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/********************* */
/*! \file idl_assertion.cpp
** \verbatim
** Original author: Dejan Jovanovic
** Major contributors: none
** Minor contributors (to current version): Morgan Deters
** This file is part of the CVC4 project.
** Copyright (c) 2009-2013 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief [[ Add one-line brief description here ]]
**
** [[ Add lengthier description here ]]
** \todo document this file
**/
#include "theory/idl/idl_assertion.h"
using namespace CVC4;
using namespace theory;
using namespace idl;
IDLAssertion::IDLAssertion()
: d_op(kind::LAST_KIND)
{}
IDLAssertion::IDLAssertion(TNode node) {
bool ok = parse(node, 1, false);
if (!ok) {
d_x = d_y = TNode::null();
} else {
if (d_op == kind::GT) {
// Turn GT into LT x - y > c is the same as y - x < -c
std::swap(d_x, d_y);
d_c = -d_c;
d_op = kind::LT;
}
if (d_op == kind::GEQ) {
// Turn GT into LT x - y >= c is the same as y - x <= -c
std::swap(d_x, d_y);
d_c = -d_c;
d_op = kind::LEQ;
}
if (d_op == kind::LT) {
// Turn strict into non-strict x - y < c is the same as x - y <= c-1
d_c = d_c - 1;
d_op = kind::LEQ;
}
}
d_original = node;
}
IDLAssertion::IDLAssertion(const IDLAssertion& other)
: d_x(other.d_x)
, d_y(other.d_y)
, d_op(other.d_op)
, d_c(other.d_c)
, d_original(other.d_original)
{}
bool IDLAssertion::propagate(IDLModel& model) const {
Debug("theory::idl::model") << model << std::endl;
Assert(ok());
// Should be d_x - d_y <= d_c, or d_x - d_c <= d_y
Integer x_value = model.getValue(d_x);
Integer y_value = model.getValue(d_y);
if (x_value - y_value > d_c) {
model.setValue(d_y, x_value - d_c, IDLReason(d_x, d_original));
Debug("theory::idl::model") << model << std::endl;
return true;
} else {
return false;
}
}
void IDLAssertion::toStream(std::ostream& out) const {
out << "IDL[" << d_x << " - " << d_y << " " << d_op << " " << d_c << "]";
}
/** Negates the given arithmetic kind */
static Kind negateOp(Kind op) {
switch (op) {
case kind::LT:
// not (a < b) = (a >= b)
return kind::GEQ;
case kind::LEQ:
// not (a <= b) = (a > b)
return kind::GT;
case kind::GT:
// not (a > b) = (a <= b)
return kind::LEQ;
case kind::GEQ:
// not (a >= b) = (a < b)
return kind::LT;
case kind::EQUAL:
// not (a = b) = (a != b)
return kind::DISTINCT;
case kind::DISTINCT:
// not (a != b) = (a = b)
return kind::EQUAL;
default:
Unreachable();
break;
}
return kind::LAST_KIND;
}
bool IDLAssertion::parse(TNode node, int c, bool negated) {
// Only unit coefficients allowed
if (c != 1 && c != -1) {
return false;
}
// Assume we're ok
bool ok = true;
// The kind of the node
switch(node.getKind()) {
case kind::NOT:
// We parse the negation
ok = parse(node[0], c, true);
// Setup the kind
if (ok) {
d_op = negateOp(d_op);
}
break;
case kind::EQUAL:
case kind::LT:
case kind::LEQ:
case kind::GT:
case kind::GEQ: {
// All relation operators are parsed on both sides
d_op = node.getKind();
ok = parse(node[0], c, negated);
if (ok) {
ok = parse(node[1],-c, negated);
}
break;
}
case kind::CONST_RATIONAL: {
// Constants
Rational m = node.getConst<Rational>();
if (m.isIntegral()) {
d_c += m.getNumerator() * (-c);
} else {
ok = false;
}
break;
}
case kind::MULT: {
// Only unit multiplication of variables
if (node.getNumChildren() == 2 && node[0].isConst()) {
Rational a = node[0].getConst<Rational>();
if (a == 1 || a == -1) {
ok = parse(node[1], c * a.sgn(), negated);
} else {
ok = false;
}
} else {
ok = false;
}
break;
}
case kind::PLUS: {
for(unsigned i = 0; i < node.getNumChildren(); ++i) {
ok = parse(node[i], c, negated);
if(!ok) {
break;
}
}
break;
}
case kind::MINUS: {
ok = parse(node[0], c, negated);
if (ok) {
ok = parse(node[1], -c, negated);
}
break;
}
case kind::UMINUS: {
ok = parse(node[0], -c, negated);
break;
}
default: {
if (c > 0) {
if (d_x.isNull()) {
d_x = node;
} else {
ok = false;
}
} else {
if (d_y.isNull()) {
d_y = node;
} else {
ok = false;
}
}
break;
}
} // End case
// Difference logic OK
return ok;
}
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