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  /*
   * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
   * (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved
   *
   *   The original version of this source code and documentation is copyrighted
   * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
   * materials are provided under terms of a License Agreement between Taligent
   * and Sun. This technology is protected by multiple US and International
   * patents. This notice and attribution to Taligent may not be removed.
   *   Taligent is a registered trademark of Taligent, Inc.
   *
   */
  
  package java.text;
  
  import libcore.icu.CollationKeyICU;
  
  /**
   * The <code>RuleBasedCollator</code> class is a concrete subclass of
   * <code>Collator</code> that provides a simple, data-driven, table
   * collator.  With this class you can create a customized table-based
   * <code>Collator</code>.  <code>RuleBasedCollator</code> maps
   * characters to sort keys.
   *
   * <p>
   * <code>RuleBasedCollator</code> has the following restrictions
   * for efficiency (other subclasses may be used for more complex languages) :
   * <ol>
   * <li>If a special collation rule controlled by a &lt;modifier&gt; is
        specified it applies to the whole collator object.
   * <li>All non-mentioned characters are at the end of the
   *     collation order.
   * </ol>
   *
   * <p>
   * The collation table is composed of a list of collation rules, where each
   * rule is of one of three forms:
   * <pre>
   *    &lt;modifier&gt;
   *    &lt;relation&gt; &lt;text-argument&gt;
   *    &lt;reset&gt; &lt;text-argument&gt;
   * </pre>
   * The definitions of the rule elements is as follows:
   * <UL>
   *    <LI><strong>Text-Argument</strong>: A text-argument is any sequence of
   *        characters, excluding special characters (that is, common
   *        whitespace characters [0009-000D, 0020] and rule syntax characters
   *        [0021-002F, 003A-0040, 005B-0060, 007B-007E]). If those
   *        characters are desired, you can put them in single quotes
   *        (e.g. ampersand =&gt; '&amp;'). Note that unquoted white space characters
   *        are ignored; e.g. <code>b c</code> is treated as <code>bc</code>.
   *    <LI><strong>Modifier</strong>: There are currently two modifiers that
   *        turn on special collation rules.
   *        <UL>
   *            <LI>'@' : Turns on backwards sorting of accents (secondary
   *                      differences), as in French.
   *            <LI>'!' : Turns on Thai/Lao vowel-consonant swapping.  If this
   *                      rule is in force when a Thai vowel of the range
   *                      &#92;U0E40-&#92;U0E44 precedes a Thai consonant of the range
   *                      &#92;U0E01-&#92;U0E2E OR a Lao vowel of the range &#92;U0EC0-&#92;U0EC4
   *                      precedes a Lao consonant of the range &#92;U0E81-&#92;U0EAE then
   *                      the vowel is placed after the consonant for collation
   *                      purposes.
   *        </UL>
   *        <p>'@' : Indicates that accents are sorted backwards, as in French.
   *    <LI><strong>Relation</strong>: The relations are the following:
   *        <UL>
   *            <LI>'&lt;' : Greater, as a letter difference (primary)
   *            <LI>';' : Greater, as an accent difference (secondary)
   *            <LI>',' : Greater, as a case difference (tertiary)
   *            <LI>'=' : Equal
   *        </UL>
   *    <LI><strong>Reset</strong>: There is a single reset
   *        which is used primarily for contractions and expansions, but which
   *        can also be used to add a modification at the end of a set of rules.
   *        <p>'&amp;' : Indicates that the next rule follows the position to where
   *            the reset text-argument would be sorted.
   * </UL>
   *
   * <p>
   * This sounds more complicated than it is in practice. For example, the
   * following are equivalent ways of expressing the same thing:
   * <blockquote>
   * <pre>
   * a &lt; b &lt; c
   * a &lt; b &amp; b &lt; c
   * a &lt; c &amp; a &lt; b
   * </pre>
   * </blockquote>
   * Notice that the order is important, as the subsequent item goes immediately
   * after the text-argument. The following are not equivalent:
   * <blockquote>
   * <pre>
   * a &lt; b &amp; a &lt; c
   * a &lt; c &amp; a &lt; b
   * </pre>
   * </blockquote>
   * Either the text-argument must already be present in the sequence, or some
   * initial substring of the text-argument must be present. (e.g. "a &lt; b &amp; ae &lt;
   * e" is valid since "a" is present in the sequence before "ae" is reset). In
   * this latter case, "ae" is not entered and treated as a single character;
   * instead, "e" is sorted as if it were expanded to two characters: "a"
   * followed by an "e". This difference appears in natural languages: in
   * traditional Spanish "ch" is treated as though it contracts to a single
   * character (expressed as "c &lt; ch &lt; d"), while in traditional German
   * a-umlaut is treated as though it expanded to two characters
   * (expressed as "a,A &lt; b,B ... &amp;ae;&#92;u00e3&amp;AE;&#92;u00c3").
   * [&#92;u00e3 and &#92;u00c3 are, of course, the escape sequences for a-umlaut.]
   * <p>
   * <strong>Ignorable Characters</strong>
   * <p>
   * For ignorable characters, the first rule must start with a relation (the
   * examples we have used above are really fragments; "a &lt; b" really should be
   * "&lt; a &lt; b"). If, however, the first relation is not "&lt;", then all the all
