370 lines
8.7 KiB
Java
370 lines
8.7 KiB
Java
// RuleBasedCollator.java - Concrete class for locale-based string compare.
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/* Copyright (C) 1999, 2000, 2001 Free Software Foundation
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.text;
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import java.util.Enumeration;
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import java.util.Hashtable;
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import java.util.Vector;
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/**
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* @author Tom Tromey <tromey@cygnus.com>
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* @date March 25, 1999
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*/
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/* Written using "Java Class Libraries", 2nd edition, plus online
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* API docs for JDK 1.2 from http://www.javasoft.com.
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* Status: Believed complete and correct
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*/
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final class RBCElement
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{
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String key;
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char relation;
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RBCElement (String key, char relation)
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{
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this.key = key;
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this.relation = relation;
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}
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}
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public class RuleBasedCollator extends Collator
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{
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public Object clone ()
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{
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RuleBasedCollator c = (RuleBasedCollator) super.clone ();
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c.map = (Hashtable) map.clone ();
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c.prefixes = (Hashtable) map.clone ();
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return c;
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}
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// A helper for CollationElementIterator.next().
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int ceiNext (CollationElementIterator cei)
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{
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if (cei.lookahead_set)
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{
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cei.lookahead_set = false;
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return cei.lookahead;
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}
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int save = cei.index;
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int max = cei.text.length();
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String s = null;
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// It is possible to have a case where `abc' has a mapping, but
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// neither `ab' nor `abd' do. In this case we must treat `abd' as
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// nothing special.
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boolean found = false;
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int i;
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for (i = save + 1; i <= max; ++i)
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{
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s = cei.text.substring(save, i);
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if (prefixes.get(s) == null)
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break;
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found = true;
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}
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// Assume s != null.
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Object obj = map.get(s);
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// The special case.
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while (found && obj == null && s.length() > 1)
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{
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--i;
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s = cei.text.substring(save, i);
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obj = map.get(s);
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}
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// Update state.
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cei.index = i;
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if (obj == null)
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{
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// This idea, and the values, come from JDK.
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// assert (s.length() == 1)
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cei.lookahead_set = true;
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cei.lookahead = s.charAt(0) << 8;
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return 0x7fff << 16;
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}
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return ((Integer) obj).intValue();
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}
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// A helper for compareTo() that returns the next character that has
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// a nonzero ordering at the indicated strength. This is also used
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// in CollationKey.
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static final int next (CollationElementIterator iter, int strength)
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{
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while (true)
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{
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int os = iter.next();
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if (os == CollationElementIterator.NULLORDER)
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return os;
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int c = 0;
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switch (strength)
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{
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case PRIMARY:
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c = os & ~0xffff;
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break;
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case SECONDARY:
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c = os & ~0x00ff;
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break;
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case TERTIARY:
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case IDENTICAL:
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c = os;
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break;
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}
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if (c != 0)
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return c;
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}
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}
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public int compare (String source, String target)
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{
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CollationElementIterator cs, ct;
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cs = new CollationElementIterator (source, this);
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ct = new CollationElementIterator (target, this);
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while (true)
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{
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int os = next (cs, strength);
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int ot = next (ct, strength);
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if (os == CollationElementIterator.NULLORDER
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&& ot == CollationElementIterator.NULLORDER)
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break;
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else if (os == CollationElementIterator.NULLORDER)
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{
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// Source string is shorter, so return "less than".
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return -1;
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}
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else if (ot == CollationElementIterator.NULLORDER)
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{
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// Target string is shorter, so return "greater than".
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return 1;
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}
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if (os != ot)
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return os - ot;
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}
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return 0;
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}
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public boolean equals (Object obj)
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{
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if (! (obj instanceof RuleBasedCollator) || ! super.equals(obj))
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return false;
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RuleBasedCollator rbc = (RuleBasedCollator) obj;
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// FIXME: this is probably wrong. Instead we should compare maps
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// directly.
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return (frenchAccents == rbc.frenchAccents
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&& rules.equals(rbc.rules));
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}
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public CollationElementIterator getCollationElementIterator (String source)
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{
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StringBuffer expand = new StringBuffer (source.length());
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int max = source.length();
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for (int i = 0; i < max; ++i)
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decomposeCharacter (source.charAt(i), expand);
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return new CollationElementIterator (expand.toString(), this);
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}
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public CollationElementIterator getCollationElementIterator (CharacterIterator source)
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{
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StringBuffer expand = new StringBuffer ();
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for (char c = source.first ();
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c != CharacterIterator.DONE;
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c = source.next ())
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decomposeCharacter (c, expand);
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return new CollationElementIterator (expand.toString(), this);
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}
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public CollationKey getCollationKey (String source)
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{
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return new CollationKey (getCollationElementIterator (source), source,
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strength);
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}
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public String getRules ()
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{
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return rules;
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}
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public int hashCode ()
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{
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return (frenchAccents ? 1231 : 1237
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^ rules.hashCode()
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^ map.hashCode()
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^ prefixes.hashCode());
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}
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private final boolean is_special (char c)
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{
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// Rules from JCL book.
