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      1 /*
      2  * Copyright (C) 2017 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.dialer.enrichedcall;
     17 
     18 import android.support.annotation.NonNull;
     19 
     20 /** Utility for comparing phone numbers. */
     21 public class FuzzyPhoneNumberMatcher {
     22 
     23   private static final int REQUIRED_MATCHED_DIGITS = 7;
     24 
     25   /**
     26    * Returns {@code true} if the given numbers can be interpreted to be the same.
     27    *
     28    * <p>This method is called numerous times when rendering the call log. Using string methods is
     29    * too slow, so character by character matching is used instead.
     30    */
     31   public static boolean matches(@NonNull String lhs, @NonNull String rhs) {
     32     return lastSevenDigitsCharacterByCharacterMatches(lhs, rhs);
     33   }
     34 
     35   /**
     36    * This strategy examines the numbers character by character starting from the end. If the last
     37    * {@link #REQUIRED_MATCHED_DIGITS} match, it returns {@code true}.
     38    */
     39   private static boolean lastSevenDigitsCharacterByCharacterMatches(
     40       @NonNull String lhs, @NonNull String rhs) {
     41     int lhsIndex = lhs.length() - 1;
     42     int rhsIndex = rhs.length() - 1;
     43 
     44     int matchedDigits = 0;
     45 
     46     while (lhsIndex >= 0 && rhsIndex >= 0) {
     47       if (!Character.isDigit(lhs.charAt(lhsIndex))) {
     48         --lhsIndex;
     49         continue;
     50       }
     51       if (!Character.isDigit(rhs.charAt(rhsIndex))) {
     52         --rhsIndex;
     53         continue;
     54       }
     55       if (lhs.charAt(lhsIndex) != rhs.charAt(rhsIndex)) {
     56         break;
     57       }
     58       --lhsIndex;
     59       --rhsIndex;
     60       ++matchedDigits;
     61     }
     62 
     63     return matchedDigits >= REQUIRED_MATCHED_DIGITS;
     64   }
     65 }
     66