Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.apache.lucene.util; /* * Some of this code came from the excellent Unicode * conversion examples from: * * http://www.unicode.org/Public/PROGRAMS/CVTUTF * * Full Copyright for that code follows: */ /* * Copyright 2001-2004 Unicode, Inc. * * Disclaimer * * This source code is provided as is by Unicode, Inc. No claims are * made as to fitness for any particular purpose. No warranties of any * kind are expressed or implied. The recipient agrees to determine * applicability of information provided. If this file has been * purchased on magnetic or optical media from Unicode, Inc., the * sole remedy for any claim will be exchange of defective media * within 90 days of receipt. * * Limitations on Rights to Redistribute This Code * * Unicode, Inc. hereby grants the right to freely use the information * supplied in this file in the creation of products supporting the * Unicode Standard, and to make copies of this file in any form * for internal or external distribution as long as this notice * remains attached. */ /* * Additional code came from the IBM ICU library. * * http://www.icu-project.org * * Full Copyright for that code follows. */ /* * Copyright (C) 1999-2010, International Business Machines * Corporation and others. All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, and/or sell copies of the * Software, and to permit persons to whom the Software is furnished to do so, * provided that the above copyright notice(s) and this permission notice appear * in all copies of the Software and that both the above copyright notice(s) and * this permission notice appear in supporting documentation. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS. * IN NO EVENT SHALL THE COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE * LIABLE FOR ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Except as contained in this notice, the name of a copyright holder shall not * be used in advertising or otherwise to promote the sale, use or other * dealings in this Software without prior written authorization of the * copyright holder. */ /** * Class to encode java's UTF16 char[] into UTF8 byte[] * without always allocating a new byte[] as * String.getBytes(StandardCharsets.UTF_8) does. * * @lucene.internal */ public final class UnicodeUtil { /** A binary term consisting of a number of 0xff bytes, likely to be bigger than other terms * (e.g. collation keys) one would normally encounter, and definitely bigger than any UTF-8 terms. * <p> * WARNING: This is not a valid UTF8 Term **/ public static final BytesRef BIG_TERM = new BytesRef(new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 }); // TODO this is unrelated here find a better place for it private UnicodeUtil() { } // no instance public static final int UNI_SUR_HIGH_START = 0xD800; public static final int UNI_SUR_HIGH_END = 0xDBFF; public static final int UNI_SUR_LOW_START = 0xDC00; public static final int UNI_SUR_LOW_END = 0xDFFF; public static final int UNI_REPLACEMENT_CHAR = 0xFFFD; private static final long UNI_MAX_BMP = 0x0000FFFF; private static final long HALF_SHIFT = 10; private static final long HALF_MASK = 0x3FFL; private static final int SURROGATE_OFFSET = Character.MIN_SUPPLEMENTARY_CODE_POINT - (UNI_SUR_HIGH_START << HALF_SHIFT) - UNI_SUR_LOW_START; /** Maximum number of UTF8 bytes per UTF16 character. */ public static final int MAX_UTF8_BYTES_PER_CHAR = 3; /** Encode characters from a char[] source, starting at * offset for length chars. It is the responsibility of the * caller to make sure that the destination array is large enough. */ public static int UTF16toUTF8(final char[] source, final int offset, final int length, byte[] out) { int upto = 0; int i = offset; final int end = offset + length; while (i < end) { final int code = (int) source[i++]; if (code < 0x80) out[upto++] = (byte) code; else if (code < 0x800) { out[upto++] = (byte) (0xC0 | (code >> 6)); out[upto++] = (byte) (0x80 | (code & 0x3F)); } else if (code < 0xD800 || code > 0xDFFF) { out[upto++] = (byte) (0xE0 | (code >> 12)); out[upto++] = (byte) (0x80 | ((code >> 6) & 0x3F)); out[upto++] = (byte) (0x80 | (code & 0x3F)); } else { // surrogate pair // confirm valid high surrogate if (code < 0xDC00 && i < end) { int utf32 = (int) source[i]; // confirm valid low surrogate and write pair if (utf32 >= 0xDC00 && utf32 <= 0xDFFF) { utf32 = (code << 10) + utf32 + SURROGATE_OFFSET; i++; out[upto++] = (byte) (0xF0 | (utf32 >> 18)); out[upto++] = (byte) (0x80 | ((utf32 >> 12) & 0x3F)); out[upto++] = (byte) (0x80 | ((utf32 >> 6) & 0x3F)); out[upto++] = (byte) (0x80 | (utf32 & 0x3F)); continue; } } // replace unpaired surrogate or out-of-order low surrogate // with substitution character out[upto++] = (byte) 0xEF; out[upto++] = (byte) 0xBF; out[upto++] = (byte) 0xBD; } } //assert matches(source, offset, length, out, upto); return upto; } /** Encode characters from this String, starting at offset * for length characters. It is the responsibility of the * caller to make sure that the destination array is large enough. */ public static int UTF16toUTF8(final CharSequence s, final int offset, final int length, byte[] out) { return UTF16toUTF8(s, offset, length, out, 0); } /** Encode characters from this String, starting at offset * for length characters. Output to the destination array * will begin at {@code outOffset}. It is the responsibility of the * caller to make sure that the destination array is large enough. * <p> * note this method returns the final output offset (outOffset + number of bytes written) */ public static int UTF16toUTF8(final CharSequence s, final int offset, final int length, byte[] out, int outOffset) { final int end = offset + length; int upto = outOffset; for (int i = offset; i < end; i++) { final int code = (int) s.charAt(i); if (code < 0x80) out[upto++] = (byte) code; else if (code < 0x800) { out[upto++] = (byte) (0xC0 | (code >> 6)); out[upto++] = (byte) (0x80 | (code & 0x3F)); } else if (code < 0xD800 || code > 0xDFFF) { out[upto++] = (byte) (0xE0 | (code >> 12)); out[upto++] = (byte) (0x80 | ((code >> 6) & 0x3F)); out[upto++] = (byte) (0x80 | (code & 0x3F)); } else { // surrogate pair // confirm valid high surrogate if (code < 0xDC00 && (i < end - 1)) { int utf32 = (int) s.charAt(i + 1); // confirm valid low surrogate and write pair if (utf32 >= 0xDC00 && utf32 <= 0xDFFF) { utf32 = (code << 10) + utf32 + SURROGATE_OFFSET; i++; out[upto++] = (byte) (0xF0 | (utf32 >> 18)); out[upto++] = (byte) (0x80 | ((utf32 >> 12) & 0x3F)); out[upto++] = (byte) (0x80 | ((utf32 >> 6) & 0x3F)); out[upto++] = (byte) (0x80 | (utf32 & 0x3F)); continue; } } // replace unpaired surrogate or out-of-order low surrogate // with substitution character out[upto++] = (byte) 0xEF; out[upto++] = (byte) 0xBF; out[upto++] = (byte) 0xBD; } } //assert matches(s, offset, length, out, upto); return upto; } /** * Calculates the number of UTF8 bytes necessary to write a UTF16 string. * * @return the number of bytes written */ public static int calcUTF16toUTF8Length(final CharSequence s, final int offset, final int len) { final int end = offset + len; int res = 0; for (int i = offset; i < end; i++) { final int code = (int) s.charAt(i); if (code < 0x80) res++; else if (code < 0x800) { res += 2; } else if (code < 0xD800 || code > 0xDFFF) { res += 3; } else { // surrogate pair // confirm valid high surrogate if (code < 0xDC00 && (i < end - 1)) { int utf32 = (int) s.charAt(i + 1); // confirm valid low surrogate and write pair if (utf32 >= 0xDC00 && utf32 <= 0xDFFF) { i++; res += 4; continue; } } res += 3; } } return res; } // Only called from assert /* private static boolean matches(char[] source, int offset, int length, byte[] result, int upto) { try { String s1 = new String(source, offset, length); String s2 = new String(result, 0, upto, StandardCharsets.UTF_8); if (!s1.equals(s2)) { //System.out.println("DIFF: s1 len=" + s1.length()); //for(int i=0;i<s1.length();i++) // System.out.println(" " + i + ": " + (int) s1.charAt(i)); //System.out.println("s2 len=" + s2.length()); //for(int i=0;i<s2.length();i++) // System.out.println(" " + i + ": " + (int) s2.charAt(i)); // If the input string was invalid, then the // difference is OK if (!validUTF16String(s1)) return true; return false; } return s1.equals(s2); } catch (UnsupportedEncodingException uee) { return false; } } // Only called from assert private static boolean matches(String source, int offset, int length, byte[] result, int upto) { try { String s1 = source.substring(offset, offset+length); String s2 = new String(result, 0, upto, StandardCharsets.UTF_8); if (!s1.equals(s2)) { // Allow a difference if s1 is not valid UTF-16 //System.out.println("DIFF: s1 len=" + s1.length()); //for(int i=0;i<s1.length();i++) // System.out.println(" " + i + ": " + (int) s1.charAt(i)); //System.out.println(" s2 