1 /*

     2  * Copyright (c) 2007, 2011, 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

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     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

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

    20  *

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

    23  * questions.

    24  */

    25 

    26 package sun.invoke.util;

    27 

    28 /**

    29  * Utility routines for dealing with bytecode-level names.

    30  * Includes universal mangling rules for the JVM.

    31  *

    32  * <h3>Avoiding Dangerous Characters </h3>

    33  *

    34  * <p>

    35  * The JVM defines a very small set of characters which are illegal

    36  * in name spellings.  We will slightly extend and regularize this set

    37  * into a group of <cite>dangerous characters</cite>.

    38  * These characters will then be replaced, in mangled names, by escape sequences.

    39  * In addition, accidental escape sequences must be further escaped.

    40  * Finally, a special prefix will be applied if and only if

    41  * the mangling would otherwise fail to begin with the escape character.

    42  * This happens to cover the corner case of the null string,

    43  * and also clearly marks symbols which need demangling.

    44  * </p>

    45  * <p>

    46  * Dangerous characters are the union of all characters forbidden

    47  * or otherwise restricted by the JVM specification,

    48  * plus their mates, if they are brackets

    49  * (<code><big><b>[</b></big></code> and <code><big><b>]</b></big></code>,

    50  * <code><big><b>&lt;</b></big></code> and <code><big><b>&gt;</b></big></code>),

    51  * plus, arbitrarily, the colon character <code><big><b>:</b></big></code>.

    52  * There is no distinction between type, method, and field names.

    53  * This makes it easier to convert between mangled names of different

    54  * types, since they do not need to be decoded (demangled).

    55  * </p>

    56  * <p>

    57  * The escape character is backslash <code><big><b>\</b></big></code>

    58  * (also known as reverse solidus).

    59  * This character is, until now, unheard of in bytecode names,

    60  * but traditional in the proposed role.

    61  *

    62  * </p>

    63  * <h3> Replacement Characters </h3>

    64  *

    65  *

    66  * <p>

    67  * Every escape sequence is two characters

    68  * (in fact, two UTF8 bytes) beginning with

    69  * the escape character and followed by a

    70  * <cite>replacement character</cite>.

    71  * (Since the replacement character is never a backslash,

    72  * iterated manglings do not double in size.)

    73  * </p>

    74  * <p>

    75  * Each dangerous character has some rough visual similarity

    76  * to its corresponding replacement character.

    77  * This makes mangled symbols easier to recognize by sight.

    78  * </p>

    79  * <p>

    80  * The dangerous characters are

    81  * <code><big><b>/</b></big></code> (forward slash, used to delimit package components),

    82  * <code><big><b>.</b></big></code> (dot, also a package delimiter),

    83  * <code><big><b>;</b></big></code> (semicolon, used in signatures),

    84  * <code><big><b>$</b></big></code> (dollar, used in inner classes and synthetic members),

    85  * <code><big><b>&lt;</b></big></code> (left angle),

    86  * <code><big><b>&gt;</b></big></code> (right angle),

    87  * <code><big><b>[</b></big></code> (left square bracket, used in array types),

    88  * <code><big><b>]</b></big></code> (right square bracket, reserved in this scheme for language use),

    89  * and <code><big><b>:</b></big></code> (colon, reserved in this scheme for language use).

    90  * Their replacements are, respectively,

    91  * <code><big><b>|</b></big></code> (vertical bar),

    92  * <code><big><b>,</b></big></code> (comma),

    93  * <code><big><b>?</b></big></code> (question mark),

    94  * <code><big><b>%</b></big></code> (percent),

    95  * <code><big><b>^</b></big></code> (caret),

    96  * <code><big><b>_</b></big></code> (underscore), and

    97  * <code><big><b>{</b></big></code> (left curly bracket),

    98  * <code><big><b>}</b></big></code> (right curly bracket),

    99  * <code><big><b>!</b></big></code> (exclamation mark).

   100  * In addition, the replacement character for the escape character itself is

   101  * <code><big><b>-</b></big></code> (hyphen),

   102  * and the replacement character for the null prefix is

   103  * <code><big><b>=</b></big></code> (equal sign).

   104  * </p>

   105  * <p>

   106  * An escape character <code><big><b>\</b></big></code>

   107  * followed by any of these replacement characters

   108  * is an escape sequence, and there are no other escape sequences.

   109  * An equal sign is only part of an escape sequence

   110  * if it is the second character in the whole string, following a backslash.

   111  * Two consecutive backslashes do <em>not</em> form an escape sequence.

