Trail.cxx

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#include <stdlib.h>
#include <assert.h>


#include "Options.hxx"
#include "Type.hxx"
#include "Trail.hxx"

using namespace boost;
using namespace sherpa;

void
Trail::link(shared_ptr<Type> from, shared_ptr<Type> to)
{  
  from = from->getType();
  to = to->getType();
  
  if (to->boundInType(from)) {
    std::cerr << "CYCLIC SUBSTITUTION "
              << from->asString(Options::debugTvP)
              << " |-> "
              << to->asString(Options::debugTvP)
              << std::endl;
    assert(false);
  }

  DEBUG(TRAIL) 
    std::cerr << "LINKING: "
              << from->asString(Options::debugTvP)
              << " |-> "
              << to->asString(Options::debugTvP)
              << std::endl;
  
  vec.push_back(from);   
  from->link = to; 
} 

void
Trail::subst(shared_ptr<Type> from, shared_ptr<Type> to)
{ 
  from = from->getType();
  to = to->getType();
  
  assert(from->typeTag == ty_tvar || from->typeTag == ty_kvar);
  
  if (to->boundInType(from)) {
    std::cerr << "CYCLIC SUBSTITUTION "
              << from->asString(Options::debugTvP)
              << " |-> "
              << to->asString(Options::debugTvP)
              << std::endl;
    assert(false);
  }

  DEBUG(TRAIL) 
    std::cerr << "SUBSTITUTING: "
              << from->asString(Options::debugTvP)
              << " |-> "
              << to->asString(Options::debugTvP)
              << std::endl;

  
  vec.push_back(from);   
  from->link = to; 
}

void
Trail::rollBack(size_t upto)
{
  assert(upto <= vec.size());
  
  for (size_t i = upto; i < vec.size(); i++) {
    vec[i]->link = GC_NULL;
    DEBUG(TRAIL) 
      std::cerr << "[RB] Releasing: "
                << vec[i]->asString(Options::debugTvP)
                << std::endl;
  }

  vec.erase(vec.begin() + upto, vec.end());
}

void
Trail::release(const size_t n, shared_ptr<Type> rel)
{
  assert(vec[n] == rel); // not getType()
  
  rel->link = GC_NULL;
  
  DEBUG(TRAIL) 
    std::cerr << "[RB] Releasing: "
              << rel->asString(Options::debugTvP)
              << std::endl;

  vec.erase(vec.begin() + n);
}

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