| package com.ibm.text; |
| import com.ibm.Utility; |
| import java.util.Enumeration; |
| import java.util.Vector; |
| |
| /** |
| * A transliterator that is composed of two or more other |
| * transliterator objects linked together. For example, if one |
| * transliterator transliterates from script A to script B, and |
| * another transliterates from script B to script C, the two may be |
| * combined to form a new transliterator from A to C. |
| * |
| * <p>Composed transliterators may not behave as expected. For |
| * example, inverses may not combine to form the identity |
| * transliterator. See the class documentation for {@link |
| * Transliterator} for details. |
| * |
| * <p>If a non-<tt>null</tt> <tt>UnicodeFilter</tt> is applied to a |
| * <tt>CompoundTransliterator</tt>, it has the effect of being |
| * logically <b>and</b>ed with the filter of each transliterator in |
| * the chain. |
| * |
| * <p>Copyright © IBM Corporation 1999. All rights reserved. |
| * |
| * @author Alan Liu |
| * @version $RCSfile: CompoundTransliterator.java,v $ $Revision: 1.5 $ $Date: 2000/01/27 18:59:19 $ |
| */ |
| public class CompoundTransliterator extends Transliterator { |
| |
| private static final boolean DEBUG = false; |
| |
| private Transliterator[] trans; |
| |
| private static final String COPYRIGHT = |
| "\u00A9 IBM Corporation 1999. All rights reserved."; |
| |
| /** |
| * Constructs a new compound transliterator given an array of |
| * transliterators. The array of transliterators may be of any |
| * length, including zero or one, however, useful compound |
| * transliterators have at least two components. |
| * @param transliterators array of <code>Transliterator</code> |
| * objects |
| * @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. |
| */ |
| public CompoundTransliterator(Transliterator[] transliterators, |
| UnicodeFilter filter) { |
| super(joinIDs(transliterators), filter); |
| trans = new Transliterator[transliterators.length]; |
| System.arraycopy(transliterators, 0, trans, 0, trans.length); |
| computeMaximumContextLength(); |
| } |
| |
| /** |
| * Constructs a new compound transliterator given an array of |
| * transliterators. The array of transliterators may be of any |
| * length, including zero or one, however, useful compound |
| * transliterators have at least two components. |
| * @param transliterators array of <code>Transliterator</code> |
| * objects |
| */ |
| public CompoundTransliterator(Transliterator[] transliterators) { |
| this(transliterators, null); |
| } |
| |
| /** |
| * Splits an ID of the form "ID;ID;..." into a compound using each |
| * of the IDs. |
| * @param ID of above form |
| * @param forward if false, does the list in reverse order, and |
| * takes the inverse of each ID. |
| */ |
| public CompoundTransliterator(String ID, int direction, |
| UnicodeFilter filter) { |
| // changed MED |
| // Later, add "rule1[filter];rule2... |
| super(ID, filter); |
| String[] list = split(ID, ';'); |
| trans = new Transliterator[list.length]; |
| for (int i = 0; i < list.length; ++i) { |
| trans[i] = getInstance(list[direction==FORWARD ? i : (list.length-1-i)], |
| direction); |
| } |
| computeMaximumContextLength(); |
| } |
| |
| public CompoundTransliterator(String ID, int direction) { |
| this(ID, direction, null); |
| } |
| |
| public CompoundTransliterator(String ID) { |
| this(ID, FORWARD, null); |
| } |
| |
| /** |
| * Return the IDs of the given list of transliterators, concatenated |
| * with ';' delimiting them. Equivalent to the perlish expression |
| * join(';', map($_.getID(), transliterators). |
| */ |
| private static String joinIDs(Transliterator[] transliterators) { |
| StringBuffer id = new StringBuffer(); |
| for (int i=0; i<transliterators.length; ++i) { |
| if (i > 0) { |
| id.append(';'); |
| } |
| id.append(transliterators[i].getID()); |
| } |
| return id.toString(); |
| } |
| |
| /** |
| * Splits a string, as in JavaScript |
| */ |
| private static String[] split(String s, char divider) { |
| // changed MED |
| |
| // see how many there are |
| int count = 1; |
| for (int i = 0; i < s.length(); ++i) { |
| if (s.charAt(i) == divider) ++count; |
| } |
| |
| // make an array with them |
| String[] result = new String[count]; |
| int last = 0; |
| int current = 0; |
| int i; |
| for (i = 0; i < s.length(); ++i) { |
| if (s.charAt(i) == divider) { |
| result[current++] = s.substring(last,i); |
| last = i+1; |
| } |
| } |
| result[current++] = s.substring(last,i); |
| return result; |
| } |
| |
| |
| /** |
| * Returns the number of transliterators in this chain. |
| * @return number of transliterators in this chain. |
| */ |
| public int getCount() { |
| return trans.length; |
| } |
| |
| /** |
| * Returns the transliterator at the given index in this chain. |
| * @param index index into chain, from 0 to <code>getCount() - 1</code> |
| * @return transliterator at the given index |
| */ |
| public Transliterator getTransliterator(int index) { |