   112  * </p>

   113  * <p>

   114  * Each escape sequence replaces a so-called <cite>original character</cite>

   115  * which is either one of the dangerous characters or the escape character.

   116  * A null prefix replaces an initial null string, not a character.

   117  * </p>

   118  * <p>

   119  * All this implies that escape sequences cannot overlap and may be

   120  * determined all at once for a whole string.  Note that a spelling

   121  * string can contain <cite>accidental escapes</cite>, apparent escape

   122  * sequences which must not be interpreted as manglings.

   123  * These are disabled by replacing their leading backslash with an

   124  * escape sequence (<code><big><b>\-</b></big></code>).  To mangle a string, three logical steps

   125  * are required, though they may be carried out in one pass:

   126  * </p>

   127  * <ol>

   128  *   <li>In each accidental escape, replace the backslash with an escape sequence

   129  * (<code><big><b>\-</b></big></code>).</li>

   130  *   <li>Replace each dangerous character with an escape sequence

   131  * (<code><big><b>\|</b></big></code> for <code><big><b>/</b></big></code>, etc.).</li>

   132  *   <li>If the first two steps introduced any change, <em>and</em>

   133  * if the string does not already begin with a backslash, prepend a null prefix (<code><big><b>\=</b></big></code>).</li>

   134  * </ol>

   135  *

   136  * To demangle a mangled string that begins with an escape,

   137  * remove any null prefix, and then replace (in parallel)

   138  * each escape sequence by its original character.

   139  * <p>Spelling strings which contain accidental

   140  * escapes <em>must</em> have them replaced, even if those

   141  * strings do not contain dangerous characters.

   142  * This restriction means that mangling a string always

   143  * requires a scan of the string for escapes.

   144  * But then, a scan would be required anyway,

   145  * to check for dangerous characters.

   146  *

   147  * </p>

   148  * <h3> Nice Properties </h3>

   149  *

   150  * <p>

   151  * If a bytecode name does not contain any escape sequence,

   152  * demangling is a no-op:  The string demangles to itself.

   153  * Such a string is called <cite>self-mangling</cite>.

   154  * Almost all strings are self-mangling.

   155  * In practice, to demangle almost any name “found in nature”,

   156  * simply verify that it does not begin with a backslash.

   157  * </p>

   158  * <p>

   159  * Mangling is a one-to-one function, while demangling

   160  * is a many-to-one function.

   161  * A mangled string is defined as <cite>validly mangled</cite> if

   162  * it is in fact the unique mangling of its spelling string.

   163  * Three examples of invalidly mangled strings are <code><big><b>\=foo</b></big></code>,

   164  * <code><big><b>\-bar</b></big></code>, and <code><big><b>baz\!</b></big></code>, which demangle to <code><big><b>foo</b></big></code>, <code><big><b>\bar</b></big></code>, and

   165  * <code><big><b>baz\!</b></big></code>, but then remangle to <code><big><b>foo</b></big></code>, <code><big><b>\bar</b></big></code>, and <code><big><b>\=baz\-!</b></big></code>.

   166  * If a language back-end or runtime is using mangled names,

   167  * it should never present an invalidly mangled bytecode

   168  * name to the JVM.  If the runtime encounters one,

   169  * it should also report an error, since such an occurrence

   170  * probably indicates a bug in name encoding which

   171  * will lead to errors in linkage.

   172  * However, this note does not propose that the JVM verifier

   173  * detect invalidly mangled names.

   174  * </p>

   175  * <p>

   176  * As a result of these rules, it is a simple matter to

   177  * compute validly mangled substrings and concatenations

   178  * of validly mangled strings, and (with a little care)

   179  * these correspond to corresponding operations on their

   180  * spelling strings.

   181  * </p>

   182  * <ul>

   183  *   <li>Any prefix of a validly mangled string is also validly mangled,

   184  * although a null prefix may need to be removed.</li>

   185  *   <li>Any suffix of a validly mangled string is also validly mangled,

   186  * although a null prefix may need to be added.</li>

   187  *   <li>Two validly mangled strings, when concatenated,

   188  * are also validly mangled, although any null prefix

   189  * must be removed from the second string,

   190  * and a trailing backslash on the first string may need escaping,

   191  * if it would participate in an accidental escape when followed

   192  * by the first character of the second string.</li>

   193  * </ul>

   194  * <p>If languages that include non-Java symbol spellings use this

   195  * mangling convention, they will enjoy the following advantages:

   196  * </p>

   197  * <ul>

   198  *   <li>They can interoperate via symbols they share in common.</li>

   199  *   <li>Low-level tools, such as backtrace printers, will have readable displays.</li>

   200  *   <li>Future JVM and language extensions can safely use the dangerous characters

   201  * for structuring symbols, but will never interfere with valid spellings.</li>

   202  *   <li>Runtimes and compilers can use standard libraries for mangling and demangling.</li>

   203  *   <li>Occasional transliterations and name composition will be simple and regular,

   204  * for classes, methods, and fields.</li>

   205  *   <li>Bytecode names will continue to be compact.

