forked from lix-project/lix
Specialize std::optional<StorePath>
so this is backwards compatible
While I am cautious to break parametricity, I think it's OK in this cases---we're not about to try to do some crazy polymorphic protocol anytime soon.
This commit is contained in:
parent
8b175f58d1
commit
47644e49ca
|
@ -70,6 +70,20 @@ void write(const Store & store, Sink & out, const StorePath & storePath)
|
|||
out << store.printStorePath(storePath);
|
||||
}
|
||||
|
||||
|
||||
template<>
|
||||
std::optional<StorePath> read(const Store & store, Source & from, Phantom<std::optional<StorePath>> _)
|
||||
{
|
||||
auto s = readString(from);
|
||||
return s == "" ? std::optional<StorePath> {} : store.parseStorePath(s);
|
||||
}
|
||||
|
||||
template<>
|
||||
void write(const Store & store, Sink & out, const std::optional<StorePath> & storePathOpt)
|
||||
{
|
||||
out << (storePathOpt ? store.printStorePath(*storePathOpt) : "");
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
|
|
@ -90,6 +90,13 @@ std::optional<T> read(const Store & store, Source & from, Phantom<std::optional<
|
|||
template<typename T>
|
||||
void write(const Store & store, Sink & out, const std::optional<T> & optVal);
|
||||
|
||||
/* Specialization which uses and empty string for the empty case, taking
|
||||
advantage of the fact StorePaths always serialize to a non-empty string.
|
||||
This is done primarily for backwards compatability, so that StorePath <=
|
||||
std::optional<StorePath>, where <= is the compatability partial order.
|
||||
*/
|
||||
template<>
|
||||
void write(const Store & store, Sink & out, const std::optional<StorePath> & optVal);
|
||||
|
||||
template<typename T>
|
||||
std::map<std::string, T> read(const Store & store, Source & from, Phantom<std::map<std::string, T>> _)
|
||||
|
|
Loading…
Reference in a new issue