len=" + s2.length()); //for(int i=0;i<s2.length();i++) // System.out.println(" " + i + ": " + (int) s2.charAt(i)); // If the input string was invalid, then the // difference is OK if (!validUTF16String(s1)) return true; return false; } return s1.equals(s2); } catch (UnsupportedEncodingException uee) { return false; } } */ public static boolean validUTF16String(CharSequence s) { final int size = s.length(); for (int i = 0; i < size; i++) { char ch = s.charAt(i); if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) { if (i < size - 1) { i++; char nextCH = s.charAt(i); if (nextCH >= UNI_SUR_LOW_START && nextCH <= UNI_SUR_LOW_END) { // Valid surrogate pair } else // Unmatched high surrogate return false; } else // Unmatched high surrogate return false; } else if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) // Unmatched low surrogate return false; } return true; } public static boolean validUTF16String(char[] s, int size) { for (int i = 0; i < size; i++) { char ch = s[i]; if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) { if (i < size - 1) { i++; char nextCH = s[i]; if (nextCH >= UNI_SUR_LOW_START && nextCH <= UNI_SUR_LOW_END) { // Valid surrogate pair } else return false; } else return false; } else if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) // Unmatched low surrogate return false; } return true; } // Borrowed from Python's 3.1.2 sources, // Objects/unicodeobject.c, and modified (see commented // out section, and the -1s) to disallow the reserved for // future (RFC 3629) 5/6 byte sequence characters, and // invalid 0xFE and 0xFF bytes. /* Map UTF-8 encoded prefix byte to sequence length. -1 (0xFF) * means illegal prefix. see RFC 2279 for details */ static final int[] utf8CodeLength; static { final int v = Integer.MIN_VALUE; utf8CodeLength = new int[] { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, v, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4 //, 5, 5, 5, 5, 6, 6, 0, 0 }; } /** * Returns the number of code points in this UTF8 sequence. * * <p>This method assumes valid UTF8 input. This method * <strong>does not perform</strong> full UTF8 validation, it will check only the * first byte of each codepoint (for multi-byte sequences any bytes after * the head are skipped). * * @throws IllegalArgumentException If invalid codepoint header byte occurs or the * content is prematurely truncated. */ public static int codePointCount(BytesRef utf8) { int pos = utf8.offset; final int limit = pos + utf8.length; final byte[] bytes = utf8.bytes; int codePointCount = 0; for (; pos < limit; codePointCount++) { int v = bytes[pos] & 0xFF; if (v < /* 0xxx xxxx */ 0x80) { pos += 1; continue; } if (v >= /* 110x xxxx */ 0xc0) { if (v < /* 111x xxxx */ 0xe0) { pos += 2; continue; } if (v < /* 1111 xxxx */ 0xf0) { pos += 3; continue; } if (v < /* 1111 1xxx */ 0xf8) { pos += 4; continue; } // fallthrough, consider 5 and 6 byte sequences invalid. } // Anything not covered above is invalid UTF8. throw new IllegalArgumentException(); } // Check if we didn't go over the limit on the last character. if (pos > limit) throw new IllegalArgumentException(); return codePointCount; } /** * <p>This method assumes valid UTF8 input. This method * <strong>does not perform</strong> full UTF8 validation, it will check only the * first byte of each codepoint (for multi-byte sequences any bytes after * the head are skipped). It is the responsibility of the caller to make sure * that the destination array is large enough. * * @throws IllegalArgumentException If invalid codepoint header byte occurs or the * content is prematurely truncated. */ public static int UTF8toUTF32(final BytesRef utf8, final int[] ints) { // TODO: ints must not be null, should be an assert int utf32Count = 0; int utf8Upto = utf8.offset; final byte[] bytes = utf8.bytes; final int utf8Limit = utf8.offset + utf8.length; while (utf8Upto < utf8Limit) { final int numBytes = utf8CodeLength[bytes[utf8Upto] & 0xFF]; int v = 0; switch (numBytes) { case 1: ints[utf32Count++] = bytes[utf8Upto++]; continue; case 2: // 5 useful bits v = bytes[utf8Upto++] & 31; break; case 3: // 4 useful bits v = bytes[utf8Upto++] & 15; break; case 4: // 3 useful bits v = bytes[utf8Upto++] & 7; break; default: throw new IllegalArgumentException("invalid utf8"); } // TODO: this may read past utf8's limit. final int limit = utf8Upto + numBytes - 1; while (utf8Upto < limit) { v = v << 6 | bytes[utf8Upto++] & 63; } ints[utf32Count++] = v; } return utf32Count; } /** Shift value for lead surrogate to form a supplementary character. */ private static final int LEAD_SURROGATE_SHIFT_ = 10; /** Mask to retrieve the significant value from a trail surrogate.