com.firenio.baseio.codec.http11.KMPUtil Maven / Gradle / Ivy
/*
* Copyright 2015 The Baseio Project
*
* 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.firenio.baseio.codec.http11;
import com.firenio.baseio.collection.IntArray;
import com.firenio.baseio.common.Util;
//关键字：前缀，后缀，部分匹配表
public class KMPUtil {
private char[] match_array;
private int[] match_table;
private String match_value;
public KMPUtil(String value) {
this.initialize(value);
}
private void initialize(String value) {
if (Util.isNullOrBlank(value)) {
throw new IllegalArgumentException("null value");
}
this.match_value = value;
this.match_array = match_value.toCharArray();
this.match_table = new int[match_value.length()];
this.initialize_part_match_table();
}
private void initialize_part_match_table() {
int length = this.match_value.length();
// 直接从两位开始比较
for (int i = 2; i < length; i++) {
match_table[i] = initialize_part_match_table0(match_array, i);
}
}
private int initialize_part_match_table0(char[] array, int length) {
int e = 0;
WORD: for (int i = 1; i < length; i++) {
int t = 0;
int p = 0;
int s = length - i;
for (int j = 0; j < i; j++) {
if (array[p++] != array[s++]) {
continue WORD;
}
t++;
}
e = t;
}
return e;
}
public int match(String value) {
return match(value, 0);
}
public int match(String value, int begin) {
if (Util.isNullOrBlank(value) || begin < 0) {
return -1;
}
if (value.length() - begin < this.match_array.length) {
return -1;
}
int source_length = value.length();
int index = begin;
int match_length = this.match_array.length;
char[] match_array = this.match_array;
int[] match_table = this.match_table;
LOOP: for (; index < source_length;) {
for (int i = 0; i < match_length; i++) {
if (value.charAt(index + i) != match_array[i]) {
if (i == 0) {
index++;
} else {
index += (i - match_table[i]);
}
continue LOOP;
}
}
return index;
}
return -1;
}
public IntArray match_all(String value) {
if (Util.isNullOrBlank(value)) {
return null;
}
if (value.length() < match_value.length()) {
return null;
}
IntArray matchs = new IntArray();
if (value.equals(match_value)) {
matchs.add(0);
return matchs;
}
int source_length = value.length();
int index = 0;
int match_length = this.match_array.length;
char[] match_array = this.match_array;
int[] match_table = this.match_table;
LOOP: for (; index < source_length;) {
if (source_length - index < match_length) {
break;
}
for (int i = 0; i < match_length; i++) {
if (value.charAt(index + i) != match_array[i]) {
if (i == 0) {
index++;
} else {
index += (i - match_table[i]);
}
continue LOOP;
}
}
matchs.add(index);
index += match_length;
}
return matchs;
}
public static void main(String[] args) {
String s1 = "1111111111111111111211111111112111121111211111111";
String match = "1112";
KMPUtil kmp = new KMPUtil(match);
System.out.println(kmp.match_all(s1));
}
}