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return ((c >= 0x0009 && c <= 0x000d)
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|| (c >= 0x0020 && c <= 0x002f)
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|| (c >= 0x003a && c <= 0x0040)
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|| (c >= 0x005b && c <= 0x0060)
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|| (c >= 0x007b && c <= 0x007e));
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}
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private final int text_argument (String rules, int index,
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StringBuffer result)
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{
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result.setLength(0);
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int len = rules.length();
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while (index < len)
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{
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char c = rules.charAt(index);
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if (c == '\'' && index + 2 < len
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&& rules.charAt(index + 2) == '\''
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&& is_special (rules.charAt(index + 1)))
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index += 2;
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else if (is_special (c) || Character.isWhitespace(c))
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return index;
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result.append(c);
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++index;
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}
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return index;
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}
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public RuleBasedCollator (String rules) throws ParseException
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{
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this.rules = rules;
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this.frenchAccents = false;
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// We keep each rule in order in a vector. At the end we traverse
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// the vector and compute collation values from it.
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int insertion_index = 0;
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Vector vec = new Vector ();
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StringBuffer argument = new StringBuffer ();
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int len = rules.length();
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for (int index = 0; index < len; ++index)
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{
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char c = rules.charAt(index);
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// Just skip whitespace.
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if (Character.isWhitespace(c))
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continue;
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// Modifier.
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if (c == '@')
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{
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frenchAccents = true;
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continue;
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}
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// Check for relation or reset operator.
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if (! (c == '<' || c == ';' || c == ',' || c == '=' || c == '&'))
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throw new ParseException ("invalid character", index);
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++index;
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while (index < len)
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{
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if (! Character.isWhitespace(rules.charAt(index)))
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break;
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++index;
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}
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if (index == len)
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throw new ParseException ("missing argument", index);
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int save = index;
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index = text_argument (rules, index, argument);
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if (argument.length() == 0)
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throw new ParseException ("invalid character", save);
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String arg = argument.toString();
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int item_index = vec.indexOf(arg);
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if (c != '&')
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{
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// If the argument already appears in the vector, then we
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// must remove it in order to re-order.
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if (item_index != -1)
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{
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vec.removeElementAt(item_index);
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if (insertion_index >= item_index)
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--insertion_index;
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}
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RBCElement r = new RBCElement (arg, c);
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vec.insertElementAt(r, insertion_index);
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++insertion_index;
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}
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else
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{
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// Reset.
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if (item_index == -1)
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throw
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new ParseException ("argument to reset not previously seen",
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save);
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insertion_index = item_index + 1;
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}
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// Ugly: in this case the resulting INDEX comes from
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// text_argument, which returns the index of the next
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// character we should examine.
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--index;
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}
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// Now construct a hash table that maps strings onto their
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// collation values.
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int primary = 0;
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int secondary = 0;
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int tertiary = 0;
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this.map = new Hashtable ();
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this.prefixes = new Hashtable ();
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Enumeration e = vec.elements();
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while (e.hasMoreElements())
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{
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RBCElement r = (RBCElement) e.nextElement();
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switch (r.relation)
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{
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case '<':
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++primary;
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secondary = 0;
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tertiary = 0;
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break;
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case ';':
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++secondary;
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tertiary = 0;
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break;
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case ',':
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++tertiary;
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break;
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case '=':
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break;
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}
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// This must match CollationElementIterator.
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map.put(r.key, new Integer (primary << 16
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| secondary << 8 | tertiary));
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// Make a map of all lookaheads we might need.
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for (int i = r.key.length() - 1; i >= 1; --i)
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prefixes.put(r.key.substring(0, i), Boolean.TRUE);
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}
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}
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// True if we are using French-style accent ordering.
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private boolean frenchAccents;
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// It's easier to just save the rules than to try to recreate them.
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private String rules;
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// This maps strings onto collation values.
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private Hashtable map;
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// An entry in this hash means that more lookahead is required for
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// the prefix string.
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private Hashtable prefixes;
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}
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