// This example uses the ClaspFacade to compute
// the stable models of the program
// a :- not b.
// b :- not a.
//
// It is similar to example2() but uses the facade's asynchronous
// interface in order to get the models one by one.
void example3() {
// See example2()
Clasp::ClaspConfig config;
config.solve.numModels = 0;
// The "interface" to the clasp library.
Clasp::ClaspFacade libclasp;
// See example2()
Clasp::Asp::LogicProgram& asp = libclasp.startAsp(config);
asp.setAtomName(1, "a");
asp.setAtomName(2, "b");
asp.startRule(Clasp::Asp::BASICRULE).addHead(1).addToBody(2, false).endRule();
asp.startRule(Clasp::Asp::BASICRULE).addHead(2).addToBody(1, false).endRule();
// We are done with problem setup.
// Prepare the problem for solving.
libclasp.prepare();
// Start the asynchronous solving process.
Clasp::ClaspFacade::AsyncResult it = libclasp.startSolveAsync();
// Get models one by one until iterator is exhausted.
while (!it.end()) {
printModel(libclasp.ctx.symbolTable(), it.model());
// Advance iterator to next model.
it.next();
}
std::cout << "No more models!" << std::endl;
}
void example2() {
// Aggregates configuration options.
// Using config, you can control many parts of the search, e.g.
// - the amount and kind of preprocessing
// - the enumerator to use and the number of models to compute
// - the heuristic used for decision making
// - the restart strategy
// - ...
Clasp::ClaspConfig config;
// We want to compute all models but
// otherwise we use the default configuration.
config.enumerate.numModels = 0;
// The "interface" to the clasp library.
Clasp::ClaspFacade libclasp;
// LogicProgram provides the interface for defining logic programs.
// The returned object is already setup and ready to use.
// See logic_program.h for details.
Clasp::Asp::LogicProgram& asp = libclasp.startAsp(config);
asp.setAtomName(1, "a");
asp.setAtomName(2, "b");
asp.startRule(Clasp::Asp::BASICRULE).addHead(1).addToBody(2, false).endRule();
asp.startRule(Clasp::Asp::BASICRULE).addHead(2).addToBody(1, false).endRule();
// We are done with problem setup.
// Prepare the problem for solving.
libclasp.prepare();
// Start the actual solving process.
ModelPrinter printer;
libclasp.solve(&printer);
std::cout << "No more models!" << std::endl;
}
void example4() {
Clasp::ClaspConfig config;
config.solve.enumMode = Clasp::EnumOptions::enum_user;
config.solve.numModels = 0;
// The "interface" to the clasp library.
Clasp::ClaspFacade libclasp;
Clasp::Asp::LogicProgram& asp = libclasp.startAsp(config);
asp.setAtomName(1, "a");
asp.setAtomName(2, "b");
asp.startRule(Clasp::Asp::BASICRULE).addHead(1).addToBody(2, false).endRule();
asp.startRule(Clasp::Asp::BASICRULE).addHead(2).addToBody(1, false).endRule();
libclasp.prepare();
// Start the actual solving process.
ModelHandler handler;
libclasp.solve(&handler);
std::cout << "No more models!" << std::endl;
}
void Solver::workerThreadMain()
{
std::unique_lock<std::mutex> lock(workerMutex);
// Set up ASP solver
Clasp::ClaspFacade clasp;
Clasp::ClaspConfig config;
config.solve.numModels = 0;
Clasp::Asp::LogicProgram& claspProgramBuilder = dynamic_cast<Clasp::Asp::LogicProgram&>(clasp.startAsp(config, true));
std::unique_ptr<Gringo::Output::LparseOutputter> lpOut(new GringoOutputProcessor(claspProgramBuilder));
claspCallback.reset(new ClaspCallback(dynamic_cast<GringoOutputProcessor&>(*lpOut), app, *this, lock));
std::unique_ptr<Gringo::Output::OutputBase> out(new Gringo::Output::OutputBase({}, *lpOut));
Gringo::Input::Program program;
Gringo::Scripts scripts;
Gringo::Defines defs;
Gringo::Input::NongroundProgramBuilder gringoProgramBuilder(scripts, program, *out, defs);
Gringo::Input::NonGroundParser parser(gringoProgramBuilder);
// Input: Original problem instance
std::unique_ptr<std::stringstream> instanceInput(new std::stringstream);
*instanceInput << app.getInputString();
// Input: Decomposition
std::unique_ptr<std::stringstream> decompositionInput(new std::stringstream);
solver::asp::Solver::declareDecomposition(decomposition, *decompositionInput);
app.getPrinter().solverInvocationInput(decomposition, decompositionInput->str());
// 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.parse();
// Ground
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();
// Prepare for solving. (This makes clasp's symbol table available.)
