linear_process_conversion_traverser.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)
//
/// \file mcrl2/lps/detail/linear_process_conversion_traverser.h
/// \brief Converts a process expression into a linear process.
 
#ifndef MCRL2_LPS_DETAIL_LINEAR_PROCESS_CONVERSION_TRAVERSER_H
#define MCRL2_LPS_DETAIL_LINEAR_PROCESS_CONVERSION_TRAVERSER_H
 
#include "mcrl2/lps/stochastic_specification.h"
#include "mcrl2/process/is_linear.h"
 
namespace mcrl2::process::detail
{
 
// TODO: join the stochastic and non-stochastic versions of the traversers
 
/// \brief Converts a process expression into linear process format.
/// Use the \p convert member functions for this.
struct linear_process_conversion_traverser: public process_expression_traverser<linear_process_conversion_traverser>
{
  using super = process_expression_traverser<linear_process_conversion_traverser>;
  using super::enter;
  using super::leave;
  using super::apply;
 
  /// \brief The result of the conversion.
  lps::action_summand_vector m_action_summands;
 
  /// \brief The result of the conversion.
  lps::deadlock_summand_vector m_deadlock_summands;
 
  /// \brief The process equation that is checked.
  process_equation m_equation;
 
  /// \brief Contains intermediary results.
  data::variable_list m_sum_variables;
 
  /// \brief Contains intermediary results.
  data::assignment_list m_next_state;
 
  /// \brief Contains intermediary results.
  lps::multi_action m_multi_action;
 
  /// \brief Contains intermediary results.
  lps::deadlock m_deadlock;
 
  /// \brief True if m_deadlock was changed.
  bool m_deadlock_changed = false;
 
  /// \brief True if m_multi_action was changed.
  bool m_multi_action_changed = false;
 
  /// \brief True if m_next_state was changed.
  bool m_next_state_changed = false;
 
  /// \brief Contains intermediary results.
  data::data_expression m_condition;
 
  /// \brief Exception that is thrown to denote that the process is not linear.
  struct non_linear_process
  {
    process_expression expr;
 
    non_linear_process(const process_expression& p)
      : expr(p)
    {}
  };
 
  /// \brief Clears the current summand
  void clear_summand()
  {
    m_sum_variables = data::variable_list();
    m_deadlock = lps::deadlock();
    m_deadlock_changed = false;
    m_multi_action = lps::multi_action();
    m_multi_action_changed = false;
    m_condition = data::sort_bool::true_();
    m_next_state = data::assignment_list();
    m_next_state_changed = false;
  }
 
  /// \brief Adds a summand to the result
  void add_summand()
  {
    if (m_multi_action_changed)
    {
      if (m_next_state_changed)
      {
        m_action_summands.emplace_back(m_sum_variables, m_condition, m_multi_action, m_next_state);
        mCRL2log(log::debug) << "adding action summand\n" << m_action_summands.back() << std::endl;
        clear_summand();
      }
      else
      {
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: encountered a multi action without process reference");
      }
    }
    else if (m_deadlock_changed)
    {
      m_deadlock_summands.emplace_back(m_sum_variables, m_condition, m_deadlock);
      mCRL2log(log::debug) << "adding deadlock summand\n" << m_deadlock_summands.back() << std::endl;
      clear_summand();
    }
  }
 
  /// \brief Visit delta node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const delta& /* x */)
  {
    m_deadlock = lps::deadlock();
    m_deadlock_changed = true;
    mCRL2log(log::debug) << "adding deadlock\n" << m_deadlock << std::endl;
  }
 
  /// \brief Visit tau node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const process::tau& /* x */)
  {
    m_multi_action = lps::multi_action();
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action tau\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit action node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param l An action label
  /// \param v A sequence of data expressions
  void leave(const process::action& x)
  {
    action a(x.label(), x.arguments());
    m_multi_action = lps::multi_action(a);
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit sum node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param v A sequence of data variables
  /// \param right A process expression
  void leave(const process::sum& x)
  {
    m_sum_variables = m_sum_variables + x.variables();
    mCRL2log(log::debug) << "adding sum variables\n" << data::pp(x.variables()) << std::endl;
  }
 
