bool glpk_wrapper::is_linear(Enode * const e) {
bool is_eq = e->isEq() && (!e->hasPolarity() || e->getPolarity() != l_False);
return
(is_eq || e->isLeq()) &&
is_expr_linear(e->get1st()) &&
is_expr_linear(e->get2nd());
}
void glpk_wrapper::set_objective(Enode * const e) {
assert(is_expr_linear(e));
LAExpression la(e);
for (auto it = la.begin(); it != la.end(); ++it) {
auto v = it->first;
auto c = it->second;
if (v != nullptr) {
glp_set_obj_coef(lp, get_index(v) + 1, c);
}
}
}
bool glpk_wrapper::is_expr_linear(Enode * const t) {
if ( t->isPlus() ) {
for (Enode * arg_list = t->getCdr(); !arg_list->isEnil(); arg_list = arg_list->getCdr()) {
if (!is_expr_linear(arg_list->getCar())) {
return false;
}
}
return true;
} else if ( t->isTimes() ) {
Enode * x = t->get1st();
Enode * y = t->get2nd();
if ( x->isConstant() ) {
return is_expr_linear(y);
} else if ( y->isConstant() ) {
return is_expr_linear(x);
} else {
return false;
}
} else {
return t->isVar() || t->isConstant();
}
}
void glpk_wrapper::set_objective(Enode * const e) {
changed = true;
for (unsigned int i = 1; i <= domain.size(); i++) {
glp_set_obj_coef(lp, i, 0);
}
if (e != nullptr) {
assert(is_expr_linear(e));
LAExpression la(e);
for (auto it = la.begin(); it != la.end(); ++it) {
auto v = it->first;
auto c = it->second;
if (v != nullptr) {
glp_set_obj_coef(lp, get_index(v) + 1, c);
}
}
}
}
