This document  describes the MP file format for storing
merged prefixes of Petri nets. The file is textual, and 
contains the following information.

- the total number of mp-conditions, mp-events, places and transitions (one line).

- for each mp-condition (from first to last, separate line for each mp-condition):
	--  the number of the original place
	--  the occurrence-depth 
	--  the initial marking

- for each mp-event (from first to last, separate line for each mp-condition):
	-- the number of the original transition
	-- the cut-off status (0 - no, 1 - yes)
	-- the size of the preset
	-- the size of the postset
	-- the list of numbers of mp-conditions in the preset
	-- the list of numbers of mp-conditions in the postset

- the maximal string length + 1 for place/transition names (on a separate line)
  (useful for memory allocation in the parser)

- for each place (from first to last, separate line for each place):
	-- the name of the place

- for each transition (from first to last, separate line for each place):
	-- the name of the transition

The following C++ code implements an MP parser, and might
hopefully be useful as a reference:

void readMP(const char* filename){
	unsigned num_mpcond,num_mpev,num_net_pl,num_net_tr;
	unsigned orig_node_num,odepth,init_marking;
	unsigned cutoff,preset_size,postset_size,mpcond_num;

	unsigned len;
	char* name;
	size_t name_len;

	unsigned line_no=1, read_fields;
	int read_chars;

	FILE* f=fopen(filename,"rb");
	if(!f){
		Error(cannot_open_file_inp(filename));
		return;
	}

	read_fields=fscanf(f," %u%*[ \t]%u%*[ \t]%u%*[ \t]%u%*[ \t]",
					&num_mpcond,
					&num_mpev,
					&num_net_pl,
					&num_net_tr );
	if(read_fields==EOF || read_fields<4) goto fail;
	fscanf(f,"\n%n",&read_chars);
	if(read_chars<1) goto fail;
	line_no++;

	this->arr_pl.destroy_all();
	this->arr_tr.destroy_all();

	for(unsigned i=0;i<num_mpcond;i++){
		read_fields=fscanf(f," %u%*[ \t]%u%*[ \t]%u%*[ \t]",
						&orig_node_num,
						&odepth,
						&init_marking );
		if(read_fields==EOF || read_fields<3) goto fail;

		if(orig_node_num<1 || orig_node_num>num_net_pl
			|| odepth<1
			|| (init_marking && odepth!=1) ) goto fail;

		fscanf(f,"\n%n",&read_chars);
		if(read_chars<1) goto fail;
		line_no++;

		CONDITION* mpcond=new CONDITION(i+1,odepth,(typename ORIGINAL_NET::PLACE*)orig_node_num,init_marking);
		this->arr_pl.add(mpcond);
	}

	for(unsigned i=0;i<num_mpev;i++){
		read_fields=fscanf(f," %u%*[ \t]%u%*[ \t]%u%*[ \t]%u%*[ \t]",
						&orig_node_num,
						&cutoff,
						&preset_size,
						&postset_size );
		if(read_fields==EOF || read_fields<4) goto fail;

		if(orig_node_num<1 || orig_node_num>num_net_tr
			|| cutoff>1
			|| preset_size<1 ) goto fail;

		EVENT* mpev=new EVENT(i+1,0);
		mpev->orig_node=(typename ORIGINAL_NET::TRANSITION*)orig_node_num;
		if(cutoff){
			mpev->cutoff_corr.assign_unspecified();
		}
		this->arr_tr.add(mpev);

		for(unsigned j=0;j<preset_size;j++){
			read_fields=fscanf(f,"%u%*[ \t]",&mpcond_num);
			if(read_fields==EOF || read_fields<1) goto fail;
			if(mpcond_num>=num_mpcond) goto fail;
			mpev->preset.add(this->arr_pl[mpcond_num]);
			this->arr_pl[mpcond_num]->postset.add(mpev);
		}
		for(unsigned j=0;j<postset_size;j++){
			read_fields=fscanf(f,"%u%*[ \t]",&mpcond_num);
			if(read_fields==EOF || read_fields<1) goto fail;
			if(mpcond_num>=num_mpcond) goto fail;
			mpev->postset.add(this->arr_pl[mpcond_num]);
			this->arr_pl[mpcond_num]->preset.add(mpev);
		}