  /// \brief Visit block node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of identifiers
  /// \param right A process expression
  void leave(const process::block& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit hide node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of identifiers
  /// \param right A process expression
  void leave(const process::hide& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit rename node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param r A sequence of rename expressions
  /// \param right A process expression
  void leave(const process::rename& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit comm node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param c A sequence of communication expressions
  /// \param right A process expression
  void leave(const process::comm& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit allow node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of multi-action names
  /// \param right A process expression
  void leave(const process::allow& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit sync node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void apply(const process::sync& x)
  {
    apply(x.left());
    lps::multi_action l = m_multi_action;
    apply(x.right());
    lps::multi_action r = m_multi_action;
    m_multi_action = l + r;
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit at node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param d A data expression
  void leave(const process::at& x)
  {
    if (is_delta(x))
    {
      m_deadlock.time() = x.time_stamp();
      mCRL2log(log::debug) << "adding deadlock\n" << m_deadlock << std::endl;
    }
    else
    {
      m_multi_action=lps::multi_action(m_multi_action.actions(), x.time_stamp());
      mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
    }
  }
 
  /// \brief Visit seq node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void apply(const process::seq& x)
  {
    apply(x.left());
 
    // Check 1) The expression right must be a process instance or a process assignment
    if (is_process_instance(x.right()))
    {
      const process_instance& p = atermpp::down_cast<process_instance>(x.right());
      // Check 2) The process equation and and the process instance must match
      if (!detail::check_process_instance(m_equation, p))
      {
        std::clog << "seq right hand side: " << process::pp(x.right()) << std::endl;
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered that does not match the process equation");
      }
      m_next_state = data::make_assignment_list(m_equation.formal_parameters(), p.actual_parameters());
      m_next_state_changed = true;
    }
    else if (is_process_instance_assignment(x.right()))
    {
      const process_instance_assignment& p = atermpp::down_cast<process_instance_assignment>(x.right());
      // Check 2) The process equation and and the process instance assignment must match
      if (!detail::check_process_instance_assignment(m_equation, p))
      {
        std::clog << "seq right hand side: " << process::pp(x.right()) << std::endl;
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered that does not match the process equation");
      }
      m_next_state = p.assignments(); // TODO: check if this is correct
      m_next_state_changed = true;
    }
    else
    {
      std::clog << "seq right hand side: " << process::pp(x.right()) << std::endl;
      throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered with an unexpected right hand side");
    }
 
    mCRL2log(log::debug) << "adding next state\n" << data::pp(m_next_state) << std::endl;
  }
 
  /// \brief Visit if_then node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param d A data expression
  /// \param right A process expression
  void leave(const process::if_then& x)
  {
    m_condition = x.condition();
    mCRL2log(log::debug) << "adding condition\n" << data::pp(m_condition) << std::endl;
  }
 
  /// \brief Visit if_then_else node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param d A data expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::if_then_else& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit bounded_init node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::bounded_init& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit merge node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::merge& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit left_merge node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::left_merge& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit choice node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void apply(const process::choice& x)
  {
    apply(x.left());
    if (!is_choice(x.left()))
    {
      add_summand();
    }
    apply(x.right());
    if (!is_choice(x.right()))
    {
      add_summand();
    }
  }
 
  /// \brief Returns true if the process equation e is linear.
  /// \param e A process equation
  void convert(const process_equation& /* e */)
  {
    clear_summand();
    apply(m_equation.expression());
    add_summand(); // needed if it is not a choice
  }
 
  /// \brief Converts a process_specification into a specification.
  /// Throws \p non_linear_process if a non-linear sub-expression is encountered.
  /// Throws \p mcrl2::runtime_error in the following cases:
  /// \li The number of equations is not equal to one
  /// \li The initial process is not a process instance, or it does not match with the equation
  /// \li A sequential process is found with a right hand side that is not a process instance,
  /// or it doesn't match the equation
  /// \param p A process specification
  /// \return The converted specification
  lps::specification convert(const process_specification& p)
  {
    m_action_summands.clear();
    m_deadlock_summands.clear();
 
