I came up with a kind of clever data type for storing short strings in a fixed size struct so they can be stored on the stack or inline without any allocations.
It’s always null-terminated so it can be passed directly as a C-style string, but it also stores the string length without using any additional data (Getting the length would normally have to iterate to find the end).
The trick is to store the number of unused bytes in the last character of the buffer. When the string is full, there are 0 unused bytes and the size byte overlaps the null terminator.
(Only works for strings < 256 chars excluding null byte)
Interesting idea, but your trick is never really going to help (you can store up to 255 bytes instead of 254). Also always using 256 bytes for every string seems wasteful.
22 characters is significantly less useful than 255 characters. I use this for resource name keys, asset file paths, and a few other scenarios. The max size is configurable, so I know that nothing I am going to store is ever going to require heap allocations (really bad to be doing every frame in a game engine).
I developed this specifically after benchmarking a simpler version and noticed a significant amount of time being spent in strlen(), and it had real benefits in my case.
Admittedly just storing a struct with a static buffer and separate size would have worked pretty much the same and eliminated the 255 char limitation, but it was fun to build.
22 characters is significantly less useful than 255 characters.
You can still use more than 22 characters; it just switches to the heap.
nothing I am going to store is ever going to require heap allocations
I would put good money that using 256 bytes everywhere is going to be slower overall than just using the heap when you need more than 22 characters. 22 is quite a lot, especially for keys. ThisReallyLongKey is still only 17.
I came up with a kind of clever data type for storing short strings in a fixed size struct so they can be stored on the stack or inline without any allocations.
It’s always null-terminated so it can be passed directly as a C-style string, but it also stores the string length without using any additional data (Getting the length would normally have to iterate to find the end).
The trick is to store the number of unused bytes in the last character of the buffer. When the string is full, there are 0 unused bytes and the size byte overlaps the null terminator.
(Only works for strings < 256 chars excluding null byte)
Implementation in C++ here: https://github.com/frustra/strayphotons/blob/master/src/common/common/InlineString.hh
Interesting idea, but your trick is never really going to help (you can store up to 255 bytes instead of 254). Also always using 256 bytes for every string seems wasteful.
I think LLVM’s small string optimisation is always going to be a better option: https://joellaity.com/2020/01/31/string.html
22 characters is significantly less useful than 255 characters. I use this for resource name keys, asset file paths, and a few other scenarios. The max size is configurable, so I know that nothing I am going to store is ever going to require heap allocations (really bad to be doing every frame in a game engine).
I developed this specifically after benchmarking a simpler version and noticed a significant amount of time being spent in strlen(), and it had real benefits in my case.
Admittedly just storing a struct with a static buffer and separate size would have worked pretty much the same and eliminated the 255 char limitation, but it was fun to build.
You can still use more than 22 characters; it just switches to the heap.
I would put good money that using 256 bytes everywhere is going to be slower overall than just using the heap when you need more than 22 characters. 22 is quite a lot, especially for keys.
ThisReallyLongKeyis still only 17.