| <!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="Contains declarations to bind to the C Data Interface."><title>arrow_array::ffi - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="arrow_array" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.0-nightly (b15a874aa 2025-11-02)" data-channel="nightly" data-search-js="search-5c29b3b5.js" data-stringdex-js="stringdex-c3e638e9.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../sidebar-items.js"></script><script defer src="../../static.files/main-ce535bd0.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="icon" href="https://arrow.apache.org/img/arrow-logo_chevrons_black-txt_transparent-bg.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]--><rustdoc-topbar><h2><a href="#">Module ffi</a></h2></rustdoc-topbar><nav class="sidebar"><div class="sidebar-crate"><a class="logo-container" href="../../arrow_array/index.html"><img src="https://arrow.apache.org/img/arrow-logo_chevrons_black-txt_white-bg.svg" alt="logo"></a><h2><a href="../../arrow_array/index.html">arrow_<wbr>array</a><span class="version">57.0.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">Module ffi</a></h2><h3><a href="#structs">Module Items</a></h3><ul class="block"><li><a href="#structs" title="Structs">Structs</a></li><li><a href="#functions" title="Functions">Functions</a></li><li><a href="#types" title="Type Aliases">Type Aliases</a></li></ul></section><div id="rustdoc-modnav"><h2 class="in-crate"><a href="../index.html">In crate arrow_<wbr>array</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../index.html">arrow_array</a></div><h1>Module <span>ffi</span> <button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../src/arrow_array/ffi.rs.html#18-1774">Source</a> </span></div><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Contains declarations to bind to the <a href="https://arrow.apache.org/docs/format/CDataInterface.html">C Data Interface</a>.</p> |
| <p>Generally, this module is divided in two main interfaces: |
| One interface maps C ABI to native Rust types, i.e. convert c-pointers, c_char, to native rust. |
| This is handled by <a href="struct.FFI_ArrowSchema.html" title="struct arrow_array::ffi::FFI_ArrowSchema">FFI_ArrowSchema</a> and <a href="struct.FFI_ArrowArray.html" title="struct arrow_array::ffi::FFI_ArrowArray">FFI_ArrowArray</a>.</p> |
| <p>The second interface maps native Rust types to the Rust-specific implementation of Arrow such as <code>format</code> to <code>Datatype</code>, |
| <code>Buffer</code>, etc. This is handled by <code>from_ffi</code> and <code>to_ffi</code>.</p> |
| <p>Export to FFI</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="comment">// create an array natively |
| |
| </span><span class="kw">let </span>array = Int32Array::from(<span class="macro">vec!</span>[<span class="prelude-val">Some</span>(<span class="number">1</span>), <span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(<span class="number">3</span>)]); |
| <span class="kw">let </span>data = array.into_data(); |
| |
| <span class="comment">// Export it |
| </span><span class="kw">let </span>(out_array, out_schema) = to_ffi(<span class="kw-2">&</span>data)<span class="question-mark">?</span>; |
| |
| <span class="comment">// import it |
| </span><span class="kw">let </span>data = <span class="kw">unsafe </span>{ from_ffi(out_array, <span class="kw-2">&</span>out_schema) }<span class="question-mark">?</span>; |
| <span class="kw">let </span>array = Int32Array::from(data); |
| |
| <span class="comment">// verify |
| </span><span class="macro">assert_eq!</span>(array, Int32Array::from(<span class="macro">vec!</span>[<span class="prelude-val">Some</span>(<span class="number">1</span>), <span class="prelude-val">None</span>, <span class="prelude-val">Some</span>(<span class="number">3</span>)]));</code></pre></div> |
| <p>Import from FFI</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="doccomment">/// A foreign data container that can export to C Data interface |
| </span><span class="kw">struct </span>ForeignArray {}; |
| |
| <span class="kw">impl </span>ForeignArray { |
| <span class="doccomment">/// Export from foreign array representation to C Data interface |
