graph.cpp

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/*
Copyright (c) 2014, Sam Schetterer, Nathan Kutz, University of Washington
Authors: Sam Schetterer
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/
#include "engineimp.h"
#include "graph.h"
void graph::insert(item_wrapper  it_p){
    if(nodes.count(it_p->name())){
        std::cout << "Warning: variable " << it_p->name() << "has already been entered\n";
        std::cout <<"Overwriting with new value\n";
    }
    _insert(it_p);
}
graph::graphnode& graph::_insert(item_wrapper  it_p){
    graphnode& g = nodes[it_p->name()];
    g.p = it_p;
    g.processed=0;
    std::vector<std::string> deps(it_p->dependencies());
    g.pointsto.clear();
    g.pointsto.insert(g.pointsto.begin(), deps.begin(), deps.end());
    return g;
}
void graph::ins_extra_deps(){
    for(auto& node : nodes){
        graphnode& g = node.second;
        if(!g.processed){
            proc_node_deps(g);
        }
    }
}
//may add support for dependencies that aren't
//input variables later if need be
void graph::proc_node_deps(graph::graphnode& g){
    g.processed=1;
    for(auto& val : g.pointsto){
        if(!nodes.count(val)){
            std::cout<<g.p->name()<<" depends on "<<val<<", which has not been inserted\n";
            exit(EXIT_FAILURE);
        }
            
        nodes[val].pointedat.push_back(g.p->name());
    }
}
//returns sorted list, all items in list are added to the graph
std::list<item_wrapper > graph::sort(const std::list<item_wrapper >& l){
    std::list<item_wrapper > outlist;
    std::list<const graphnode*> queuelist;
    for(const auto& val: l){
        insert(val);
    }
    ins_extra_deps();
    //populate the list of nodes without dependencies
    for(const auto& node : nodes){
        const graphnode& g = node.second;
        if(g.pointedat.empty()){
            queuelist.push_back(&g);
        }
    }
    //perform topological sort algorithm
    while(!queuelist.empty()){
        const graphnode& g = *queuelist.front();
        queuelist.pop_front();
        outlist.push_front(g.p);
        for(const auto& val : g.pointsto){
            graphnode& gn = nodes[val];
            gn.pointedat.remove(g.p->name());
            if(gn.pointedat.empty()){
                queuelist.push_back(&gn);
            }
        }
    }
    //check to see if list was fully sorted 
    if(l.size() != outlist.size()){
        err("Topological sort has failed, check for cyclical input dependencies",
                "graph::sort", "engine/graph.cpp", FATAL_ERROR);
    }
    return outlist;
}