| #if FEATURE_COLLATION |
| using Icu.Collation; |
| using Lucene.Net.Collation.TokenAttributes; |
| using Lucene.Net.Util; |
| using System.Reflection; |
| |
| namespace Lucene.Net.Collation |
| { |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /// <summary> |
| /// <para> |
| /// Converts each token into its <see cref="System.Globalization.SortKey"/>, and then |
| /// encodes the bytes as an index term. |
| /// </para> |
| /// <para> |
| /// <strong>WARNING:</strong> Make sure you use exactly the same <see cref="Collator"/> at |
| /// index and query time -- <see cref="System.Globalization.SortKey"/>s are only comparable when produced by |
| /// the same <see cref="Collator"/>. Since <see cref="RuleBasedCollator"/>s are not |
| /// independently versioned, it is unsafe to search against stored |
| /// <see cref="System.Globalization.SortKey"/>s unless the following are exactly the same (best practice is |
| /// to store this information with the index and check that they remain the |
| /// same at query time): |
| /// </para> |
| /// <list type="number"> |
| /// <item><description>JVM vendor</description></item> |
| /// <item><description>JVM version, including patch version</description></item> |
| /// <item><description> |
| /// The language (and country and variant, if specified) of the Locale |
| /// used when constructing the collator via |
| /// <see cref="Collator.Create(System.Globalization.CultureInfo)"/>. |
| /// </description></item> |
| /// <item><description> |
| /// The collation strength used - see <see cref="Collator.Strength"/> |
| /// </description></item> |
| /// </list> |
| /// <para> |
| /// The <c>ICUCollationAttributeFactory</c> in the analysis-icu package |
| /// uses ICU4J's Collator, which makes its |
| /// version available, thus allowing collation to be versioned independently |
| /// from the JVM. ICUCollationAttributeFactory is also significantly faster and |
| /// generates significantly shorter keys than CollationAttributeFactory. See |
| /// <a href="http://site.icu-project.org/charts/collation-icu4j-sun" |
| /// >http://site.icu-project.org/charts/collation-icu4j-sun</a> for key |
| /// generation timing and key length comparisons between ICU4J and |
| /// <see cref="Collator"/> over several languages. |
| /// </para> |
| /// <para> |
| /// CollationKeys generated by java.text.Collators are not compatible |
| /// with those those generated by ICU Collators. Specifically, if you use |
| /// CollationAttributeFactory to generate index terms, do not use |
| /// ICUCollationAttributeFactory on the query side, or vice versa. |
| /// </para> |
| /// </summary> |
| public class CollationAttributeFactory : AttributeSource.AttributeFactory |
| { |
| private readonly Collator collator; |
| private readonly AttributeSource.AttributeFactory @delegate; |
| |
| /// <summary> |
| /// Create a <see cref="CollationAttributeFactory"/>, using |
| /// <see cref="AttributeSource.AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY"/> as the |
| /// factory for all other attributes. </summary> |
| /// <param name="collator"> <see cref="System.Globalization.SortKey"/> generator </param> |
| public CollationAttributeFactory(Collator collator) |
| : this(AttributeSource.AttributeFactory.DEFAULT_ATTRIBUTE_FACTORY, collator) |
| { |
| } |
| |
| /// <summary> |
| /// Create a <see cref="CollationAttributeFactory"/>, using the supplied Attribute Factory |
| /// as the factory for all other attributes. </summary> |
| /// <param name="delegate"> Attribute Factory </param> |
| /// <param name="collator"> <see cref="System.Globalization.SortKey"/> generator </param> |
| public CollationAttributeFactory(AttributeSource.AttributeFactory @delegate, Collator collator) |
| { |
| this.@delegate = @delegate; |
| this.collator = collator; |
| } |
| |
| public override Attribute CreateAttributeInstance<T>() |
| { |
| return typeof(T).IsAssignableFrom(typeof(CollatedTermAttributeImpl)) |
| ? new CollatedTermAttributeImpl(this.collator) |
| : this.@delegate.CreateAttributeInstance<T>(); |
| } |
| } |
| } |
| #endif |