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Add mention of RFC 2128 (use_nested_groups) in the reference #230

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Feb 6, 2018
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Add mention of RFC 2128 (use_nested_groups) in the reference #230

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33 changes: 16 additions & 17 deletions src/items/use-declarations.md
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Original file line number Diff line number Diff line change
@@ -1,16 +1,13 @@
# Use declarations

> **<sup>Syntax:<sup>**
> **<sup>Syntax:</sup>**
> _UseDeclaration_ :
> &nbsp;&nbsp; &nbsp;&nbsp; `use` [_SimplePath_]&nbsp;(`as` [IDENTIFIER])<sup>?</sup> `;`
> &nbsp;&nbsp; | `use` ([_SimplePath_]<sup>?</sup> `::`)<sup>?</sup> `{` _UseDeclarationItems_ `}` `;`
> &nbsp;&nbsp; | `use` ([_SimplePath_]<sup>?</sup> `::`)<sup>?</sup> `*` `;`
> &nbsp;&nbsp; ([_Visibility_])<sup>?</sup> `use` _UseTree_ `;`
>
> _UseDeclarationItems_ :
> &nbsp;&nbsp; _UseDeclarationItem_ ( `,` _UseDeclarationItem_ )<sup>*</sup> `,`<sup>?<sup>
>
> _UseDeclarationItem_ :
> &nbsp;&nbsp; ( `self` | [IDENTIFIER] ) ( `as` [IDENTIFIER] )<sup>?</sup>
> _UseTree_ :
> &nbsp;&nbsp; &nbsp;&nbsp; ([_SimplePath_]<sup>?</sup> `::`)<sup>?</sup> `*`
> &nbsp;&nbsp; | ([_SimplePath_]<sup>?</sup> `::`)<sup>?</sup> `{` (_UseTree_ ( `,` _UseTree_ )<sup>*</sup> `,`<sup>?</sup>)<sup>?</sup> `}`
> &nbsp;&nbsp; | [_SimplePath_] `as` [IDENTIFIER]

A _use declaration_ creates one or more local name bindings synonymous with
some other [path]. Usually a `use` declaration is used to shorten the path
Expand All @@ -27,16 +24,17 @@ and [blocks], usually at the top.

Use declarations support a number of convenient shortcuts:

* Simultaneously binding a list of paths differing only in their final element,
using the glob-like brace syntax `use a::b::{c,d,e,f};`
* Simultaneously binding a list of paths differing only in their final element
and their immediate parent module, using the `self` keyword, such as `use
a::b::{self, c, d};`
* Simultaneously binding a list of paths with a common prefix, using the
glob-like brace syntax `use a::b::{c, d, e::f, g::h::i};`
* Simultaneously binding a list of paths with a common prefix and their common
parent module, using the `self` keyword, such as `use a::b::{self, c, d::e};`
* Rebinding the target name as a new local name, using the syntax `use p::q::r
as x;`. This can also be used with the last two features: `use a::b::{self as
ab, c as abc}`.
as x;`. This can also be used with the last two features:
`use a::b::{self as ab, c as abc}`.
* Binding all paths matching a given prefix, using the asterisk wildcard syntax
`use a::b::*;`
`use a::b::*;`.
* Nesting groups of the previous features multiple times, such as
`use a::b::{self as ab, c, d::{*, e::f}};`

An example of `use` declarations:

Expand Down Expand Up @@ -126,3 +124,4 @@ fn main() {}

[IDENTIFIER]: identifiers.html
[_SimplePath_]: paths.html
[_Visibility_]: visibility-and-privacy.html