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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License
     15  */
     16 package com.android.providers.contacts;
     17 
     18 import com.ibm.icu4jni.text.CollationAttribute;
     19 import com.ibm.icu4jni.text.CollationKey; // TODO: java.text.CollationKey post-froyo
     20 import com.ibm.icu4jni.text.Collator;
     21 import com.ibm.icu4jni.text.RuleBasedCollator;
     22 import java.util.Locale;
     23 
     24 /**
     25  * Converts a name to a normalized form by removing all non-letter characters and normalizing
     26  * UNICODE according to http://unicode.org/unicode/reports/tr15
     27  */
     28 public class NameNormalizer {
     29 
     30     private static final RuleBasedCollator sCompressingCollator;
     31     static {
     32         sCompressingCollator = (RuleBasedCollator)Collator.getInstance(Locale.getDefault());
     33         sCompressingCollator.setStrength(Collator.PRIMARY);
     34         sCompressingCollator.setDecomposition(Collator.CANONICAL_DECOMPOSITION);
     35     }
     36 
     37     private static final RuleBasedCollator sComplexityCollator;
     38     static {
     39         sComplexityCollator = (RuleBasedCollator)Collator.getInstance(Locale.getDefault());
     40         sComplexityCollator.setStrength(Collator.TERTIARY);
     41         sComplexityCollator.setAttribute(CollationAttribute.CASE_FIRST,
     42                 CollationAttribute.VALUE_LOWER_FIRST);
     43     }
     44 
     45     /**
     46      * Converts the supplied name to a string that can be used to perform approximate matching
     47      * of names.  It ignores non-letter characters and removes accents.
     48      */
     49     public static String normalize(String name) {
     50         CollationKey key = sCompressingCollator.getCollationKey(lettersAndDigitsOnly(name));
     51         return Hex.encodeHex(key.toByteArray(), true);
     52     }
     53 
     54     /**
     55      * Compares "complexity" of two names, which is determined by the presence
     56      * of mixed case characters, accents and, if all else is equal, length.
     57      */
     58     public static int compareComplexity(String name1, String name2) {
     59         int diff = sComplexityCollator.compare(lettersAndDigitsOnly(name1),
     60                 lettersAndDigitsOnly(name2));
     61         if (diff != 0) {
     62             return diff;
     63         }
     64 
     65         return name1.length() - name2.length();
     66     }
     67 
     68     /**
     69      * Returns a string containing just the letters from the original string.
     70      */
     71     private static String lettersAndDigitsOnly(String name) {
     72         char[] letters = name.toCharArray();
     73         int length = 0;
     74         for (int i = 0; i < letters.length; i++) {
     75             final char c = letters[i];
     76             if (Character.isLetterOrDigit(c)) {
     77                 letters[length++] = c;
     78             }
     79         }
     80 
     81         if (length != letters.length) {
     82             return new String(letters, 0, length);
     83         }
     84 
     85         return name;
     86     }
     87 }
     88