Strings are usable in component data now

Today's ECS preview release included the ability to use bool and char in component data, so I started wondering if it would be possible to implement an "ECS string" using this... But then I remembered running across the "NativeString" types a while ago, but they weren't really usable from component data at the time (only NativeStringView).

I checked on Discord, and dzamani there pointed out there were some changes to NativeStrings.. and lo and behold, you can use strings in ECS components now

Code (CSharp):

1. [Serializable]
2. public struct StringTests : IComponentData {
3.     public NativeString64 TestString;
4. }

Code (CSharp):

1. public class StringTestSystem : ComponentSystem
2. {
3.     protected override void OnUpdate() {
4.  
5.         Entities.ForEach((ref StringTests strings) => { Debug.LogWarning($"!! {strings.TestString}"); });
6.     }
7. }

For reference, these are the types I've been playing with:
NativeString64 (64 bytes long, 30 characters).
NativeString512 (512 bytes, 254 chars)
NativeString4096 (4096 bytes, 2046 chars)

For example the 64 byte string is stored as:
private unsafe fixed uint buffer[15]

So its 15x4 + 4 (for storing length) = 64 bytes.

There are also more related types I haven't dug into yet, including something called "Word".. and I see the following comments in the source code:

Code (CSharp):

1. // A "Words" is an integer that refers to 4,096 or fewer chars of UTF-16 text in a global storage blob.
2. // Each should refer to *at most* about one printed page of text.
3. // If you need more text, consider using one Words struct for each printed page's worth.
4. // If you need to store the text of "War and Peace" in a single object, you've come to the wrong place.

 

Small correction: char is 16 bit -> NativeString64 can only store 30 characters.

 

Thanks, that was actually a typo fixed it

 

Words, as I understand, is just a way to avoid recreating strings you already had and keep them together.

But there is one thing I don't get, how is this `private unsafe fixed uint buffer[15]` blittable.

 

*smashes that like button*

 

Is there anyway we can use this in non ecs projects with c# jobs? Our data structures use strings a lot and it would be really useful to jobify the work done on them.

 

What version is this? preview.27?

 

Preview 28

 

Afaik you should be able to use this in native arrays

 

Huzzah!

It's the fixed keyword that allows that. It embeds the array as part of the struct.

 

while i don't think there is anything stopping you from doing this, for example, from a monobehaviour or your own custom class update, don't you need to complete the job immediately, defeating the purpose?

 

Depends on what you are doing. If you are doing work that can be done in parallel you will benefit from multiple worker threads. You could also call complete in a LateUpdate.

 

Native string is not promoted in auto generated component..

 

Did you find a solution?

 

No. But I have not searched for it hard.

 

HELP. Native string is not promoted in auto generated component..

 

This is correct. It's not promoted for anyone right now. (0.6.0)

 

There are also FixedStrings