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<!DOCTYPE html> < html lang = "en" > < head > < meta charset = "utf-8" > < meta name = "viewport" content = "width=device-width, initial-scale=1.0" > < meta name = "generator" content = "rustdoc" > < meta name = "description" content = "Creates a `SmallVec` containing the arguments." > < title > smallvec in smallvec - Rust< / title > < script > if ( window . location . protocol !== "file:" ) document . head . insertAdjacentHTML ( "beforeend" , "SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2" . split ( "," ) . map ( f => ` <link rel="preload" as="font" type="font/woff2" crossorigin href="../static.files/ ${ f } "> ` ) . join ( "" ) ) < / script > < link rel = "stylesheet" href = "../static.files/normalize-76eba96aa4d2e634.css" > < link rel = "stylesheet" href = "../static.files/rustdoc-dd39b87e5fcfba68.css" > < meta name = "rustdoc-vars" data-root-path = "../" data-static-root-path = "../static.files/" data-current-crate = "smallvec" data-themes = "" data-resource-suffix = "" data-rustdoc-version = "1.80.0 (051478957 2024-07-21)" data-channel = "1.80.0" data-search-js = "search-d52510db62a78183.js" data-settings-js = "settings-4313503d2e1961c2.js" > < script src = "../static.files/storage-118b08c4c78b968e.js" > < / script > < script defer src = "sidebar-items.js" > < / script > < script defer src = "../static.files/main-20a3ad099b048cf2.js" > < / script > < noscript > < link rel = "stylesheet" href = "../static.files/noscript-df360f571f6edeae.css" > < / noscript > < link rel = "alternate icon" type = "image/png" href = "../static.files/favicon-32x32-422f7d1d52889060.png" > < link rel = "icon" type = "image/svg+xml" href = "../static.files/favicon-2c020d218678b618.svg" > < / head > < body class = "rustdoc macro" > <!-- [if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif] --> < nav class = "mobile-topbar" > < button class = "sidebar-menu-toggle" title = "show sidebar" > < / button > < / nav > < nav class = "sidebar" > < div class = "sidebar-crate" > < h2 > < a href = "../smallvec/index.html" > smallvec< / a > < span class = "version" > 1.13.2< / span > < / h2 > < / div > < div class = "sidebar-elems" > < / div > < / nav > < div class = "sidebar-resizer" > < / div > < main > < div class = "width-limiter" > < rustdoc-search > < / rustdoc-search > < section id = "main-content" class = "content" > < div class = "main-heading" > < h1 > Macro < a href = "index.html" > smallvec< / a > ::< wbr > < a class = "macro" href = "#" > smallvec< / a > < button id = "copy-path" title = "Copy item path to clipboard" > Copy item path< / button > < / h1 > < span class = "out-of-band" > < a class = "src" href = "../src/smallvec/lib.rs.html#182-199" > source< / a > · < button id = "toggle-all-docs" title = "collapse all docs" > [< span > − < / span > ]< / button > < / span > < / div > < pre class = "rust item-decl" > < span class = "macro" > macro_rules!< / span > smallvec {
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(@one < span class = "macro-nonterminal" > $x< / span > :expr) => { ... };
(< span class = "macro-nonterminal" > $elem< / span > :expr; < span class = "macro-nonterminal" > $n< / span > :expr) => { ... };
($(< span class = "macro-nonterminal" > $x< / span > :expr),< span class = "kw-2" > *< / span > $(,)< span class = "kw-2" > *< / span > ) => { ... };
}< / pre > < details class = "toggle top-doc" open > < summary class = "hideme" > < span > Expand description< / span > < / summary > < div class = "docblock" > < p > Creates a < a href = "struct.SmallVec.html" title = "struct smallvec::SmallVec" > < code > SmallVec< / code > < / a > containing the arguments.< / p >
< p > < code > smallvec!< / code > allows < code > SmallVec< / code > s to be defined with the same syntax as array expressions.
There are two forms of this macro:< / p >
< ul >
< li > Create a < a href = "struct.SmallVec.html" title = "struct smallvec::SmallVec" > < code > SmallVec< / code > < / a > containing a given list of elements:< / li >
< / ul >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "kw" > let < / span > v: SmallVec< [< span class = "kw" > _< / span > ; < span class = "number" > 128< / span > ]> = < span class = "macro" > smallvec!< / span > [< span class = "number" > 1< / span > , < span class = "number" > 2< / span > , < span class = "number" > 3< / span > ];
< span class = "macro" > assert_eq!< / span > (v[< span class = "number" > 0< / span > ], < span class = "number" > 1< / span > );
< span class = "macro" > assert_eq!< / span > (v[< span class = "number" > 1< / span > ], < span class = "number" > 2< / span > );
< span class = "macro" > assert_eq!< / span > (v[< span class = "number" > 2< / span > ], < span class = "number" > 3< / span > );< / code > < / pre > < / div >
< ul >
< li > Create a < a href = "struct.SmallVec.html" title = "struct smallvec::SmallVec" > < code > SmallVec< / code > < / a > from a given element and size:< / li >
< / ul >
< div class = "example-wrap" > < pre class = "rust rust-example-rendered" > < code > < span class = "kw" > let < / span > v: SmallVec< [< span class = "kw" > _< / span > ; < span class = "number" > 0x8000< / span > ]> = < span class = "macro" > smallvec!< / span > [< span class = "number" > 1< / span > ; < span class = "number" > 3< / span > ];
< span class = "macro" > assert_eq!< / span > (v, SmallVec::from_buf([< span class = "number" > 1< / span > , < span class = "number" > 1< / span > , < span class = "number" > 1< / span > ]));< / code > < / pre > < / div >
< p > Note that unlike array expressions this syntax supports all elements
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which implement < a href = "https://doc.rust-lang.org/1.80.0/core/clone/trait.Clone.html" title = "trait core::clone::Clone" > < code > Clone< / code > < / a > and the number of elements doesn’
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a constant.< / p >
< p > This will use < code > clone< / code > to duplicate an expression, so one should be careful
using this with types having a nonstandard < code > Clone< / code > implementation. For
example, < code > smallvec![Rc::new(1); 5]< / code > will create a vector of five references
to the same boxed integer value, not five references pointing to independently
boxed integers.< / p >
< / div > < / details > < / section > < / div > < / main > < / body > < / html >
