = 0;
for( int i=0; i<len; i++ ) {
char ch = s.charAt(i);
if(WhiteSpaceProcessor.isWhiteSpace(ch)) {
// skip whitespace
} else
if('0'<=ch && ch<='9') {
r = r*10 + (ch-'0');
} else
if(ch=='-') {
sign = -1;
} else
if(ch=='+') {
// noop
} else
throw new NumberFormatException("Not a number: "+s);
}
return r*sign;
}
public long parseLong(String lexicalXSLong) {
return _parseLong(lexicalXSLong);
}
public static long _parseLong(CharSequence s) {
return Long.valueOf(removeOptionalPlus(WhiteSpaceProcessor.trim(s)).toString());
}
public short parseShort(String lexicalXSDShort) {
return _parseShort(lexicalXSDShort);
}
public static short _parseShort(CharSequence s) {
return (short)_parseInt(s);
}
public String printShort(short val) {
return _printShort(val);
}
public static String _printShort(short val) {
return String.valueOf(val);
}
public BigDecimal parseDecimal(String content) {
return _parseDecimal(content);
}
public static BigDecimal _parseDecimal(CharSequence content) {
content = WhiteSpaceProcessor.trim(content);
return new BigDecimal(content.toString());
// from purely XML Schema perspective,
// this implementation has a problem, since
// in xs:decimal "1.0" and "1" is equal whereas the above
// code will return different values for those two forms.
//
// the code was originally using com.sun.msv.datatype.xsd.NumberType.load,
// but a profiling showed that the process of normalizing "1.0" into "1"
// could take non-trivial time.
//
// also, from the user's point of view, one might be surprised if
// 1 (not 1.0) is returned from "1.000"
}
public float parseFloat(String lexicalXSDFloat) {
return _parseFloat(lexicalXSDFloat);
}
public static float _parseFloat( CharSequence _val ) {
String s = WhiteSpaceProcessor.trim(_val).toString();
/* Incompatibilities of XML Schema's float "xfloat" and Java's float "jfloat"
* jfloat.valueOf ignores leading and trailing whitespaces,
whereas this is not allowed in xfloat.
* jfloat.valueOf allows "float type suffix" (f, F) to be
appended after float literal (e.g., 1.52e-2f), whereare
this is not the case of xfloat.
gray zone
---------
* jfloat allows ".523". And there is no clear statement that mentions
this case in xfloat. Although probably this is allowed.
*
*/
if(s.equals("NaN")) return Float.NaN;
if(s.equals("INF")) return Float.POSITIVE_INFINITY;
if(s.equals("-INF")) return Float.NEGATIVE_INFINITY;
if(s.length()==0
|| !isDigitOrPeriodOrSign(s.charAt(0))
|| !isDigitOrPeriodOrSign(s.charAt(s.length()-1)) )
throw new NumberFormatException();
// these screening process is necessary due to the wobble of Float.valueOf method
return Float.parseFloat(s);
}
public String printFloat(float v) {
return _printFloat(v);
}
public static String _printFloat(float v) {
if( v==Float.NaN ) return "NaN";
if( v==Float.POSITIVE_INFINITY ) return "INF";
if( v==Float.NEGATIVE_INFINITY ) return "-INF";
return String.valueOf(v);
}
public double parseDouble(String lexicalXSDDouble) {
return _parseDouble(lexicalXSDDouble);
}
public static double _parseDouble( CharSequence _val ) {
String val = WhiteSpaceProcessor.trim(_val).toString();
if(val.equals("NaN")) return Double.NaN;
if(val.equals("INF")) return Double.POSITIVE_INFINITY;
if(val.equals("-INF")) return Double.NEGATIVE_INFINITY;
if(val.length()==0
|| !isDigitOrPeriodOrSign(val.charAt(0))
|| !isDigitOrPeriodOrSign(val.charAt(val.length()-1)) )
throw new NumberFormatException(val);
// these screening process is necessary due to the wobble of Float.valueOf method
return Double.parseDouble(val);
}
public boolean parseBoolean(String lexicalXSDBoolean) {
return _parseBoolean(lexicalXSDBoolean);
}
public static boolean _parseBoolean(CharSequence literal) {
int i=0;
int len = literal.length();
char ch;
do {
ch = literal.charAt(i++);
} while(WhiteSpaceProcessor.isWhiteSpace(ch) && i<len);
// if we are strict about errors, check i==len. and report an error
if( ch=='t' || ch=='1' ) return true;
if( ch=='f' || ch=='0' ) return false;
return false;
}
public String printBoolean(boolean val) {
return val?"true":"false";
}
public static String _printBoolean(boolean val) {
return val?"true":"false";
}
public byte parseByte(String lexicalXSDByte) {
return _parseByte(lexicalXSDByte);
}
public static byte _parseByte(CharSequence literal) {
return (byte)_parseInt(literal);
}
public String printByte(byte val) {
return _printByte(val);
}
public static String _printByte(byte val) {
return String.valueOf(val);
}
public QName parseQName(String lexicalXSDQName, NamespaceContext nsc) {
return _parseQName(lexicalXSDQName,nsc);
}
/**
* @return null if fails to convert.