   * text-arguments up to the first "&lt;" are ignorable. For example, ", - &lt; a &lt; b"
   * makes "-" an ignorable character, as we saw earlier in the word
   * "black-birds". In the samples for different languages, you see that most
   * accents are ignorable.
   *
   * <p><strong>Normalization and Accents</strong>
   * <p>
   * <code>RuleBasedCollator</code> automatically processes its rule table to
   * include both pre-composed and combining-character versions of
   * accented characters.  Even if the provided rule string contains only
   * base characters and separate combining accent characters, the pre-composed
   * accented characters matching all canonical combinations of characters from
   * the rule string will be entered in the table.
   * <p>
   * This allows you to use a RuleBasedCollator to compare accented strings
   * even when the collator is set to NO_DECOMPOSITION.  There are two caveats,
   * however.  First, if the strings to be collated contain combining
   * sequences that may not be in canonical order, you should set the collator to
   * CANONICAL_DECOMPOSITION or FULL_DECOMPOSITION to enable sorting of
   * combining sequences.  Second, if the strings contain characters with
   * compatibility decompositions (such as full-width and half-width forms),
   * you must use FULL_DECOMPOSITION, since the rule tables only include
   * canonical mappings.
   *
   * <p><strong>Errors</strong>
   * <p>
   * The following are errors:
   * <UL>
   *     <LI>A text-argument contains unquoted punctuation symbols
   *        (e.g. "a &lt; b-c &lt; d").
   *     <LI>A relation or reset character not followed by a text-argument
   *        (e.g. "a &lt; ,b").
   *     <LI>A reset where the text-argument (or an initial substring of the
   *         text-argument) is not already in the sequence.
   *         (e.g. "a &lt; b &amp; e &lt; f")
   * </UL>
   * If you produce one of these errors, a <code>RuleBasedCollator</code> throws
   * a <code>ParseException</code>.
   *
   * <p><strong>Examples</strong>
   * <p>Simple:     "&lt; a &lt; b &lt; c &lt; d"
   * <p>Norwegian:  "&lt; a, A &lt; b, B &lt; c, C &lt; d, D &lt; e, E &lt; f, F
   *                 &lt; g, G &lt; h, H &lt; i, I &lt; j, J &lt; k, K &lt; l, L
   *                 &lt; m, M &lt; n, N &lt; o, O &lt; p, P &lt; q, Q &lt; r, R
   *                 &lt; s, S &lt; t, T &lt; u, U &lt; v, V &lt; w, W &lt; x, X
   *                 &lt; y, Y &lt; z, Z
   *                 &lt; &#92;u00E6, &#92;u00C6
   *                 &lt; &#92;u00F8, &#92;u00D8
   *                 &lt; &#92;u00E5 = a&#92;u030A, &#92;u00C5 = A&#92;u030A;
   *                      aa, AA"
   *
   * <p>
   * To create a <code>RuleBasedCollator</code> object with specialized
   * rules tailored to your needs, you construct the <code>RuleBasedCollator</code>
   * with the rules contained in a <code>String</code> object. For example:
   * <blockquote>
   * <pre>
   * String simple = "&lt; a&lt; b&lt; c&lt; d";
   * RuleBasedCollator mySimple = new RuleBasedCollator(simple);
   * </pre>
   * </blockquote>
   * Or:
   * <blockquote>
   * <pre>
   * String Norwegian = "&lt; a, A &lt; b, B &lt; c, C &lt; d, D &lt; e, E &lt; f, F &lt; g, G &lt; h, H &lt; i, I" +
   *                    "&lt; j, J &lt; k, K &lt; l, L &lt; m, M &lt; n, N &lt; o, O &lt; p, P &lt; q, Q &lt; r, R" +
   *                    "&lt; s, S &lt; t, T &lt; u, U &lt; v, V &lt; w, W &lt; x, X &lt; y, Y &lt; z, Z" +
   *                    "&lt; &#92;u00E6, &#92;u00C6" +     // Latin letter ae &amp; AE
   *                    "&lt; &#92;u00F8, &#92;u00D8" +     // Latin letter o &amp; O with stroke
   *                    "&lt; &#92;u00E5 = a&#92;u030A," +  // Latin letter a with ring above
   *                    "  &#92;u00C5 = A&#92;u030A;" +  // Latin letter A with ring above
   *                    "  aa, AA";
   * RuleBasedCollator myNorwegian = new RuleBasedCollator(Norwegian);
   * </pre>
   * </blockquote>
   *
   * <p>
   * A new collation rules string can be created by concatenating rules
   * strings. For example, the rules returned by {@link #getRules()} could
   * be concatenated to combine multiple <code>RuleBasedCollator</code>s.
   *
   * <p>
   * The following example demonstrates how to change the order of
   * non-spacing accents,
   * <blockquote>
   * <pre>
   * // old rule
   * String oldRules = "=&#92;u0301;&#92;u0300;&#92;u0302;&#92;u0308"    // main accents
   *                 + ";&#92;u0327;&#92;u0303;&#92;u0304;&#92;u0305"    // main accents
   *                 + ";&#92;u0306;&#92;u0307;&#92;u0309;&#92;u030A"    // main accents
   *                 + ";&#92;u030B;&#92;u030C;&#92;u030D;&#92;u030E"    // main accents
   *                 + ";&#92;u030F;&#92;u0310;&#92;u0311;&#92;u0312"    // main accents
   *                 + "&lt; a , A ; ae, AE ; &#92;u00e6 , &#92;u00c6"
   *                 + "&lt; b , B &lt; c, C &lt; e, E &amp; C &lt; d, D";
   * // change the order of accent characters
   * String addOn = "&amp; &#92;u0300 ; &#92;u0308 ; &#92;u0302";
   * RuleBasedCollator myCollator = new RuleBasedCollator(oldRules + addOn);
   * </pre>
   * </blockquote>
   *
   * @see        Collator
   * @see        CollationElementIterator
   * @author     Helena Shih, Laura Werner, Richard Gillam
   */
  public class RuleBasedCollator extends Collator{
      // Android-added: protected constructor taking an ICU RuleBasedCollator.
      RuleBasedCollator(android.icu.text.RuleBasedCollator wrapper) {
          super(wrapper);
      }
  
