JDK8/Java8源码在线阅读
/*
* Copyright (c) 2005, 2009, Oracle and/or its affiliates. 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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/*
*******************************************************************************
* (C) Copyright IBM Corp. and others, 1996-2009 - All Rights Reserved *
* *
* The original version of this source code and documentation is copyrighted *
* and owned by IBM, These materials are provided under terms of a License *
* Agreement between IBM and Sun. This technology is protected by multiple *
* US and International patents. This notice and attribution to IBM may not *
* to removed. *
*******************************************************************************
*/
package sun.text.normalizer;
public final class Utility {
/**
* Convenience utility to compare two Object[]s
* Ought to be in System.
* @param len the length to compare.
* The start indices and start+len must be valid.
*/
public final static boolean arrayRegionMatches(char[] source, int sourceStart,
char[] target, int targetStart,
int len)
{
int sourceEnd = sourceStart + len;
int delta = targetStart - sourceStart;
for (int i = sourceStart; i < sourceEnd; i++) {
if (source[i]!=target[i + delta])
return false;
}
return true;
}
/**
* Convert characters outside the range U+0020 to U+007F to
* Unicode escapes, and convert backslash to a double backslash.
*/
public static final String escape(String s) {
StringBuffer buf = new StringBuffer();
for (int i=0; i<s.length(); ) {
int c = UTF16.charAt(s, i);
i += UTF16.getCharCount(c);
if (c >= ' ' && c <= 0x007F) {
if (c == '\\') {
buf.append("\\\\"); // That is, "\\"
} else {
buf.append((char)c);
}
} else {
boolean four = c <= 0xFFFF;
buf.append(four ? "\\u" : "\\U");
hex(c, four ? 4 : 8, buf);
}
}
return buf.toString();
}
/* This map must be in ASCENDING ORDER OF THE ESCAPE CODE */
static private final char[] UNESCAPE_MAP = {
/*" 0x22, 0x22 */
/*' 0x27, 0x27 */
/*? 0x3F, 0x3F */
/*\ 0x5C, 0x5C */
/*a*/ 0x61, 0x07,
/*b*/ 0x62, 0x08,
/*e*/ 0x65, 0x1b,
/*f*/ 0x66, 0x0c,
/*n*/ 0x6E, 0x0a,
/*r*/ 0x72, 0x0d,
/*t*/ 0x74, 0x09,
/*v*/ 0x76, 0x0b
};
/**
* Convert an escape to a 32-bit code point value. We attempt
* to parallel the icu4c unescapeAt() function.
* @param offset16 an array containing offset to the character
* <em>after</em> the backslash. Upon return offset16[0] will
* be updated to point after the escape sequence.
* @return character value from 0 to 10FFFF, or -1 on error.
*/
public static int unescapeAt(String s, int[] offset16) {
int c;
int result = 0;
int n = 0;
int minDig = 0;
int maxDig = 0;
int bitsPerDigit = 4;
int dig;
int i;
boolean braces = false;
/* Check that offset is in range */
int offset = offset16[0];
int length = s.length();
if (offset < 0 || offset >= length) {
return -1;
}
/* Fetch first UChar after '\\' */
c = UTF16.charAt(s, offset);
offset += UTF16.getCharCount(c);
/* Convert hexadecimal and octal escapes */
switch (c) {
case 'u':
minDig = maxDig = 4;
break;
case 'U':
minDig = maxDig = 8;
break;
case 'x':
minDig = 1;
if (offset < length && UTF16.charAt(s, offset) == 0x7B /*{*/) {
++offset;
braces = true;
maxDig = 8;
} else {
maxDig = 2;
}
break;
default:
dig = UCharacter.digit(c, 8);
if (dig >= 0) {
minDig = 1;
maxDig = 3;
n = 1; /* Already have first octal digit */
bitsPerDigit = 3;
result = dig;
}
break;
}
if (minDig != 0) {
while (offset < length && n < maxDig) {
c = UTF16.charAt(s, offset);
dig = UCharacter.digit(c, (bitsPerDigit == 3) ? 8 : 16);
if (dig < 0) {
break;
}
result = (result << bitsPerDigit) | dig;
offset += UTF16.getCharCount(c);
++n;
}
if (n < minDig) {
return -1;
}
if (braces) {
if (c != 0x7D /*}*/) {
return -1;
}
++offset;
}
if (result < 0 || result >= 0x110000) {
return -1;
}
// If an escape sequence specifies a lead surrogate, see
// if there is a trail surrogate after it, either as an
// escape or as a literal. If so, join them up into a
// supplementary.
