void ConstraintGraph::Change::undo(ConstraintGraph &cg) {
/// Temporarily change the active scope to null, so we don't record
/// any changes made while performing the undo operation.
llvm::SaveAndRestore<ConstraintGraphScope *> prevActiveScope(cg.ActiveScope,
nullptr);
switch (Kind) {
case ChangeKind::AddedTypeVariable:
cg.removeNode(TypeVar);
break;
case ChangeKind::AddedConstraint:
cg.removeConstraint(TheConstraint);
break;
case ChangeKind::RemovedConstraint:
cg.addConstraint(TheConstraint);
break;
case ChangeKind::ExtendedEquivalenceClass: {
auto &node = cg[EquivClass.TypeVar];
node.EquivalenceClass.erase(
node.EquivalenceClass.begin() + EquivClass.PrevSize,
node.EquivalenceClass.end());
break;
}
case ChangeKind::BoundTypeVariable:
cg.unbindTypeVariable(Binding.TypeVar, Binding.FixedType);
break;
}
}
void ConstraintGraph::Change::undo(ConstraintGraph &cg) {
/// Temporarily change the active scope to null, so we don't record
/// any changes made while performing the undo operation.
llvm::SaveAndRestore<ConstraintGraphScope *> prevActiveScope(cg.ActiveScope,
nullptr);
switch (Kind) {
case ChangeKind::AddedTypeVariable:
cg.removeNode(TypeVar);
break;
case ChangeKind::AddedConstraint:
cg.removeConstraint(TheConstraint);
break;
case ChangeKind::RemovedConstraint:
cg.addConstraint(TheConstraint);
break;
case ChangeKind::ExtendedEquivalenceClass: {
auto &node = cg[EquivClass.TypeVar];
node.EquivalenceClass.erase(
node.EquivalenceClass.begin() + EquivClass.PrevSize,
node.EquivalenceClass.end());
break;
}
case ChangeKind::BoundTypeVariable:
cg.unbindTypeVariable(Binding.TypeVar, Binding.FixedType);
break;
case ChangeKind::AddedMemberType: {
auto &node = cg[MemberType.TypeVar];
// Erase the member type entry from the
auto known = node.MemberTypeIndex.find(MemberType.Name);
assert(known != node.MemberTypeIndex.end() && "Constraint graph corrupted");
unsigned index = known->second;
node.MemberTypeIndex.erase(known);
// If this was not the last member type, swap it with the last
// member type.
if (index != node.MemberTypes.size()-1) {
node.MemberTypes[index] = node.MemberTypes.back();
node.MemberTypeIndex[node.MemberTypes[index].first] = index;
}
// Pop off the last member type.
node.MemberTypes.pop_back();
break;
}
}
}