ItemTreePtr Solver::compute()
{
const auto nodeStackElement = app.getPrinter().visitNode(decomposition);
// Compute item trees of child nodes
ChildItemTrees childItemTrees;
for(const auto& child : decomposition.getChildren()) {
ItemTreePtr itree = child->getSolver().compute();
if(!itree)
return itree;
childItemTrees.emplace(child->getNode().getGlobalId(), std::move(itree));
}
// Input: Child item trees
std::unique_ptr<std::stringstream> childItemTreesInput(new std::stringstream);
*childItemTreesInput << "% Child item tree facts" << std::endl;
for(const auto& childItemTree : childItemTrees) {
std::ostringstream rootItemSetName;
rootItemSetName << 'n' << childItemTree.first;
asp_utils::declareItemTree(*childItemTreesInput, childItemTree.second.get(), tableMode, childItemTree.first, rootItemSetName.str());
}
app.getPrinter().solverInvocationInput(decomposition, childItemTreesInput->str());
// Input: Induced subinstance
std::unique_ptr<std::stringstream> instanceInput(new std::stringstream);
asp_utils::induceSubinstance(*instanceInput, app.getInstance(), decomposition.getNode().getBag());
app.getPrinter().solverInvocationInput(decomposition, instanceInput->str());
// Input: Decomposition
std::unique_ptr<std::stringstream> decompositionInput(new std::stringstream);
asp_utils::declareDecomposition(decomposition, *decompositionInput);
app.getPrinter().solverInvocationInput(decomposition, decompositionInput->str());
// Set up ASP solver
Clasp::ClaspConfig config;
config.solve.numModels = 0;
Clasp::ClaspFacade clasp;
// TODO The last parameter of clasp.startAsp in the next line is "allowUpdate". Does setting it to false have benefits?
Clasp::Asp::LogicProgram& claspProgramBuilder = dynamic_cast<Clasp::Asp::LogicProgram&>(clasp.startAsp(config));
std::unique_ptr<Gringo::Output::LparseOutputter> lpOut(newGringoOutputProcessor(claspProgramBuilder, childItemTrees, tableMode));
std::unique_ptr<Gringo::Output::OutputBase> out(new Gringo::Output::OutputBase({}, *lpOut));
Gringo::Input::Program program;
asp_utils::DummyGringoModule module;
Gringo::Scripts scripts(module);
Gringo::Defines defs;
Gringo::Input::NongroundProgramBuilder gringoProgramBuilder(scripts, program, *out, defs);
Gringo::Input::NonGroundParser parser(gringoProgramBuilder);
// Pass input to ASP solver
for(const auto& file : encodingFiles)
parser.pushFile(std::string(file));
parser.pushStream("<instance>", std::move(instanceInput));
parser.pushStream("<decomposition>", std::move(decompositionInput));
parser.pushStream("<child_itrees>", std::move(childItemTreesInput));
parser.parse();
// Ground and solve
program.rewrite(defs);
program.check();
if(Gringo::message_printer()->hasError())
throw std::runtime_error("Grounding stopped because of errors");
auto gPrg = program.toGround(out->domains);
Gringo::Ground::Parameters params;
params.add("base", {});
gPrg.ground(params, scripts, *out);
params.clear();
// Finalize ground program and create solver variables
claspProgramBuilder.endProgram();
std::unique_ptr<asp_utils::ClaspCallback> cb(newClaspCallback(tableMode, *lpOut, childItemTrees, app, decomposition.isRoot(), decomposition, cardinalityCost));
cb->prepare(claspProgramBuilder);
clasp.prepare();
clasp.solve(cb.get());
if(printStatistics) {
std::cout << "Solver statistics for decomposition node " << decomposition.getNode().getGlobalId() << ':' << std::endl;
Clasp::Cli::TextOutput{true, Clasp::Cli::TextOutput::format_asp}.printStatistics(clasp.summary(), true);
}
ItemTreePtr result = cb->finalize(decomposition.isRoot(), app.isPruningDisabled() == false || decomposition.isRoot());
app.getPrinter().solverInvocationResult(decomposition, result.get());
return result;
}
