linguist/samples/C++/json_reader.cpp

// Copyright 2007-2010 Baptiste Lepilleur
// Distributed under MIT license, or public domain if desired and
// recognized in your jurisdiction.
// See file LICENSE for detail or copy at http://jsoncpp.sourceforge.net/LICENSE

/*
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

// Source - https://github.com/Ij888/ApacheCordovaRecipes/blob/6e8a2c1d9de7302f74bc3dbac54a021f0499bbb3/jqmsandbox/plugins/cordova-plugin-globalization/src/blackberry10/native/public/json_reader.cpp

#include <json/reader.h>
#include <json/value.h>
#include <utility>
#include <cstdio>
#include <cassert>
#include <cstring>
#include <iostream>
#include <stdexcept>

#if _MSC_VER >= 1400 // VC++ 8.0
#pragma warning( disable : 4996 )   // disable warning about strdup being deprecated.
#endif

namespace Json {

// QNX is strict about declaring C symbols in the std namespace.
#ifdef __QNXNTO__
using std::memcpy;
using std::sprintf;
using std::sscanf;
#endif

// Implementation of class Features
// ////////////////////////////////

Features::Features()
   : allowComments_( true )
   , strictRoot_( false )
{
}


Features 
Features::all()
{
   return Features();
}


Features 
Features::strictMode()
{
   Features features;
   features.allowComments_ = false;
   features.strictRoot_ = true;
   return features;
}

// Implementation of class Reader
// ////////////////////////////////


static inline bool 
in( Reader::Char c, Reader::Char c1, Reader::Char c2, Reader::Char c3, Reader::Char c4 )
{
   return c == c1  ||  c == c2  ||  c == c3  ||  c == c4;
}

static inline bool 
in( Reader::Char c, Reader::Char c1, Reader::Char c2, Reader::Char c3, Reader::Char c4, Reader::Char c5 )
{
   return c == c1  ||  c == c2  ||  c == c3  ||  c == c4  ||  c == c5;
}


static bool 
containsNewLine( Reader::Location begin, 
                 Reader::Location end )
{
   for ( ;begin < end; ++begin )
      if ( *begin == '\n'  ||  *begin == '\r' )
         return true;
   return false;
}

static std::string codePointToUTF8(unsigned int cp)
{
   std::string result;
   
   // based on description from http://en.wikipedia.org/wiki/UTF-8

   if (cp <= 0x7f) 
   {
      result.resize(1);
      result[0] = static_cast<char>(cp);
   } 
   else if (cp <= 0x7FF) 
   {
      result.resize(2);
      result[1] = static_cast<char>(0x80 | (0x3f & cp));
      result[0] = static_cast<char>(0xC0 | (0x1f & (cp >> 6)));
   } 
   else if (cp <= 0xFFFF) 
   {
      result.resize(3);
      result[2] = static_cast<char>(0x80 | (0x3f & cp));
      result[1] = 0x80 | static_cast<char>((0x3f & (cp >> 6)));
      result[0] = 0xE0 | static_cast<char>((0xf & (cp >> 12)));
   }
   else if (cp <= 0x10FFFF) 
   {
      result.resize(4);
      result[3] = static_cast<char>(0x80 | (0x3f & cp));
      result[2] = static_cast<char>(0x80 | (0x3f & (cp >> 6)));
      result[1] = static_cast<char>(0x80 | (0x3f & (cp >> 12)));
      result[0] = static_cast<char>(0xF0 | (0x7 & (cp >> 18)));
   }

   return result;
}


// Class Reader
// //////////////////////////////////////////////////////////////////

Reader::Reader()
   : features_( Features::all() )
{
}


Reader::Reader( const Features &features )
   : features_( features )
{
}


bool
Reader::parse( const std::string &document, 
               Value &root,
               bool collectComments )
{
   document_ = document;
   const char *begin = document_.c_str();
   const char *end = begin + document_.length();
   return parse( begin, end, root, collectComments );
}


bool
Reader::parse( std::istream& sin,
               Value &root,
               bool collectComments )
{
   //std::istream_iterator<char> begin(sin);
   //std::istream_iterator<char> end;
   // Those would allow streamed input from a file, if parse() were a
   // template function.