| /// e.g. <https://github.com/apache/arrow/blob/fc1f9ebbc4c3ae77d5cfc2f9322f4373d3d19b8a/python/pyarrow/array.pxi#L1552> |
| </span><span class="kw">fn </span>export_to_c(<span class="kw-2">&</span><span class="self">self</span>, array: <span class="kw-2">*mut </span>FFI_ArrowArray, schema: <span class="kw-2">*mut </span>FFI_ArrowSchema) { |
| <span class="comment">// ... |
| </span>} |
| } |
| |
| <span class="doccomment">/// Import an [`ArrayRef`] from a [`ForeignArray`] |
| </span><span class="kw">fn </span>import_array(foreign: <span class="kw-2">&</span>ForeignArray) -> <span class="prelude-ty">Result</span><ArrayRef, ArrowError> { |
| <span class="kw">let </span><span class="kw-2">mut </span>schema = FFI_ArrowSchema::empty(); |
| <span class="kw">let </span><span class="kw-2">mut </span>array = FFI_ArrowArray::empty(); |
| foreign.export_to_c(<span class="macro">addr_of_mut!</span>(array), <span class="macro">addr_of_mut!</span>(schema)); |
| <span class="prelude-val">Ok</span>(make_array(<span class="kw">unsafe </span>{ from_ffi(array, <span class="kw-2">&</span>schema) }<span class="question-mark">?</span>)) |
| }</code></pre></div></div></details><h2 id="structs" class="section-header">Structs<a href="#structs" class="anchor">§</a></h2><dl class="item-table"><dt><a class="struct" href="struct.FFI_ArrowArray.html" title="struct arrow_array::ffi::FFI_ArrowArray">FFI_<wbr>Arrow<wbr>Array</a></dt><dd>ABI-compatible struct for ArrowArray from C Data Interface |
| See <a href="https://arrow.apache.org/docs/format/CDataInterface.html#structure-definitions">https://arrow.apache.org/docs/format/CDataInterface.html#structure-definitions</a></dd><dt><a class="struct" href="struct.FFI_ArrowSchema.html" title="struct arrow_array::ffi::FFI_ArrowSchema">FFI_<wbr>Arrow<wbr>Schema</a></dt><dd>ABI-compatible struct for <code>ArrowSchema</code> from C Data Interface |
| See <a href="https://arrow.apache.org/docs/format/CDataInterface.html#structure-definitions">https://arrow.apache.org/docs/format/CDataInterface.html#structure-definitions</a></dd><dt><a class="struct" href="struct.ImportedArrowArray.html" title="struct arrow_array::ffi::ImportedArrowArray">Imported<wbr>Arrow<wbr>Array</a><span title="Restricted Visibility"> 🔒</span> </dt></dl><h2 id="functions" class="section-header">Functions<a href="#functions" class="anchor">§</a></h2><dl class="item-table"><dt><a class="fn" href="fn.bit_width.html" title="fn arrow_array::ffi::bit_width">bit_<wbr>width</a><span title="Restricted Visibility"> 🔒</span> </dt><dt><a class="fn" href="fn.create_buffer.html" title="fn arrow_array::ffi::create_buffer">create_<wbr>buffer</a><span title="Restricted Visibility"> 🔒</span> <sup title="unsafe function">⚠</sup></dt><dd>returns a new buffer corresponding to the index <code>i</code> of the FFI array. It may not exist (null pointer). |
| <code>bits</code> is the number of bits that the native type of this buffer has. |
| The size of the buffer will be <code>ceil(self.length * bits, 8)</code>.</dd><dt><a class="fn" href="fn.export_array_into_raw.html" title="fn arrow_array::ffi::export_array_into_raw">export_<wbr>array_<wbr>into_<wbr>raw</a><sup title="unsafe function">⚠</sup><wbr><span class="stab deprecated" title="">Deprecated</span></dt><dd>Exports an array to raw pointers of the C Data Interface provided by the consumer.</dd><dt><a class="fn" href="fn.from_ffi.html" title="fn arrow_array::ffi::from_ffi">from_<wbr>ffi</a><sup title="unsafe function">⚠</sup></dt><dd>Import [ArrayData] from the C Data Interface</dd><dt><a class="fn" href="fn.from_ffi_and_data_type.html" title="fn arrow_array::ffi::from_ffi_and_data_type">from_<wbr>ffi_<wbr>and_<wbr>data_<wbr>type</a><sup title="unsafe function">⚠</sup></dt><dd>Import [ArrayData] from the C Data Interface</dd><dt><a class="fn" href="fn.to_ffi.html" title="fn arrow_array::ffi::to_ffi">to_ffi</a></dt><dd>Export to the C Data Interface</dd></dl><h2 id="types" class="section-header">Type Aliases<a href="#types" class="anchor">§</a></h2><dl class="item-table"><dt><a class="type" href="type.Result.html" title="type arrow_array::ffi::Result">Result</a><span title="Restricted Visibility"> 🔒</span> </dt></dl></section></div></main></body></html> |