      // IMPLEMENTATION NOTES:  The implementation of the collation algorithm is
      // divided across three classes: RuleBasedCollator, RBCollationTables, and
      // CollationElementIterator.  RuleBasedCollator contains the collator's
      // transient state and includes the code that uses the other classes to
      // implement comparison and sort-key building.  RuleBasedCollator also
      // contains the logic to handle French secondary accent sorting.
      // A RuleBasedCollator has two CollationElementIterators.  State doesn't
      // need to be preserved in these objects between calls to compare() or
      // getCollationKey(), but the objects persist anyway to avoid wasting extra
      // creation time.  compare() and getCollationKey() are synchronized to ensure
      // thread safety with this scheme.  The CollationElementIterator is responsible
      // for generating collation elements from strings and returning one element at
      // a time (sometimes there's a one-to-many or many-to-one mapping between
      // characters and collation elements-- this class handles that).
      // CollationElementIterator depends on RBCollationTables, which contains the
      // collator's static state.  RBCollationTables contains the actual data
      // tables specifying the collation order of characters for a particular locale
      // or use.  It also contains the base logic that CollationElementIterator
      // uses to map from characters to collation elements.  A single RBCollationTables
      // object is shared among all RuleBasedCollators for the same locale, and
      // thus by all the CollationElementIterators they create.
  
