scan_name.cpp

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/*
* SCAN Name Abstraction
* (C) 2008-2009,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/scan_name.h>
#include <botan/parsing.h>
#include <botan/exceptn.h>

namespace Botan {

namespace {

std::string make_arg(const std::vector<std::pair<size_t, std::string>>& name, size_t start)
   {
   std::string output = name[start].second;
   size_t level = name[start].first;

   size_t paren_depth = 0;

   for(size_t i = start + 1; i != name.size(); ++i)
      {
      if(name[i].first <= name[start].first)
         break;

      if(name[i].first > level)
         {
         output += "(" + name[i].second;
         ++paren_depth;
         }
      else if(name[i].first < level)
         {
         for (size_t j = name[i].first; j < level; j++) {
            output += ")";
            --paren_depth;
         }
         output += "," + name[i].second;
         }
      else
         {
         if(output[output.size() - 1] != '(')
            output += ",";
         output += name[i].second;
         }

      level = name[i].first;
      }

   for(size_t i = 0; i != paren_depth; ++i)
      output += ")";

   return output;
   }

}

SCAN_Name::SCAN_Name(const char* algo_spec) : SCAN_Name(std::string(algo_spec))
   {
   }

SCAN_Name::SCAN_Name(std::string algo_spec) : m_orig_algo_spec(algo_spec), m_alg_name(), m_args(), m_mode_info()
   { 
   if(algo_spec.size() == 0)
      throw Invalid_Argument("Expected algorithm name, got empty string");

   std::vector<std::pair<size_t, std::string>> name;
   size_t level = 0;
   std::pair<size_t, std::string> accum = std::make_pair(level, "");

   const std::string decoding_error = "Bad SCAN name '" + algo_spec + "': ";

   for(size_t i = 0; i != algo_spec.size(); ++i)
      {
      char c = algo_spec[i];

      if(c == '/' || c == ',' || c == '(' || c == ')')
         {
         if(c == '(')
            ++level;
         else if(c == ')')
            {
            if(level == 0)
               throw Decoding_Error(decoding_error + "Mismatched parens");
            --level;
            }

         if(c == '/' && level > 0)
            accum.second.push_back(c);
         else
            {
            if(accum.second != "")
               name.push_back(accum);
            accum = std::make_pair(level, "");
            }
         }
      else
         accum.second.push_back(c);
      }

   if(accum.second != "")
      name.push_back(accum);

   if(level != 0)
      throw Decoding_Error(decoding_error + "Missing close paren");

   if(name.size() == 0)
      throw Decoding_Error(decoding_error + "Empty name");

   m_alg_name = name[0].second;

   bool in_modes = false;

   for(size_t i = 1; i != name.size(); ++i)
      {
      if(name[i].first == 0)
         {
         m_mode_info.push_back(make_arg(name, i));
         in_modes = true;
         }
      else if(name[i].first == 1 && !in_modes)
         m_args.push_back(make_arg(name, i));
      }
   }

std::string SCAN_Name::arg(size_t i) const
   {
   if(i >= arg_count())
      throw Invalid_Argument("SCAN_Name::arg " + std::to_string(i) +
                             " out of range for '" + to_string() + "'");
   return m_args[i];
   }

std::string SCAN_Name::arg(size_t i, const std::string& def_value) const
   {
   if(i >= arg_count())
      return def_value;
   return m_args[i];
   }

size_t SCAN_Name::arg_as_integer(size_t i, size_t def_value) const
   {
   if(i >= arg_count())
      return def_value;
   return to_u32bit(m_args[i]);
   }

}