		fscanf(f,"\n%n",&read_chars);
		if(read_chars<1) goto fail;
		line_no++;
	}

	read_fields=fscanf(f," %u%*[ \t]",&len);
	if(read_fields==EOF || read_fields<1) goto fail;
	fscanf(f,"\n%n",&read_chars);
	if(read_chars<1) goto fail;
	line_no++;

	name=new char[len+2];
	if(!this->net){
		this->net=new ORIGINAL_NET();
	}
	this->net->arr_pl.destroy_all();
	this->net->arr_tr.destroy_all();

	for(unsigned i=0;i<num_net_pl;i++){
		fgets(name,len+1,f);
		name_len=strlen(name);
		// \n is included if encountered
		if(!name_len || name[name_len-1]!='\n') goto fail;
		name[name_len-1]='\0';
		typename ORIGINAL_NET::PLACE* pl=new typename ORIGINAL_NET::PLACE(name,i+1);
		this->net->arr_pl.add(pl);
	}

	for(unsigned i=0;i<num_net_tr;i++){
		fgets(name,len+1,f);
		name_len=strlen(name);
		// \n is included if encountered
		if(!name_len || name[name_len-1]!='\n') goto fail;
		name[name_len-1]='\0';
		typename ORIGINAL_NET::TRANSITION* tr=new typename ORIGINAL_NET::TRANSITION(name,i+1);
		this->net->arr_tr.add(tr);
	}

	// fix the orig_node field of all mp-conditions and mp-events
	for(unsigned i=0;i<this->arr_pl.numit;i++){
		CONDITION* mpcond=this->arr_pl[i];
		mpcond->orig_node=this->net->arr_pl[(unsigned)mpcond->orig_node-1];
	}
	for(unsigned i=0;i<this->arr_tr.numit;i++){
		EVENT* mpev=this->arr_tr[i];
		mpev->orig_node=this->net->arr_tr[(unsigned)mpev->orig_node-1];
	}

	// calculate the initial marking
	for(unsigned i=0;i<this->arr_pl.numit;i++){
		CONDITION* mpcond=this->arr_pl[i];
		typename ORIGINAL_NET::PLACE* pl=mpcond->orig_node;
		for(unsigned j=0;j<mpcond->init_marking;++j){
			pl->init_marking.add(new PNToken(PNToken::t_dot));
		}
	}

	for(unsigned i=0;i<this->arr_tr.numit;i++){
		EVENT* mpev=this->arr_tr[i];
		typename ORIGINAL_NET::TRANSITION* tr=mpev->orig_node;
		if(tr->preset.numit || tr->postset.numit) continue;
		for(unsigned j=0;j<mpev->preset.numit;j++){
			typename ORIGINAL_NET::PLACE* pl=mpev->preset[j]->orig_node;
			tr->preset.add(pl);
			pl->postset.add(tr);
		}
		for(unsigned j=0;j<mpev->postset.numit;j++){
			typename ORIGINAL_NET::PLACE* pl=mpev->postset[j]->orig_node;
			tr->postset.add(pl);
			pl->preset.add(tr);
		}
		
	}
	// sort places' presets and postsets
	for(unsigned i=0;i<this->net->arr_pl.numit;i++){
		this->net->arr_pl[i]->template sort_preset<cmp_numbers<TRANSITION>>();
		this->net->arr_pl[i]->template sort_postset<cmp_numbers<TRANSITION>>();
	}
	// sort transitions' presets and postsets
	for(unsigned i=0;i<this->net->arr_tr.numit;i++){
		this->net->arr_tr[i]->template sort_preset<cmp_numbers<PLACE>>();
		this->net->arr_tr[i]->template sort_postset<cmp_numbers<PLACE>>();
	}

	delete[] name;
	goto exit;

fail:
	Error(syntax_error(filename,line_no));
exit:
	fclose(f);
}