if (offset < length &&
UTF16.isLeadSurrogate((char) result)) {
int ahead = offset+1;
c = s.charAt(offset); // [sic] get 16-bit code unit
if (c == '\\' && ahead < length) {
int o[] = new int[] { ahead };
c = unescapeAt(s, o);
ahead = o[0];
}
if (UTF16.isTrailSurrogate((char) c)) {
offset = ahead;
result = UCharacterProperty.getRawSupplementary(
(char) result, (char) c);
}
}
offset16[0] = offset;
return result;
}
/* Convert C-style escapes in table */
for (i=0; i<UNESCAPE_MAP.length; i+=2) {
if (c == UNESCAPE_MAP[i]) {
offset16[0] = offset;
return UNESCAPE_MAP[i+1];
} else if (c < UNESCAPE_MAP[i]) {
break;
}
}
/* Map \cX to control-X: X & 0x1F */
if (c == 'c' && offset < length) {
c = UTF16.charAt(s, offset);
offset16[0] = offset + UTF16.getCharCount(c);
return 0x1F & c;
}
/* If no special forms are recognized, then consider
* the backslash to generically escape the next character. */
offset16[0] = offset;
return c;
}
/**
* Convert a integer to size width hex uppercase digits.
* E.g., hex('a', 4, str) => "0041".
* Append the output to the given StringBuffer.
* If width is too small to fit, nothing will be appended to output.
*/
public static StringBuffer hex(int ch, int width, StringBuffer output) {
return appendNumber(output, ch, 16, width);
}
/**
* Convert a integer to size width (minimum) hex uppercase digits.
* E.g., hex('a', 4, str) => "0041". If the integer requires more
* than width digits, more will be used.
*/
public static String hex(int ch, int width) {
StringBuffer buf = new StringBuffer();
return appendNumber(buf, ch, 16, width).toString();
}
/**
* Skip over a sequence of zero or more white space characters
* at pos. Return the index of the first non-white-space character
* at or after pos, or str.length(), if there is none.
*/
public static int skipWhitespace(String str, int pos) {
while (pos < str.length()) {
int c = UTF16.charAt(str, pos);
if (!UCharacterProperty.isRuleWhiteSpace(c)) {
break;
}
pos += UTF16.getCharCount(c);
}
return pos;
}
static final char DIGITS[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z'
};
/**
* Append the digits of a positive integer to the given
* <code>StringBuffer</code> in the given radix. This is
* done recursively since it is easiest to generate the low-
* order digit first, but it must be appended last.
*
* @param result is the <code>StringBuffer</code> to append to
* @param n is the positive integer
* @param radix is the radix, from 2 to 36 inclusive
* @param minDigits is the minimum number of digits to append.
*/
private static void recursiveAppendNumber(StringBuffer result, int n,
int radix, int minDigits)
{
int digit = n % radix;
if (n >= radix || minDigits > 1) {
recursiveAppendNumber(result, n / radix, radix, minDigits - 1);
}
result.append(DIGITS[digit]);
}
/**
* Append a number to the given StringBuffer in the given radix.
* Standard digits '0'-'9' are used and letters 'A'-'Z' for
* radices 11 through 36.
* @param result the digits of the number are appended here
* @param n the number to be converted to digits; may be negative.
* If negative, a '-' is prepended to the digits.
* @param radix a radix from 2 to 36 inclusive.
* @param minDigits the minimum number of digits, not including
* any '-', to produce. Values less than 2 have no effect. One
* digit is always emitted regardless of this parameter.
* @return a reference to result
*/
public static StringBuffer appendNumber(StringBuffer result, int n,
int radix, int minDigits)
throws IllegalArgumentException
{
if (radix < 2 || radix > 36) {
throw new IllegalArgumentException("Illegal radix " + radix);
}
int abs = n;
if (n < 0) {
abs = -n;
result.append("-");
}
recursiveAppendNumber(result, abs, radix, minDigits);
return result;
}
/**
* Return true if the character is NOT printable ASCII. The tab,
* newline and linefeed characters are considered unprintable.
*/
public static boolean isUnprintable(int c) {
return !(c >= 0x20 && c <= 0x7E);
}
/**
* Escape unprintable characters using <backslash>uxxxx notation
* for U+0000 to U+FFFF and <backslash>Uxxxxxxxx for U+10000 and
* above. If the character is printable ASCII, then do nothing
* and return FALSE. Otherwise, append the escaped notation and
* return TRUE.
*/
public static boolean escapeUnprintable(StringBuffer result, int c) {
if (isUnprintable(c)) {
result.append('\\');
if ((c & ~0xFFFF) != 0) {
result.append('U');
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