public static Task InsertOrUpdate <T>(
string _fileName,
T itemToUpdate,
MatchForUpdate <T> matcher,
Func <T, T> cloneWithUpdateVersion)
{
using (var stream = FileUtils.GetReadWriteStream(_fileName))
{
var list = stream.ReadList <T>();
var found = false;
for (int idx = 0; idx < list.Count && !found; idx++)
{
var item = list[idx];
bool shouldUpdate = false;
(found, shouldUpdate) = matcher(item, itemToUpdate);
if (shouldUpdate)
{
list[idx] = cloneWithUpdateVersion(itemToUpdate);
}
}
if (!found)
{
list.Add(cloneWithUpdateVersion(itemToUpdate));
}
stream.WriteList(list);
}
return(Task.FromResult(true));
}
public static Task DeleteItem <T>(
string fileName,
T itemToDelete,
MatchForUpdate <T> matcher)
{
using (var stream = FileUtils.GetReadWriteStream(fileName))
{
var list = stream.ReadList <T>();
var found = false;
for (int idx = 0; idx < list.Count && !found; idx++)
{
var item = list[idx];
bool shouldUpdate = false;
(found, shouldUpdate) = matcher(item, itemToDelete);
if (shouldUpdate)
{
list.RemoveAt(idx);
}
}
stream.WriteList(list);
}
return(Task.FromResult(true));
}
public static Task <bool> Exists <T>(
string fileName,
T itemToFind,
MatchForUpdate <T> matcher)
{
var found = false;
using (var stream = FileUtils.GetReadStream(fileName))
{
var list = stream.ReadList <T>();
for (int idx = 0; idx < list.Count && !found; idx++)
{
var item = list[idx];
bool shouldUpdate = false;
(found, shouldUpdate) = matcher(item, itemToFind);
}
}
return(Task.FromResult(found));
}