    // Check 1) The number of equations must be one
    if (p.equations().size() != 1)
    {
      throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: the number of process equations is not equal to 1!");
    }
    m_equation = p.equations().front();
 
    lps::process_initializer proc_init;
 
    if (is_process_instance(p.init()))
    {
      const process_instance& init = atermpp::down_cast<process_instance>(p.init());
      if (!check_process_instance(m_equation, init))
      {
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: the initial process does not match the process equation");
      }
      proc_init = lps::process_initializer(init.actual_parameters());
    }
    else if (is_process_instance_assignment(p.init()))
    {
      const process_instance_assignment& init = atermpp::down_cast<process_instance_assignment>(p.init());
      if (!check_process_instance_assignment(m_equation, init))
      {
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: the initial process does not match the process equation");
      }
      proc_init = lps::process_initializer(data::right_hand_sides(init.assignments()));
    }
    else
    {
      throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: the initial process has an unexpected value");
    }
 
    // Do the conversion
    convert(m_equation);
 
    lps::linear_process proc(m_equation.formal_parameters(), m_deadlock_summands, m_action_summands);
    return lps::specification(p.data(), p.action_labels(), p.global_variables(), proc, proc_init);
  }
};
 
/// \brief Converts a process expression into linear process format.
/// Use the \p convert member functions for this.
struct stochastic_linear_process_conversion_traverser: public process_expression_traverser<stochastic_linear_process_conversion_traverser>
{
  using super = process_expression_traverser<stochastic_linear_process_conversion_traverser>;
  using super::enter;
  using super::leave;
  using super::apply;
 
  /// \brief The result of the conversion.
  lps::stochastic_action_summand_vector m_action_summands;
 
  /// \brief The result of the conversion.
  lps::deadlock_summand_vector m_deadlock_summands;
 
  /// \brief The process equation that is checked.
  process_equation m_equation;
 
  /// \brief Contains intermediary results.
  data::variable_list m_sum_variables;
 
  /// \brief Contains intermediary results.
  data::assignment_list m_next_state;
 
  /// \brief Contains intermediary results.
  lps::multi_action m_multi_action;
 
  /// \brief Contains intermediary results.
  lps::deadlock m_deadlock;
 
  /// \brief Contains intermediary results.
  lps::stochastic_distribution m_distribution;
 
  /// \brief True if m_deadlock was changed.
  bool m_deadlock_changed = false;
 
  /// \brief True if m_multi_action was changed.
  bool m_multi_action_changed = false;
 
  /// \brief True if m_next_state was changed.
  bool m_next_state_changed = false;
 
  /// \brief Contains intermediary results.
  data::data_expression m_condition;
 
  /// \brief Exception that is thrown to denote that the process is not linear.
  struct non_linear_process
  {
    process_expression expr;
 
    non_linear_process(const process_expression& p)
      : expr(p)
    {}
  };
 
  /// \brief Clears the current summand
  void clear_summand()
  {
    m_sum_variables = data::variable_list();
    m_deadlock = lps::deadlock();
    m_deadlock_changed = false;
    m_multi_action = lps::multi_action();
    m_multi_action_changed = false;
    m_condition = data::sort_bool::true_();
    m_distribution = lps::stochastic_distribution();
    m_next_state = data::assignment_list();
    m_next_state_changed = false;
  }
 
  /// \brief Adds a summand to the result
  void add_summand()
  {
    if (m_multi_action_changed)
    {
      if (m_next_state_changed)
      {
        m_action_summands.emplace_back(m_sum_variables, m_condition, m_multi_action, m_next_state, m_distribution);
        mCRL2log(log::debug) << "adding action summand\n" << m_action_summands.back() << std::endl;
        clear_summand();
      }
      else
      {
        throw mcrl2::runtime_error("Error in stochastic_linear_process_conversion_traverser::convert: encountered a multi action without process reference");
      }
    }
    else if (m_deadlock_changed)
    {
      m_deadlock_summands.emplace_back(m_sum_variables, m_condition, m_deadlock);
      mCRL2log(log::debug) << "adding deadlock summand\n" << m_deadlock_summands.back() << std::endl;
      clear_summand();
    }
  }
 
