Java example source code file (Surrogate.java)
The Surrogate.java Java example source code
/*
* Copyright (c) 1997, 2010, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.codemodel.internal.util;
import java.nio.CharBuffer;
import java.nio.charset.CoderResult;
/**
* Utility class for dealing with surrogates.
*
* @author Mark Reinhold
* @version 1.11, 03/01/23
*/
class Surrogate {
private Surrogate() { }
// UTF-16 surrogate-character ranges
//
public static final char MIN_HIGH = '\uD800';
public static final char MAX_HIGH = '\uDBFF';
public static final char MIN_LOW = '\uDC00';
public static final char MAX_LOW = '\uDFFF';
public static final char MIN = MIN_HIGH;
public static final char MAX = MAX_LOW;
// Range of UCS-4 values that need surrogates in UTF-16
//
public static final int UCS4_MIN = 0x10000;
public static final int UCS4_MAX = (1 << 20) + UCS4_MIN - 1;
/**
* Tells whether or not the given UTF-16 value is a high surrogate.
*/
public static boolean isHigh(int c) {
return (MIN_HIGH <= c) && (c <= MAX_HIGH);
}
/**
* Tells whether or not the given UTF-16 value is a low surrogate.
*/
public static boolean isLow(int c) {
return (MIN_LOW <= c) && (c <= MAX_LOW);
}
/**
* Tells whether or not the given UTF-16 value is a surrogate character,
*/
public static boolean is(int c) {
return (MIN <= c) && (c <= MAX);
}
/**
* Tells whether or not the given UCS-4 character must be represented as a
* surrogate pair in UTF-16.
*/
public static boolean neededFor(int uc) {
return (uc >= UCS4_MIN) && (uc <= UCS4_MAX);
}
/**
* Returns the high UTF-16 surrogate for the given UCS-4 character.
*/
public static char high(int uc) {
return (char)(0xd800 | (((uc - UCS4_MIN) >> 10) & 0x3ff));
}
/**
* Returns the low UTF-16 surrogate for the given UCS-4 character.
*/
public static char low(int uc) {
return (char)(0xdc00 | ((uc - UCS4_MIN) & 0x3ff));
}
/**
* Converts the given surrogate pair into a 32-bit UCS-4 character.
*/
public static int toUCS4(char c, char d) {
return (((c & 0x3ff) << 10) | (d & 0x3ff)) + 0x10000;
}
/**
* Surrogate parsing support. Charset implementations may use instances of
* this class to handle the details of parsing UTF-16 surrogate pairs.
*/
public static class Parser {
public Parser() { }
private int character; // UCS-4
private CoderResult error = CoderResult.UNDERFLOW;
private boolean isPair;
/**
* Returns the UCS-4 character previously parsed.
*/
public int character() {
return character;
}
/**
* Tells whether or not the previously-parsed UCS-4 character was
* originally represented by a surrogate pair.
*/
public boolean isPair() {
return isPair;
}
/**
* Returns the number of UTF-16 characters consumed by the previous
* parse.
*/
public int increment() {
return isPair ? 2 : 1;
}
/**
* If the previous parse operation detected an error, return the object
* describing that error.
*/
public CoderResult error() {
return error;
}
/**
* Returns an unmappable-input result object, with the appropriate
* input length, for the previously-parsed character.
*/
public CoderResult unmappableResult() {
return CoderResult.unmappableForLength(isPair ? 2 : 1);
}
/**
* Parses a UCS-4 character from the given source buffer, handling
* surrogates.
*
* @param c The first character
* @param in The source buffer, from which one more character
* will be consumed if c is a high surrogate
*
* @return Either a parsed UCS-4 character, in which case the isPair()
* and increment() methods will return meaningful values, or
* -1, in which case error() will return a descriptive result
* object
*/
public int parse(char c, CharBuffer in) {
if (isHigh(c)) {
if (!in.hasRemaining()) {
error = CoderResult.UNDERFLOW;
return -1;
}
char d = in.get();
if (isLow(d)) {
character = toUCS4(c, d);
isPair = true;
error = null;
return character;
}
error = CoderResult.malformedForLength(1);
return -1;
}
if (isLow(c)) {
error = CoderResult.malformedForLength(1);
return -1;
}
character = c;
isPair = false;
error = null;
return character;
}
/**
* Parses a UCS-4 character from the given source buffer, handling
* surrogates.