   // Since std::string is reference-counted, this at least does not
   // create an extra copy.
   std::string doc;
   std::getline(sin, doc, (char)EOF);
   return parse( doc, root, collectComments );
}

bool 
Reader::parse( const char *beginDoc, const char *endDoc, 
               Value &root,
               bool collectComments )
{
   if ( !features_.allowComments_ )
   {
      collectComments = false;
   }

   begin_ = beginDoc;
   end_ = endDoc;
   collectComments_ = collectComments;
   current_ = begin_;
   lastValueEnd_ = 0;
   lastValue_ = 0;
   commentsBefore_ = "";
   errors_.clear();
   while ( !nodes_.empty() )
      nodes_.pop();
   nodes_.push( &root );
   
   bool successful = readValue();
   Token token;
   skipCommentTokens( token );
   if ( collectComments_  &&  !commentsBefore_.empty() )
      root.setComment( commentsBefore_, commentAfter );
   if ( features_.strictRoot_ )
   {
      if ( !root.isArray()  &&  !root.isObject() )
      {
         // Set error location to start of doc, ideally should be first token found in doc
         token.type_ = tokenError;
         token.start_ = beginDoc;
         token.end_ = endDoc;
         addError( "A valid JSON document must be either an array or an object value.",
                   token );
         return false;
      }
   }
   return successful;
}


bool
Reader::readValue()
{
   Token token;
   skipCommentTokens( token );
   bool successful = true;

   if ( collectComments_  &&  !commentsBefore_.empty() )
   {
      currentValue().setComment( commentsBefore_, commentBefore );
      commentsBefore_ = "";
   }


   switch ( token.type_ )
   {
   case tokenObjectBegin:
      successful = readObject( token );
      break;
   case tokenArrayBegin:
      successful = readArray( token );
      break;
   case tokenNumber:
      successful = decodeNumber( token );
      break;
   case tokenString:
      successful = decodeString( token );
      break;
   case tokenTrue:
      currentValue() = true;
      break;
   case tokenFalse:
      currentValue() = false;
      break;
   case tokenNull:
      currentValue() = Value();
      break;
   default:
      return addError( "Syntax error: value, object or array expected.", token );
   }

   if ( collectComments_ )
   {
      lastValueEnd_ = current_;
      lastValue_ = &currentValue();
   }

   return successful;
}


void 
Reader::skipCommentTokens( Token &token )
{
   if ( features_.allowComments_ )
   {
      do
      {
         readToken( token );
      }
      while ( token.type_ == tokenComment );
   }
   else
   {
      readToken( token );
   }
}


bool 
Reader::expectToken( TokenType type, Token &token, const char *message )
{
   readToken( token );
   if ( token.type_ != type )
      return addError( message, token );
   return true;
}


bool 
Reader::readToken( Token &token )
{
   skipSpaces();
   token.start_ = current_;
   Char c = getNextChar();
   bool ok = true;
   switch ( c )
   {
   case '{':
      token.type_ = tokenObjectBegin;
      break;
   case '}':
      token.type_ = tokenObjectEnd;
      break;
   case '[':
      token.type_ = tokenArrayBegin;
      break;
   case ']':
      token.type_ = tokenArrayEnd;
      break;
   case '"':
      token.type_ = tokenString;
      ok = readString();
      break;
   case '/':
      token.type_ = tokenComment;
      ok = readComment();
      break;
   case '0':
   case '1':
   case '2':
   case '3':
   case '4':
   case '5':
   case '6':
   case '7':
   case '8':
   case '9':
   case '-':
      token.type_ = tokenNumber;
      readNumber();
      break;
   case 't':
      token.type_ = tokenTrue;
      ok = match( "rue", 3 );
      break;
   case 'f':
      token.type_ = tokenFalse;
      ok = match( "alse", 4 );
      break;
   case 'n':
      token.type_ = tokenNull;
      ok = match( "ull", 3 );
      break;
   case ',':
      token.type_ = tokenArraySeparator;
      break;
   case ':':
      token.type_ = tokenMemberSeparator;
      break;
   case 0:
      token.type_ = tokenEndOfStream;
      break;
   default:
      ok = false;
      break;
   }
   if ( !ok )
      token.type_ = tokenError;
   token.end_ = current_;
   return true;
}


void 
Reader::skipSpaces()
{
   while ( current_ != end_ )
   {
      Char c = *current_;
      if ( c == ' '  ||  c == '\t'  ||  c == '\r'  ||  c == '\n' )
         ++current_;
      else
         break;
   }
}