  /// \brief Visit delta node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const delta& /* x */)
  {
    m_deadlock = lps::deadlock();
    m_deadlock_changed = true;
    mCRL2log(log::debug) << "adding deadlock\n" << m_deadlock << std::endl;
  }
 
  /// \brief Visit tau node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const process::tau& /* x */)
  {
    m_multi_action = lps::multi_action();
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action tau\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit action node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param l An action label
  /// \param v A sequence of data expressions
  void leave(const process::action& x)
  {
    action a(x.label(), x.arguments());
    m_multi_action = lps::multi_action(a);
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit sum node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param v A sequence of data variables
  /// \param right A process expression
  void leave(const process::sum& x)
  {
    m_sum_variables = m_sum_variables + x.variables();
    mCRL2log(log::debug) << "adding sum variables\n" << data::pp(x.variables()) << std::endl;
  }
 
  /// \brief Visit block node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of identifiers
  /// \param right A process expression
  void leave(const process::block& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit hide node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of identifiers
  /// \param right A process expression
  void leave(const process::hide& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit rename node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param r A sequence of rename expressions
  /// \param right A process expression
  void leave(const process::rename& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit comm node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param c A sequence of communication expressions
  /// \param right A process expression
  void leave(const process::comm& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit allow node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param s A sequence of multi-action names
  /// \param right A process expression
  void leave(const process::allow& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit sync node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void apply(const process::sync& x)
  {
    apply(x.left());
    lps::multi_action l = m_multi_action;
    apply(x.right());
    lps::multi_action r = m_multi_action;
    m_multi_action = l + r;
    m_multi_action_changed = true;
    mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
  }
 
  /// \brief Visit at node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param d A data expression
  void leave(const process::at& x)
  {
    if (is_delta(x))
    {
      m_deadlock.time() = x.time_stamp();
      mCRL2log(log::debug) << "adding deadlock\n" << m_deadlock << std::endl;
    }
    else
    {
      m_multi_action=lps::multi_action(m_multi_action.actions(), x.time_stamp());
      mCRL2log(log::debug) << "adding multi action\n" << m_multi_action << std::endl;
    }
  }
 
  /// \brief Visit seq node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void apply(const process::seq& x)
  {
    apply(x.left());
 
    process_expression right = x.right();
    if (is_stochastic_operator(right))
    {
      auto const& op = atermpp::down_cast<stochastic_operator>(right);
      m_distribution = lps::stochastic_distribution(op.variables(), op.distribution());
      right = op.operand();
    }
 
    // Check 1) The expression right must be a process instance or a process assignment
    if (is_process_instance(right))
    {
      const process_instance& p = atermpp::down_cast<process_instance>(right);
      // Check 2) The process equation and and the process instance must match
      if (!detail::check_process_instance(m_equation, p))
      {
        std::clog << "seq right hand side: " << process::pp(right) << std::endl;
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered that does not match the process equation");
      }
      m_next_state = data::make_assignment_list(m_equation.formal_parameters(), p.actual_parameters());
      m_next_state_changed = true;
    }
    else if (is_process_instance_assignment(right))
    {
      const process_instance_assignment& p = atermpp::down_cast<process_instance_assignment>(right);
      // Check 2) The process equation and and the process instance assignment must match
      if (!detail::check_process_instance_assignment(m_equation, p))
      {
        std::clog << "seq right hand side: " << process::pp(right) << std::endl;
        throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered that does not match the process equation");
      }
      m_next_state = p.assignments(); // TODO: check if this is correct
      m_next_state_changed = true;
    }
    else
    {
      std::clog << "seq right hand side: " << process::pp(right) << std::endl;
      throw mcrl2::runtime_error("Error in linear_process_conversion_traverser::convert: seq expression encountered with an unexpected right hand side");
    }
 
    mCRL2log(log::debug) << "adding next state\n" << data::pp(m_next_state) << std::endl;
  }
 
  /// \brief Visit if_then node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param d A data expression
  /// \param right A process expression
  void leave(const process::if_then& x)
  {
    m_condition = x.condition();
    mCRL2log(log::debug) << "adding condition\n" << data::pp(m_condition) << std::endl;
  }
 
