/*********************                                                        */
/*! \file theory_builtin.cpp
 ** \verbatim
 ** Original author: mdeters
 ** Major contributors: none
 ** Minor contributors (to current version): none
 ** This file is part of the CVC4 prototype.
 ** Copyright (c) 2009, 2010  The Analysis of Computer Systems Group (ACSys)
 ** Courant Institute of Mathematical Sciences
 ** New York University
 ** See the file COPYING in the top-level source directory for licensing
 ** information.\endverbatim
 **
 ** \brief Implementation of the builtin theory.
 **
 ** Implementation of the builtin theory.
 **/

#include "theory/builtin/theory_builtin.h"
#include "expr/kind.h"

using namespace std;
using namespace CVC4;
using namespace CVC4::theory::builtin;

namespace CVC4 {
namespace theory {
namespace builtin {

Node TheoryBuiltin::blastDistinct(TNode in) {
  Debug("theory-rewrite") << "TheoryBuiltin::blastDistinct: " << in << std::endl;
  Assert(in.getKind() == kind::DISTINCT);
  if(in.getNumChildren() == 2) {
    // if this is the case exactly 1 != pair will be generated so the
    // AND is not required
    Node eq = NodeManager::currentNM()->mkNode(CVC4::kind::EQUAL, in[0], in[1]);
    Node neq = NodeManager::currentNM()->mkNode(CVC4::kind::NOT, eq);
    return neq;
  }
  // assume that in.getNumChildren() > 2 => diseqs.size() > 1
  vector<Node> diseqs;
  for(TNode::iterator i = in.begin(); i != in.end(); ++i) {
    TNode::iterator j = i;
    while(++j != in.end()) {
      Node eq = NodeManager::currentNM()->mkNode(CVC4::kind::EQUAL, *i, *j);
      Node neq = NodeManager::currentNM()->mkNode(CVC4::kind::NOT, eq);
      diseqs.push_back(neq);
    }
  }
  Node out = NodeManager::currentNM()->mkNode(CVC4::kind::AND, diseqs);
  return out;
}

RewriteResponse TheoryBuiltin::preRewrite(TNode in, bool topLevel) {
  switch(in.getKind()) {
  case kind::DISTINCT:
    return RewritingComplete(blastDistinct(in));

  case kind::EQUAL:
    // EQUAL is a special case that should never end up here
    Unreachable("TheoryBuiltin can't rewrite EQUAL !");

  default:
    return RewritingComplete(in);
  }
}

}/* CVC4::theory::builtin namespace */
}/* CVC4::theory */
}/* CVC4 namespace */