package cn.lili.common.sensitive;
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import java.io.Serializable;
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/**
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* 字符指针
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*
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* @author Bulbasaur
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* @since 2020-02-25 14:10:16
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*/
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public class StringPointer implements Serializable, CharSequence, Comparable<StringPointer> {
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private static final long serialVersionUID = 1L;
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protected final char[] value;
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protected final int offset;
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protected final int length;
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private int hash = 0;
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public StringPointer(String str) {
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value = str.toCharArray();
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offset = 0;
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length = value.length;
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}
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public StringPointer(char[] value, int offset, int length) {
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this.value = value;
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this.offset = offset;
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this.length = length;
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}
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/**
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* 计算该位置后（包含）2个字符的hash值
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*
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* @param i 从 0 到 length - 2
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* @return 从 0 到 length - 2
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*/
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public int nextTwoCharHash(int i) {
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return 31 * value[offset + i] + value[offset + i + 1];
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}
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/**
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* 计算该位置后（包含）2个字符和为1个int型的值<br/>
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* int值相同表示2个字符相同
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*
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* @param i 从 0 到 length - 2
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* @return int值
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*/
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public int nextTwoCharMix(int i) {
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return (value[offset + i] << 16) | value[offset + i + 1];
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}
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/**
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* 该位置后（包含）的字符串，是否以某个词（word）开头
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*
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* @param i 从 0 到 length - 2
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* @param word 词
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* @return 是否？
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*/
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public boolean nextStartsWith(int i, StringPointer word) {
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//是否长度超出
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if (word.length > length - i) {
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return false;
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}
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//从尾开始判断
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for (int c = word.length - 1; c >= 0; c--) {
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if (value[offset + i + c] != word.value[word.offset + c]) {
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return false;
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}
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}
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return true;
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}
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/**
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* 填充（替换）
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*
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* @param begin 从此位置开始（含）
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* @param end 到此位置结束（不含）
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* @param fillWith 以此字符填充（替换）
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*/
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public void fill(int begin, int end, char fillWith) {
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for (int i = begin; i < end; i++) {
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value[offset + i] = fillWith;
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}
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}
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@Override
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public int length() {
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return length;
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}
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@Override
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public char charAt(int i) {
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return value[offset + i];
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}
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public StringPointer substring(int begin) {
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return new StringPointer(value, offset + begin, length - begin);
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}
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public StringPointer substring(int begin, int end) {
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return new StringPointer(value, offset + begin, end - begin);
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}
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@Override
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public CharSequence subSequence(int start, int end) {
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return substring(start, end);
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}
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@Override
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public String toString() {
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return new String(value, offset, length);
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}
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@Override
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public int hashCode() {
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int h = hash;
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if (h == 0 && length > 0) {
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for (int i = 0; i < length; i++) {
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h = 31 * h + value[offset + i];
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}
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hash = h;
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}
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return h;
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}
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@Override
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public boolean equals(Object anObject) {
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if (this == anObject) {
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return true;
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}
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if (anObject instanceof StringPointer) {
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StringPointer that = (StringPointer) anObject;
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if (length == that.length) {
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char[] v1 = this.value;
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char[] v2 = that.value;
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for (int i = 0; i < this.length; i++) {
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if (v1[this.offset + i] != v2[that.offset + i]) {
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return false;
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}
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}
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return true;
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}
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}
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return false;
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}
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@Override
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public int compareTo(StringPointer that) {
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int len1 = this.length;
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int len2 = that.length;
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int lim = Math.min(len1, len2);
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char[] v1 = this.value;
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char[] v2 = that.value;
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int k = 0;
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while (k < lim) {
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char c1 = v1[this.offset + k];
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char c2 = v2[that.offset + k];
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if (c1 != c2) {
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return c1 - c2;
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}
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k++;
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}
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return len1 - len2;
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}
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}
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