7 ms·

Proposal for a full-fledged C String

12 points by alcover 4y ago

Dynamic allocation, SSO, views, refcounting, etc.. are spread on various implementations. C++ separates string and string_view. And they're not fully compatible. (Ex. you can't concat cross-type !?). Rust has str, &str, String Box<str>, ... ? In the spirit of "a slice of a string is still a string", why not pack it all into a single type ? And offer security in the process. Here's the scheme : https://github.com/alcover/buffet/raw/main/assets/schema.png https://github.com/alcover/buffet/raw/main/assets/schema.png Here's the code : https://github.com/alcover/buffet https://github.com/alcover/buffet NB: I'm talking string/byte buffer. Higher string tooling like Utf8 would go a layer above.

iExploder 4y ago
interesting idea, I had a few questions when looking at it - afaik size_t and char* types are implementation dependent, not sure if this could cause problems, maybe you already thought about the implications? - are you hard set on using GPL?
- alcover 4y ago
  No prob with size_t and char* I think. They'll nicely solidify to 4 bytes on 32-bit platforms. I'd need to test for maximum though in size_t .len case. GPL : Not really. Maybe LGPL would do. I want the lib to promote open source and that's it.
  - iExploder 4y ago
    > No prob with size_t and char* I think. They'll nicely solidify to 4 bytes on 32-bit platforms. I'd need to test for maximum though in size_t .len case. I mean on 32 bit platform the offset to union tag would be different depending on the struct the union holds, unless I'm missing something
    - alcover 4y ago
      The hard values in the readme may be confusing. The real model is union { struct { char* data; size_t len; size_t off:8*sizeof(size_t)-TAGBITS, tag:TAGBITS; } ptr; struct { char data[sizeof(BuffetPtr)-2]; uint8_t refcnt; uint8_t len:8-TAGBITS, tag:TAGBITS; } sso; } where the tag falls into place. I tried an older version on 32 bit and it worked ok.
      - iExploder 4y ago
        ahhh thanks, now that makes more sense to me
  - colburnmh 4y ago
    MIT might be a better license for broad adoption. Both GPL and LGPL are viral licenses. They serve a purpose, but you need to assess if that purpose is the same as yours.
    - alcover 4y ago
      Would you object to MIT now and GPL/dual later when mature ? Though I suppose the license doesn't count when people are just trying the lib (which they seemingly don't..)
      - OmarAssadi 4y ago
        If it were dual-licensed, I think it’d be hard to find anyone who’d object. GPL is scary to me, though, since I prefer to license my stuff under pretty unrestrictive licenses, and I don’t really want to deal with the virality.
    - iExploder 4y ago
      exactly my thoughts, generally GPL any version or (L)GPLv3 or greater means your library will never be included in a commercial product, hence crippling the mass adaption
rurban 4y ago
we had this optimized string before here. I really wanted to try it out in a compiler or runtime, but hadn't had the time yet. anyone else already tried it?
- alcover 4y ago
  > anyone else already tried it? That's what I wonder too... working on this without any return other than lots of github stars is a bit discouraging.
mikewarot 4y ago
I think the model that Free Pascal uses could be adapted to C. It's a reference counted, counted string of bytes. The pointer to the string actually points past the allocation, reference count, length, etc.. at the first byte of the string. There is a \0 added on the end for safety when passing to OS calls. Code to modify the string does a copy, decrement the ref count of the original, and then modify of the new string. Copies of a string are essentially free. You can return them from functions, etc. with no worry about allocation. The run-time handles all of that. In C, there are mechanisms for running macros when a variable goes out of scope, those could be used to decrement the reference counter to a string used locally inside a function. (Returning the string would need to increase it's ref count first, of course)
deleted 4y ago
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12 points by alcover 4y ago

iExploder 4y ago

interesting idea, I had a few questions when looking at it - afaik size_t and char* types are implementation dependent, not sure if this could cause problems, maybe you already thought about the implications? - are you hard set on using GPL?

alcover 4y ago
No prob with size_t and char* I think. They'll nicely solidify to 4 bytes on 32-bit platforms. I'd need to test for maximum though in size_t .len case. GPL : Not really. Maybe LGPL would do. I want the lib to promote open source and that's it.
- iExploder 4y ago
  > No prob with size_t and char* I think. They'll nicely solidify to 4 bytes on 32-bit platforms. I'd need to test for maximum though in size_t .len case. I mean on 32 bit platform the offset to union tag would be different depending on the struct the union holds, unless I'm missing something
  - alcover 4y ago
    The hard values in the readme may be confusing. The real model is union { struct { char* data; size_t len; size_t off:8*sizeof(size_t)-TAGBITS, tag:TAGBITS; } ptr; struct { char data[sizeof(BuffetPtr)-2]; uint8_t refcnt; uint8_t len:8-TAGBITS, tag:TAGBITS; } sso; } where the tag falls into place. I tried an older version on 32 bit and it worked ok.
    - iExploder 4y ago
      ahhh thanks, now that makes more sense to me
- colburnmh 4y ago
  MIT might be a better license for broad adoption. Both GPL and LGPL are viral licenses. They serve a purpose, but you need to assess if that purpose is the same as yours.
  - alcover 4y ago
    Would you object to MIT now and GPL/dual later when mature ? Though I suppose the license doesn't count when people are just trying the lib (which they seemingly don't..)
    - OmarAssadi 4y ago
      If it were dual-licensed, I think it’d be hard to find anyone who’d object. GPL is scary to me, though, since I prefer to license my stuff under pretty unrestrictive licenses, and I don’t really want to deal with the virality.
  - iExploder 4y ago
    exactly my thoughts, generally GPL any version or (L)GPLv3 or greater means your library will never be included in a commercial product, hence crippling the mass adaption

rurban 4y ago

we had this optimized string before here. I really wanted to try it out in a compiler or runtime, but hadn't had the time yet. anyone else already tried it?

alcover 4y ago
> anyone else already tried it? That's what I wonder too... working on this without any return other than lots of github stars is a bit discouraging.

mikewarot 4y ago

I think the model that Free Pascal uses could be adapted to C. It's a reference counted, counted string of bytes. The pointer to the string actually points past the allocation, reference count, length, etc.. at the first byte of the string. There is a \0 added on the end for safety when passing to OS calls. Code to modify the string does a copy, decrement the ref count of the original, and then modify of the new string. Copies of a string are essentially free. You can return them from functions, etc. with no worry about allocation. The run-time handles all of that. In C, there are mechanisms for running macros when a variable goes out of scope, those could be used to decrement the reference counter to a string used locally inside a function. (Returning the string would need to increase it's ref count first, of course)

deleted 4y ago

[deleted]