content: /**
   * 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 com.aliyun.odps.mapred.utils;
  
  public class UTF8ByteArrayUtils {
  
    /**
     * Find the first occurrence of the given byte b in a UTF-8 encoded string
     *
     * @param utf
     *     a byte array containing a UTF-8 encoded string
     * @param start
     *     starting offset
     * @param end
     *     ending position
     * @param b
     *     the byte to find
     * @return position that first byte occures otherwise -1
     */
    public static int findByte(byte[] utf, int start, int end, byte b) {
      for (int i = start; i < end; i++) {
        if (utf[i] == b) {
          return i;
        }
      }
      return -1;
    }
  
    /**
     * Find the first occurrence of the given bytes b in a UTF-8 encoded string
     *
     * @param utf
     *     a byte array containing a UTF-8 encoded string
     * @param start
     *     starting offset
     * @param end
     *     ending position
     * @param b
     *     the bytes to find
     * @return position that first byte occures otherwise -1
     */
    public static int findBytes(byte[] utf, int start, int end, byte[] b) {
      int matchEnd = end - b.length;
      for (int i = start; i <= matchEnd; i++) {
        boolean matched = true;
        for (int j = 0; j < b.length; j++) {
          if (utf[i + j] != b[j]) {
            matched = false;
            break;
          }
        }
        if (matched) {
          return i;
        }
      }
      return -1;
    }
  
    /**
     * Find the nth occurrence of the given byte b in a UTF-8 encoded string
     *
     * @param utf
     *     a byte array containing a UTF-8 encoded string
     * @param start
     *     starting offset
     * @param length
     *     the length of byte array
     * @param b
     *     the byte to find
     * @param n
     *     the desired occurrence of the given byte
     * @return position that nth occurrence of the given byte if exists; otherwise -1
     */
    public static int findNthByte(byte[] utf, int start, int length, byte b, int n) {
      int pos = -1;
      int nextStart = start;
      for (int i = 0; i < n; i++) {
        pos = findByte(utf, nextStart, length, b);
        if (pos < 0) {
          return pos;
        }
        nextStart = pos + 1;
      }
      return pos;
    }
  
    /**
     * Find the nth occurrence of the given byte b in a UTF-8 encoded string
     *
     * @param utf
     *     a byte array containing a UTF-8 encoded string
     * @param b
     *     the byte to find
     * @param n
     *     the desired occurrence of the given byte
     * @return position that nth occurrence of the given byte if exists; otherwise -1
     */
    public static int findNthByte(byte[] utf, byte b, int n) {
      return findNthByte(utf, 0, utf.length, b, n);
    }
  
    private static enum UnescapeState {
      NORMAL, START_ESCAPE, ESCAPE_N, ESCAPE_NN, INVALID
    }
  
    /**
     * Do basical unescaping for field separator.
     * Only support '\t', '\ooo', '\\'.
     */
    public static String unescapeSeparator(String separator) {
      StringBuilder sb = new StringBuilder();
  
      UnescapeState state = UnescapeState.NORMAL;
      int num = 0;
      for (char c : separator.toCharArray()) {
        switch (state) {
          case NORMAL:
            if (c == '\\') {
              state = UnescapeState.START_ESCAPE;
            } else {
              sb.append(c);
            }
            break;
          case START_ESCAPE:
            if (c == 't') {
              sb.append('\t');
              state = UnescapeState.NORMAL;
            } else if (c == '\\') {
              sb.append('\\');
              state = UnescapeState.NORMAL;
            } else if (c >= '0' && c <= '7') {
              num = c - '0';
              state = UnescapeState.ESCAPE_N;
            } else {
              state = UnescapeState.INVALID;
            }
            break;
          case ESCAPE_N:
            if (c >= '0' && c <= '7') {
              num = num * 8 + (c - '0');
              state = UnescapeState.ESCAPE_NN;
            } else {
              state = UnescapeState.INVALID;
            }
            break;
          case ESCAPE_NN:
            if (c >= '0' && c <= '7') {
              num = num * 8 + (c - '0');
              if (num > 0x7f) {
                state = UnescapeState.INVALID;
                break;
              }
              sb.append((char) num);
              state = UnescapeState.NORMAL;
            } else {
              state = UnescapeState.INVALID;
            }
            break;
          default:
            // unreachable
            throw new IllegalStateException("Not handled unescaping state:" + state);
        }
        if (state.equals(UnescapeState.INVALID)) {
          break;
        }
      }
      if (!state.equals(UnescapeState.NORMAL)) {
        throw new IllegalArgumentException("Invalid escaping in separator:'" + separator + "'");
      }
      return sb.toString();
    }
  
  }
  
  