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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) {
return const_cast<const MaxStrategy<Domain>*>(this)->get(e);
}
virtual unsigned int get(const MaxExpression<Domain>& e) const = 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()))
{}
void setRho(DynamicVariableAssignment<Domain>& rho) {
_rho = ρ
}
unsigned int get(const MaxExpression<Domain>& e) const {
solver_log::strategy << indent() << "Look up " << e << std::endl;
return _values[e];
}
unsigned int get(const MaxExpression<Domain>& e) {
solver_log::strategy << indent() << "Solve for " << e << std::endl;
solve(e);
return _values[e];
}
void invalidate(const MaxExpression<Domain>& v) {
if (_stable.contains(v)) {
solver_log::strategy << indent() << "Invalidating " << v << std::endl;
//solver_log::debug << indent() << " influence sets " << _influence << std::endl;
_stable.remove(v);
IdSet<MaxExpression<Domain> > infl = _influence[v];
for (typename IdSet<MaxExpression<Domain> >::iterator
it = infl.begin(),
end = infl.end();
it != end;
++it) {
invalidate(_system.maxExpression(*it));
}
}
}
private:
void solve(const MaxExpression<Domain>& x) {
if (!_stable.contains(x)) {
_stable.insert(x);
solver_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, _values[x]);
stack_depth--;
if (val != _values[x]) {
solver_log::strategy << x << " => " << *x.arguments()[val] << std::endl;
_values[x] = val;
_rho->invalidate(*_system.varFromExpr(x));
//_rho->stabilise();
IdSet<MaxExpression<Domain> > infl = _influence[x];
_stable.filter(infl);
for (typename IdSet<MaxExpression<Domain> >::iterator
it = infl.begin(),
end = infl.end();
it != end;
++it) {
solve(_system.maxExpression(*it));
}
} else {
solver_log::strategy << indent() << x << " did not change: "
<< x << " => " << *x.arguments()[val] << std::endl;
}
} else {
solver_log::strategy << indent() << x << " is stable: "
<< x << " => " << *x.arguments()[_values[x]] << std::endl;
}
}
struct DependencyAssignment : public VariableAssignment<Domain>{
DependencyAssignment(DynamicMaxStrategy& strat,
DynamicVariableAssignment<Domain>& rho,
const MaxExpression<Domain>& expr)
: _strat(strat),
_rho(rho),
_expr(expr),
_current(strat._system.variableCount()) {
}
const Domain operator[](const Variable<Domain>& var) {
// force evaluation to get touched variables
Domain value = _rho[var];
_strat._influence[*_strat._system[var]].insert(_expr);
// invalidate touched variables
IdSet<Variable<Domain> > changed = _rho.get_changed();
for (typename IdSet<Variable<Domain> >::iterator
it = changed.begin(),
ei = changed.end();
it != ei;
++it) {
_strat.invalidate(*_strat._system[_strat._system.variable(*it)]);
}
return value;
}
private:
DynamicMaxStrategy& _strat;
DynamicVariableAssignment<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) const {
_strat._influence[e].insert(_expr);
return _strat._values[e];
}
unsigned int get(const MaxExpression<Domain>& e) {
_strat.solve(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;
};
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];
// this will automatically work sufficiently to get the final
// strategy for this variable's RHS
_strategy.get(rhs);
// this will automatically solve for the value of the RHS, if required
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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