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Punycode
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‎src/main/java/net/siisise/lang/Punycode.java

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/*
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* Copyright 2025 okome.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package net.siisise.lang;
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import net.siisise.io.Packet;
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import net.siisise.io.PacketA;
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import net.siisise.math.Matics;
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/**
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* RFC 3492 Punycode
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* 参考 https://qiita.com/msmania/items/dc0e2b8c2c5de0707435
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*/
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public class Punycode {
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private static final int BASE = 36;
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private static final int TMIN = 1;
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private static final int TMAX = 26;
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private static final int SKEW = 38;
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private static final int DAMP = 700;
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private static final int INITIAL_BIAS = 72;
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private static final int INITIAL_N = 128;
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private static final char DELIMIT = '-';
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/**
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* 国際化ドメイン名をACE xn-- ASCII列に変換する
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* @param u
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* @return Punycode
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*/
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public static java.lang.String toASCII(java.lang.String u) {
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CodePoint cp = new CodePoint(u);
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if ( cp.length() >= 64 ) {
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throw new IllegalStateException();
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}
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int[] cpch = cp.codePoints().toArray();
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Packet st = new PacketA();
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// 分離とソート unicodeの大きい方から code と位置に変換
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do {
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int index = -1;
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int co = 0; // (n, i)
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for (int i = cpch.length - 1; i >= 0; i--) {
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if ( cpch[i] > co ) {
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index = i;
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co = cpch[i];
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}
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}
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if ( co < 128 ) {
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break;
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}
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co = co * cpch.length + index;
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st.backWrite(Bin.toByte(co));
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int[] tmpch = new int[cpch.length - 1];
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System.arraycopy(cpch, 0, tmpch, 0, index);
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System.arraycopy(cpch, index+1, tmpch, index, tmpch.length - index);
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cpch = tmpch;
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} while ( true );
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// 残ったのがASCII
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StringBuilder sb = new StringBuilder();
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for (int c : cpch) {
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sb.append((char)c); // ASCIIのみ
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}
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if (sb.length() > 0) {
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// ASCII あり
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// xn-- を付ける場合 ASCII + 国際化両方あり
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sb.append('-');
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}
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if (st.size() == 0) { // 国際化なし ASCIIのみ
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return sb.toString();
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}
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// delta変換
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int n = INITIAL_N;
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int bias = INITIAL_BIAS;
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byte[] dc = new byte[4];
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int tn = cpch.length;
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int c = n * tn - 1;
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tn++;
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int d = DAMP;
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while (st.length() > 0) {
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int ostat = c + n + 1;
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st.read(dc);
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c = Bin.btoi(dc)[0];
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n = c / tn;
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int delta = c - ostat;
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sb.append(toCh(delta, bias)); // delta からコード
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bias = adapt(delta, d, tn);
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d = 2;
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tn++;
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}
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return sb.toString();
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}
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/**
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* bias の重み.
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* @param delta 前の差分
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* @param div
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* @param tn n番目の文字 (1開始)
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* @return
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*/
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private static int adapt(int delta, int div, int tn) {
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// 1.
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delta /= div;
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// 2.
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delta += delta / tn;
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int n = 0;
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while (delta > ((BASE - TMIN) * TMAX) / 2) {
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delta /= BASE - TMIN;
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n++;
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}
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return (BASE * n) + (((BASE - TMIN + 1) * delta) / (delta + SKEW));
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}
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/**
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* 下からj桁目ぐらいの閾値 thresholds
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* BASE(36) * (j+1) - bias
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* 最小 TMIN 最大 TMAX に制限
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* @param j
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* @param bias 可変値
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* @return t_j
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*/
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private static int t(int j, int bias) {
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return Matics.range(BASE * (j+1) - bias, TMIN, TMAX);
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}
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static final char[] CODE = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','0','1','2','3','4','5','6','7','8','9'};
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/**
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* 1文字デルタからコード
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* BASE = 36
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* @param n delta
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* @return
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*/
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private static java.lang.String toCh(int n, int bias) {
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StringBuilder sb = new StringBuilder();
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int i = 0;
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int k = t(i, bias);
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while (n >= k) {
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n -= k;
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sb.append(CODE[k + (n % (BASE - k))]);
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n = n / (BASE - k);
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i++;
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k = t(i, bias);
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}
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sb.append(CODE[n]);
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return sb.toString();
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}
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public static java.lang.String toUnicode(java.lang.String a) {
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int delimit_index = a.lastIndexOf(DELIMIT);
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StringBuilder sb = new StringBuilder();
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if ( delimit_index >= 0) {
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java.lang.String ascii = a.substring(0,delimit_index);
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if (delimit_index == a.length() - 1) {
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return ascii;
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}
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sb.append(ascii);
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}
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char[] ex = a.substring(delimit_index + 1).toCharArray();
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int of = 0;
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int w = 1;
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int bias = INITIAL_BIAS;
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int d = DAMP;
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int n = 0;
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int tn = sb.codePointCount(0, sb.length()) + 1;
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int c = INITIAL_N * tn;
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for (int i = 0; i < ex.length; i++) {
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int k = t(i - of, bias);
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int m = num(ex[i]);
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n += m * w;
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if (m >= k) {
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w *= BASE - k;
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} else {
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c += n;
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int idx = c % tn;
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c /= tn;
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char[] cp = Character.toChars(c);
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sb.insert(sb.offsetByCodePoints(0, idx), cp);
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// 次の文字
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of = i+1;
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bias = adapt(n, d, tn);
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tn++;
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c = c*tn + idx + 1;
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d = 2;
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w = 1;
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n = 0;
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}
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}
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return sb.toString();
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}
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static int num(char ch) {
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if ( ch >= 'a' && ch <= 'z') {
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return ch - 'a';
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} else if ( ch >= 'A' && ch <= 'Z') {
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return ch - 'A';
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} else if ( ch >= '0' && ch <= '9') {
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return ch - '0' + 26;
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}
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throw new IllegalStateException();
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}
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}

