org.apache.drill.exec.expr.fn.impl.StringFunctionUtil.java Source code

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Here is the source code for org.apache.drill.exec.expr.fn.impl.StringFunctionUtil.java

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/**
 * 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.");
    }

}