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pcwalton opened this issue Apr 30, 2013 · 7 comments · Fixed by #10333
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Add a method to convert a vector of Ascii to a string slice without copying #6120

pcwalton opened this issue Apr 30, 2013 · 7 comments · Fixed by #10333
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I-slow Issue: Problems and improvements with respect to performance of generated code.

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@pcwalton
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As it says.
@Kimundi
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Kimundi commented Apr 30, 2013

The problem is that that's not generally possible without reqiring that the Ascii vector is one random byte longer than the slice you want. A str slice is one hidden byte longer than a vec slice.

@Kimundi
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Kimundi commented Apr 30, 2013

One way to solve this would be to turn ~[Ascii] into an own type AsciiStr, which holds the invariant that its always null terminated. Or we could just say that a [Ascii] may be optionally null terminated, that a trailing null is never considerd part of the string it represents, and that certain operations reqire it.

@emberian
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I think #7599 enables this cleanly?

@Kimundi
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Kimundi commented Jul 12, 2013

@cmr I'm not sure how that Issue is related.

@emberian
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@Kimundi err yeah, nevermind, sorry

@huonw
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huonw commented Jul 13, 2013

@erickt was experimenting with removing the null-terminator on ~strs, which would make this possible. (Preferably by implementing the std::str::Str trait.)

@huonw huonw mentioned this issue Nov 7, 2013
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huonw commented Nov 7, 2013

Triage: null terminators are gone, so this will be fixed when #10333 lands.

bors added a commit that referenced this issue Nov 8, 2013
@bors
auto merge of #10333 : huonw/rust/ascii, r=alexcrichton
27eb85d 
This renames to_str_ascii to as_str_ascii and makes it non-copying,
which is possible now that strings no longer have a hidden extra
byte/null terminator.

Fixes #6120.
@huonw huonw closed this as completed in b95a8c6 Nov 8, 2013
flip1995 pushed a commit to flip1995/rust that referenced this issue Oct 9, 2020
@bors
Auto merge of rust-lang#6120 - phansch:replace-lazy-static, r=Manishe…
2771918 
…arth

Replace some lazy_static usage with once_cell feature

This replaces some `lazy_static` usage with [`SyncLazy`](https://doc.rust-lang.org/nightly/std/lazy/struct.SyncLazy.html) of the unstable `once_cell` feature.

changelog: none
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std::ascii: Provide a copyless [Ascii] -> str method. huonw/rust
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@pcwalton @emberian @huonw @Kimundi