*/
public static QName _parseQName(CharSequence text, NamespaceContext nsc) {
int length = text.length();
// trim whitespace
int start=0;
while(start<length && WhiteSpaceProcessor.isWhiteSpace(text.charAt(start)))
start++;
int end = length;
while(end>start && WhiteSpaceProcessor.isWhiteSpace(text.charAt(end-1)))
end--;
if(end==start)
throw new IllegalArgumentException("input is empty");
String uri;
String localPart;
String prefix;
// search ':'
int idx=start+1; // no point in searching the first char. that's not valid.
while(idx<end && text.charAt(idx)!=':' )
idx++;
if( idx==end ) {
uri = nsc.getNamespaceURI("");
localPart = text.subSequence(start,end).toString();
prefix = "";
} else {
// Prefix exists, check everything
prefix = text.subSequence(start,idx).toString();
localPart = text.subSequence(idx+1,end).toString();
uri = nsc.getNamespaceURI(prefix);
// uri can never be null according to javadoc,
// but some users reported that there are implementations that return null.
if(uri==null || uri.length()==0) // crap. the NamespaceContext interface is broken.
// error: unbound prefix
throw new IllegalArgumentException("prefix "+prefix+" is not bound to a namespace");
}
return new QName(uri,localPart,prefix);
}
public Calendar parseDateTime(String lexicalXSDDateTime) {
return _parseDateTime(lexicalXSDDateTime);
}
public static GregorianCalendar _parseDateTime(CharSequence s) {
String val = WhiteSpaceProcessor.trim(s).toString();
return datatypeFactory.newXMLGregorianCalendar(val).toGregorianCalendar();
}
public String printDateTime(Calendar val) {
return _printDateTime(val);
}
public static String _printDateTime(Calendar val) {
return CalendarFormatter.doFormat("%Y-%M-%DT%h:%m:%s%z",val);
}
public byte[] parseBase64Binary(String lexicalXSDBase64Binary) {
return _parseBase64Binary(lexicalXSDBase64Binary);
}
public byte[] parseHexBinary(String s) {
final int len = s.length();
// "111" is not a valid hex encoding.
if( len%2 != 0 )
throw new IllegalArgumentException("hexBinary needs to be even-length: "+s);
byte[] out = new byte[len/2];
for( int i=0; i<len; i+=2 ) {
int h = hexToBin(s.charAt(i ));
int l = hexToBin(s.charAt(i+1));
if( h==-1 || l==-1 )
throw new IllegalArgumentException("contains illegal character for hexBinary: "+s);
out[i/2] = (byte)(h*16+l);
}
return out;
}
private static int hexToBin( char ch ) {
if( '0'<=ch && ch<='9' ) return ch-'0';
if( 'A'<=ch && ch<='F' ) return ch-'A'+10;
if( 'a'<=ch && ch<='f' ) return ch-'a'+10;
return -1;
}
private static final char[] hexCode = "0123456789ABCDEF".toCharArray();
public String printHexBinary(byte[] data) {
StringBuilder r = new StringBuilder(data.length*2);
for ( byte b : data) {
r.append(hexCode[(b >> 4) & 0xF]);
r.append(hexCode[(b & 0xF)]);
}
return r.toString();
}
public long parseUnsignedInt(String lexicalXSDUnsignedInt) {
return _parseLong(lexicalXSDUnsignedInt);
}
public String printUnsignedInt(long val) {
return _printLong(val);
}
public int parseUnsignedShort(String lexicalXSDUnsignedShort) {
return _parseInt(lexicalXSDUnsignedShort);
}
public Calendar parseTime(String lexicalXSDTime) {
return datatypeFactory.newXMLGregorianCalendar(lexicalXSDTime).toGregorianCalendar();
}
public String printTime(Calendar val) {
return CalendarFormatter.doFormat("%h:%m:%s%z",val);
}
public Calendar parseDate(String lexicalXSDDate) {
return datatypeFactory.newXMLGregorianCalendar(lexicalXSDDate).toGregorianCalendar();
}
public String printDate(Calendar val) {
return CalendarFormatter.doFormat((new StringBuilder("%Y-%M-%D").append("%z")).toString(),val);
}
public String parseAnySimpleType(String lexicalXSDAnySimpleType) {
return lexicalXSDAnySimpleType;
// return (String)SimpleURType.theInstance._createValue( lexicalXSDAnySimpleType, null );
}
public String printString(String val) {
// return StringType.theInstance.convertToLexicalValue( val, null );
return val;