   206  * When mangled, spellings will at most double in length, either in

   207  * UTF8 or UTF16 format, and most will not change at all.</li>

   208  * </ul>

   209  *

   210  *

   211  * <h3> Suggestions for Human Readable Presentations </h3>

   212  *

   213  *

   214  * <p>

   215  * For human readable displays of symbols,

   216  * it will be better to present a string-like quoted

   217  * representation of the spelling, because JVM users

   218  * are generally familiar with such tokens.

   219  * We suggest using single or double quotes before and after

   220  * mangled symbols which are not valid Java identifiers,

   221  * with quotes, backslashes, and non-printing characters

   222  * escaped as if for literals in the Java language.

   223  * </p>

   224  * <p>

   225  * For example, an HTML-like spelling

   226  * <code><big><b>&lt;pre&gt;</b></big></code> mangles to

   227  * <code><big><b>\^pre\_</b></big></code> and could

   228  * display more cleanly as

   229  * <code><big><b>'&lt;pre&gt;'</b></big></code>,

   230  * with the quotes included.

   231  * Such string-like conventions are <em>not</em> suitable

   232  * for mangled bytecode names, in part because

   233  * dangerous characters must be eliminated, rather

   234  * than just quoted.  Otherwise internally structured

   235  * strings like package prefixes and method signatures

   236  * could not be reliably parsed.

   237  * </p>

   238  * <p>

   239  * In such human-readable displays, invalidly mangled

   240  * names should <em>not</em> be demangled and quoted,

   241  * for this would be misleading.  Likewise, JVM symbols

   242  * which contain dangerous characters (like dots in field

   243  * names or brackets in method names) should not be

   244  * simply quoted.  The bytecode names

   245  * <code><big><b>\=phase\,1</b></big></code> and

   246  * <code><big><b>phase.1</b></big></code> are distinct,

   247  * and in demangled displays they should be presented as

   248  * <code><big><b>'phase.1'</b></big></code> and something like

   249  * <code><big><b>'phase'.1</b></big></code>, respectively.

   250  * </p>

   251  *

   252  * @author John Rose

   253  * @version 1.2, 02/06/2008

   254  * @see http://blogs.sun.com/jrose/entry/symbolic_freedom_in_the_vm

   255  */

   256 public class BytecodeName {

   257     private BytecodeName() { }  // static only class

   258 

   259     /** Given a source name, produce the corresponding bytecode name.

   260      * The source name should not be qualified, because any syntactic

   261      * markers (dots, slashes, dollar signs, colons, etc.) will be mangled.

   262      * @param s the source name

   263      * @return a valid bytecode name which represents the source name

   264      */

   265     public static String toBytecodeName(String s) {

   266         String bn = mangle(s);

   267         assert((Object)bn == s || looksMangled(bn)) : bn;

   268         assert(s.equals(toSourceName(bn))) : s;

   269         return bn;

   270     }

   271 

   272     /** Given an unqualified bytecode name, produce the corresponding source name.

   273      * The bytecode name must not contain dangerous characters.

   274      * In particular, it must not be qualified or segmented by colon {@code ':'}.

   275      * @param s the bytecode name

   276      * @return the source name, which may possibly have unsafe characters

   277      * @throws IllegalArgumentException if the bytecode name is not {@link #isSafeBytecodeName safe}

   278      * @see #isSafeBytecodeName(java.lang.String)

   279      */

   280     public static String toSourceName(String s) {

   281         checkSafeBytecodeName(s);

   282         String sn = s;

   283         if (looksMangled(s)) {

   284             sn = demangle(s);

   285             assert(s.equals(mangle(sn))) : s+" => "+sn+" => "+mangle(sn);

   286         }

   287         return sn;

   288     }

   289 

   290     /**

   291      * Given a bytecode name from a classfile, separate it into

   292      * components delimited by dangerous characters.

   293      * Each resulting array element will be either a dangerous character,

   294      * or else a safe bytecode name.

