| /* |
| * 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.drill.exec.expr.fn.impl; |
| |
| import io.netty.buffer.ByteBuf; |
| |
| import org.apache.drill.common.exceptions.DrillRuntimeException; |
| |
| public class StringFunctionUtil { |
| |
| /* Decode the input bytebuf using UTF-8, and return the number of characters |
| */ |
| public static int getUTF8CharLength(ByteBuf buffer, int start, int end) { |
| int charCount = 0; |
| |
| for (int idx = start, charLen = 0; idx < end; idx += charLen) { |
| charLen = utf8CharLen(buffer, idx); |
| ++charCount; //Advance the counter, since we find one char. |
| } |
| return charCount; |
| } |
| |
| /* Decode the input bytebuf using UTF-8. Search in the range of [start, end], find |
| * the position of the first byte of next char after we see "charLength" chars. |
| * |
| */ |
| public static int getUTF8CharPosition(ByteBuf buffer, int start, int end, int charLength) { |
| int charCount = 0; |
| |
| if (start >= end) { |
| return -1; //wrong input here. |
| } |
| |
| for (int idx = start, charLen = 0; idx < end; idx += charLen) { |
| charLen = utf8CharLen(buffer, idx); |
| ++charCount; //Advance the counter, since we find one char. |
| if (charCount == charLength + 1) { |
| return idx; |
| } |
| } |
| return end; |
| } |
| |
| public static int stringLeftMatchUTF8(ByteBuf str, int strStart, int strEnd, |
| ByteBuf substr, int subStart, int subEnd) { |
| for (int i = strStart; i <= strEnd - (subEnd - subStart); i++) { |
| int j = subStart; |
| for (; j< subEnd; j++) { |
| if (str.getByte(i + j - subStart) != substr.getByte(j)) { |
| break; |
| } |
| } |
| |
| if (j == subEnd && j!= subStart) { // found a matched substr (non-empty) in str. |
| return i; // found a match. |
| } |
| } |
| |
| return -1; |
| } |
| |
| public static int utf8CharLen(ByteBuf buffer, int idx) { |
| byte firstByte = buffer.getByte(idx); |
| if (firstByte >= 0) { // 1-byte char. First byte is 0xxxxxxx. |
| return 1; |
| } else if ((firstByte & 0xE0) == 0xC0) { // 2-byte char. First byte is 110xxxxx |
| return 2; |
| } else if ((firstByte & 0xF0) == 0xE0) { // 3-byte char. First byte is 1110xxxx |
| return 3; |
| } else if ((firstByte & 0xF8) == 0xF0) { //4-byte char. First byte is 11110xxx |
| return 4; |
| } |
| throw new DrillRuntimeException("Unexpected byte 0x" + Integer.toString((int)firstByte & 0xff, 16) |
| + " at position " + idx + " encountered while decoding UTF8 string."); |
| } |
| |
| public static int utf8CharLen(byte currentByte) { |
| if (currentByte >= 0) { // 1-byte char. First byte is 0xxxxxxx. |
| return 1; |
| } |
| else if ((currentByte & 0xE0) == 0xC0 ) { // 2-byte char. First byte is 110xxxxx |
| return 2; |
| } |
| else if ((currentByte & 0xF0) == 0xE0 ) { // 3-byte char. First byte is 1110xxxx |
| return 3; |
| } |
| else if ((currentByte & 0xF8) == 0xF0) { //4-byte char. First byte is 11110xxx |
| return 4; |
| } |
| throw new DrillRuntimeException("Unexpected byte 0x" + Integer.toString((int)currentByte & 0xff, 16) + " encountered while decoding UTF8 string."); |
| } |
| |
| } |