}
public String printInt(int val) {
return _printInt(val);
}
public static String _printInt(int val) {
return String.valueOf(val);
}
public String printLong(long val) {
return _printLong(val);
}
public static String _printLong(long val) {
return String.valueOf(val);
}
public String printDecimal(BigDecimal val) {
return _printDecimal(val);
}
public static String _printDecimal(BigDecimal val) {
return val.toPlainString();
}
public String printDouble(double v) {
return _printDouble(v);
}
public static String _printDouble(double v) {
if( v==Double.NaN ) return "NaN";
if( v==Double.POSITIVE_INFINITY ) return "INF";
if( v==Double.NEGATIVE_INFINITY ) return "-INF";
return String.valueOf(v);
}
public String printQName(QName val, NamespaceContext nsc) {
return _printQName(val,nsc);
}
public static String _printQName(QName val, NamespaceContext nsc) {
// Double-check
String qname;
String prefix = nsc.getPrefix( val.getNamespaceURI() );
String localPart = val.getLocalPart();
if( prefix == null || prefix.length()==0 ) { // be defensive
qname = localPart;
} else {
qname = prefix + ':' + localPart;
}
return qname;
}
public String printBase64Binary(byte[] val) {
return _printBase64Binary(val);
}
public String printUnsignedShort(int val) {
return String.valueOf(val);
}
public String printAnySimpleType(String val) {
return val;
}
/**
* Just return the string passed as a parameter but
* installs an instance of this class as the DatatypeConverter
* implementation. Used from static fixed value initializers.
*/
public static String installHook( String s ) {
DatatypeConverter.setDatatypeConverter(theInstance);
return s;
}
// base64 decoder
//====================================
private static final byte[] decodeMap = initDecodeMap();
private static final byte PADDING = 127;
private static byte[] initDecodeMap() {
byte[] map = new byte[128];
int i;
for( i=0; i<128; i++ ) map[i] = -1;
for( i='A'; i<='Z'; i++ ) map[i] = (byte)(i-'A');
for( i='a'; i<='z'; i++ ) map[i] = (byte)(i-'a'+26);
for( i='0'; i<='9'; i++ ) map[i] = (byte)(i-'0'+52);
map['+'] = 62;
map['/'] = 63;
map['='] = PADDING;
return map;
}
/**
* computes the length of binary data speculatively.
*
* <p>
* Our requirement is to create byte[] of the exact length to store the binary data.
* If we do this in a straight-forward way, it takes two passes over the data.
* Experiments show that this is a non-trivial overhead (35% or so is spent on
* the first pass in calculating the length.)
*
* <p>
* So the approach here is that we compute the length speculatively, without looking
* at the whole contents. The obtained speculative value is never less than the
* actual length of the binary data, but it may be bigger. So if the speculation
* goes wrong, we'll pay the cost of reallocation and buffer copying.
*
* <p>
* If the base64 text is tightly packed with no indentation nor illegal char
* (like what most web services produce), then the speculation of this method
* will be correct, so we get the performance benefit.
*/
private static int guessLength( String text ) {
final int len = text.length();
// compute the tail '=' chars
int j=len-1;
for(; j>=0; j-- ) {
byte code = decodeMap[text.charAt(j)];
if(code==PADDING)
continue;
if(code==-1)
// most likely this base64 text is indented. go with the upper bound
return text.length()/4*3;
break;
}
j++; // text.charAt(j) is now at some base64 char, so +1 to make it the size
int padSize = len-j;
if(padSize >2) // something is wrong with base64. be safe and go with the upper bound
return text.length()/4*3;
// so far this base64 looks like it's unindented tightly packed base64.
// take a chance and create an array with the expected size
return text.length()/4*3-padSize;
}
/**
* @param text
* base64Binary data is likely to be long, and decoding requires
* each character to be accessed twice (once for counting length, another
* for decoding.)
