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PowerDNS Versatile Database Driven Nameserver
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Copyright (C) 2002 PowerDNS.COM BV
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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void HuffmanCodec::set(char c,const string &code)
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HuffmanCodec::HuffmanCodec()
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set('9',"1000111100");
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set('*',"100011110100");
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set('q',"100011110101");
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set('7',"10001111011");
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for(map<char,string>::const_iterator i=d_dict.begin();i!=d_dict.end();++i) {
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d_min=min(d_min,i->second.length());
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d_max=max(d_max,i->second.length());
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(d_rdict[i->second.length()])[i->second]=i->first;
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d_last_compressed=d_last_out="";
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void HuffmanCodec::passthrough(bool shoulddo)
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d_passthrough=shoulddo;
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// Bitify input: 1001101110101001000101
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//Decode got offered: '1001101110101001'
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void HuffmanCodec::decode(const string &compressed, string &out)
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if(compressed==d_last_compressed) {
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unbitify(compressed, full);
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// cout<<"Decode got offered: '"<<full<<"'"<<endl;
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size_t cleft=full.length();
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out.reserve(full.length()/5);
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map<string,char>::const_iterator i;
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for(mlen=d_min;mlen<=cleft && mlen<=d_max;++mlen) {
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if(d_rdict[mlen].empty())
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i=d_rdict[mlen].find(full.substr(pos,mlen));
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if(i!=d_rdict[mlen].end()) { // match
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d_last_compressed=compressed;
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out.append(1,i->second);
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throw AhuException("Unable to parse huffman symbol "+full.substr(pos));
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d_last_compressed=compressed;
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void HuffmanCodec::encode(const string &in, string &out)
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for(string::const_iterator i=in.begin();i!=in.end();++i) {
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map<char,string>::const_iterator j=d_dict.find(tolower(*i));
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if(j==d_dict.end()) {
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throw AhuException("Trying to huffman encode an unknown symbol '"+c+"'");
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full.append(j->second);
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full.append(d_dict[0]);
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// cout<<"full: "<<full<<endl;
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void HuffmanCodec::bitify(const string &full, string &out)
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unsigned char bitpos=0;
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unsigned char curbyte=0;
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// cout<<"Bitify input: "<<full<<endl;
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for(string::const_iterator i=full.begin();i!=full.end();++i) {
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curbyte|= (*i=='1')<<(7-bitpos);
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out.append(1,curbyte);
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out.append(1,curbyte);
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void HuffmanCodec::unbitify(const string &in, string &full)
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full.reserve(in.length()*8);
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for(string::const_iterator i=in.begin();i!=in.end();++i) {
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full.append(os.str());
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int main(int argc, char **argv)
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// hc.initDictionary(dict);
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// cout<<"in: "<<in.length()<<endl;
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hc.encode(in,compressed);
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// cout<<"compressed: "<<compressed.length()<<endl;
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// cout<<"Compressed: '"<<compressed<<"'"<<endl;
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hc.decode(compressed,out);
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cout<<"'"<<out<<"'"<<endl;
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catch(AhuException &ae) {
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cerr<<"Fatal error: "<<ae.reason<<endl;