1 /*

     2  * Copyright (c) 2002, 2003, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package build.tools.generatecharacter;

    27 

    28 import java.text.*;

    29 import java.util.*;

    30 

    31 public class Utility {

    32     static byte peekByte(String s, int index) {

    33         char c = s.charAt(index/2);

    34         return ((index&1)==0)?(byte)(c>>8):(byte)c;

    35     }

    36 

    37     static short peekShort(String s, int index) {

    38         return (short)s.charAt(index);

    39     }

    40 

    41     static int peekInt(String s, int index) {

    42         index *= 2;

    43         return (((int)s.charAt(index)) << 16) | s.charAt(index+1);

    44     }

    45 

    46     static void poke(String s, int index, byte value) {

    47         int mask = 0xFF00;

    48         int ivalue = value;

    49         if ((index&1)==0) {

    50             ivalue <<= 8;

    51             mask = 0x00FF;

    52         }

    53         index /= 2;

    54         if (index == s.length()) {

    55             s = s + (char)ivalue;

    56         }

    57         else if (index == 0) {

    58             s = (char)(ivalue|(s.charAt(0)&mask)) + s.substring(1);

    59         }

    60         else {

    61             s = s.substring(0, index) + (char)(ivalue|(s.charAt(index)&mask))

    62                 + s.substring(index+1);

    63         }

    64     }

    65 

    66     static void poke(String s, int index, short value) {

    67         if (index == s.length()) {

    68             s = s + (char)value;

    69         }

    70         else if (index == 0) {

    71             s = (char)value + s.substring(1);

    72         }

    73         else {

    74             s = s.substring(0, index) + (char)value + s.substring(index+1);

    75         }

    76     }

    77 

    78     static void poke(String s, int index, int value) {

    79         index *= 2;

    80         char hi = (char)(value >> 16);

    81         if (index == s.length()) {

    82             s = s + hi + (char)value;

    83         }

    84         else if (index == 0) {

    85             s = hi + (char)value + s.substring(2);

    86         }

    87         else {

    88             s = s.substring(0, index) + hi + (char)value + s.substring(index+2);

    89         }

    90     }

    91 

    92     /**

    93      * The ESCAPE character is used during run-length encoding.  It signals

    94      * a run of identical chars.

    95      */

    96     static final char ESCAPE = '\uA5A5';

    97 

    98     /**

    99      * The ESCAPE_BYTE character is used during run-length encoding.  It signals

   100      * a run of identical bytes.

   101      */

   102     static final byte ESCAPE_BYTE = (byte)0xA5;

   103 

   104     /**

   105      * Construct a string representing a short array.  Use run-length encoding.

   106      * A character represents itself, unless it is the ESCAPE character.  Then

   107      * the following notations are possible:

   108      *   ESCAPE ESCAPE   ESCAPE literal

   109      *   ESCAPE n c      n instances of character c

   110      * Since an encoded run occupies 3 characters, we only encode runs of 4 or

   111      * more characters.  Thus we have n > 0 and n != ESCAPE and n <= 0xFFFF.

   112      * If we encounter a run where n == ESCAPE, we represent this as:

   113      *   c ESCAPE n-1 c

   114      * The ESCAPE value is chosen so as not to collide with commonly

   115      * seen values.

   116      */

   117     static final String arrayToRLEString(short[] a) {

   118         StringBuffer buffer = new StringBuffer();

   119         // for (int i=0; i<a.length; ++i) buffer.append((char) a[i]);

   120         buffer.append((char) (a.length >> 16));

   121         buffer.append((char) a.length);

   122         short runValue = a[0];

   123         int runLength = 1;

   124         for (int i=1; i<a.length; ++i) {

   125             short s = a[i];

   126             if (s == runValue && runLength < 0xFFFF) ++runLength;

   127             else {

   128                 encodeRun(buffer, runValue, runLength);

   129                 runValue = s;

   130                 runLength = 1;

   131             }

   132         }

   133         encodeRun(buffer, runValue, runLength);

   134         return buffer.toString();

   135     }

   136 

   137     /**

   138      * Construct a string representing a byte array.  Use run-length encoding.

   139      * Two bytes are packed into a single char, with a single extra zero byte at

   140      * the end if needed.  A byte represents itself, unless it is the

   141      * ESCAPE_BYTE.  Then the following notations are possible:

   142      *   ESCAPE_BYTE ESCAPE_BYTE   ESCAPE_BYTE literal

   143      *   ESCAPE_BYTE n b           n instances of byte b

   144      * Since an encoded run occupies 3 bytes, we only encode runs of 4 or

   145      * more bytes.  Thus we have n > 0 and n != ESCAPE_BYTE and n <= 0xFF.

   146      * If we encounter a run where n == ESCAPE_BYTE, we represent this as:

   147      *   b ESCAPE_BYTE n-1 b

   148      * The ESCAPE_BYTE value is chosen so as not to collide with commonly

   149      * seen values.