bool 
Reader::match( Location pattern, 
               int patternLength )
{
   if ( end_ - current_ < patternLength )
      return false;
   int index = patternLength;
   while ( index-- )
      if ( current_[index] != pattern[index] )
         return false;
   current_ += patternLength;
   return true;
}


bool
Reader::readComment()
{
   Location commentBegin = current_ - 1;
   Char c = getNextChar();
   bool successful = false;
   if ( c == '*' )
      successful = readCStyleComment();
   else if ( c == '/' )
      successful = readCppStyleComment();
   if ( !successful )
      return false;

   if ( collectComments_ )
   {
      CommentPlacement placement = commentBefore;
      if ( lastValueEnd_  &&  !containsNewLine( lastValueEnd_, commentBegin ) )
      {
         if ( c != '*'  ||  !containsNewLine( commentBegin, current_ ) )
            placement = commentAfterOnSameLine;
      }

      addComment( commentBegin, current_, placement );
   }
   return true;
}


void 
Reader::addComment( Location begin, 
                    Location end, 
                    CommentPlacement placement )
{
   assert( collectComments_ );
   if ( placement == commentAfterOnSameLine )
   {
      assert( lastValue_ != 0 );
      lastValue_->setComment( std::string( begin, end ), placement );
   }
   else
   {
      if ( !commentsBefore_.empty() )
         commentsBefore_ += "\n";
      commentsBefore_ += std::string( begin, end );
   }
}


bool 
Reader::readCStyleComment()
{
   while ( current_ != end_ )
   {
      Char c = getNextChar();
      if ( c == '*'  &&  *current_ == '/' )
         break;
   }
   return getNextChar() == '/';
}


bool 
Reader::readCppStyleComment()
{
   while ( current_ != end_ )
   {
      Char c = getNextChar();
      if (  c == '\r'  ||  c == '\n' )
         break;
   }
   return true;
}


void 
Reader::readNumber()
{
   while ( current_ != end_ )
   {
      if ( !(*current_ >= '0'  &&  *current_ <= '9')  &&
           !in( *current_, '.', 'e', 'E', '+', '-' ) )
         break;
      ++current_;
   }
}

bool
Reader::readString()
{
   Char c = 0;
   while ( current_ != end_ )
   {
      c = getNextChar();
      if ( c == '\\' )
         getNextChar();
      else if ( c == '"' )
         break;
   }
   return c == '"';
}


bool 
Reader::readObject( Token &tokenStart )
{
   Token tokenName;
   std::string name;
   currentValue() = Value( objectValue );
   while ( readToken( tokenName ) )
   {
      bool initialTokenOk = true;
      while ( tokenName.type_ == tokenComment  &&  initialTokenOk )
         initialTokenOk = readToken( tokenName );
      if  ( !initialTokenOk )
         break;
      if ( tokenName.type_ == tokenObjectEnd  &&  name.empty() )  // empty object
         return true;
      if ( tokenName.type_ != tokenString )
         break;
      
      name = "";
      if ( !decodeString( tokenName, name ) )
         return recoverFromError( tokenObjectEnd );

      Token colon;
      if ( !readToken( colon ) ||  colon.type_ != tokenMemberSeparator )
      {
         return addErrorAndRecover( "Missing ':' after object member name", 
                                    colon, 
                                    tokenObjectEnd );
      }
      Value &value = currentValue()[ name ];
      nodes_.push( &value );
      bool ok = readValue();
      nodes_.pop();
      if ( !ok ) // error already set
         return recoverFromError( tokenObjectEnd );

      Token comma;
      if ( !readToken( comma )
            ||  ( comma.type_ != tokenObjectEnd  &&  
                  comma.type_ != tokenArraySeparator &&
		  comma.type_ != tokenComment ) )
      {
         return addErrorAndRecover( "Missing ',' or '}' in object declaration", 
                                    comma, 
                                    tokenObjectEnd );
      }
      bool finalizeTokenOk = true;
      while ( comma.type_ == tokenComment &&
              finalizeTokenOk )
         finalizeTokenOk = readToken( comma );
      if ( comma.type_ == tokenObjectEnd )
         return true;
   }
   return addErrorAndRecover( "Missing '}' or object member name", 
                              tokenName, 
                              tokenObjectEnd );
}


bool 
Reader::readArray( Token &tokenStart )
{
   currentValue() = Value( arrayValue );
   skipSpaces();
   if ( *current_ == ']' ) // empty array
   {
      Token endArray;
      readToken( endArray );
      return true;
   }
   int index = 0;
   while ( true )
   {
      Value &value = currentValue()[ index++ ];
      nodes_.push( &value );
      bool ok = readValue();
      nodes_.pop();
      if ( !ok ) // error already set
         return recoverFromError( tokenArrayEnd );