clasp.prepare();
claspCallback->prepare(clasp.ctx.symbolTable());
// We need to know which clasp variable corresponds to each childItem(_) atom.
for(const auto& pair : clasp.ctx.symbolTable()) {
if(!pair.second.name.empty()) {
const std::string name = pair.second.name.c_str();
if(name.compare(0, 10, "childItem(") == 0) {
const std::string argument = name.substr(10, name.length()-11);
itemsToVars.emplace(argument, pair.first);
}
}
}
// Let main thread finish the constructor
wakeMainThreadRequested = true;
wakeMainThread.notify_one();
// Wait until we should do work
wakeWorkerThread.wait(lock, [&]() { return wakeWorkerThreadRequested; });
wakeWorkerThreadRequested = false;
if(decomposition.getChildren().empty()) {
// This is a leaf solver.
clasp.solve(claspCallback.get());
}
else {
// Get the first row from each child node
std::unordered_map<unsigned int, ItemTree::Children::const_iterator> childRows;
childRows.reserve(decomposition.getChildren().size());
for(const auto& child : decomposition.getChildren()) {
const ItemTree::Children::const_iterator newRow = dynamic_cast<Solver&>(child->getSolver()).nextRow();
if(newRow == dynamic_cast<Solver&>(child->getSolver()).getItemTreeSoFar()->getChildren().end()) {
// Notify main thread that solving is complete
noMoreModels = true;
wakeMainThreadRequested = true;
wakeMainThread.notify_one();
return;
}
childRows.emplace(child->getNode().getGlobalId(), newRow);
}
// Let the combination of these rows be the input for our ASP call
ItemTreeNode::ExtensionPointerTuple rootExtensionPointers;
for(const auto& child : decomposition.getChildren())
rootExtensionPointers.emplace(child->getNode().getGlobalId(), dynamic_cast<Solver&>(child->getSolver()).getItemTreeSoFar()->getNode());
claspCallback->setRootExtensionPointers(std::move(rootExtensionPointers));
ItemTreeNode::ExtensionPointerTuple extendedRows;
for(const auto& nodeIdAndRow : childRows)
extendedRows.emplace(nodeIdAndRow.first, (*nodeIdAndRow.second)->getNode());
claspCallback->setExtendedRows(std::move(extendedRows));
{
Clasp::Asp::LogicProgram& prg = static_cast<Clasp::Asp::LogicProgram&>(clasp.update());
for(const auto& nodeIdAndRow : childRows) {
for(const auto& item : (*nodeIdAndRow.second)->getNode()->getItems()) {
prg.freeze(itemsToVars.at(item), Clasp::value_true);
}
}
}
clasp.prepare();
claspCallback->prepare(clasp.ctx.symbolTable());
clasp.solve(claspCallback.get());
{
// XXX Necessary to update so often? Is the overhead bad?
Clasp::Asp::LogicProgram& prg = static_cast<Clasp::Asp::LogicProgram&>(clasp.update());
for(const auto& nodeIdAndRow : childRows) {
for(const auto& item : (*nodeIdAndRow.second)->getNode()->getItems()) {
prg.freeze(itemsToVars.at(item), Clasp::value_false);
}
}
}
// Now there are no models anymore for this row combination
// Until there are no new rows anymore, generate one new row at some child node and combine it with all rows from other child nodes
bool foundNewRow;
do {
foundNewRow = false;
for(const auto& child : decomposition.getChildren()) {
ItemTree::Children::const_iterator newRow = dynamic_cast<Solver&>(child->getSolver()).nextRow();
if(newRow != dynamic_cast<Solver&>(child->getSolver()).getItemTreeSoFar()->getChildren().end()) {
foundNewRow = true;
aspCallsOnNewRowFromChild(newRow, child, clasp);
}
}
} while(foundNewRow);
}
// Notify main thread that solving is complete
noMoreModels = true;
wakeMainThreadRequested = true;
wakeMainThread.notify_one();
}
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;
}