192 lines
No EOL
23 KiB
HTML
192 lines
No EOL
23 KiB
HTML
<!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="API documentation for the Rust `FindSpec` enum in crate `edn`.">
|
||
<meta name="keywords" content="rust, rustlang, rust-lang, FindSpec">
|
||
|
||
<title>edn::query::FindSpec - Rust</title>
|
||
|
||
<link rel="stylesheet" type="text/css" href="../../normalize.css">
|
||
<link rel="stylesheet" type="text/css" href="../../rustdoc.css"
|
||
id="mainThemeStyle">
|
||
|
||
<link rel="stylesheet" type="text/css" href="../../dark.css">
|
||
<link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle">
|
||
<script src="../../storage.js"></script>
|
||
|
||
|
||
|
||
|
||
</head>
|
||
<body class="rustdoc enum">
|
||
<!--[if lte IE 8]>
|
||
<div class="warning">
|
||
This old browser is unsupported and will most likely display funky
|
||
things.
|
||
</div>
|
||
<![endif]-->
|
||
|
||
|
||
|
||
<nav class="sidebar">
|
||
<div class="sidebar-menu">☰</div>
|
||
|
||
<p class='location'>Enum FindSpec</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#variants">Variants</a><div class="sidebar-links"><a href="#variant.FindRel">FindRel</a><a href="#variant.FindColl">FindColl</a><a href="#variant.FindTuple">FindTuple</a><a href="#variant.FindScalar">FindScalar</a></div><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.is_unit_limited">is_unit_limited</a><a href="#method.expected_column_count">expected_column_count</a><a href="#method.requires_distinct">requires_distinct</a><a href="#method.columns">columns</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Debug">Debug</a><a href="#impl-Eq">Eq</a><a href="#impl-PartialEq">PartialEq</a></div><a class="sidebar-title" href="#synthetic-implementations">Auto Trait Implementations</a><div class="sidebar-links"><a href="#impl-Send">!Send</a><a href="#impl-Sync">!Sync</a></div></div><p class='location'><a href='../index.html'>edn</a>::<wbr><a href='index.html'>query</a></p><script>window.sidebarCurrent = {name: 'FindSpec', ty: 'enum', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
|
||
</nav>
|
||
|
||
<div class="theme-picker">
|
||
<button id="theme-picker" aria-label="Pick another theme!">
|
||
<img src="../../brush.svg" width="18" alt="Pick another theme!">
|
||
</button>
|
||
<div id="theme-choices"></div>
|
||
</div>
|
||
<script src="../../theme.js"></script>
|
||
<nav class="sub">
|
||
<form class="search-form js-only">
|
||
<div class="search-container">
|
||
<input class="search-input" name="search"
|
||
autocomplete="off"
|
||
placeholder="Click or press ‘S’ to search, ‘?’ for more options…"
|
||
type="search">
|
||
</div>
|
||
</form>
|
||
</nav>
|
||
|
||
<section id='main' class="content"><h1 class='fqn'><span class='in-band'>Enum <a href='../index.html'>edn</a>::<wbr><a href='index.html'>query</a>::<wbr><a class="enum" href=''>FindSpec</a></span><span class='out-of-band'><span id='render-detail'>
|
||
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
|
||
[<span class='inner'>−</span>]
|
||
</a>
|
||
</span><a class='srclink' href='../../src/edn/query.rs.html#654-670' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust enum'>pub enum FindSpec {
|
||
FindRel(<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>>),
|
||
FindColl(<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>),
|
||
FindTuple(<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>>),
|
||
FindScalar(<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>),
|
||
}</pre></div><div class='docblock'><p>A definition of the first part of a find query: the
|
||
<code>[:find ?foo ?bar…]</code> bit.</p>
|
||
<p>There are four different kinds of find specs, allowing you to query for
|
||
a single value, a collection of values from different entities, a single
|
||
tuple (relation), or a collection of tuples.</p>
|
||
<p>Examples:</p>
|
||
|
||
<pre class="rust rust-example-rendered">
|
||
|
||
|
||
<span class="kw">let</span> <span class="ident">elements</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[
|
||
<span class="ident">Element</span>::<span class="ident">Variable</span>(<span class="ident">Variable</span>::<span class="ident">from_valid_name</span>(<span class="string">"?foo"</span>)),
|
||
<span class="ident">Element</span>::<span class="ident">Variable</span>(<span class="ident">Variable</span>::<span class="ident">from_valid_name</span>(<span class="string">"?bar"</span>)),
|
||
];
|
||
<span class="kw">let</span> <span class="ident">rel</span> <span class="op">=</span> <span class="ident">FindSpec</span>::<span class="ident">FindRel</span>(<span class="ident">elements</span>);
|
||
|
||
<span class="kw">if</span> <span class="kw">let</span> <span class="ident">FindSpec</span>::<span class="ident">FindRel</span>(<span class="ident">elements</span>) <span class="op">=</span> <span class="ident">rel</span> {
|
||