*/ private static final int TRAIL_SURROGATE_MASK_ = 0x3FF; /** Trail surrogate minimum value */ private static final int TRAIL_SURROGATE_MIN_VALUE = 0xDC00; /** Lead surrogate minimum value */ private static final int LEAD_SURROGATE_MIN_VALUE = 0xD800; /** The minimum value for Supplementary code points */ private static final int SUPPLEMENTARY_MIN_VALUE = 0x10000; /** Value that all lead surrogate starts with */ private static final int LEAD_SURROGATE_OFFSET_ = LEAD_SURROGATE_MIN_VALUE - (SUPPLEMENTARY_MIN_VALUE >> LEAD_SURROGATE_SHIFT_); /** * Cover JDK 1.5 API. Create a String from an array of codePoints. * * @param codePoints The code array * @param offset The start of the text in the code point array * @param count The number of code points * @return a String representing the code points between offset and count * @throws IllegalArgumentException If an invalid code point is encountered * @throws IndexOutOfBoundsException If the offset or count are out of bounds. */ public static String newString(int[] codePoints, int offset, int count) { if (count < 0) { throw new IllegalArgumentException(); } char[] chars = new char[count]; int w = 0; for (int r = offset, e = offset + count; r < e; ++r) { int cp = codePoints[r]; if (cp < 0 || cp > 0x10ffff) { throw new IllegalArgumentException(); } while (true) { try { if (cp < 0x010000) { chars[w] = (char) cp; w++; } else { chars[w] = (char) (LEAD_SURROGATE_OFFSET_ + (cp >> LEAD_SURROGATE_SHIFT_)); chars[w + 1] = (char) (TRAIL_SURROGATE_MIN_VALUE + (cp & TRAIL_SURROGATE_MASK_)); w += 2; } break; } catch (IndexOutOfBoundsException ex) { int newlen = (int) (Math.ceil((double) codePoints.length * (w + 2) / (r - offset + 1))); char[] temp = new char[newlen]; System.arraycopy(chars, 0, temp, 0, w); chars = temp; } } } return new String(chars, 0, w); } // for debugging public static String toHexString(String s) { StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.length(); i++) { char ch = s.charAt(i); if (i > 0) { sb.append(' '); } if (ch < 128) { sb.append(ch); } else { if (ch >= UNI_SUR_HIGH_START && ch <= UNI_SUR_HIGH_END) { sb.append("H:"); } else if (ch >= UNI_SUR_LOW_START && ch <= UNI_SUR_LOW_END) { sb.append("L:"); } else if (ch > UNI_SUR_LOW_END) { if (ch == 0xffff) { sb.append("F:"); } else { sb.append("E:"); } } sb.append("0x").append(Integer.toHexString(ch)); } } return sb.toString(); } /** * Interprets the given byte array as UTF-8 and converts to UTF-16. It is the * responsibility of the caller to make sure that the destination array is large enough. * <p> * NOTE: Full characters are read, even if this reads past the length passed (and * can result in an ArrayOutOfBoundsException if invalid UTF-8 is passed). * Explicit checks for valid UTF-8 are not performed. */ // TODO: broken if chars.offset != 0 public static int UTF8toUTF16(byte[] utf8, int offset, int length, char[] out) { int out_offset = 0; final int limit = offset + length; while (offset < limit) { int b = utf8[offset++] & 0xff; if (b < 0xc0) { assert b < 0x80; out[out_offset++] = (char) b; } else if (b < 0xe0) { out[out_offset++] = (char) (((b & 0x1f) << 6) + (utf8[offset++] & 0x3f)); } else if (b < 0xf0) { out[out_offset++] = (char) (((b & 0xf) << 12) + ((utf8[offset] & 0x3f) << 6) + (utf8[offset + 1] & 0x3f)); offset += 2; } else { assert b < 0xf8 : "b = 0x" + Integer.toHexString(b); int ch = ((b & 0x7) << 18) + ((utf8[offset] & 0x3f) << 12) + ((utf8[offset + 1] & 0x3f) << 6) + (utf8[offset + 2] & 0x3f); offset += 3; if (ch < UNI_MAX_BMP) { out[out_offset++] = (char) ch; } else { int chHalf = ch - 0x0010000; out[out_offset++] = (char) ((chHalf >> 10) + 0xD800); out[out_offset++] = (char) ((chHalf & HALF_MASK) + 0xDC00); } } } return out_offset; } /** Returns the maximum number of utf8 bytes required to encode a utf16 (e.g., java char[], String) */ public static int maxUTF8Length(int utf16Length) { return Math.multiplyExact(utf16Length, MAX_UTF8_BYTES_PER_CHAR); } /** * Utility method for {@link #UTF8toUTF16(byte[], int, int, char[])} * @see #UTF8toUTF16(byte[], int, int, char[]) */ public static int UTF8toUTF16(BytesRef bytesRef, char[] chars) { return UTF8toUTF16(bytesRef.bytes, bytesRef.offset, bytesRef.length, chars); } }