*
* @param c The first character
* @param ia The input array, from which one more character
* will be consumed if c is a high surrogate
* @param ip The input index
* @param il The input limit
*
* @return Either a parsed UCS-4 character, in which case the isPair()
* and increment() methods will return meaningful values, or
* -1, in which case error() will return a descriptive result
* object
*/
public int parse(char c, char[] ia, int ip, int il) {
if (isHigh(c)) {
if (il - ip < 2) {
error = CoderResult.UNDERFLOW;
return -1;
}
char d = ia[ip + 1];
if (isLow(d)) {
character = toUCS4(c, d);
isPair = true;
error = null;
return character;
}
error = CoderResult.malformedForLength(1);
return -1;
}
if (isLow(c)) {
error = CoderResult.malformedForLength(1);
return -1;
}
character = c;
isPair = false;
error = null;
return character;
}
}
/**
* Surrogate generation support. Charset implementations may use instances
* of this class to handle the details of generating UTF-16 surrogate
* pairs.
*/
public static class Generator {
public Generator() { }
private CoderResult error = CoderResult.OVERFLOW;
/**
* If the previous generation operation detected an error, return the
* object describing that error.
*/
public CoderResult error() {
return error;
}
/**
* Generates one or two UTF-16 characters to represent the given UCS-4
* character.
*
* @param uc The UCS-4 character
* @param len The number of input bytes from which the UCS-4 value
* was constructed (used when creating result objects)
* @param dst The destination buffer, to which one or two UTF-16
* characters will be written
*
* @return Either a positive count of the number of UTF-16 characters
* written to the destination buffer, or -1, in which case
* error() will return a descriptive result object
*/
public int generate(int uc, int len, CharBuffer dst) {
if (uc <= 0xffff) {
if (is(uc)) {
error = CoderResult.malformedForLength(len);
return -1;
}
if (dst.remaining() < 1) {
error = CoderResult.OVERFLOW;
return -1;
}
dst.put((char)uc);
error = null;
return 1;
}
if (uc < UCS4_MIN) {
error = CoderResult.malformedForLength(len);
return -1;
}
if (uc <= UCS4_MAX) {
if (dst.remaining() < 2) {
error = CoderResult.OVERFLOW;
return -1;
}
dst.put(high(uc));
dst.put(low(uc));
error = null;
return 2;
}
error = CoderResult.unmappableForLength(len);
return -1;
}
/**
* Generates one or two UTF-16 characters to represent the given UCS-4
* character.
*
* @param uc The UCS-4 character
* @param len The number of input bytes from which the UCS-4 value
* was constructed (used when creating result objects)
* @param da The destination array, to which one or two UTF-16
* characters will be written
* @param dp The destination position
* @param dl The destination limit
*
* @return Either a positive count of the number of UTF-16 characters
* written to the destination buffer, or -1, in which case
* error() will return a descriptive result object
*/
public int generate(int uc, int len, char[] da, int dp, int dl) {
if (uc <= 0xffff) {
if (is(uc)) {
error = CoderResult.malformedForLength(len);
return -1;
}
if (dl - dp < 1) {
error = CoderResult.OVERFLOW;
return -1;
}
da[dp] = (char)uc;
error = null;
return 1;
}
if (uc < UCS4_MIN) {
error = CoderResult.malformedForLength(len);
return -1;
}
if (uc <= UCS4_MAX) {
if (dl - dp < 2) {
error = CoderResult.OVERFLOW;
return -1;
}
da[dp] = high(uc);
da[dp + 1] = low(uc);
error = null;
return 2;
}
error = CoderResult.unmappableForLength(len);
return -1;
}
}
}
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