variable_substitution.h

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// Author(s): Wieger Wesselink
// Copyright: see the accompanying file COPYING or copy at
// https://github.com/mCRL2org/mCRL2/blob/master/COPYING
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
 
#ifndef MCRL2_DATA_SUBSTITUTIONS_VARIABLE_SUBSTITUTION_H
#define MCRL2_DATA_SUBSTITUTIONS_VARIABLE_SUBSTITUTION_H
 
#include "mcrl2/data/is_simple_substitution.h"
#include "mcrl2/data/find.h"
#include "mcrl2/data/undefined.h"
 
namespace mcrl2 {
 
namespace data {
 
struct variable_substitution
{
  using variable_type = variable;
  using expression_type = data_expression;
  using argument_type = variable;
  using result_type = data_expression;
 
  const variable& lhs;
  const data_expression& rhs;
 
  variable_substitution(const variable& lhs_, const data_expression& rhs_)
  : lhs(lhs_),
    rhs(rhs_)
  {}
 
  const data_expression& operator()(const variable& x) const
  {
    if (x == lhs)
    {
      return rhs;
    }
    return x;
  }
};
 
inline
std::set<data::variable> substitution_variables(const variable_substitution& sigma)
{
  std::set<data::variable> result;
  data::find_free_variables(sigma.rhs, std::inserter(result, result.end()));
  return result;
}
 
} // namespace data
 
} // namespace mcrl2
 
#endif // MCRL2_DATA_SUBSTITUTIONS_VARIABLE_SUBSTITUTION_H