   295      * (The safe name might possibly be mangled to hide further dangerous characters.)

   296      * For example, the qualified class name {@code java/lang/String}

   297      * will be parsed into the array {@code {"java", '/', "lang", '/', "String"}}.

   298      * The name {@code <init>} will be parsed into { '<', "init", '>'}}

   299      * The name {@code foo/bar$:baz} will be parsed into

   300      * {@code {"foo", '/', "bar", '$', ':', "baz"}}.

   301      * The name {@code ::\=:foo:\=bar\!baz} will be parsed into

   302      * {@code {':', ':', "", ':', "foo", ':', "bar:baz"}}.

   303      */

   304     public static Object[] parseBytecodeName(String s) {

   305         int slen = s.length();

   306         Object[] res = null;

   307         for (int pass = 0; pass <= 1; pass++) {

   308             int fillp = 0;

   309             int lasti = 0;

   310             for (int i = 0; i <= slen; i++) {

   311                 int whichDC = -1;

   312                 if (i < slen) {

   313                     whichDC = DANGEROUS_CHARS.indexOf(s.charAt(i));

   314                     if (whichDC < DANGEROUS_CHAR_FIRST_INDEX)  continue;

   315                 }

   316                 // got to end of string or next dangerous char

   317                 if (lasti < i) {

   318                     // normal component

   319                     if (pass != 0)

   320                         res[fillp] = toSourceName(s.substring(lasti, i));

   321                     fillp++;

   322                     lasti = i+1;

   323                 }

   324                 if (whichDC >= DANGEROUS_CHAR_FIRST_INDEX) {

   325                     if (pass != 0)

   326                         res[fillp] = DANGEROUS_CHARS_CA[whichDC];

   327                     fillp++;

   328                     lasti = i+1;

   329                 }

   330             }

   331             if (pass != 0)  break;

   332             // between passes, build the result array

   333             res = new Object[fillp];

   334             if (fillp <= 1 && lasti == 0) {

   335                 if (fillp != 0)  res[0] = toSourceName(s);

   336                 break;

   337             }

   338         }

   339         return res;

   340     }

   341 

   342     /**

   343      * Given a series of components, create a bytecode name for a classfile.

   344      * This is the inverse of {@link #parseBytecodeName(java.lang.String)}.

   345      * Each component must either be an interned one-character string of

   346      * a dangerous character, or else a safe bytecode name.

   347      * @param components a series of name components

   348      * @return the concatenation of all components

   349      * @throws IllegalArgumentException if any component contains an unsafe

   350      *          character, and is not an interned one-character string

   351      * @throws NullPointerException if any component is null

   352      */

   353     public static String unparseBytecodeName(Object[] components) {

   354         Object[] components0 = components;

   355         for (int i = 0; i < components.length; i++) {

   356             Object c = components[i];

   357             if (c instanceof String) {

   358                 String mc = toBytecodeName((String) c);

   359                 if (i == 0 && components.length == 1)

   360                     return mc;  // usual case

   361                 if ((Object)mc != c) {

   362                     if (components == components0)

   363                         components = components.clone();

   364                     components[i] = c = mc;

   365                 }

   366             }

   367         }

   368         return appendAll(components);

   369     }

   370     private static String appendAll(Object[] components) {

   371         if (components.length <= 1) {

   372             if (components.length == 1) {

   373                 return String.valueOf(components[0]);

   374             }

   375             return "";

   376         }

   377         int slen = 0;

   378         for (Object c : components) {

   379             if (c instanceof String)

   380                 slen += String.valueOf(c).length();

   381             else

   382                 slen += 1;

   383         }

   384         StringBuilder sb = new StringBuilder(slen);

   385         for (Object c : components) {

   386             sb.append(c);

   387         }

   388         return sb.toString();

   389     }

   390 

   391     /**

   392      * Given a bytecode name, produce the corresponding display name.

   393      * This is the source name, plus quotes if needed.

   394      * If the bytecode name contains dangerous characters,

   395      * assume that they are being used as punctuation,

   396      * and pass them through unchanged.

   397      * Non-empty runs of non-dangerous characters are demangled

   398      * if necessary, and the resulting names are quoted if

   399      * they are not already valid Java identifiers, or if

   400      * they contain a dangerous character (i.e., dollar sign "$").

   401      * Single quotes are used when quoting.

   402      * Within quoted names, embedded single quotes and backslashes

   403      * are further escaped by prepended backslashes.

