void act(ActionBlock &action_block, Relation &results, Index &assertions, Index &retractions) {
if (action_block.action_variables.begin != action_block.action_variables.end) {
cerr << "[ERROR] Action variables are unsupported." << endl;
return;
}
Action *action = action_block.actions.begin;
for (; action != action_block.actions.end; ++action) {
switch (action->type) {
case ASSERT_FACT:
case RETRACT_FACT: {
if (action->get.atom.type == ATOM) {
if (action->type == RETRACT_FACT) {
cerr << "[ERROR] Retraction of atoms is currently unsupported." << endl;
return;
}
act(action->get.atom.get.atom, results);
continue;
}
if (action->get.atom.type != FRAME) {
cerr << "[ERROR] For now, supporting only assertion of frames/triples." << endl;
return;
}
Frame frame = action->get.atom.get.frame;
Tuple triple(3);
if (frame.object.type == LIST || frame.object.type == FUNCTION) {
cerr << "[ERROR] Not supporting lists or functions in action target." << endl;
return;
}
if (frame.object.type == CONSTANT) {
triple[0] = frame.object.get.constant;
}
pair<Term, Term> *slot = frame.slots.begin;
for (; slot != frame.slots.end; ++slot) {
if (slot->first.type == LIST || slot->first.type == FUNCTION ||
slot->second.type == LIST || slot->second.type == FUNCTION) {
cerr << "[ERROR] Not supporting lists or function in action target." << endl;
return;
}
if (slot->first.type == CONSTANT) {
triple[1] = slot->first.get.constant;
}
if (slot->second.type == CONSTANT) {
triple[2] = slot->second.get.constant;
}
if (!results.empty() && frame.object.type == CONSTANT && slot->first.type == CONSTANT && slot->second.type == CONSTANT) {
if (action->type == ASSERT_FACT) {
assertions.insert(triple);
} else {
retractions.insert(triple);
}
continue;
}
Relation::iterator tuple = results.begin();
for (; tuple != results.end(); ++tuple) {
if (frame.object.type == VARIABLE) {
triple[0] = tuple->at(frame.object.get.variable);
}
if (slot->first.type == VARIABLE) {
triple[1] = tuple->at(slot->first.get.variable);
}
if (slot->second.type == VARIABLE) {
triple[2] = tuple->at(slot->second.get.variable);
}
if (action->type == ASSERT_FACT) {
assertions.insert(triple);
} else {
retractions.insert(triple);
}
}
}
return;
}
default: {
cerr << "[ERROR] Currently supporting on ASSERT_FACT and RETRACT_FACT actions." << endl;
return;
}
}
}
}
void query(Condition &condition, set<varint_t> &allvars, Relation &results) {
deque<void*> negated;
Relation intermediate;
switch (condition.type) {
case ATOMIC: {
query(condition.get.atom, allvars, results);
return;
}
case CONJUNCTION: {
Condition *subformula = condition.get.subformulas.begin;
for (; subformula != condition.get.subformulas.end; ++subformula) {
if (subformula->type == NEGATION) {
negated.push_back((void*)subformula->get.subformulas.begin);
continue;
}
Relation subresult;
set<varint_t> newvars;
// TODO vvv this won't work right if a non-special query
// has not been performed first
if (special(*subformula, intermediate, subresult)) {
if (subformula == condition.get.subformulas.begin) {
cerr << "[ERROR] Must have non-special query at beginning of conjunction." << endl;
}
intermediate.swap(subresult);
continue;
}
query(*subformula, newvars, subresult);
if (subformula == condition.get.subformulas.begin) {
intermediate.swap(subresult);
} else {
vector<size_t> joinvars(allvars.size() + newvars.size());
vector<size_t>::iterator jit = set_intersection(allvars.begin(),
allvars.end(), newvars.begin(), newvars.end(), joinvars.begin());
joinvars.resize(jit - joinvars.begin());
join(intermediate, subresult, joinvars, intermediate);
}
allvars.insert(newvars.begin(), newvars.end());
}
break;
}
case DISJUNCTION: {
cerr << "[ERROR] Disjunction is not supported." << endl;
return;
}
case EXISTENTIAL: {
// assuming all quantified variables are uniquely named in the scope of the rule
Condition *subformula = condition.get.subformulas.begin;
for (; subformula != condition.get.subformulas.end; ++subformula) {
if (subformula->type == NEGATION) {
negated.push_back((void*)subformula->get.subformulas.begin);
}
Relation subresult;
query(*subformula, allvars, subresult);
intermediate.splice(intermediate.end(), subresult);
}
break;
}
case NEGATION: {
cerr << "[ERROR] This should never happen. query should not be called directly on negated formulas." << endl;
return;
}
default: {
cerr << "[ERROR] Unhandled case " << (int)condition.type << " on line " << __LINE__ << endl;
return;
}
}
// TODO deal with negation later, if at all
#if 1
deque<void*>::iterator it = negated.begin();
for (; !intermediate.empty() && it != negated.end(); ++it) {
Relation negresult;
Condition *cond = (Condition*) *it;
if (special(*cond, intermediate, negresult)) {
intermediate.sort();
negresult.sort();
Relation leftover(intermediate.size());
Relation::iterator iit = set_difference(intermediate.begin(),
intermediate.end(), negresult.begin(), negresult.end(),
leftover.begin());
Relation newinter;
newinter.splice(newinter.end(), leftover,
leftover.begin(), iit);
intermediate.swap(newinter);
continue;
}
query(*((Condition*)(*it)), allvars, negresult);
minusrel(intermediate, negresult, intermediate);
}
#endif
results.swap(intermediate);
}