content: /*
   * Copyright 1999-2101 Alibaba Group.
   *
   * Licensed 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.alibaba.fastjson.util;
  
  import java.io.Closeable;
  import java.nio.ByteBuffer;
  import java.nio.CharBuffer;
  import java.nio.charset.CharacterCodingException;
  import java.nio.charset.CharsetDecoder;
  import java.nio.charset.CoderResult;
  
  import com.alibaba.fastjson.JSONException;
  
  /**
   * @author wenshao<szujobs@hotmail.com>
   */
  public class IOUtils {
  
      public static void close(Closeable x) {
          if (x != null) {
              try {
                  x.close();
              } catch (Exception e) {
                  // skip
              }
          }
      }
  
      // Requires positive x
      public static int stringSize(long x) {
          long p = 10;
          for (int i = 1; i < 19; i++) {
              if (x < p) return i;
              p = 10 * p;
          }
          return 19;
      }
  
      public static void getChars(long i, int index, char[] buf) {
          long q;
          int r;
          int charPos = index;
          char sign = 0;
  
          if (i < 0) {
              sign = '-';
              i = -i;
          }
  
          // Get 2 digits/iteration using longs until quotient fits into an int
          while (i > Integer.MAX_VALUE) {
              q = i / 100;
              // really: r = i - (q * 100);
              r = (int) (i - ((q << 6) + (q << 5) + (q << 2)));
              i = q;
              buf[--charPos] = DigitOnes[r];
              buf[--charPos] = DigitTens[r];
          }
  
          // Get 2 digits/iteration using ints
          int q2;
          int i2 = (int) i;
          while (i2 >= 65536) {
              q2 = i2 / 100;
              // really: r = i2 - (q * 100);
              r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
              i2 = q2;
              buf[--charPos] = DigitOnes[r];
              buf[--charPos] = DigitTens[r];
          }
  
          // Fall thru to fast mode for smaller numbers
          // assert(i2 <= 65536, i2);
          for (;;) {
              q2 = (i2 * 52429) >>> (16 + 3);
              r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
              buf[--charPos] = digits[r];
              i2 = q2;
              if (i2 == 0) break;
          }
          if (sign != 0) {
              buf[--charPos] = sign;
          }
      }
  
      /**
       * Places characters representing the integer i into the character array buf. The characters are placed into the
       * buffer backwards starting with the least significant digit at the specified index (exclusive), and working
       * backwards from there. Will fail if i == Integer.MIN_VALUE
       */
      public static void getChars(int i, int index, char[] buf) {
          int q, r;
          int charPos = index;
          char sign = 0;
  
          if (i < 0) {
              sign = '-';
              i = -i;
          }
  
          // Generate two digits per iteration
          while (i >= 65536) {
              q = i / 100;
              // really: r = i - (q * 100);
              r = i - ((q << 6) + (q << 5) + (q << 2));
              i = q;
              buf[--charPos] = DigitOnes[r];
              buf[--charPos] = DigitTens[r];
          }
  
          // Fall thru to fast mode for smaller numbers
          // assert(i <= 65536, i);
          for (;;) {
              q = (i * 52429) >>> (16 + 3);
              r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
              buf[--charPos] = digits[r];
              i = q;
              if (i == 0) break;
          }
          if (sign != 0) {
              buf[--charPos] = sign;
          }
      }
  
      public static void getChars(byte b, int index, char[] buf) {
          int i = b;
          int q, r;
          int charPos = index;
          char sign = 0;
  
          if (i < 0) {
              sign = '-';
              i = -i;
          }
  
          // Fall thru to fast mode for smaller numbers
          // assert(i <= 65536, i);
          for (;;) {
              q = (i * 52429) >>> (16 + 3);
              r = i - ((q << 3) + (q << 1)); // r = i-(q*10) ...
              buf[--charPos] = digits[r];
              i = q;
              if (i == 0) break;
          }
          if (sign != 0) {
              buf[--charPos] = sign;
          }
      }
  
      /**
       * All possible chars for representing a number as a String
       */
      final static char[] digits    = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
              'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
  
      final static char[] DigitTens = { '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '1', '1', '1', '1', '1', '1',
              '1', '1', '1', '1', '2', '2', '2', '2', '2', '2', '2', '2', '2', '2', '3', '3', '3', '3', '3', '3', '3',
              '3', '3', '3', '4', '4', '4', '4', '4', '4', '4', '4', '4', '4', '5', '5', '5', '5', '5', '5', '5', '5',
              '5', '5', '6', '6', '6', '6', '6', '6', '6', '6', '6', '6', '7', '7', '7', '7', '7', '7', '7', '7', '7',
              '7', '8', '8', '8', '8', '8', '8', '8', '8', '8', '8', '9', '9', '9', '9', '9', '9', '9', '9', '9', '9', };
  
      final static char[] DigitOnes = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5',
              '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6',
              '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7',
              '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8',
              '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', };
  
      final static int[]  sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999, Integer.MAX_VALUE };
  
      // Requires positive x
      static int stringSize(int x) {
          for (int i = 0;; i++)
              if (x <= sizeTable[i]) return i + 1;
      }
  
      public static void decode(CharsetDecoder charsetDecoder, ByteBuffer byteBuf, CharBuffer charByte) {
          try {
              CoderResult cr = charsetDecoder.decode(byteBuf, charByte, true);
  
              if (!cr.isUnderflow()) {
                  cr.throwException();
              }
  
              cr = charsetDecoder.flush(charByte);
  
              if (!cr.isUnderflow()) {
                  cr.throwException();
              }
          } catch (CharacterCodingException x) {
              // Substitution is always enabled,
              // so this shouldn't happen
              throw new JSONException(x.getMessage(), x);
          }
      }
  }
  