static llvm::Optional<unsigned>
mapOffsetToOlderSnapshot(unsigned Offset,
ImmutableTextSnapshotRef NewSnap,
ImmutableTextSnapshotRef OldSnap) {
SmallVector<ReplaceImmutableTextUpdateRef, 16> Updates;
OldSnap->foreachReplaceUntil(NewSnap,
[&](ReplaceImmutableTextUpdateRef Upd)->bool {
Updates.push_back(Upd);
return true;
});
// Walk the updates backwards and "undo" them.
for (auto I = Updates.rbegin(), E = Updates.rend(); I != E; ++I) {
auto Upd = *I;
if (Upd->getByteOffset() <= Offset &&
Offset < Upd->getByteOffset() + Upd->getText().size())
return None; // Offset is part of newly inserted text.
if (Upd->getByteOffset() <= Offset) {
Offset += Upd->getLength(); // "bring back" what was removed.
Offset -= Upd->getText().size(); // "remove" what was added.
}
}
return Offset;
}
static llvm::Optional<unsigned>
mapOffsetToNewerSnapshot(unsigned Offset,
ImmutableTextSnapshotRef OldSnap,
ImmutableTextSnapshotRef NewSnap) {
bool Completed = OldSnap->foreachReplaceUntil(NewSnap,
[&](ReplaceImmutableTextUpdateRef Upd)->bool {
if (Upd->getByteOffset() <= Offset &&
Offset < Upd->getByteOffset() + Upd->getLength())
return false; // Offset is part of removed text.
if (Upd->getByteOffset() <= Offset) {
Offset += Upd->getText().size();
Offset -= Upd->getLength();
}
return true;
});
if (Completed)
return Offset;
return None;
}