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">elements</span>.<span class="ident">len</span>());
|
||
}
|
||
</pre>
|
||
</div><h2 id='variants' class='variants small-section-header'>
|
||
Variants<a href='#variants' class='anchor'></a></h2>
|
||
<span id="variant.FindRel" class="variant small-section-header"><a href="#variant.FindRel" class="anchor field"></a><span id='FindRel.v' class='invisible'><code>FindRel(<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>>)</code></span></span><div class='docblock'><p>Returns an array of arrays, represented as a single array with length a multiple of width.</p>
|
||
</div><span id="variant.FindColl" class="variant small-section-header"><a href="#variant.FindColl" class="anchor field"></a><span id='FindColl.v' class='invisible'><code>FindColl(<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>)</code></span></span><div class='docblock'><p>Returns an array of scalars, usually homogeneous.
|
||
This is equivalent to mapping over the results of a <code>FindRel</code>,
|
||
returning the first value of each.</p>
|
||
</div><span id="variant.FindTuple" class="variant small-section-header"><a href="#variant.FindTuple" class="anchor field"></a><span id='FindTuple.v' class='invisible'><code>FindTuple(<a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>>)</code></span></span><div class='docblock'><p>Returns a single tuple: a heterogeneous array of scalars. Equivalent to
|
||
taking the first result from a <code>FindRel</code>.</p>
|
||
</div><span id="variant.FindScalar" class="variant small-section-header"><a href="#variant.FindScalar" class="anchor field"></a><span id='FindScalar.v' class='invisible'><code>FindScalar(<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>)</code></span></span><div class='docblock'><p>Returns a single scalar value. Equivalent to taking the first result
|
||
from a <code>FindColl</code>.</p>
|
||
</div>
|
||
<h2 id='methods' class='small-section-header'>
|
||
Methods<a href='#methods' class='anchor'></a>
|
||
</h2>
|
||
<h3 id='impl' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#673-725' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='docblock'><p>Returns true if the provided <code>FindSpec</code> returns at most one result.</p>
|
||
</div><div class='impl-items'><h4 id='method.is_unit_limited' class="method"><span id='is_unit_limited.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.is_unit_limited' class='fnname'>is_unit_limited</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#674-682' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><h4 id='method.expected_column_count' class="method"><span id='expected_column_count.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.expected_column_count' class='fnname'>expected_column_count</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#684-691' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><h4 id='method.requires_distinct' class="method"><span id='requires_distinct.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.requires_distinct' class='fnname'>requires_distinct</a>(&self) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#712-714' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns true if the provided <code>FindSpec</code> cares about distinct results.</p>
|
||
<p>I use the words "cares about" because find is generally defined in terms of producing distinct
|
||
results at the Datalog level.</p>
|
||
<p>Two of the find specs (scalar and tuple) produce only a single result. Those don't need to be
|
||
run with <code>SELECT DISTINCT</code>, because we're only consuming a single result. Those queries will be
|
||
run with <code>LIMIT 1</code>.</p>
|
||
<p>Additionally, some projections cannot produce duplicate results: <code>[:find (max ?x) …]</code>, for
|
||
example.</p>
|
||
<p>This function gives us the hook to add that logic when we're ready.</p>
|
||
<p>Beyond this, <code>DISTINCT</code> is not always needed. For example, in some kinds of accumulation or
|
||
sampling projections we might not need to do it at the SQL level because we're consuming into
|
||
a dupe-eliminating data structure like a Set, or we know that a particular query cannot produce
|
||
duplicate results.</p>
|
||
