// static
already_AddRefed<DeleteTextTransaction>
DeleteTextTransaction::MaybeCreateForPreviousCharacter(
EditorBase& aEditorBase,
CharacterData& aCharData,
uint32_t aOffset)
{
if (NS_WARN_IF(!aOffset)) {
return nullptr;
}
nsAutoString data;
aCharData.GetData(data);
if (NS_WARN_IF(data.IsEmpty())) {
return nullptr;
}
uint32_t length = 1;
uint32_t offset = aOffset - 1;
if (offset &&
NS_IS_LOW_SURROGATE(data[offset]) &&
NS_IS_HIGH_SURROGATE(data[offset - 1])) {
++length;
--offset;
}
return DeleteTextTransaction::MaybeCreate(aEditorBase, aCharData,
offset, length);
}
// static
already_AddRefed<DeleteTextTransaction>
DeleteTextTransaction::MaybeCreateForNextCharacter(
EditorBase& aEditorBase,
CharacterData& aCharData,
uint32_t aOffset)
{
nsAutoString data;
aCharData.GetData(data);
if (NS_WARN_IF(aOffset >= data.Length()) ||
NS_WARN_IF(data.IsEmpty())) {
return nullptr;
}
uint32_t length = 1;
if (aOffset + 1 < data.Length() &&
NS_IS_HIGH_SURROGATE(data[aOffset]) &&
NS_IS_LOW_SURROGATE(data[aOffset + 1])) {
++length;
}
return DeleteTextTransaction::MaybeCreate(aEditorBase, aCharData,
aOffset, length);
}