prevent memory growing

[azadkuh]

it's better to add:

allocator.deallocate();

to the bigining of jsonParse() to stop allocator instance growing every time if the instance has been used before.

users may forget to call deallocate() or introduce a new instance of allocator every time they call jsonParse().

[vivkin]

No it's not. User is smart enough to care about memory. Parser just parsing, instead solving memory management issues

[azadkuh]

definitely users are smart!

one of the key Characteristics of a Good API is Hard to misuse regardless of users intelligence.

because they are focused on their own logic / application and they may have no time to fully understand your great implementation.

another approach: jsonParse() can return an error status code if allocator is already allocated.

[vivkin]

In allocator maybe allocated buffer for copy of source buffer or something similar