/*
* Copyright 2013 Takao Nakaguchi
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.trie4j.bv;
/**
* Utility class for BitVector.
* @author Takao Nakaguchi
*/
public class BitVectorUtil {
public static void divide01(BitVector org, BitVector vec0, BitVector vec1){
if(org.size() == 0) return;
if(org.size() == 1){
if(!org.isZero(0)) throw new IllegalArgumentException("invalid bv for trie");
vec0.append1();
return;
}
boolean zeroCounting = org.isZero(0);
int n = org.size();
for(int i = 1; i < n; i++){
if(zeroCounting){
if(org.isZero(i)){
vec0.append1();
} else{
vec0.append0();
zeroCounting = false;
}
} else{
if(org.isZero(i)){
vec1.append0();
zeroCounting = true;
} else{
vec1.append1();
}
}
}
}
/**
* Append bits from bit string. The "bit string" is the array
* of string that contains 8 characters which is '0' or '1'.
* @param bv bit vector
* @param bs the array of bit string
*/
public static void appendBitStrings(BitVector bv, String[] bs){
for(String s : bs){
if(s.length() != 8) throw new RuntimeException(
"The length of bit string must be 8 while " + s.length());
for(char c : s.toCharArray()){
if(c == '0') bv.append0();
else if(c == '1') bv.append1();
else throw new RuntimeException("invalid char '" + c + "' for bit string.");
}
}
}
}