Line data    Source code

       1             : // Author(s): Wieger Wesselink
       2             : // Copyright: see the accompanying file COPYING or copy at
       3             : // https://github.com/mCRL2org/mCRL2/blob/master/COPYING
       4             : //
       5             : // Distributed under the Boost Software License, Version 1.0.
       6             : // (See accompanying file LICENSE_1_0.txt or copy at
       7             : // http://www.boost.org/LICENSE_1_0.txt)
       8             : //
       9             : /// \file mcrl2/data/replace_constants_by_variables.h
      10             : /// \brief add your file description here.
      11             : 
      12             : #ifndef MCRL2_DATA_REPLACE_CONSTANTS_BY_VARIABLES_H
      13             : #define MCRL2_DATA_REPLACE_CONSTANTS_BY_VARIABLES_H
      14             : 
      15             : #include "mcrl2/data/rewriter.h"
      16             : #include "mcrl2/data/builder.h"
      17             : 
      18             : namespace mcrl2 {
      19             : 
      20             : namespace data {
      21             : 
      22             : namespace detail {
      23             : 
      24             : /// \brief Replace each constant data application c by a fresh variable v, and add extend the substitution sigma
      25             : /// with the assignment v := r(c). This can be used in rewriting, to avoid that c is rewritten by the rewriter
      26             : /// multiple times.
      27             : template <template <class> class Builder>
      28             : struct replace_constants_by_variables_builder: public Builder<replace_constants_by_variables_builder<Builder>>
      29             : {
      30             :   typedef Builder<replace_constants_by_variables_builder<Builder>> super;
      31             :   using super::apply;
      32             :   using super::update;
      33             : 
      34             :   data::set_identifier_generator id_generator;
      35             :   std::unordered_map<data::data_expression, data::variable> substitutions;
      36             :   const data::rewriter& r;
      37             :   data::mutable_indexed_substitution<>& sigma;
      38             : 
      39           0 :   bool is_constant(const data::data_expression& x) const
      40             :   {
      41           0 :     return data::find_free_variables(x).empty();
      42             :   }
      43             : 
      44           0 :   replace_constants_by_variables_builder(const data::rewriter& r_, data::mutable_indexed_substitution<>& sigma_)
      45           0 :     : r(r_), sigma(sigma_)
      46           0 :   {}
      47             : 
      48             :   template <class T>
      49           0 :   void apply(T& result, const data::application& x)
      50             :   {
      51           0 :     auto i = substitutions.find(x);
      52           0 :     if (i != substitutions.end())
      53             :     {
      54           0 :       result = i->second;
      55             :     }
      56           0 :     else if (is_constant(x))
      57             :     {
      58           0 :       data::variable v(id_generator("@rewr_var"), x.sort());
      59           0 :       substitutions[x] = v;
      60           0 :       sigma[v] = r(x, sigma);
      61           0 :       result = v;
      62           0 :     }
      63             :     else
      64             :     {
      65           0 :       super::apply(result, x);
      66             :     }
      67           0 :   }
      68             : };
      69             : 
      70             : } // namespace detail
      71             : 
      72             : } // namespace data
      73             : 
      74             : } // namespace mcrl2
      75             : 
      76             : #endif // MCRL2_DATA_REPLACE_CONSTANTS_BY_VARIABLES_H