</div><h4 id='method.columns' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><R></span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><R></h3><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><R> <span class="where fmt-newline">where<br> R: <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline">impl<W> <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><W> <span class="where fmt-newline">where<br> W: <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Write.html" title="trait std::io::Write">Write</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline">impl<I> <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><I> <span class="where fmt-newline">where<br> I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <I as <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a>>::<a class="type" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item" title="type core::iter::iterator::Iterator::Item">Item</a>;</span></code></div></div><span id='columns.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.columns' class='fnname'>columns</a><'s>(&'s self) -> <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/boxed/struct.Box.html" title="struct alloc::boxed::Box">Box</a><<a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a><Item = &<a class="enum" href="../../edn/query/enum.Element.html" title="enum edn::query::Element">Element</a>> + 's></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#716-724' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4></div>
|
||
<h2 id='implementations' class='small-section-header'>
|
||
Trait Implementations<a href='#implementations' class='anchor'></a>
|
||
</h2>
|
||
<div id='implementations-list'>
|
||
<h3 id='impl-Debug' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl-Debug' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, __arg_0: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
|
||
</div></div><h3 id='impl-Eq' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a> for <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl-Eq' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'></div><h3 id='impl-PartialEq' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a> for <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl-PartialEq' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.eq' class="method"><span id='eq.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq' class='fnname'>eq</a>(&self, __arg_0: &<a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a>) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>This method tests for <code>self</code> and <code>other</code> values to be equal, and is used by <code>==</code>. <a href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq">Read more</a></p>
|
||
</div><h4 id='method.ne' class="method"><span id='ne.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#method.ne' class='fnname'>ne</a>(&self, __arg_0: &<a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a>) -> <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/edn/query.rs.html#653' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>This method tests for <code>!=</code>.</p>
|
||
</div></div></div>
|
||
<h2 id='synthetic-implementations' class='small-section-header'>
|
||
Auto Trait Implementations<a href='#synthetic-implementations' class='anchor'></a>
|
||
</h2>
|
||
<div id='synthetic-implementations-list'>
|
||
<h3 id='impl-Send' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl !<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> for <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl-Send' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div><h3 id='impl-Sync' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl !<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a> for <a class="enum" href="../../edn/query/enum.FindSpec.html" title="enum edn::query::FindSpec">FindSpec</a></code><a href='#impl-Sync' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div></div></section>
|
||
<section id='search' class="content hidden"></section>
|
||
|
||
<section class="footer"></section>
|
||
|
||
<aside id="help" class="hidden">
|
||
<div>
|
||
<h1 class="hidden">Help</h1>
|
||
|
||
<div class="shortcuts">
|
||
<h2>Keyboard Shortcuts</h2>
|
||
|
||
<dl>
|
||
<dt><kbd>?</kbd></dt>
|
||
<dd>Show this help dialog</dd>
|
||
<dt><kbd>S</kbd></dt>
|
||
<dd>Focus the search field</dd>
|
||
<dt><kbd>↑</kbd></dt>
|
||
<dd>Move up in search results</dd>
|
||
<dt><kbd>↓</kbd></dt>
|
||
<dd>Move down in search results</dd>
|
||
<dt><kbd>↹</kbd></dt>
|
||
<dd>Switch tab</dd>
|
||
<dt><kbd>⏎</kbd></dt>
|
||
<dd>Go to active search result</dd>
|
||
<dt><kbd>+</kbd></dt>
|
||
<dd>Expand all sections</dd>
|
||
<dt><kbd>-</kbd></dt>
|
||
<dd>Collapse all sections</dd>
|
||
</dl>
|
||
</div>
|
||
|
||
<div class="infos">
|
||
<h2>Search Tricks</h2>
|
||
|
||
<p>
|
||
Prefix searches with a type followed by a colon (e.g.
|
||
<code>fn:</code>) to restrict the search to a given type.
|
||
</p>
|
||
|
||
<p>
|
||
Accepted types are: <code>fn</code>, <code>mod</code>,
|
||
<code>struct</code>, <code>enum</code>,
|
||
<code>trait</code>, <code>type</code>, <code>macro</code>,
|
||
and <code>const</code>.
|
||
</p>
|
||
|
||
<p>
|
||
Search functions by type signature (e.g.
|
||
<code>vec -> usize</code> or <code>* -> vec</code>)
|
||
</p>
|
||
</div>
|
||
</div>
|
||
</aside>
|
||
|
||
|
||
|
||
<script>
|
||
window.rootPath = "../../";
|
||
window.currentCrate = "edn";
|
||
</script>
|
||
<script src="../../main.js"></script>
|
||
<script defer src="../../search-index.js"></script>
|
||
</body>
|
||
</html> |