jars/icu4j-4_4_2-src/main/classes/translit/src/com/ibm/icu/text/CaseFoldTransliterator.java

   1 /*\r
   2  *******************************************************************************\r
   3  * Copyright (C) 2009, Google, International Business Machines Corporation     *\r
   4  * and others. All Rights Reserved.                                            *\r
   5  *******************************************************************************\r
   6  */\r
   7 package com.ibm.icu.text;\r
   8 \r
   9 import java.io.IOException;\r
  10 \r
  11 import com.ibm.icu.impl.UCaseProps;\r
  12 \r
  13 /**\r
  14  * A transliterator that performs locale-sensitive toLower()\r
  15  * case mapping.\r
  16  */\r
  17 class CaseFoldTransliterator extends Transliterator{\r
  18 \r
  19     /**\r
  20      * Package accessible ID.\r
  21      */\r
  22     static final String _ID = "Any-CaseFold";\r
  23     \r
  24     // TODO: Add variants for tr, az, lt, default = default locale\r
  25 \r
  26     /**\r
  27      * System registration hook.\r
  28      */\r
  29     static void register() {\r
  30         Transliterator.registerFactory(_ID, new Transliterator.Factory() {\r
  31             public Transliterator getInstance(String ID) {\r
  32                 return new CaseFoldTransliterator();\r
  33             }\r
  34         });\r
  35 \r
  36         Transliterator.registerSpecialInverse("CaseFold", "Upper", false);\r
  37     }\r
  38 \r
  39     private UCaseProps csp;\r
  40     private ReplaceableContextIterator iter;\r
  41     private StringBuffer result;\r
  42 \r
  43     /**\r
  44      * Constructs a transliterator.\r
  45      */\r
  46 \r
  47     public CaseFoldTransliterator() {\r
  48         super(_ID, null);\r
  49         try {\r
  50             csp=UCaseProps.getSingleton();\r
  51         } catch (IOException e) {\r
  52             csp=null;\r
  53         }\r
  54         iter=new ReplaceableContextIterator();\r
  55         result = new StringBuffer();\r
  56     }\r
  57 \r
  58     /**\r
  59      * Implements {@link Transliterator#handleTransliterate}.\r
  60      */\r
  61     protected void handleTransliterate(Replaceable text,\r
  62                                        Position offsets, boolean isIncremental) {\r
  63         if(csp==null) {\r
  64             return;\r
  65         }\r
  66 \r
  67         if(offsets.start >= offsets.limit) {\r
  68             return;\r
  69         } \r
  70 \r
  71         iter.setText(text);\r
  72         result.setLength(0);\r
  73         int c, delta;\r
  74 \r
  75         // Walk through original string\r
  76         // If there is a case change, modify corresponding position in replaceable\r
  77 \r
  78         iter.setIndex(offsets.start);\r
  79         iter.setLimit(offsets.limit);\r
  80         iter.setContextLimits(offsets.contextStart, offsets.contextLimit);\r
  81         while((c=iter.nextCaseMapCP())>=0) {\r
  82             c=csp.toFullFolding(c, result, 0); // toFullFolding(int c, StringBuffer out, int options)\r
  83 \r
  84             if(iter.didReachLimit() && isIncremental) {\r
  85                 // the case mapping function tried to look beyond the context limit\r
  86                 // wait for more input\r
  87                 offsets.start=iter.getCaseMapCPStart();\r
  88                 return;\r
  89             }\r
  90 \r
  91             /* decode the result */\r
  92             if(c<0) {\r
  93                 /* c mapped to itself, no change */\r
  94                 continue;\r
  95             } else if(c<=UCaseProps.MAX_STRING_LENGTH) {\r
  96                 /* replace by the mapping string */\r
  97                 delta=iter.replace(result.toString());\r
  98                 result.setLength(0);\r
  99             } else {\r
 100                 /* replace by single-code point mapping */\r
 101                 delta=iter.replace(UTF16.valueOf(c));\r
 102             }\r
 103 \r
 104             if(delta!=0) {\r
 105                 offsets.limit += delta;\r
 106                 offsets.contextLimit += delta;\r
 107             }\r
 108         }\r
 109         offsets.start = offsets.limit;\r
 110     }\r
 111 }\r