*
* A benchmark showed that taking {@link String} is faster, presumably
* because JIT can inline a lot of string access (with data of 1K chars, it was twice as fast)
*/
public static byte[] _parseBase64Binary(String text) {
final int buflen = guessLength(text);
final byte[] out = new byte[buflen];
int o=0;
final int len = text.length();
int i;
final byte[] quadruplet = new byte[4];
int q=0;
// convert each quadruplet to three bytes.
for( i=0; i<len; i++ ) {
char ch = text.charAt(i);
byte v = decodeMap[ch];
if( v!=-1 )
quadruplet[q++] = v;
if(q==4) {
// quadruplet is now filled.
out[o++] = (byte)((quadruplet[0]<<2)|(quadruplet[1]>>4));
if( quadruplet[2]!=PADDING )
out[o++] = (byte)((quadruplet[1]<<4)|(quadruplet[2]>>2));
if( quadruplet[3]!=PADDING )
out[o++] = (byte)((quadruplet[2]<<6)|(quadruplet[3]));
q=0;
}
}
if(buflen==o) // speculation worked out to be OK
return out;
// we overestimated, so need to create a new buffer
byte[] nb = new byte[o];
System.arraycopy(out,0,nb,0,o);
return nb;
}
private static final char[] encodeMap = initEncodeMap();
private static char[] initEncodeMap() {
char[] map = new char[64];
int i;
for( i= 0; i<26; i++ ) map[i] = (char)('A'+i);
for( i=26; i<52; i++ ) map[i] = (char)('a'+(i-26));
for( i=52; i<62; i++ ) map[i] = (char)('0'+(i-52));
map[62] = '+';
map[63] = '/';
return map;
}
public static char encode( int i ) {
return encodeMap[i&0x3F];
}
public static byte encodeByte( int i ) {
return (byte)encodeMap[i&0x3F];
}
public static String _printBase64Binary(byte[] input) {
return _printBase64Binary(input, 0, input.length);
}
public static String _printBase64Binary(byte[] input, int offset, int len) {
char[] buf = new char[((len+2)/3)*4];
int ptr = _printBase64Binary(input,offset,len,buf,0);
assert ptr==buf.length;
return new String(buf);
}
/**
* Encodes a byte array into a char array by doing base64 encoding.
*
* The caller must supply a big enough buffer.
*
* @return
* the value of {@code ptr+((len+2)/3)*4}, which is the new offset
* in the output buffer where the further bytes should be placed.
*/
public static int _printBase64Binary(byte[] input, int offset, int len, char[] buf, int ptr) {
for( int i=offset; i<len; i+=3 ) {
switch( len-i ) {
case 1:
buf[ptr++] = encode(input[i]>>2);
buf[ptr++] = encode(((input[i])&0x3)<<4);
buf[ptr++] = '=';
buf[ptr++] = '=';
break;
case 2:
buf[ptr++] = encode(input[i]>>2);
buf[ptr++] = encode(
((input[i]&0x3)<<4) |
((input[i+1]>>4)&0xF));
buf[ptr++] = encode((input[i+1]&0xF)<<2);
buf[ptr++] = '=';
break;
default:
buf[ptr++] = encode(input[i]>>2);
buf[ptr++] = encode(
((input[i]&0x3)<<4) |
((input[i+1]>>4)&0xF));
buf[ptr++] = encode(
((input[i+1]&0xF)<<2)|
((input[i+2]>>6)&0x3));
buf[ptr++] = encode(input[i+2]&0x3F);
break;
}
}
return ptr;
}
/**
* Encodes a byte array into another byte array by first doing base64 encoding
* then encoding the result in ASCII.
*
* The caller must supply a big enough buffer.
*
* @return
* the value of {@code ptr+((len+2)/3)*4}, which is the new offset
* in the output buffer where the further bytes should be placed.
