| /* |
| ******************************************************************************* |
| * Copyright (C) 1996-2000, International Business Machines Corporation and * |
| * others. All Rights Reserved. * |
| ******************************************************************************* |
| * |
| * $Source: /xsrl/Nsvn/icu/icu4j/src/com/ibm/text/Attic/TransliterationRuleSet.java,v $ |
| * $Date: 2000/06/29 21:59:23 $ |
| * $Revision: 1.10 $ |
| * |
| ***************************************************************************************** |
| */ |
| package com.ibm.text; |
| |
| import java.util.*; |
| |
| /** |
| * A set of rules for a <code>RuleBasedTransliterator</code>. This set encodes |
| * the transliteration in one direction from one set of characters or short |
| * strings to another. A <code>RuleBasedTransliterator</code> consists of up to |
| * two such sets, one for the forward direction, and one for the reverse. |
| * |
| * <p>A <code>TransliterationRuleSet</code> has one important operation, that of |
| * finding a matching rule at a given point in the text. This is accomplished |
| * by the <code>findMatch()</code> method. |
| * |
| * <p>Copyright © IBM Corporation 1999. All rights reserved. |
| * |
| * @author Alan Liu |
| * @version $RCSfile: TransliterationRuleSet.java,v $ $Revision: 1.10 $ $Date: 2000/06/29 21:59:23 $ |
| * |
| * $Log: TransliterationRuleSet.java,v $ |
| * Revision 1.10 2000/06/29 21:59:23 alan4j |
| * Fix handling of Transliterator.Position fields |
| * |
| * Revision 1.9 2000/03/10 04:07:24 johnf |
| * Copyright update |
| * |
| * Revision 1.8 2000/02/03 18:11:19 Alan |
| * Use array rather than hashtable for char-to-set map |
| * |
| * Revision 1.7 2000/01/27 18:59:19 Alan |
| * Use Position rather than int[] and move all subclass overrides to one method (handleTransliterate) |
| * |
| * Revision 1.6 2000/01/18 20:36:17 Alan |
| * Make UnicodeSet inherit from UnicodeFilter |
| * |
| * Revision 1.5 2000/01/04 21:43:57 Alan |
| * Add rule indexing, and move masking check to TransliterationRuleSet. |
| * |
| * Revision 1.4 1999/12/22 01:40:54 Alan |
| * Consolidate rule pattern anteContext, key, and postContext into one string. |
| * |
| * Revision 1.3 1999/12/22 01:05:54 Alan |
| * Improve masking checking; turn it off by default, for better performance |
| * |
| * Revision 1.2 1999/12/22 00:01:36 Alan |
| * Detect a>x masking a>y |
| * |
| */ |
| class TransliterationRuleSet { |
| /** |
| * Vector of rules, in the order added. This is only used while the rule |
| * set is getting built. After that, freeze() reorders and indexes the |
| * rules, and this Vector is freed. |
| */ |
| private Vector ruleVector; |
| |
| /** |
| * Length of the longest preceding context |
| */ |
| private int maxContextLength; |
| |
| /** |
| * Sorted and indexed table of rules. This is created by freeze() from |
| * the rules in ruleVector. |
| */ |
| private TransliterationRule[] rules; |
| |
| /** |
| * Index table. For text having a first character c, compute x = c&0xFF. |
| * Now use rules[index[x]..index[x+1]-1]. This index table is created by |
| * freeze(). |
| */ |
| private int[] index; |
| |
| private static final String COPYRIGHT = |
| "\u00A9 IBM Corporation 1999. All rights reserved."; |
| |
| /** |
| * Construct a new empty rule set. |
| */ |
| public TransliterationRuleSet() { |
| ruleVector = new Vector(); |
| maxContextLength = 0; |
| } |
| |
| /** |
| * Return the maximum context length. |
| * @return the length of the longest preceding context. |
| */ |
| public int getMaximumContextLength() { |
| return maxContextLength; |
| } |
| |
| /** |
| * Add a rule to this set. Rules are added in order, and order is |
| * significant. |
| * @param rule the rule to add |
| */ |
| public void addRule(TransliterationRule rule) { |
| if (ruleVector == null) { |
| throw new IllegalArgumentException("Cannot add rules after freezing"); |
| } |
| ruleVector.addElement(rule); |
| int len; |
| if ((len = rule.getAnteContextLength()) > maxContextLength) { |
| maxContextLength = len; |
| } |
| } |
| |
| /** |
| * Close this rule set to further additions, check it for masked rules, |
| * and index it to optimize performance. Once this method is called, |
| * addRule() can no longer be called. |
| * @exception IllegalArgumentException if some rules are masked |
| */ |
| public void freeze(RuleBasedTransliterator.Data variables) { |
| /* Construct the rule array and index table. We reorder the |
| * rules by sorting them into 256 bins. Each bin contains all |
| * rules matching the index value for that bin. A rule |
| * matches an index value if string whose first key character |
| * has a low byte equal to the index value can match the rule. |
| * |
| * Each bin contains zero or more rules, in the same order |
| * they were found originally. However, the total rules in |
| * the bins may exceed the number in the original vector, |
| * since rules that have a variable as their first key |
| * character will generally fall into more than one bin. |
| * |
| * That is, each bin contains all rules that either have that |
| * first index value as their first key character, or have |
| * a set containing the index value as their first character. |
| */ |
| int n = ruleVector.size(); |
| index = new int[257]; // [sic] |
| Vector v = new Vector(2*n); // heuristic; adjust as needed |
| |
| /* Precompute the index values. This saves a LOT of time. |
| */ |
| int[] indexValue = new int[n]; |
| for (int j=0; j<n; ++j) { |