   150      */

   151     static final String arrayToRLEString(byte[] a) {

   152         StringBuffer buffer = new StringBuffer();

   153         buffer.append((char) (a.length >> 16));

   154         buffer.append((char) a.length);

   155         byte runValue = a[0];

   156         int runLength = 1;

   157         byte[] state = new byte[2];

   158         for (int i=1; i<a.length; ++i) {

   159             byte b = a[i];

   160             if (b == runValue && runLength < 0xFF) ++runLength;

   161             else {

   162                 encodeRun(buffer, runValue, runLength, state);

   163                 runValue = b;

   164                 runLength = 1;

   165             }

   166         }

   167         encodeRun(buffer, runValue, runLength, state);

   168 

   169         // We must save the final byte, if there is one, by padding

   170         // an extra zero.

   171         if (state[0] != 0) appendEncodedByte(buffer, (byte)0, state);

   172 

   173         return buffer.toString();

   174     }

   175 

   176     /**

   177      * Encode a run, possibly a degenerate run (of < 4 values).

   178      * @param length The length of the run; must be > 0 && <= 0xFFFF.

   179      */

   180     private static final void encodeRun(StringBuffer buffer, short value, int length) {

   181         if (length < 4) {

   182             for (int j=0; j<length; ++j) {

   183                 if (value == (int) ESCAPE) buffer.append(ESCAPE);

   184                 buffer.append((char) value);

   185             }

   186         }

   187         else {

   188             if (length == (int) ESCAPE) {

   189                 if (value == (int) ESCAPE) buffer.append(ESCAPE);

   190                 buffer.append((char) value);

   191                 --length;

   192             }

   193             buffer.append(ESCAPE);

   194             buffer.append((char) length);

   195             buffer.append((char) value); // Don't need to escape this value

   196         }

   197     }

   198 

   199     /**

   200      * Encode a run, possibly a degenerate run (of < 4 values).

   201      * @param length The length of the run; must be > 0 && <= 0xFF.

   202      */

   203     private static final void encodeRun(StringBuffer buffer, byte value, int length,

   204                                         byte[] state) {

   205         if (length < 4) {

   206             for (int j=0; j<length; ++j) {

   207                 if (value == ESCAPE_BYTE) appendEncodedByte(buffer, ESCAPE_BYTE, state);

   208                 appendEncodedByte(buffer, value, state);

   209             }

   210         }

   211         else {

   212             if (length == ESCAPE_BYTE) {

   213                 if (value == ESCAPE_BYTE) appendEncodedByte(buffer, ESCAPE_BYTE, state);

   214                 appendEncodedByte(buffer, value, state);

   215                 --length;

   216             }

   217             appendEncodedByte(buffer, ESCAPE_BYTE, state);

   218             appendEncodedByte(buffer, (byte)length, state);

   219             appendEncodedByte(buffer, value, state); // Don't need to escape this value

   220         }

   221     }

   222 

   223     /**

   224      * Append a byte to the given StringBuffer, packing two bytes into each

   225      * character.  The state parameter maintains intermediary data between

   226      * calls.

   227      * @param state A two-element array, with state[0] == 0 if this is the

   228      * first byte of a pair, or state[0] != 0 if this is the second byte

   229      * of a pair, in which case state[1] is the first byte.

   230      */

   231     private static final void appendEncodedByte(StringBuffer buffer, byte value,

   232                                                 byte[] state) {

   233         if (state[0] != 0) {

   234             char c = (char) ((state[1] << 8) | (((int) value) & 0xFF));

   235             buffer.append(c);

   236             state[0] = 0;

   237         }

   238         else {

   239             state[0] = 1;

   240             state[1] = value;

   241         }

   242     }

   243 

   244     /**

   245      * Construct an array of shorts from a run-length encoded string.

   246      */

   247     static final short[] RLEStringToShortArray(String s) {

   248         int length = (((int) s.charAt(0)) << 16) | ((int) s.charAt(1));

   249         short[] array = new short[length];

   250         int ai = 0;

   251         for (int i=2; i<s.length(); ++i) {

   252             char c = s.charAt(i);

   253             if (c == ESCAPE) {

   254                 c = s.charAt(++i);

   255                 if (c == ESCAPE) array[ai++] = (short) c;

   256                 else {

   257                     int runLength = (int) c;

   258                     short runValue = (short) s.charAt(++i);

   259                     for (int j=0; j<runLength; ++j) array[ai++] = runValue;

   260                 }

   261             }

   262             else {

   263                 array[ai++] = (short) c;

   264             }

   265         }

   266 

   267         if (ai != length)

   268             throw new InternalError("Bad run-length encoded short array");

   269 

   270         return array;

   271     }

   272 

   273     /**

   274      * Construct an array of bytes from a run-length encoded string.

