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#ifndef MAX_EXPRESSION_HPP
#define MAX_EXPRESSION_HPP
#include <ostream>
#include "Expression.hpp"
#include "EquationSystem.hpp"
#include "IdSet.hpp"
template<typename Domain>
struct MaxStrategy {
virtual ~MaxStrategy() { }
virtual unsigned int get(const MaxExpression<Domain>& e) = 0;
};
unsigned int stack_depth = 1;
std::string indent() {
std::string result = "";
for (unsigned int i = 0; i < stack_depth; ++i) {
result += '\t';
}
return result;
}
#include "VariableAssignment.hpp"
template<typename Domain>
struct DynamicVariableAssignment;
template<typename Domain>
struct DynamicMaxStrategy : public MaxStrategy<Domain> {
DynamicMaxStrategy(
const EquationSystem<Domain>& system
) : _system(system),
_rho(NULL),
_values(system.maxExpressionCount(), 0),
_stable(system.maxExpressionCount()),
_influence(system.maxExpressionCount(),
IdSet<MaxExpression<Domain> >(system.maxExpressionCount())),
_var_influence(system.variableCount(),
IdSet<MaxExpression<Domain> >(system.maxExpressionCount())),
_frozen(false)
{}
void freeze() {
_frozen = true;
}
void thaw() {
_frozen = false;
}
bool is_frozen() {
return _frozen;
}
void setRho(DynamicVariableAssignment<Domain>& rho) {
_rho = ρ
}
unsigned int get(const MaxExpression<Domain>& e) {
if (!_frozen)
solve(e);
return _values[e];
}
void invalidate(const Variable<Domain>& v) {
log::strategy << indent() << "Invalidating " << v << " - " << *_system[v] << std::endl;
_stable.filter(_var_influence[v]);
IdSet<MaxExpression<Domain> > infl = _var_influence[v];
_var_influence[v].clear();
for (typename IdSet<MaxExpression<Domain> >::iterator
it = infl.begin(),
end = infl.end();
it != end;
++it) {
solve(_system.maxExpression(*it));
}
}
private:
void solve(const MaxExpression<Domain>& x) {
if (!_stable.contains(x)) {
_stable.insert(x);
log::strategy << indent() << "Stabilise " << x << std::endl;
stack_depth++;
DependencyAssignment assignment(*this, *_rho, x);
DependencyStrategy depStrat(*this, x);
unsigned int val = x.bestStrategy(assignment, depStrat);
stack_depth--;
if (val != _values[x]) {
log::strategy << x << " => " << *x.arguments()[val] << std::endl;
IdSet<MaxExpression<Domain> > oldInfluence = _influence[x];
_influence[x].clear();
_values[x] = val;
_rho->invalidate(*_system.varFromExpr(x));
_rho->thaw();
this->freeze();
_rho->stabilise();
_rho->freeze();
this->thaw();
_stable.filter(oldInfluence);
for (typename IdSet<MaxExpression<Domain> >::iterator
it = oldInfluence.begin(),
end = oldInfluence.end();
it != end;
++it) {
solve(_system.maxExpression(*it));
}
} else {
log::strategy << indent() << x << " did not change: "
<< x << " => " << *x.arguments()[val] << std::endl;
}
} else {
log::strategy << indent() << x << " is stable: "
<< x << " => " << *x.arguments()[_values[x]] << std::endl;
}
}
struct DependencyAssignment : public VariableAssignment<Domain>{
DependencyAssignment(DynamicMaxStrategy& strat,
VariableAssignment<Domain>& rho,
const MaxExpression<Domain>& expr)
: _strat(strat),
_rho(rho),
_expr(expr),
_current(strat._system.variableCount()) {
}
const Domain operator[](const Variable<Domain>& var) {
_strat._var_influence[var].insert(_expr);
if (_current.contains(var)) {
return _rho[var];
} else {
_current.insert(var);
Domain val = _strat._system[var]->eval(_rho, _strat);
_current.remove(var);
return val;
}
}
private:
DynamicMaxStrategy& _strat;
VariableAssignment<Domain>& _rho;
const MaxExpression<Domain>& _expr;
IdSet<Variable<Domain> > _current;
};
struct DependencyStrategy : public MaxStrategy<Domain> {
DependencyStrategy(DynamicMaxStrategy& strat, const MaxExpression<Domain>& expr)
: _strat(strat),
_expr(expr) {
}
unsigned int get(const MaxExpression<Domain>& e) {
_strat.solve(e);
if (&_expr != &e) {
_strat._influence[e].insert(_expr);
}
return _strat._values[e];
}
private:
DynamicMaxStrategy& _strat;
const MaxExpression<Domain>& _expr;
};
private:
const EquationSystem<Domain>& _system;
DynamicVariableAssignment<Domain>* _rho;
IdMap<MaxExpression<Domain>,unsigned int> _values;
IdSet<MaxExpression<Domain> > _stable;
IdMap<MaxExpression<Domain>,IdSet<MaxExpression<Domain> > > _influence;
IdMap<Variable<Domain>,IdSet<MaxExpression<Domain> > > _var_influence;
bool _frozen;
};
template<typename Domain>
struct Solver {
Solver(const EquationSystem<Domain>& system)
: _system(system),
_strategy(system),
_rho(_system, _strategy, -infinity<Domain>()) {
_strategy.setRho(_rho);
}
Domain solve(Variable<Domain>& var) {
MaxExpression<Domain>& rhs = *_system[var];
do {
_rho.has_changed(false);
// improve strategy
_rho.freeze();
_strategy.thaw();
_strategy.get(rhs);
// iterate fixpoint
_strategy.freeze();
_rho.thaw();
_rho.stabilise();
} while (_rho.has_changed());
return _rho[var];
}
private:
const EquationSystem<Domain>& _system;
DynamicMaxStrategy<Domain> _strategy;
DynamicVariableAssignment<Domain> _rho;
};
/*template<typename Domain>
std::ostream& operator<<(std::ostream& cout, const MaxStrategy<Domain>& strat) {
strat.print(cout);
return cout;
}*/
#endif
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