/home/marsyas/marsyas/src/marsyas/Expr.h

/*
** Copyright (C) 1998-2007 George Tzanetakis <gtzan@cs.uvic.ca>
**  
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
** 
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#ifndef MARSYAS_EXPR_H
#define MARSYAS_EXPR_H

#include <string>

namespace Marsyas
{
class ExNode;
class Expr;
class Ex {
    std::string init_; std::string expr_;
public:
    Ex(std::string e) { init_=""; expr_=e; };
    Ex(std::string i, std::string e) { init_=i; expr_=e; };
    void parse(Expr* e, ExNode*& init, ExNode*& expr);
};
class Rp : public Ex {
public:
    Rp(std::string e) : Ex(e,"") {};
    Rp(std::string e, std::string r) : Ex(e,r) {};
};
class ExFile {
    std::string iex_, ex_, rp_, rr_;
    bool file_read_;
    void read(std::string fname);
    void store(int pos, std::string data);
public:
    ExFile(std::string n) { file_read_=false; read(n); }
    Ex getEx() { return Ex(iex_,ex_); }
    Rp getRp() { return Rp(rp_,rr_); }
};

class ExRecord;
class MarSystem;
class Scheduler;
class TmTimer;
class Expr {
    friend class Ex;
    bool initialized_;
    ExRecord* symbol_table_;
    ExNode* init_expr_; ExNode* expr_;
    ExNode* rept_; ExNode* rate_;

    MarSystem* marsym_;  Scheduler* sched_;  TmTimer* timer_;

    void set(MarSystem* m, Ex& e, Rp& r);

public:
    Expr();
    Expr(MarSystem* msym, Ex e); // repeat_ evaluates to false
    Expr(MarSystem* msym, Ex e, Rp r);
    Expr(MarSystem* msym, ExFile e);

    virtual ~Expr();

    virtual void eval();   // evaluate expression_ for side effects
    virtual bool repeat(); // evaluate repeat_ expression, return result
    std::string repeat_interval();
    bool has_rate() { return rate_!=NULL; }

    void setScheduler(Scheduler* v);
    void setTimer(TmTimer* t);
    void post();
};

}//namespace Marsyas

#endif

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