   404      *

   405      * @param s the original bytecode name (which may be qualified)

   406      * @return a human-readable presentation

   407      */

   408     public static String toDisplayName(String s) {

   409         Object[] components = parseBytecodeName(s);

   410         for (int i = 0; i < components.length; i++) {

   411             if (!(components[i] instanceof String))

   412                 continue;

   413             String sn = (String) components[i];

   414             // note that the name is already demangled!

   415             //sn = toSourceName(sn);

   416             if (!isJavaIdent(sn) || sn.indexOf('$') >=0 ) {

   417                 components[i] = quoteDisplay(sn);

   418             }

   419         }

   420         return appendAll(components);

   421     }

   422     private static boolean isJavaIdent(String s) {

   423         int slen = s.length();

   424         if (slen == 0)  return false;

   425         if (!Character.isJavaIdentifierStart(s.charAt(0)))

   426             return false;

   427         for (int i = 1; i < slen; i++) {

   428             if (!Character.isJavaIdentifierPart(s.charAt(i)))

   429                 return false;

   430         }

   431         return true;

   432     }

   433     private static String quoteDisplay(String s) {

   434         // TO DO:  Replace wierd characters in s by C-style escapes.

   435         return "'"+s.replaceAll("['\\\\]", "\\\\$0")+"'";

   436     }

   437 

   438     private static void checkSafeBytecodeName(String s)

   439             throws IllegalArgumentException {

   440         if (!isSafeBytecodeName(s)) {

   441             throw new IllegalArgumentException(s);

   442         }

   443     }

   444 

   445     /**

   446      * Report whether a simple name is safe as a bytecode name.

   447      * Such names are acceptable in class files as class, method, and field names.

   448      * Additionally, they are free of "dangerous" characters, even if those

   449      * characters are legal in some (or all) names in class files.

   450      * @param s the proposed bytecode name

   451      * @return true if the name is non-empty and all of its characters are safe

   452      */

   453     public static boolean isSafeBytecodeName(String s) {

   454         if (s.length() == 0)  return false;

   455         // check occurrences of each DANGEROUS char

   456         for (char xc : DANGEROUS_CHARS_A) {

   457             if (xc == ESCAPE_C)  continue;  // not really that dangerous

   458             if (s.indexOf(xc) >= 0)  return false;

   459         }

   460         return true;

   461     }

   462 

   463     /**

   464      * Report whether a character is safe in a bytecode name.

   465      * This is true of any unicode character except the following

   466      * <em>dangerous characters</em>: {@code ".;:$[]<>/"}.

   467      * @param s the proposed character

   468      * @return true if the character is safe to use in classfiles

   469      */

   470     public static boolean isSafeBytecodeChar(char c) {

   471         return DANGEROUS_CHARS.indexOf(c) < DANGEROUS_CHAR_FIRST_INDEX;

   472     }

   473 

   474     private static boolean looksMangled(String s) {

   475         return s.charAt(0) == ESCAPE_C;

   476     }

   477 

   478     private static String mangle(String s) {

   479         if (s.length() == 0)

   480             return NULL_ESCAPE;

   481 

   482         // build this lazily, when we first need an escape:

   483         StringBuilder sb = null;

   484 

   485         for (int i = 0, slen = s.length(); i < slen; i++) {

   486             char c = s.charAt(i);

   487 

   488             boolean needEscape = false;

   489             if (c == ESCAPE_C) {

   490                 if (i+1 < slen) {

   491                     char c1 = s.charAt(i+1);

   492                     if ((i == 0 && c1 == NULL_ESCAPE_C)

   493                         || c1 != originalOfReplacement(c1)) {

   494                         // an accidental escape

   495                         needEscape = true;

   496                     }

   497                 }

   498             } else {

   499                 needEscape = isDangerous(c);

   500             }

   501 

   502             if (!needEscape) {

   503                 if (sb != null)  sb.append(c);

   504                 continue;

   505             }

   506 

   507             // build sb if this is the first escape

   508             if (sb == null) {

   509                 sb = new StringBuilder(s.length()+10);

   510                 // mangled names must begin with a backslash:

   511                 if (s.charAt(0) != ESCAPE_C && i > 0)

   512                     sb.append(NULL_ESCAPE);

   513                 // append the string so far, which is unremarkable:

   514                 sb.append(s.substring(0, i));

   515             }

   516 

   517             // rewrite \ to \-, / to \|, etc.

