com.blazebit.persistence.impl.util.BoyerMooreCaseInsensitiveAsciiLastPatternFinder Maven / Gradle / Ivy
/*
* Copyright 2014 - 2020 Blazebit.
*
* 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 com.blazebit.persistence.impl.util;
/**
* @author Christian Beikov
* @since 1.2.0
*/
public class BoyerMooreCaseInsensitiveAsciiLastPatternFinder extends AbstractPatternFinder {
// Only support ASCII
private static final int RADIX = 256;
private final int[] left;
private final char[] pattern;
public BoyerMooreCaseInsensitiveAsciiLastPatternFinder(String pattern) {
final int length = pattern.length();
this.pattern = new char[length];
this.left = new int[RADIX];
for (int i = 0; i < RADIX; i++) {
this.left[i] = length - 1;
}
for (int i = length - 1; i >= 0; i--) {
final char c = Character.toLowerCase(pattern.charAt(i));
this.pattern[i] = c;
this.left[c] = i;
}
}
public int indexIn(char[] text, int start, int end) {
int m = pattern.length;
int skip;
for (int i = end - m; i >= start; i -= skip) {
skip = 0;
for (int j = 0; j < m; j++) {
final char c = Character.toLowerCase(text[i + j]);
if (pattern[j] != c) {
skip = Math.max(1, left[c] - j);
break;
}
}
if (skip == 0) {
return i;
}
}
return -1;
}
@Override
public int indexIn(CharSequence text, int start, int end) {
int m = pattern.length;
int skip;
for (int i = end - m; i >= start; i -= skip) {
skip = 0;
for (int j = 0; j < m; j++) {
final char c = Character.toLowerCase(text.charAt(i + j));
if (pattern[j] != c) {
skip = Math.max(1, left[c] - j);
break;
}
}
if (skip == 0) {
return i;
}
}
return -1;
}
}