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livetrax/libs/canvas/kiwi/constraint.h

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/*-----------------------------------------------------------------------------
| Copyright (c) 2013-2017, Nucleic Development Team.
|
| Distributed under the terms of the Modified BSD License.
|
| The full license is in the file LICENSE, distributed with this software.
|----------------------------------------------------------------------------*/
#pragma once
#include <ostream>
#include <map>
#include <vector>
#include "expression.h"
#include "shareddata.h"
#include "strength.h"
#include "term.h"
#include "variable.h"
namespace kiwi
{
enum RelationalOperator
{
OP_LE,
OP_GE,
OP_EQ
};
static std::ostream& operator<< (std::ostream& o, RelationalOperator op)
{
switch (op) {
case OP_LE:
o << "<=";
break;
case OP_GE:
o << ">=";
break;
case OP_EQ:
o << "==";
break;
}
return o;
}
class Constraint
{
public:
Constraint() : m_data(0) {}
Constraint(const Expression &expr,
RelationalOperator op,
double strength = strength::required) : m_data(new ConstraintData(expr, op, strength)) {}
Constraint(const Constraint &other, double strength) : m_data(new ConstraintData(other, strength)) {}
~Constraint() {}
const Expression &expression() const
{
return m_data->m_expression;
}
RelationalOperator op() const
{
return m_data->m_op;
}
double strength() const
{
return m_data->m_strength;
}
bool operator!() const
{
return !m_data;
}
bool involves (Variable const & v) const {
if (expression().involves (v)) {
return true;
}
return false;
}
private:
static Expression reduce(const Expression &expr)
{
std::map<Variable, double> vars;
typedef std::vector<Term>::const_iterator iter_t;
iter_t end = expr.terms().end();
for (iter_t it = expr.terms().begin(); it != end; ++it)
vars[it->variable()] += it->coefficient();
std::vector<Term> terms(vars.begin(), vars.end());
return Expression(terms, expr.constant());
}
class ConstraintData : public SharedData
{
public:
ConstraintData(const Expression &expr,
RelationalOperator op,
double strength) : SharedData(),
m_expression(reduce(expr)),
m_strength(strength::clip(strength)),
m_op(op) {}
ConstraintData(const Constraint &other, double strength) : SharedData(),
m_expression(other.expression()),
m_strength(strength::clip(strength)),
m_op(other.op()) {}
~ConstraintData() {}
Expression m_expression;
double m_strength;
RelationalOperator m_op;
private:
ConstraintData(const ConstraintData &other);
ConstraintData &operator=(const ConstraintData &other);
};
SharedDataPtr<ConstraintData> m_data;
friend bool operator<(const Constraint &lhs, const Constraint &rhs)
{
return lhs.m_data < rhs.m_data;
}
friend bool operator==(const Constraint &lhs, const Constraint &rhs)
{
return lhs.m_data == rhs.m_data;
}
friend bool operator!=(const Constraint &lhs, const Constraint &rhs)
{
return lhs.m_data != rhs.m_data;
}
};
static std::ostream& operator<< (std::ostream& o, kiwi::Constraint const & c)
{
return o << c.expression() << " OP " << c.op();
}
} // namespace kiwi