‎src/test/java/net/siisise/lang/PunycodeTest.java

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/*
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* Copyright 2025 okome.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package net.siisise.lang;
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import org.junit.jupiter.api.Test;
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import static org.junit.jupiter.api.Assertions.*;
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/**
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* Punycode test
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*/
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public class PunycodeTest {
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public PunycodeTest() {
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}
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/**
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* Test of toASCII method, of class Punycode.
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*/
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@Test
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public void testToASCII() {
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System.out.println("toASCII");
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java.lang.String u = "3年B組金八先生";
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java.lang.String expResult = "3B-ww4c5e180e575a65lsy2b";
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java.lang.String result = Punycode.toASCII(u);
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assertEquals(expResult, result);
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u = "\u0644\u064a\u0647\u0645\u0627\u0628\u062A\u0643\u0644\u0645\u0648\u0634\u0639\u0631\u0628\u064A\u061F";
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expResult = "egbpdaj6bu4bxfgehfvwxn";
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result = Punycode.toASCII(u);
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assertEquals(expResult, result);
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u = "\u4ED6\u4EEC\u4E3A\u4EC0\u4E48\u4E0D\u8BF4\u4E2D\u6587";
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expResult = "ihqwcrb4cv8a8dqg056pqjye";
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result = Punycode.toASCII(u);
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assertEquals(expResult, result);
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u = "安室奈美恵-with-SUPER-MONKEYS";
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expResult = "-with-SUPER-MONKEYS-pc58ag80a8qai00g7n9n";
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result = Punycode.toASCII(u);
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assertEquals(expResult, result);
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}
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/**
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* Test of toUnicode method, of class Punycode.
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*/
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@Test
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public void testToUnicode() {
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System.out.println("toUnicode");
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java.lang.String a = "3B-ww4c5e180e575a65lsy2b";
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java.lang.String expResult = "3年B組金八先生";
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java.lang.String result = Punycode.toUnicode(a);
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assertEquals(expResult, result);
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}
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}

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