      Token token;
      // Accept Comment after last item in the array.
      ok = readToken( token );
      while ( token.type_ == tokenComment  &&  ok )
      {
         ok = readToken( token );
      }
      bool badTokenType = ( token.type_ == tokenArraySeparator  &&  
                            token.type_ == tokenArrayEnd );
      if ( !ok  ||  badTokenType )
      {
         return addErrorAndRecover( "Missing ',' or ']' in array declaration", 
                                    token, 
                                    tokenArrayEnd );
      }
      if ( token.type_ == tokenArrayEnd )
         break;
   }
   return true;
}


bool 
Reader::decodeNumber( Token &token )
{
   bool isDouble = false;
   for ( Location inspect = token.start_; inspect != token.end_; ++inspect )
   {
      isDouble = isDouble  
                 ||  in( *inspect, '.', 'e', 'E', '+' )  
                 ||  ( *inspect == '-'  &&  inspect != token.start_ );
   }
   if ( isDouble )
      return decodeDouble( token );
   Location current = token.start_;
   bool isNegative = *current == '-';
   if ( isNegative )
      ++current;
   Value::UInt threshold = (isNegative ? Value::UInt(-Value::minInt) 
                                       : Value::maxUInt) / 10;
   Value::UInt value = 0;
   while ( current < token.end_ )
   {
      Char c = *current++;
      if ( c < '0'  ||  c > '9' )
         return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );
      if ( value >= threshold )
         return decodeDouble( token );
      value = value * 10 + Value::UInt(c - '0');
   }
   if ( isNegative )
      currentValue() = -Value::Int( value );
   else if ( value <= Value::UInt(Value::maxInt) )
      currentValue() = Value::Int( value );
   else
      currentValue() = value;
   return true;
}


bool 
Reader::decodeDouble( Token &token )
{
   double value = 0;
   const int bufferSize = 32;
   int count;
   int length = int(token.end_ - token.start_);
   if ( length <= bufferSize )
   {
      Char buffer[bufferSize];
      memcpy( buffer, token.start_, length );
      buffer[length] = 0;
      count = sscanf( buffer, "%lf", &value );
   }
   else
   {
      std::string buffer( token.start_, token.end_ );
      count = sscanf( buffer.c_str(), "%lf", &value );
   }

   if ( count != 1 )
      return addError( "'" + std::string( token.start_, token.end_ ) + "' is not a number.", token );
   currentValue() = value;
   return true;
}


bool 
Reader::decodeString( Token &token )
{
   std::string decoded;
   if ( !decodeString( token, decoded ) )
      return false;
   currentValue() = decoded;
   return true;
}


bool 
Reader::decodeString( Token &token, std::string &decoded )
{
   decoded.reserve( token.end_ - token.start_ - 2 );
   Location current = token.start_ + 1; // skip '"'
   Location end = token.end_ - 1;      // do not include '"'
   while ( current != end )
   {
      Char c = *current++;
      if ( c == '"' )
         break;
      else if ( c == '\\' )
      {
         if ( current == end )
            return addError( "Empty escape sequence in string", token, current );
         Char escape = *current++;
         switch ( escape )
         {
         case '"': decoded += '"'; break;
         case '/': decoded += '/'; break;
         case '\\': decoded += '\\'; break;
         case 'b': decoded += '\b'; break;
         case 'f': decoded += '\f'; break;
         case 'n': decoded += '\n'; break;
         case 'r': decoded += '\r'; break;
         case 't': decoded += '\t'; break;
         case 'u':
            {
               unsigned int unicode;
               if ( !decodeUnicodeCodePoint( token, current, end, unicode ) )
                  return false;
               decoded += codePointToUTF8(unicode);
            }
            break;
         default:
            return addError( "Bad escape sequence in string", token, current );
         }
      }
      else
      {
         decoded += c;
      }
   }
   return true;
}

bool
Reader::decodeUnicodeCodePoint( Token &token, 
                                     Location &current, 
                                     Location end, 
                                     unsigned int &unicode )
{

