StringUtils.cpp Example File

 // -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-

 /*
  * Copyright (C) 2010-2011 ZXing authors
  *
  * 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.
  */

 #include <zxing/common/StringUtils.h>
 #include <zxing/DecodeHints.h>
 #include <sstream>

 using namespace std;
 using namespace zxing;
 using namespace zxing::common;

 // N.B.: these are the iconv strings for at least some versions of iconv

 char const* const StringUtils::PLATFORM_DEFAULT_ENCODING = "UTF-8";
 char const* const StringUtils::ASCII = "ASCII";
 char const* const StringUtils::SHIFT_JIS = "SHIFT_JIS";
 char const* const StringUtils::GB2312 = "GBK";
 char const* const StringUtils::EUC_JP = "EUC-JP";
 char const* const StringUtils::UTF8 = "UTF-8";
 char const* const StringUtils::ISO88591 = "ISO8859-1";
 const bool StringUtils::ASSUME_SHIFT_JIS = false;

 string
 StringUtils::guessEncoding(byte* bytes, int length,
                            Hashtable const& hints) {
   Hashtable::const_iterator i = hints.find(DecodeHints::CHARACTER_SET);
   if (i != hints.end()) {
     return i->second;
   }
   typedef bool boolean;
   // For now, merely tries to distinguish ISO-8859-1, UTF-8 and Shift_JIS,
   // which should be by far the most common encodings.
   boolean canBeISO88591 = true;
   boolean canBeShiftJIS = true;
   boolean canBeUTF8 = true;
   int utf8BytesLeft = 0;
   //int utf8LowChars = 0;
   int utf2BytesChars = 0;
   int utf3BytesChars = 0;
   int utf4BytesChars = 0;
   int sjisBytesLeft = 0;
   //int sjisLowChars = 0;
   int sjisKatakanaChars = 0;
   //int sjisDoubleBytesChars = 0;
   int sjisCurKatakanaWordLength = 0;
   int sjisCurDoubleBytesWordLength = 0;
   int sjisMaxKatakanaWordLength = 0;
   int sjisMaxDoubleBytesWordLength = 0;
   //int isoLowChars = 0;
   //int isoHighChars = 0;
   int isoHighOther = 0;

   typedef byte byte;
   boolean utf8bom = length > 3 &&
     bytes[0] == (byte) 0xEF &&
     bytes[1] == (byte) 0xBB &&
     bytes[2] == (byte) 0xBF;

   for (int i = 0;
        i < length && (canBeISO88591 || canBeShiftJIS || canBeUTF8);
        i++) {

     int value = bytes[i] & 0xFF;

     // UTF-8 stuff
     if (canBeUTF8) {
       if (utf8BytesLeft > 0) {
         if ((value & 0x80) == 0) {
           canBeUTF8 = false;
         } else {
           utf8BytesLeft--;
         }
       } else if ((value & 0x80) != 0) {
         if ((value & 0x40) == 0) {
           canBeUTF8 = false;
         } else {
           utf8BytesLeft++;
           if ((value & 0x20) == 0) {
             utf2BytesChars++;
           } else {
             utf8BytesLeft++;
             if ((value & 0x10) == 0) {
               utf3BytesChars++;
             } else {
               utf8BytesLeft++;
               if ((value & 0x08) == 0) {
                 utf4BytesChars++;
               } else {
                 canBeUTF8 = false;
               }
             }
           }
         }
       } //else {
       //utf8LowChars++;
       //}
     }

     // ISO-8859-1 stuff
     if (canBeISO88591) {
       if (value > 0x7F && value < 0xA0) {
         canBeISO88591 = false;
       } else if (value > 0x9F) {
         if (value < 0xC0 || value == 0xD7 || value == 0xF7) {
           isoHighOther++;
         } //else {
         //isoHighChars++;
         //}
       } //else {
       //isoLowChars++;
       //}
     }

     // Shift_JIS stuff
     if (canBeShiftJIS) {
       if (sjisBytesLeft > 0) {
         if (value < 0x40 || value == 0x7F || value > 0xFC) {
           canBeShiftJIS = false;
         } else {
           sjisBytesLeft--;
         }
       } else if (value == 0x80 || value == 0xA0 || value > 0xEF) {
         canBeShiftJIS = false;
       } else if (value > 0xA0 && value < 0xE0) {
         sjisKatakanaChars++;
         sjisCurDoubleBytesWordLength = 0;
         sjisCurKatakanaWordLength++;
         if (sjisCurKatakanaWordLength > sjisMaxKatakanaWordLength) {
           sjisMaxKatakanaWordLength = sjisCurKatakanaWordLength;
         }
       } else if (value > 0x7F) {
         sjisBytesLeft++;
         //sjisDoubleBytesChars++;
         sjisCurKatakanaWordLength = 0;
         sjisCurDoubleBytesWordLength++;
         if (sjisCurDoubleBytesWordLength > sjisMaxDoubleBytesWordLength) {
           sjisMaxDoubleBytesWordLength = sjisCurDoubleBytesWordLength;
         }
       } else {
         //sjisLowChars++;
         sjisCurKatakanaWordLength = 0;
         sjisCurDoubleBytesWordLength = 0;
       }
     }
   }

   if (canBeUTF8 && utf8BytesLeft > 0) {
     canBeUTF8 = false;
   }
   if (canBeShiftJIS && sjisBytesLeft > 0) {
     canBeShiftJIS = false;
   }

   // Easy -- if there is BOM or at least 1 valid not-single byte character (and no evidence it can't be UTF-8), done
   if (canBeUTF8 && (utf8bom || utf2BytesChars + utf3BytesChars + utf4BytesChars > 0)) {
     return UTF8;
   }
   // Easy -- if assuming Shift_JIS or at least 3 valid consecutive not-ascii characters (and no evidence it can't be), done
   if (canBeShiftJIS && (ASSUME_SHIFT_JIS || sjisMaxKatakanaWordLength >= 3 || sjisMaxDoubleBytesWordLength >= 3)) {
     return SHIFT_JIS;
   }
   // Distinguishing Shift_JIS and ISO-8859-1 can be a little tough for short words. The crude heuristic is:
   // - If we saw
   //   - only two consecutive katakana chars in the whole text, or
   //   - at least 10% of bytes that could be "upper" not-alphanumeric Latin1,
   // - then we conclude Shift_JIS, else ISO-8859-1
   if (canBeISO88591 && canBeShiftJIS) {
     return (sjisMaxKatakanaWordLength == 2 && sjisKatakanaChars == 2) || isoHighOther * 10 >= length
       ? SHIFT_JIS : ISO88591;
   }

   // Otherwise, try in order ISO-8859-1, Shift JIS, UTF-8 and fall back to default platform encoding
   if (canBeISO88591) {
     return ISO88591;
   }
   if (canBeShiftJIS) {
     return SHIFT_JIS;
   }
   if (canBeUTF8) {
     return UTF8;
   }
   // Otherwise, we take a wild guess with platform encoding
   return PLATFORM_DEFAULT_ENCODING;
 }

 string StringUtils::intToStr(int number)
 {
     std::ostringstream ostr; //output string stream
     ostr << number; //use the string stream just like cout,
     //except the stream prints not to stdout but to a string.

     return ostr.str(); //the str() function of the stream
 }