*/
public static int _printBase64Binary(byte[] input, int offset, int len, byte[] out, int ptr) {
byte[] buf = out;
int max = len+offset;
for( int i=offset; i<max; i+=3 ) {
switch( max-i ) {
case 1:
buf[ptr++] = encodeByte(input[i]>>2);
buf[ptr++] = encodeByte(((input[i])&0x3)<<4);
buf[ptr++] = '=';
buf[ptr++] = '=';
break;
case 2:
buf[ptr++] = encodeByte(input[i]>>2);
buf[ptr++] = encodeByte(
((input[i]&0x3)<<4) |
((input[i+1]>>4)&0xF));
buf[ptr++] = encodeByte((input[i+1]&0xF)<<2);
buf[ptr++] = '=';
break;
default:
buf[ptr++] = encodeByte(input[i]>>2);
buf[ptr++] = encodeByte(
((input[i]&0x3)<<4) |
((input[i+1]>>4)&0xF));
buf[ptr++] = encodeByte(
((input[i+1]&0xF)<<2)|
((input[i+2]>>6)&0x3));
buf[ptr++] = encodeByte(input[i+2]&0x3F);
break;
}
}
return ptr;
}
private static CharSequence removeOptionalPlus(CharSequence s) {
int len = s.length();
if(len<=1 || s.charAt(0)!='+') return s;
s = s.subSequence(1,len);
char ch = s.charAt(0);
if('0'<=ch && ch<='9') return s;
if('.'==ch ) return s;
throw new NumberFormatException();
}
private static boolean isDigitOrPeriodOrSign( char ch ) {
if( '0'<=ch && ch<='9' ) return true;
if( ch=='+' || ch=='-' || ch=='.' ) return true;
return false;
}
private static final DatatypeFactory datatypeFactory;
static {
try {
datatypeFactory = DatatypeFactory.newInstance();
} catch (DatatypeConfigurationException e) {
throw new Error(e);
}
}
private static final class CalendarFormatter {
public static String doFormat( String format, Calendar cal ) throws IllegalArgumentException {
int fidx = 0;
int flen = format.length();
StringBuilder buf = new StringBuilder();
while(fidx<flen) {
char fch = format.charAt(fidx++);
if(fch!='%') { // not a meta character
buf.append(fch);
continue;
}
// seen meta character. we don't do error check against the format
switch (format.charAt(fidx++)) {
case 'Y' : // year
formatYear(cal, buf);
break;
case 'M' : // month
formatMonth(cal, buf);
break;
case 'D' : // days
formatDays(cal, buf);
break;
case 'h' : // hours
formatHours(cal, buf);
break;
case 'm' : // minutes
formatMinutes(cal, buf);
break;
case 's' : // parse seconds.
formatSeconds(cal, buf);
break;
case 'z' : // time zone
formatTimeZone(cal,buf);
break;
default :
// illegal meta character. impossible.
throw new InternalError();
}
}
return buf.toString();
}
private static void formatYear(Calendar cal, StringBuilder buf) {
int year = cal.get(Calendar.YEAR);
String s;
if (year <= 0) // negative value
s = Integer.toString(1 - year);
else // positive value
s = Integer.toString(year);
while (s.length() < 4)
s = '0' + s;
if (year <= 0)
s = '-' + s;
buf.append(s);
}
private static void formatMonth(Calendar cal, StringBuilder buf) {
formatTwoDigits(cal.get(Calendar.MONTH)+1,buf);
}
private static void formatDays(Calendar cal, StringBuilder buf) {
formatTwoDigits(cal.get(Calendar.DAY_OF_MONTH),buf);
}
private static void formatHours(Calendar cal, StringBuilder buf) {
formatTwoDigits(cal.get(Calendar.HOUR_OF_DAY),buf);
}
private static void formatMinutes(Calendar cal, StringBuilder buf) {
formatTwoDigits(cal.get(Calendar.MINUTE),buf);
}
private static void formatSeconds(Calendar cal, StringBuilder buf) {
formatTwoDigits(cal.get(Calendar.SECOND),buf);
if (cal.isSet(Calendar.MILLISECOND)) { // milliseconds
int n = cal.get(Calendar.MILLISECOND);
if(n!=0) {
String ms = Integer.toString(n);
while (ms.length() < 3)
ms = '0' + ms; // left 0 paddings.
buf.append('.');
buf.append(ms);
}
}
}
/** formats time zone specifier. */
private static void formatTimeZone(Calendar cal,StringBuilder buf) {
TimeZone tz = cal.getTimeZone();
if (tz == null) return;
// otherwise print out normally.
int offset;
if (tz.inDaylightTime(cal.getTime())) {
offset = tz.getRawOffset() + (tz.useDaylightTime()?3600000:0);
} else {
offset = tz.getRawOffset();
}
if(offset==0) {
buf.append('Z');
return;
}
if (offset >= 0)
buf.append('+');
else {
buf.append('-');
offset *= -1;
}
offset /= 60 * 1000; // offset is in milli-seconds
formatTwoDigits(offset / 60, buf);
buf.append(':');
formatTwoDigits(offset % 60, buf);
}
/** formats Integer into two-character-wide string. */
private static void formatTwoDigits(int n,StringBuilder buf) {
// n is always non-negative.
if (n < 10) buf.append('0');
buf.append(n);
}
}
}