| return trans[index]; |
| } |
| |
| /** |
| * Implements {@link Transliterator#handleTransliterate}. |
| */ |
| protected void handleTransliterate(Replaceable text, |
| Position index, boolean incremental) { |
| /* Call each transliterator with the same start value and |
| * initial cursor index, but with the limit index as modified |
| * by preceding transliterators. The cursor index must be |
| * reset for each transliterator to give each a chance to |
| * transliterate the text. The initial cursor index is known |
| * to still point to the same place after each transliterator |
| * is called because each transliterator will not change the |
| * text between start and the initial value of cursor. |
| * |
| * IMPORTANT: After the first transliterator, each subsequent |
| * transliterator only gets to transliterate text committed by |
| * preceding transliterators; that is, the cursor (output |
| * value) of transliterator i becomes the limit (input value) |
| * of transliterator i+1. Finally, the overall limit is fixed |
| * up before we return. |
| * |
| * Assumptions we make here: |
| * (1) start <= cursor <= limit ;cursor valid on entry |
| * (2) cursor <= cursor' <= limit' ;cursor doesn't move back |
| * (3) cursor <= limit' ;text before cursor unchanged |
| * - cursor' is the value of cursor after calling handleKT |
| * - limit' is the value of limit after calling handleKT |
| */ |
| |
| /** |
| * Example: 3 transliterators. This example illustrates the |
| * mechanics we need to implement. S, C, and L are the start, |
| * cursor, and limit. gl is the globalLimit. |
| * |
| * 1. h-u, changes hex to Unicode |
| * |
| * 4 7 a d 0 4 7 a |
| * abc/u0061/u => abca/u |
| * S C L S C L gl=f->a |
| * |
| * 2. upup, changes "x" to "XX" |
| * |
| * 4 7 a 4 7 a |
| * abca/u => abcAA/u |
| * S CL S C |
| * L gl=a->b |
| * 3. u-h, changes Unicode to hex |
| * |
| * 4 7 a 4 7 a d 0 3 |
| * abcAA/u => abc/u0041/u0041/u |
| * S C L S C |
| * L gl=b->15 |
| * 4. return |
| * |
| * 4 7 a d 0 3 |
| * abc/u0041/u0041/u |
| * S C L |
| */ |
| |
| /** |
| * One more wrinkle. If there is a filter F for the compound |
| * transliterator as a whole, then we need to modify every |
| * non-null filter f in the chain to be f' = F & f. Then, |
| * when we're done, we restore the original filters. |
| * |
| * A possible future optimization is to change f to f' at |
| * construction time, but then if anyone else is using the |
| * transliterators in the chain outside of this context, they |
| * will get unexpected results. |
| */ |
| UnicodeFilter F = getFilter(); |
| UnicodeFilter[] f = null; |
| if (F != null) { |
| f = new UnicodeFilter[trans.length]; |
| for (int i=0; i<f.length; ++i) { |
| f[i] = trans[i].getFilter(); |
| trans[i].setFilter(UnicodeFilterLogic.and(F, f[i])); |
| } |
| } |
| |
| try { |
| int cursor = index.cursor; |
| int limit = index.limit; |
| int globalLimit = limit; |
| /* globalLimit is the overall limit. We keep track of this |
| * since we overwrite index.limit with the previous |
| * index.cursor. After each transliteration, we update |
| * globalLimit for insertions or deletions that have happened. |
| */ |
| |
| for (int i=0; i<trans.length; ++i) { |
| index.cursor = cursor; // Reset cursor |
| index.limit = limit; |
| |
| if (DEBUG) { |
| System.out.print(Utility.escape(i + ": \"" + |
| substring(text, index.start, index.cursor) + '|' + |
| substring(text, index.cursor, index.limit) + |
| "\" -> \"")); |
| } |
| |
| trans[i].handleTransliterate(text, index, incremental); |
| |
| if (DEBUG) { |
| System.out.println(Utility.escape( |
| substring(text, index.start, index.cursor) + '|' + |
| substring(text, index.cursor, index.limit) + |
| '"')); |
| } |
| |
| // Adjust overall limit for insertions/deletions |
| globalLimit += index.limit - limit; |
| limit = index.cursor; // Move limit to end of committed text |
| } |
| // Cursor is good where it is -- where the last |
| // transliterator left it. Limit needs to be put back |
| // where it was, modulo adjustments for deletions/insertions. |
| index.limit = globalLimit; |
| |
| } finally { |
| // Fixup the transliterator filters, if we had to modify them. |
| if (f != null) { |
| for (int i=0; i<f.length; ++i) { |
| trans[i].setFilter(f[i]); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Compute and set the length of the longest context required by this transliterator. |
| * This is <em>preceding</em> context. |
| */ |
| private void computeMaximumContextLength() { |
| int max = 0; |
| for (int i=0; i<trans.length; ++i) { |
| int len = trans[i].getMaximumContextLength(); |
| if (len > max) { |
| max = len; |
| } |
| } |
| setMaximumContextLength(max); |
| } |
| |
| /** |
| * DEBUG |
| * Returns a substring of a Replaceable. |
| */ |
| private static final String substring(Replaceable str, int start, int limit) { |
| StringBuffer buf = new StringBuffer(); |
| while (start < limit) { |
| buf.append(str.charAt(start++)); |
| } |
| return buf.toString(); |
| } |
| } |