| TransliterationRule r = (TransliterationRule) ruleVector.elementAt(j); |
| indexValue[j] = r.getIndexValue(variables); |
| } |
| for (int x=0; x<256; ++x) { |
| index[x] = v.size(); |
| for (int j=0; j<n; ++j) { |
| if (indexValue[j] >= 0) { |
| if (indexValue[j] == x) { |
| v.addElement(ruleVector.elementAt(j)); |
| } |
| } else { |
| // If the indexValue is < 0, then the first key character is |
| // a set, and we must use the more time-consuming |
| // matchesIndexValue check. In practice this happens |
| // rarely, so we seldom tread this code path. |
| TransliterationRule r = (TransliterationRule) ruleVector.elementAt(j); |
| if (r.matchesIndexValue(x, variables)) { |
| v.addElement(r); |
| } |
| } |
| } |
| } |
| index[256] = v.size(); |
| |
| /* Freeze things into an array. |
| */ |
| rules = new TransliterationRule[v.size()]; |
| v.copyInto(rules); |
| ruleVector = null; |
| |
| StringBuffer errors = null; |
| |
| /* Check for masking. This is MUCH faster than our old check, |
| * which was each rule against each following rule, since we |
| * only have to check for masking within each bin now. It's |
| * 256*O(n2^2) instead of O(n1^2), where n1 is the total rule |
| * count, and n2 is the per-bin rule count. But n2<<n1, so |
| * it's a big win. |
| */ |
| for (int x=0; x<256; ++x) { |
| for (int j=index[x]; j<index[x+1]-1; ++j) { |
| TransliterationRule r1 = rules[j]; |
| for (int k=j+1; k<index[x+1]; ++k) { |
| TransliterationRule r2 = rules[k]; |
| if (r1.masks(r2)) { |
| if (errors == null) { |
| errors = new StringBuffer(); |
| } else { |
| errors.append("\n"); |
| } |
| errors.append("Rule " + r1 + " masks " + r2); |
| } |
| } |
| } |
| } |
| |
| if (errors != null) { |
| throw new IllegalArgumentException(errors.toString()); |
| } |
| } |
| |
| /** |
| * Attempt to find a matching rule at the specified point in the text. |
| * @param text the text, both translated and untranslated |
| * @param start the beginning index, inclusive; <code>0 <= start |
| * <= limit</code>. |
| * @param limit the ending index, exclusive; <code>start <= limit |
| * <= text.length()</code>. |
| * @param cursor position at which to translate next, representing offset |
| * into text. This value must be between <code>start</code> and |
| * <code>limit</code>. |
| * @param variables a dictionary mapping variables to the sets they |
| * represent (maps <code>Character</code> to <code>UnicodeSet</code>) |
| * @param filter the filter. Any character for which |
| * <tt>filter.contains()</tt> returns <tt>false</tt> will not be |
| * altered by this transliterator. If <tt>filter</tt> is |
| * <tt>null</tt> then no filtering is applied. |
| * @return the matching rule, or null if none found. |
| */ |
| public TransliterationRule findMatch(Replaceable text, |
| Transliterator.Position pos, |
| RuleBasedTransliterator.Data variables, |
| UnicodeFilter filter) { |
| /* We only need to check our indexed bin of the rule table, |
| * based on the low byte of the first key character. |
| */ |
| int x = text.charAt(pos.start) & 0xFF; |
| for (int i=index[x]; i<index[x+1]; ++i) { |
| if (rules[i].matches(text, pos, variables, filter)) { |
| return rules[i]; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Attempt to find a matching rule at the specified point in the text. |
| * Unlike <code>findMatch()</code>, this method does an incremental match. |
| * An incremental match requires that there be no partial matches that might |
| * pre-empt the full match that is found. If there are partial matches, |
| * then null is returned. A non-null result indicates that a full match has |
| * been found, and that it cannot be pre-empted by a partial match |
| * regardless of what additional text is added to the translation buffer. |
| * @param text the text, both translated and untranslated |
| * @param start the beginning index, inclusive; <code>0 <= start |
| * <= limit</code>. |
| * @param limit the ending index, exclusive; <code>start <= limit |
| * <= text.length()</code>. |
| * @param cursor position at which to translate next, representing offset |
| * into text. This value must be between <code>start</code> and |
| * <code>limit</code>. |
| * @param variables a dictionary mapping variables to the sets they |
| * represent (maps <code>Character</code> to <code>UnicodeSet</code>) |
| * @param partial output parameter. <code>partial[0]</code> is set to |
| * true if a partial match is returned. |
| * @param filter the filter. Any character for which |
| * <tt>filter.contains()</tt> returns <tt>false</tt> will not be |
| * altered by this transliterator. If <tt>filter</tt> is |
| * <tt>null</tt> then no filtering is applied. |
| * @return the matching rule, or null if none found, or if the text buffer |
| * does not have enough text yet to unambiguously match a rule. |
| */ |
| public TransliterationRule findIncrementalMatch(Replaceable text, |
| Transliterator.Position pos, |
| RuleBasedTransliterator.Data variables, |
| boolean partial[], |
| UnicodeFilter filter) { |
| /* We only need to check our indexed bin of the rule table, |
| * based on the low byte of the first key character. |
| */ |
| partial[0] = false; |
| int x = text.charAt(pos.start) & 0xFF; |
| for (int i=index[x]; i<index[x+1]; ++i) { |
| int match = rules[i].getMatchDegree(text, pos, |
| variables, filter); |
| switch (match) { |
| case TransliterationRule.FULL_MATCH: |
| return rules[i]; |
| case TransliterationRule.PARTIAL_MATCH: |
| partial[0] = true; |
| return null; |
| } |
| } |
| return null; |
| } |
| } |