   518             sb.append(ESCAPE_C);

   519             sb.append(replacementOf(c));

   520         }

   521 

   522         if (sb != null)   return sb.toString();

   523 

   524         return s;

   525     }

   526 

   527     private static String demangle(String s) {

   528         // build this lazily, when we first meet an escape:

   529         StringBuilder sb = null;

   530 

   531         int stringStart = 0;

   532         if (s.startsWith(NULL_ESCAPE))

   533             stringStart = 2;

   534 

   535         for (int i = stringStart, slen = s.length(); i < slen; i++) {

   536             char c = s.charAt(i);

   537 

   538             if (c == ESCAPE_C && i+1 < slen) {

   539                 // might be an escape sequence

   540                 char rc = s.charAt(i+1);

   541                 char oc = originalOfReplacement(rc);

   542                 if (oc != rc) {

   543                     // build sb if this is the first escape

   544                     if (sb == null) {

   545                         sb = new StringBuilder(s.length());

   546                         // append the string so far, which is unremarkable:

   547                         sb.append(s.substring(stringStart, i));

   548                     }

   549                     ++i;  // skip both characters

   550                     c = oc;

   551                 }

   552             }

   553 

   554             if (sb != null)

   555                 sb.append(c);

   556         }

   557 

   558         if (sb != null)   return sb.toString();

   559 

   560         return s.substring(stringStart);

   561     }

   562 

   563     static char ESCAPE_C = '\\';

   564     // empty escape sequence to avoid a null name or illegal prefix

   565     static char NULL_ESCAPE_C = '=';

   566     static String NULL_ESCAPE = ESCAPE_C+""+NULL_ESCAPE_C;

   567 

   568     static final String DANGEROUS_CHARS   = "\\/.;:$[]<>"; // \\ must be first

   569     static final String REPLACEMENT_CHARS =  "-|,?!%{}^_";

   570     static final int DANGEROUS_CHAR_FIRST_INDEX = 1; // index after \\

   571     static char[] DANGEROUS_CHARS_A   = DANGEROUS_CHARS.toCharArray();

   572     static char[] REPLACEMENT_CHARS_A = REPLACEMENT_CHARS.toCharArray();

   573     static final Character[] DANGEROUS_CHARS_CA;

   574     static {

   575         Character[] dcca = new Character[DANGEROUS_CHARS.length()];

   576         for (int i = 0; i < dcca.length; i++)

   577             dcca[i] = Character.valueOf(DANGEROUS_CHARS.charAt(i));

   578         DANGEROUS_CHARS_CA = dcca;

   579     }

   580 

   581     static final long[] SPECIAL_BITMAP = new long[2];  // 128 bits

   582     static {

   583         String SPECIAL = DANGEROUS_CHARS + REPLACEMENT_CHARS;

   584         //System.out.println("SPECIAL = "+SPECIAL);

   585         for (char c : SPECIAL.toCharArray()) {

   586             SPECIAL_BITMAP[c >>> 6] |= 1L << c;

   587         }

   588     }

   589     static boolean isSpecial(char c) {

   590         if ((c >>> 6) < SPECIAL_BITMAP.length)

   591             return ((SPECIAL_BITMAP[c >>> 6] >> c) & 1) != 0;

   592         else

   593             return false;

   594     }

   595     static char replacementOf(char c) {

   596         if (!isSpecial(c))  return c;

   597         int i = DANGEROUS_CHARS.indexOf(c);

   598         if (i < 0)  return c;

   599         return REPLACEMENT_CHARS.charAt(i);

   600     }

   601     static char originalOfReplacement(char c) {

   602         if (!isSpecial(c))  return c;

   603         int i = REPLACEMENT_CHARS.indexOf(c);

   604         if (i < 0)  return c;

   605         return DANGEROUS_CHARS.charAt(i);

   606     }

   607     static boolean isDangerous(char c) {

   608         if (!isSpecial(c))  return false;

   609         return (DANGEROUS_CHARS.indexOf(c) >= DANGEROUS_CHAR_FIRST_INDEX);

   610     }

   611     static int indexOfDangerousChar(String s, int from) {

   612         for (int i = from, slen = s.length(); i < slen; i++) {

   613             if (isDangerous(s.charAt(i)))

   614                 return i;

   615         }

   616         return -1;

   617     }

   618     static int lastIndexOfDangerousChar(String s, int from) {

   619         for (int i = Math.min(from, s.length()-1); i >= 0; i--) {

   620             if (isDangerous(s.charAt(i)))

   621                 return i;

   622         }

   623         return -1;

   624     }

   625 

   626 

   627 }