      /**
       * RuleBasedCollator constructor.  This takes the table rules and builds
       * a collation table out of them.  Please see RuleBasedCollator class
       * description for more details on the collation rule syntax.
       * @see java.util.Locale
       * @param rules the collation rules to build the collation table from.
       * @exception ParseException A format exception
       * will be thrown if the build process of the rules fails. For
       * example, build rule "a &lt; ? &lt; d" will cause the constructor to
       * throw the ParseException because the '?' is not quoted.
       */
      public RuleBasedCollator(String rules) throws ParseException {
          // BEGIN Android-changed: Switched to ICU.
          if (rules == null) {
              throw new NullPointerException("rules == null");
          }
          try {
              icuColl = new android.icu.text.RuleBasedCollator(rules);
          } catch (Exception e) {
              if (e instanceof ParseException) {
                  throw (ParseException) e;
              }
              /*
               * -1 means it's not a ParseException. Maybe IOException thrown when
               * an error occurred while reading internal data.
               */
              throw new ParseException(e.getMessage(), -1);
          }
          // END Android-changed: Switched to ICU.
      }
  
      // Android-removed: (String rules, int decomp) constructor and copy constructor.
  
      // Android-changed: document that getRules() won't return rules in common case.
      /**
       * Gets the table-based rules for the collation object.
       *
       * <p>On Android, the returned string will be empty unless this instance was
       * constructed using {@link #RuleBasedCollator(String)}.
       *
       * @return returns the collation rules that the table collation object
       * was created from.
       */
      public String getRules()
      {
          // Android-changed: Switched to ICU.
          return collAsICU().getRules();
      }
  
      /**
       * Returns a CollationElementIterator for the given String.
       *
       * @param source the string to be collated
       * @return a {@code CollationElementIterator} object
       * @see CollationElementIterator
       */
      public CollationElementIterator getCollationElementIterator(String source) {
          // Android-changed: Switch to ICU and check for null value.
          if (source == null) {
              throw new NullPointerException("source == null");
          }
          return new CollationElementIterator(collAsICU().getCollationElementIterator(source));
      }
  
      /**
       * Returns a CollationElementIterator for the given CharacterIterator.
       *
       * @param source the character iterator to be collated
       * @return a {@code CollationElementIterator} object
       * @see CollationElementIterator
       * @since 1.2
       */
      public CollationElementIterator getCollationElementIterator(
                                                  CharacterIterator source) {
          // Android-changed: Switch to ICU and check for null value.
         if (source == null) {
              throw new NullPointerException("source == null");
          }
          return new CollationElementIterator(collAsICU().getCollationElementIterator(source));
      }
  
      /**
       * Compares the character data stored in two different strings based on the
       * collation rules.  Returns information about whether a string is less
       * than, greater than or equal to another string in a language.
       * This can be overriden in a subclass.
       *
       * @exception NullPointerException if <code>source</code> or <code>target</code> is null.
       */
      public synchronized int compare(String source, String target)
      {
          if (source == null || target == null) {
              throw new NullPointerException();
          }
          // Android-changed: Switched to ICU.
          return icuColl.compare(source, target);
      }
  
      /**
       * Transforms the string into a series of characters that can be compared
       * with CollationKey.compareTo. This overrides java.text.Collator.getCollationKey.
       * It can be overriden in a subclass.
       */
      public synchronized CollationKey getCollationKey(String source)
      {
          // Android-changed: Switched to ICU.
          if (source == null) {
              return null;
          }
          return new CollationKeyICU(source, icuColl.getCollationKey(source));
      }
  
      /**
       * Standard override; no change in semantics.
       */
      public Object clone() {
          // Android-changed: remove special case for cloning.
          return super.clone();
      }
  
      /**
       * Compares the equality of two collation objects.
       * @param obj the table-based collation object to be compared with this.
       * @return true if the current table-based collation object is the same
       * as the table-based collation object obj; false otherwise.
       */
      public boolean equals(Object obj) {
          if (obj == null) return false;
          // Android-changed: delegate to super class, as that already compares icuColl.
          return super.equals(obj);
      }
  
      /**
       * Generates the hash code for the table-based collation object
       */
      public int hashCode() {
          // Android-changed: Switched to ICU.
          return icuColl.hashCode();
      }
  
      // Android-added: collAsIcu helper method.
      private android.icu.text.RuleBasedCollator collAsICU() {
          return (android.icu.text.RuleBasedCollator) icuColl;
      }
  
      // Android-removed: private constants and fields.
  }
  