| /* |
| * 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.orc.impl; |
| |
| import java.nio.charset.StandardCharsets; |
| |
| public final class Utf8Utils { |
| |
| public static int charLength(byte[] data, int offset, int length) { |
| int chars = 0; |
| for (int i = 0; i < length; i++) { |
| if (isUtfStartByte(data[offset +i ])) { |
| chars++; |
| } |
| } |
| return chars; |
| } |
| |
| /** |
| * Return the number of bytes required to read at most |
| * maxLength characters in full from a utf-8 encoded byte array provided |
| * by data[offset:offset+length]. This does not validate utf-8 data, but |
| * operates correctly on already valid utf-8 data. |
| * |
| * @param maxCharLength |
| * @param data |
| * @param offset |
| * @param length |
| */ |
| public static int truncateBytesTo(int maxCharLength, byte[] data, int offset, int length) { |
| int chars = 0; |
| if (length <= maxCharLength) { |
| return length; |
| } |
| for (int i = 0; i < length; i++) { |
| if (isUtfStartByte(data[offset +i ])) { |
| chars++; |
| } |
| if (chars > maxCharLength) { |
| return i; |
| } |
| } |
| // everything fits |
| return length; |
| } |
| |
| /** |
| * Checks if b is the first byte of a UTF-8 character. |
| * |
| */ |
| public static boolean isUtfStartByte(byte b) { |
| return (b & 0xC0) != 0x80; |
| } |
| |
| /** |
| * Find the start of the last character that ends in the current string. |
| * @param text the bytes of the utf-8 |
| * @param from the first byte location |
| * @param until the last byte location |
| * @return the index of the last character |
| */ |
| public static int findLastCharacter(byte[] text, int from, int until) { |
| int posn = until; |
| /* we don't expect characters more than 5 bytes */ |
| while (posn >= from) { |
| if (isUtfStartByte(text[posn])) { |
| return posn; |
| } |
| posn -= 1; |
| } |
| /* beginning of a valid char not found */ |
| throw new IllegalArgumentException( |
| "Could not truncate string, beginning of a valid char not found"); |
| } |
| |
| /** |
| * Get the code point at a given location in the byte array. |
| * @param source the bytes of the string |
| * @param from the offset to start at |
| * @param len the number of bytes in the character |
| * @return the code point |
| */ |
| public static int getCodePoint(byte[] source, int from, int len) { |
| return new String(source, from, len, StandardCharsets.UTF_8) |
| .codePointAt(0); |
| } |
| |
| } |