   if ( !decodeUnicodeEscapeSequence( token, current, end, unicode ) )
      return false;
   if (unicode >= 0xD800 && unicode <= 0xDBFF)
   {
      // surrogate pairs
      if (end - current < 6)
         return addError( "additional six characters expected to parse unicode surrogate pair.", token, current );
      unsigned int surrogatePair;
      if (*(current++) == '\\' && *(current++)== 'u')
      {
         if (decodeUnicodeEscapeSequence( token, current, end, surrogatePair ))
         {
            unicode = 0x10000 + ((unicode & 0x3FF) << 10) + (surrogatePair & 0x3FF);
         } 
         else
            return false;
      } 
      else
         return addError( "expecting another \\u token to begin the second half of a unicode surrogate pair", token, current );
   }
   return true;
}

bool 
Reader::decodeUnicodeEscapeSequence( Token &token, 
                                     Location &current, 
                                     Location end, 
                                     unsigned int &unicode )
{
   if ( end - current < 4 )
      return addError( "Bad unicode escape sequence in string: four digits expected.", token, current );
   unicode = 0;
   for ( int index =0; index < 4; ++index )
   {
      Char c = *current++;
      unicode *= 16;
      if ( c >= '0'  &&  c <= '9' )
         unicode += c - '0';
      else if ( c >= 'a'  &&  c <= 'f' )
         unicode += c - 'a' + 10;
      else if ( c >= 'A'  &&  c <= 'F' )
         unicode += c - 'A' + 10;
      else
         return addError( "Bad unicode escape sequence in string: hexadecimal digit expected.", token, current );
   }
   return true;
}


bool 
Reader::addError( const std::string &message, 
                  Token &token,
                  Location extra )
{
   ErrorInfo info;
   info.token_ = token;
   info.message_ = message;
   info.extra_ = extra;
   errors_.push_back( info );
   return false;
}


bool 
Reader::recoverFromError( TokenType skipUntilToken )
{
   int errorCount = int(errors_.size());
   Token skip;
   while ( true )
   {
      if ( !readToken(skip) )
         errors_.resize( errorCount ); // discard errors caused by recovery
      if ( skip.type_ == skipUntilToken  ||  skip.type_ == tokenEndOfStream )
         break;
   }
   errors_.resize( errorCount );
   return false;
}


bool 
Reader::addErrorAndRecover( const std::string &message, 
                            Token &token,
                            TokenType skipUntilToken )
{
   addError( message, token );
   return recoverFromError( skipUntilToken );
}


Value &
Reader::currentValue()
{
   return *(nodes_.top());
}


Reader::Char 
Reader::getNextChar()
{
   if ( current_ == end_ )
      return 0;
   return *current_++;
}


void 
Reader::getLocationLineAndColumn( Location location,
                                  int &line,
                                  int &column ) const
{
   Location current = begin_;
   Location lastLineStart = current;
   line = 0;
   while ( current < location  &&  current != end_ )
   {
      Char c = *current++;
      if ( c == '\r' )
      {
         if ( *current == '\n' )
            ++current;
         lastLineStart = current;
         ++line;
      }
      else if ( c == '\n' )
      {
         lastLineStart = current;
         ++line;
      }
   }
   // column & line start at 1
   column = int(location - lastLineStart) + 1;
   ++line;
}


std::string
Reader::getLocationLineAndColumn( Location location ) const
{
   int line, column;
   getLocationLineAndColumn( location, line, column );
   char buffer[18+16+16+1];
   sprintf( buffer, "Line %d, Column %d", line, column );
   return buffer;
}


std::string 
Reader::getFormatedErrorMessages() const
{
   std::string formattedMessage;
   for ( Errors::const_iterator itError = errors_.begin();
         itError != errors_.end();
         ++itError )
   {
      const ErrorInfo &error = *itError;
      formattedMessage += "* " + getLocationLineAndColumn( error.token_.start_ ) + "\n";
      formattedMessage += "  " + error.message_ + "\n";
      if ( error.extra_ )
         formattedMessage += "See " + getLocationLineAndColumn( error.extra_ ) + " for detail.\n";
   }
   return formattedMessage;
}


std::istream& operator>>( std::istream &sin, Value &root )
{
    Json::Reader reader;
    bool ok = reader.parse(sin, root, true);
    //JSON_ASSERT( ok );
    if (!ok) throw std::runtime_error(reader.getFormatedErrorMessages());
    return sin;
}


} // namespace Json