Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 2011, 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 com.sun.tools.javac.file.JavacFileManager;

 import com.sun.tools.javac.util.Log;

 import com.sun.tools.javac.util.Name;

 import com.sun.tools.javac.util.Names;

 import java.nio.CharBuffer;

 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 provide features for saving chars into a buffer and to retrieve

  * them at a later stage.

  *

  *  <p><b>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.</b>

  */

 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 fac the factory which created this Scanner

      * @param input the input, might be modified

      * @param inputLength the size of the input.

      * 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 {

                 char[] newInput = new char[inputLength + 1];

                 System.arraycopy(input, 0, newInput, 0, input.length);

                 input = newInput;

             }

         }

         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) {

         if (sp == sbuf.length) {

             char[] newsbuf = new char[sbuf.length * 2];

             System.arraycopy(sbuf, 0, newsbuf, 0, sbuf.length);

             sbuf = newsbuf;

         }

         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</code> and

      * extends to the character at index <code>endIndex - 1</code>.

      * Thus the length of the substring is <code>endIndex-beginIndex</code>.

      * This behavior is like

      * <code>String.substring(beginIndex, endIndex)</code>.

      * Unicode escape sequences are not translated.

      *

      * @param beginIndex the beginning index, inclusive.

      * @param endIndex the ending index, exclusive.

      * @throws IndexOutOfBounds 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;

     }

 }