field_codec_var_bytes.cpp

#include "field_codec_var_bytes.h"
#include "dccl/field_codec_manager.h"
#include "dccl/codecs3/field_codec_default.h"
 
 
using namespace dccl::logger;
 
 
dccl::Bitset dccl::v3::VarBytesCodec::encode()
{
    return dccl::Bitset(min_size());
}
 
dccl::Bitset dccl::v3::VarBytesCodec::encode(const std::string& wire_value)
{
    std::string s = wire_value;
    if(s.size() > dccl_field_options().max_length())
    {
        if(this->strict())
            throw(dccl::OutOfRangeException(std::string("Bytes too long for field: ") + FieldCodecBase::this_field()->DebugString(), this->this_field()));
        
        dccl::dlog.is(DEBUG2) && dccl::dlog << "Bytes " << s <<  " exceeds `dccl.max_length`, truncating" << std::endl;
        s.resize(dccl_field_options().max_length()); 
    }
            
    dccl::Bitset value_bits;
    value_bits.from_byte_string(s);
    
    dccl::Bitset length_bits(presence_size() + prefix_size(), s.length());
 
    if(!use_required()) // set the presence bit
    {
        length_bits <<= 1;
        length_bits.set(0);
    }
    
    dccl::dlog.is(DEBUG2) && dccl::dlog << "dccl::v3::VarBytesCodec value_bits: " << value_bits << std::endl;    
 
    
    dccl::dlog.is(DEBUG2) && dccl::dlog << "dccl::v3::VarBytesCodec length_bits: " << length_bits << std::endl;    
    
    // adds to MSBs
    for(int i = 0, n = value_bits.size(); i < n; ++i)
        length_bits.push_back(value_bits[i]);
 
    dccl::dlog.is(DEBUG2) && dccl::dlog << "dccl::v3::VarBytesCodec created: " << length_bits << std::endl;
    
    return length_bits;
}
 
std::string dccl::v3::VarBytesCodec::decode(dccl::Bitset* bits)
{
    if(!use_required())
    {
        if(bits->to_ulong() == 0)
        {
            throw dccl::NullValueException();
        }
        else
        {
            bits->get_more_bits(prefix_size());
            (*bits) >>= 1;
        }
    }
    
    
    unsigned value_length = bits->to_ulong();
    unsigned header_length = presence_size() + prefix_size();
        
    dccl::dlog.is(DEBUG2) && dccl::dlog << "Length of string is = " << value_length << std::endl;
        
    dccl::dlog.is(DEBUG2) && dccl::dlog << "bits before get_more_bits " << *bits << std::endl;    
 
    // grabs more bits to add to the MSBs of `bits`
    bits->get_more_bits(value_length*dccl::BITS_IN_BYTE);
        
    dccl::dlog.is(DEBUG2) && dccl::dlog << "bits after get_more_bits " << *bits << std::endl;    
    dccl::Bitset string_body_bits = *bits;
    string_body_bits >>= header_length;
    string_body_bits.resize(bits->size() - header_length);
 
    dccl::dlog.is(DEBUG2) && dccl::dlog << "string_body_bits " << string_body_bits << std::endl;    
 
    
    return string_body_bits.to_byte_string();
}
 
unsigned dccl::v3::VarBytesCodec::size()
{
    return min_size();
}
 
unsigned dccl::v3::VarBytesCodec::size(const std::string& wire_value)
{   
    return std::min(presence_size() + prefix_size() + static_cast<unsigned>(wire_value.length()*dccl::BITS_IN_BYTE), max_size());
}
 
 
unsigned dccl::v3::VarBytesCodec::max_size()
{
    return presence_size() + prefix_size() + dccl_field_options().max_length() * dccl::BITS_IN_BYTE;
}
 
unsigned dccl::v3::VarBytesCodec::min_size()
{
    if(use_required())
        return prefix_size();
    else
        return presence_size();
}
 
 
void dccl::v3::VarBytesCodec::validate()
{
    require(dccl_field_options().has_max_length(), "missing (dccl.field).max_length");
}