/**
* 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.");
}
}