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| <h1 id="Lucene_Net_Expressions" data-uid="Lucene.Net.Expressions" class="text-break">Namespace Lucene.Net.Expressions |
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| <h1 id="the-expressions-module-for-apache-lucene">The Expressions Module for Apache Lucene</h1> |
| <p> The expressions module is new to Lucene 4.6. It provides an API for dynamically computing per-document values based on string expressions. </p> |
| <p> The module is organized in two sections: 1. <a class="xref" href="Lucene.Net.Expressions.html">Lucene.Net.Expressions</a> - The abstractions and simple utilities for common operations like sorting on an expression 2. <xref:Lucene.Net.Expressions.Js> - A compiler for a subset of JavaScript expressions </p> |
| <p> For sample code showing how to use the API, see <a class="xref" href="Lucene.Net.Expressions.Expression.html">Expression</a>. </p> |
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| <div class="markdown level0 conceptual"></div> |
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| <h3 id="classes">Classes |
| </h3> |
| <h4><a class="xref" href="Lucene.Net.Expressions.Bindings.html">Bindings</a></h4> |
| <section><p>Binds variable names in expressions to actual data.</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Expressions.Expression.html">Expression</a></h4> |
| <section><p>Base class that computes the value of an expression for a document.</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Expressions.SimpleBindings.html">SimpleBindings</a></h4> |
| <section><p>Simple class that binds expression variable names to |
| <a class="xref" href="../Lucene.Net/Lucene.Net.Search.SortField.html">SortField</a>s or other |
| <a class="xref" href="Lucene.Net.Expressions.Expression.html">Expression</a>s. |
| <p> |
| Example usage:</p> |
| <pre><code>SimpleBindings bindings = new SimpleBindings(); |
| // document's text relevance score |
| bindings.Add(new SortField("_score", SortFieldType.SCORE)); |
| // integer NumericDocValues field (or from FieldCache) |
| bindings.Add(new SortField("popularity", SortFieldType.INT)); |
| // another expression |
| bindings.Add("recency", myRecencyExpression); |
| // create a sort field in reverse order |
| Sort sort = new Sort(expr.GetSortField(bindings, true));</code></pre> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></section> |
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