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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="Document tree traversal to mutate an exclusive borrow of a document tree in place."><title>toml_edit::visit_mut - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-ac92e1bbe349e143.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="toml_edit" data-themes="" data-resource-suffix="" data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)" data-channel="1.76.0" data-search-js="search-2b6ce74ff89ae146.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../static.files/storage-f2adc0d6ca4d09fb.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../static.files/main-305769736d49e732.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-feafe1bb7466e4bd.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><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 mod"><!--[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">&#9776;</button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../toml_edit/index.html">toml_edit</a><span class="version">0.22.6</span></h2></div><h2 class="location"><a href="#">Module visit_mut</a></h2><div class="sidebar-elems"><section><ul class="block"><li><a href="#traits">Traits</a></li><li><a href="#functions">Functions</a></li></ul></section><h2><a href="../index.html">In crate toml_edit</a></h2></div></nav><div class="sidebar-resizer"></div>
<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../../toml_edit/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Module <a href="../index.html">toml_edit</a>::<wbr><a class="mod" href="#">visit_mut</a><button id="copy-path" title="Copy item path to clipboard"><img src="../../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../../src/toml_edit/visit_mut.rs.html#1-256">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Document tree traversal to mutate an exclusive borrow of a document tree in place.</p>
<p>Each method of the <a href="trait.VisitMut.html" title="trait toml_edit::visit_mut::VisitMut"><code>VisitMut</code></a> trait is a hook that can be overridden
to customize the behavior when mutating the corresponding type of node.
By default, every method recursively visits the substructure of the
input by invoking the right visitor method of each of its fields.</p>
<div class="example-wrap"><pre class="rust rust-example-rendered"><code>
<span class="kw">pub trait </span>VisitMut {
<span class="comment">/* ... */
</span><span class="kw">fn </span>visit_item_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>, i: <span class="kw-2">&amp;mut </span>Item) {
visit_item_mut(<span class="self">self</span>, i);
}
<span class="comment">/* ... */
</span>}
<span class="kw">pub fn </span>visit_item_mut&lt;V&gt;(v: <span class="kw-2">&amp;mut </span>V, node: <span class="kw-2">&amp;mut </span>Item)
<span class="kw">where
</span>V: VisitMut + <span class="question-mark">?</span>Sized,
{
<span class="kw">match </span>node {
Item::None =&gt; {}
Item::Value(value) =&gt; v.visit_value_mut(value),
Item::Table(table) =&gt; v.visit_table_mut(table),
Item::ArrayOfTables(array) =&gt; v.visit_array_of_tables_mut(array),
}
}</code></pre></div>
<p>The API is modeled after <a href="https://docs.rs/syn/1/syn/visit_mut"><code>syn::visit_mut</code></a>.</p>
<h2 id="examples"><a href="#examples">Examples</a></h2>
<p>This visitor replaces every floating point value with its decimal string representation, to
2 decimal points.</p>
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>toml_edit::visit_mut::<span class="kw-2">*</span>;
<span class="kw">struct </span>FloatToString;
<span class="kw">impl </span>VisitMut <span class="kw">for </span>FloatToString {
<span class="kw">fn </span>visit_value_mut(<span class="kw-2">&amp;mut </span><span class="self">self</span>, node: <span class="kw-2">&amp;mut </span>Value) {
<span class="kw">if let </span>Value::Float(f) = node {
<span class="comment">// Convert the float to a string.
</span><span class="kw">let </span><span class="kw-2">mut </span>s = Formatted::new(<span class="macro">format!</span>(<span class="string">"{:.2}"</span>, f.value()));
<span class="comment">// Copy over the formatting.
</span>std::mem::swap(s.decor_mut(), f.decor_mut());
<span class="kw-2">*</span>node = Value::String(s);
}
<span class="comment">// Most of the time, you will also need to call the default implementation to recurse
// further down the document tree.
</span>visit_value_mut(<span class="self">self</span>, node);
}
}
<span class="kw">let </span>input = <span class="string">r#"
banana = 3.26
table = { apple = 4.5 }
"#</span>;
<span class="kw">let </span><span class="kw-2">mut </span>document: Document = input.parse().unwrap();
<span class="kw">let </span><span class="kw-2">mut </span>visitor = FloatToString;
visitor.visit_document_mut(<span class="kw-2">&amp;mut </span>document);
<span class="kw">let </span>output = <span class="string">r#"
banana = "3.26"
table = { apple = "4.50" }
"#</span>;
<span class="macro">assert_eq!</span>(<span class="macro">format!</span>(<span class="string">"{}"</span>, document), output);</code></pre></div>
<p>For a more complex example where the visitor has internal state, see <code>examples/visit.rs</code>
<a href="https://github.com/toml-rs/toml/blob/main/crates/toml_edit/examples/visit.rs">on GitHub</a>.</p>
</div></details><h2 id="traits" class="section-header"><a href="#traits">Traits</a></h2><ul class="item-table"><li><div class="item-name"><a class="trait" href="trait.VisitMut.html" title="trait toml_edit::visit_mut::VisitMut">VisitMut</a></div><div class="desc docblock-short">Document tree traversal to mutate an exclusive borrow of a document tree in-place.</div></li></ul><h2 id="functions" class="section-header"><a href="#functions">Functions</a></h2><ul class="item-table"><li><div class="item-name"><a class="fn" href="fn.visit_array_mut.html" title="fn toml_edit::visit_mut::visit_array_mut">visit_array_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_array_of_tables_mut.html" title="fn toml_edit::visit_mut::visit_array_of_tables_mut">visit_array_of_tables_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_document_mut.html" title="fn toml_edit::visit_mut::visit_document_mut">visit_document_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_inline_table_mut.html" title="fn toml_edit::visit_mut::visit_inline_table_mut">visit_inline_table_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_item_mut.html" title="fn toml_edit::visit_mut::visit_item_mut">visit_item_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_table_like_kv_mut.html" title="fn toml_edit::visit_mut::visit_table_like_kv_mut">visit_table_like_kv_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_table_like_mut.html" title="fn toml_edit::visit_mut::visit_table_like_mut">visit_table_like_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_table_mut.html" title="fn toml_edit::visit_mut::visit_table_mut">visit_table_mut</a></div></li><li><div class="item-name"><a class="fn" href="fn.visit_value_mut.html" title="fn toml_edit::visit_mut::visit_value_mut">visit_value_mut</a></div></li></ul></section></div></main></body></html>