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/*
* Copyright (c) 2011, 2013, 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.tools.javac.parser;
import java.nio.CharBuffer;
import java.util.Arrays;
import com.sun.tools.javac.file.JavacFileManager;
import com.sun.tools.javac.util.ArrayUtils;
import com.sun.tools.javac.util.Log;
import com.sun.tools.javac.util.Name;
import com.sun.tools.javac.util.Names;
import static com.sun.tools.javac.util.LayoutCharacters.*;
/** The char reader used by the javac lexer/tokenizer. Returns the sequence of
* characters contained in the input stream, handling unicode escape accordingly.
* Additionally, it provides features for saving chars into a buffer and to retrieve
* them at a later stage.
*
* This is NOT part of any supported API.
* If you write code that depends on this, you do so at your own risk.
* This code and its internal interfaces are subject to change or
* deletion without notice.
*/
public class UnicodeReader {
/** The input buffer, index of next character to be read,
* index of one past last character in buffer.
*/
protected char[] buf;
protected int bp;
protected final int buflen;
/** The current character.
*/
protected char ch;
/** The buffer index of the last converted unicode character
*/
protected int unicodeConversionBp = -1;
protected Log log;
protected Names names;
/** A character buffer for saved chars.
*/
protected char[] sbuf = new char[128];
protected int sp;
/**
* Create a scanner from the input array. This method might
* modify the array. To avoid copying the input array, ensure
* that {@code inputLength < input.length} or
* {@code input[input.length -1]} is a white space character.
*
* @param sf the factory which created this Scanner
* @param buffer the input, might be modified
* Must be positive and less than or equal to input.length.
*/
protected UnicodeReader(ScannerFactory sf, CharBuffer buffer) {
this(sf, JavacFileManager.toArray(buffer), buffer.limit());
}
protected UnicodeReader(ScannerFactory sf, char[] input, int inputLength) {
log = sf.log;
names = sf.names;
if (inputLength == input.length) {
if (input.length > 0 && Character.isWhitespace(input[input.length - 1])) {
inputLength--;
} else {
input = Arrays.copyOf(input, inputLength + 1);
}
}
buf = input;
buflen = inputLength;
buf[buflen] = EOI;
bp = -1;
scanChar();
}
/** Read next character.
*/
protected void scanChar() {
if (bp < buflen) {
ch = buf[++bp];
if (ch == '\\') {
convertUnicode();
}
}
}
/** Read next character in comment, skipping over double '\' characters.
*/
protected void scanCommentChar() {
scanChar();
if (ch == '\\') {
if (peekChar() == '\\' && !isUnicode()) {
skipChar();
} else {
convertUnicode();
}
}
}
/** Append a character to sbuf.
*/
protected void putChar(char ch, boolean scan) {
sbuf = ArrayUtils.ensureCapacity(sbuf, sp);
sbuf[sp++] = ch;
if (scan)
scanChar();
}
protected void putChar(char ch) {
putChar(ch, false);
}
protected void putChar(boolean scan) {
putChar(ch, scan);
}
Name name() {
return names.fromChars(sbuf, 0, sp);
}
String chars() {
return new String(sbuf, 0, sp);
}
/** Convert unicode escape; bp points to initial '\' character
* (Spec 3.3).
*/
protected void convertUnicode() {
if (ch == '\\' && unicodeConversionBp != bp) {
bp++; ch = buf[bp];
if (ch == 'u') {
do {
bp++; ch = buf[bp];
} while (ch == 'u');
int limit = bp + 3;
if (limit < buflen) {
int d = digit(bp, 16);
int code = d;
while (bp < limit && d >= 0) {
bp++; ch = buf[bp];
d = digit(bp, 16);
code = (code << 4) + d;
}
if (d >= 0) {
ch = (char)code;
unicodeConversionBp = bp;
return;
}
}
log.error(bp, "illegal.unicode.esc");
} else {
bp--;
ch = '\\';
}
}
}
/** Are surrogates supported?
*/
final static boolean surrogatesSupported = surrogatesSupported();
private static boolean surrogatesSupported() {
try {
Character.isHighSurrogate('a');
return true;
} catch (NoSuchMethodError ex) {
return false;
}
}
/** Scan surrogate pairs. If 'ch' is a high surrogate and
* the next character is a low surrogate, then put the low
* surrogate in 'ch', and return the high surrogate.
* otherwise, just return 0.
*/
protected char scanSurrogates() {
if (surrogatesSupported && Character.isHighSurrogate(ch)) {
char high = ch;
scanChar();
if (Character.isLowSurrogate(ch)) {
return high;
}
ch = high;
}
return 0;
}
/** Convert an ASCII digit from its base (8, 10, or 16)
* to its value.
*/
protected int digit(int pos, int base) {
char c = ch;
int result = Character.digit(c, base);
if (result >= 0 && c > 0x7f) {
log.error(pos + 1, "illegal.nonascii.digit");
ch = "0123456789abcdef".charAt(result);
}
return result;
}
protected boolean isUnicode() {
return unicodeConversionBp == bp;
}
protected void skipChar() {
bp++;
}
protected char peekChar() {
return buf[bp + 1];
}
/**
* Returns a copy of the input buffer, up to its inputLength.
* Unicode escape sequences are not translated.
*/
public char[] getRawCharacters() {
char[] chars = new char[buflen];
System.arraycopy(buf, 0, chars, 0, buflen);
return chars;
}
/**
* Returns a copy of a character array subset of the input buffer.
* The returned array begins at the {@code beginIndex} and
* extends to the character at index {@code endIndex - 1}.
* Thus the length of the substring is {@code endIndex-beginIndex}.
* This behavior is like
* {@code String.substring(beginIndex, endIndex)}.
* Unicode escape sequences are not translated.
*
* @param beginIndex the beginning index, inclusive.
* @param endIndex the ending index, exclusive.
* @throws ArrayIndexOutOfBoundsException if either offset is outside of the
* array bounds
*/
public char[] getRawCharacters(int beginIndex, int endIndex) {
int length = endIndex - beginIndex;
char[] chars = new char[length];
System.arraycopy(buf, beginIndex, chars, 0, length);
return chars;
}
}