   275      */

   276     static final byte[] RLEStringToByteArray(String s) {

   277         int length = (((int) s.charAt(0)) << 16) | ((int) s.charAt(1));

   278         byte[] array = new byte[length];

   279         boolean nextChar = true;

   280         char c = 0;

   281         int node = 0;

   282         int runLength = 0;

   283         int i = 2;

   284         for (int ai=0; ai<length; ) {

   285             // This part of the loop places the next byte into the local

   286             // variable 'b' each time through the loop.  It keeps the

   287             // current character in 'c' and uses the boolean 'nextChar'

   288             // to see if we've taken both bytes out of 'c' yet.

   289             byte b;

   290             if (nextChar) {

   291                 c = s.charAt(i++);

   292                 b = (byte) (c >> 8);

   293                 nextChar = false;

   294             }

   295             else {

   296                 b = (byte) (c & 0xFF);

   297                 nextChar = true;

   298             }

   299 

   300             // This part of the loop is a tiny state machine which handles

   301             // the parsing of the run-length encoding.  This would be simpler

   302             // if we could look ahead, but we can't, so we use 'node' to

   303             // move between three nodes in the state machine.

   304             switch (node) {

   305             case 0:

   306                 // Normal idle node

   307                 if (b == ESCAPE_BYTE) {

   308                     node = 1;

   309                 }

   310                 else {

   311                     array[ai++] = b;

   312                 }

   313                 break;

   314             case 1:

   315                 // We have seen one ESCAPE_BYTE; we expect either a second

   316                 // one, or a run length and value.

   317                 if (b == ESCAPE_BYTE) {

   318                     array[ai++] = ESCAPE_BYTE;

   319                     node = 0;

   320                 }

   321                 else {

   322                     runLength = b;

   323                     // Interpret signed byte as unsigned

   324                     if (runLength < 0) runLength += 0x100;

   325                     node = 2;

   326                 }

   327                 break;

   328             case 2:

   329                 // We have seen an ESCAPE_BYTE and length byte.  We interpret

   330                 // the next byte as the value to be repeated.

   331                 for (int j=0; j<runLength; ++j) array[ai++] = b;

   332                 node = 0;

   333                 break;

   334             }

   335         }

   336 

   337         if (node != 0)

   338             throw new InternalError("Bad run-length encoded byte array");

   339 

   340         if (i != s.length())

   341             throw new InternalError("Excess data in RLE byte array string");

   342 

   343         return array;

   344     }

   345 

   346     /**

   347      * Format a String for representation in a source file.  This includes

   348      * breaking it into lines escaping characters using octal notation

   349      * when necessary (control characters and double quotes).

   350      */

   351     static final String formatForSource(String s) {

   352         return formatForSource(s, "        ");

   353     }

   354 

   355     /**

   356      * Format a String for representation in a source file.  This includes

   357      * breaking it into lines escaping characters using octal notation

   358      * when necessary (control characters and double quotes).

   359      */

   360     static final String formatForSource(String s, String indent) {

   361         StringBuffer buffer = new StringBuffer();

   362         for (int i=0; i<s.length();) {

   363             if (i > 0) buffer.append("+\n");

   364             int limit = buffer.length() + 78; // Leave 2 for trailing <"+>

   365             buffer.append(indent + '"');

   366             while (i<s.length() && buffer.length()<limit) {

   367                 char c = s.charAt(i++);

   368                 /* This works too but it's kind of unnecessary; might as

   369                    well keep things simple.

   370                 if (c == '\\' || c == '"') {

   371                     // Escape backslash and double-quote.  Don't need to

   372                     // escape single-quote.

   373                     buffer.append("\\" + c);

   374                 }

   375                 else if (c >= '\u0020' && c <= '\u007E') {

   376                     // Printable ASCII ranges from ' ' to '~'

   377                     buffer.append(c);

   378                 }

   379                 else

   380                 */

   381                 if (c <= '\377') {

   382                     // Represent control characters

   383                     // using octal notation; otherwise the string we form

   384                     // won't compile, since Unicode escape sequences are

   385                     // processed before tokenization.

   386                     buffer.append('\\');

   387                     buffer.append(HEX_DIGIT[(c & 0700) >> 6]); // HEX_DIGIT works for octal

   388                     buffer.append(HEX_DIGIT[(c & 0070) >> 3]);

   389                     buffer.append(HEX_DIGIT[(c & 0007)]);

   390                 }

   391                 else {

   392                     // Handle the rest with Unicode

   393                     buffer.append("\\u");

   394                     buffer.append(HEX_DIGIT[(c & 0xF000) >> 12]);

   395                     buffer.append(HEX_DIGIT[(c & 0x0F00) >> 8]);

   396                     buffer.append(HEX_DIGIT[(c & 0x00F0) >> 4]);

   397                     buffer.append(HEX_DIGIT[(c & 0x000F)]);

   398                 }

   399             }

   400             buffer.append('"');

   401         }

   402         return buffer.toString();

   403     }

   404 

   405     static final char[] HEX_DIGIT = {'0','1','2','3','4','5','6','7',

   406                                      '8','9','A','B','C','D','E','F'};

   407 }