  /// \brief Visit if_then_else node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param d A data expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::if_then_else& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit bounded_init node
  /// \return The result of visiting the node
  /// \param x A process expression
  /// \param left A process expression
  /// \param right A process expression
  void leave(const process::bounded_init& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit merge node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const process::merge& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit left_merge node
  /// \return The result of visiting the node
  /// \param x A process expression
  void leave(const process::left_merge& x)
  {
    throw non_linear_process(x);
  }
 
  /// \brief Visit stochastic operator node
  /// \param x A process expression
  void leave(const process::stochastic_operator& x)
  {
    m_distribution = lps::stochastic_distribution(x.variables(), x.distribution());
  }
 
  /// \brief Visit choice node
  /// \return The result of visiting the node
  /// \param x A process expression
  void apply(const process::choice& x)
  {
    apply(x.left());
    if (!is_choice(x.left()))
    {
      add_summand();
    }
    apply(x.right());
    if (!is_choice(x.right()))
    {
      add_summand();
    }
  }
 
  /// \brief Returns true if the process equation e is linear.
  /// \param e A process equation
  void convert(const process_equation& /* e */)
  {
    clear_summand();
    apply(m_equation.expression());
    add_summand(); // needed if it is not a choice
  }
 
  /// \brief Converts a process_specification into a stochastic_specification.
  /// Throws \p non_linear_process if a non-linear sub-expression is encountered.
  /// Throws \p mcrl2::runtime_error in the following cases:
  /// \li The number of equations is not equal to one
  /// \li The initial process is not a process instance, or it does not match with the equation
  /// \li A sequential process is found with a right hand side that is not a process instance,
  /// or it doesn't match the equation
  /// \param p A process specification
  /// \return The converted specification
  lps::stochastic_specification convert(const process_specification& p)
  {
    m_action_summands.clear();
    m_deadlock_summands.clear();
 
    // Check 1) The number of equations must be one
    if (p.equations().size() != 1)
    {
      throw mcrl2::runtime_error("Error in stochastic_linear_process_conversion_traverser::convert: the number of process equations is not equal to 1!");
    }
 
    m_equation = p.equations().front();
 
    // convert the initial state
    lps::stochastic_process_initializer proc_init;
    process_expression p_init = p.init();
    lps::stochastic_distribution dist;
    if (is_stochastic_operator(p.init()))
    {
      auto const& s = atermpp::down_cast<stochastic_operator>(p.init());
      dist = lps::stochastic_distribution(s.variables(), s.distribution());
      p_init = s.operand();
    }
    if (is_process_instance(p_init))
    {
      const process_instance& init = atermpp::down_cast<process_instance>(p_init);
      if (!check_process_instance(m_equation, init))
      {
        throw mcrl2::runtime_error("Error in stochastic_linear_process_conversion_traverser::convert: the initial process does not match the process equation");
      }
      proc_init = lps::stochastic_process_initializer(init.actual_parameters(), dist);
    }
    else if (is_process_instance_assignment(p.init()))
    {
      const process_instance_assignment& init = atermpp::down_cast<process_instance_assignment>(p_init);
      if (!check_process_instance_assignment(m_equation, init))
      {
        throw mcrl2::runtime_error("Error in stochastic_linear_process_conversion_traverser::convert: the initial process does not match the process equation");
      }
      proc_init = lps::stochastic_process_initializer(data::right_hand_sides(init.assignments()), dist);
    }
    else
    {
      throw mcrl2::runtime_error("Error in stochastic_linear_process_conversion_traverser::convert: the initial process has an unexpected value");
    }
 
    convert(m_equation);
 
    lps::stochastic_linear_process proc(m_equation.formal_parameters(), m_deadlock_summands, m_action_summands);
 
    return lps::stochastic_specification(p.data(), p.action_labels(), p.global_variables(), proc, proc_init);
  }
};
 
} // namespace mcrl2::process::detail
 
#endif // MCRL2_LPS_DETAIL_LINEAR_PROCESS_CONVERSION_TRAVERSER_H