stefankandic commented on code in PR #44968: URL: https://github.com/apache/spark/pull/44968#discussion_r1474830118
########## common/unsafe/src/main/java/org/apache/spark/sql/catalyst/util/CollationFactory.java: ########## @@ -0,0 +1,171 @@ +/* + * 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. + */ +package org.apache.spark.sql.catalyst.util; + +import java.util.*; +import java.util.function.BiFunction; +import java.util.function.ToLongFunction; + +import com.ibm.icu.util.ULocale; +import com.ibm.icu.text.Collator; + +import org.apache.spark.SparkException; +import org.apache.spark.unsafe.types.UTF8String; + +/** + * Static entry point for collation aware string functions. + * Provides functionality to the UTF8String object which respects defined collation settings. + */ +public final class CollationFactory { + /** + * Entry encapsulating all information about a collation. + */ + public static class Collation { + public final String collationName; + public final Collator collator; + public final Comparator<UTF8String> comparator; + + /** + * Version of the collation. This is the version of the ICU library used to create the collator. + * For non-ICU collations (e.g. UTF8 Binary) the version is set to "1.0". + */ + public final String version; + + /** + * Collation sensitive hash function. Output for two UTF8Strings will be the same if they are + * equal according to the collation. + */ + public final ToLongFunction<UTF8String> hashFunction; + + /** + * Potentially faster way than using comparator to compare two UTF8Strings for equality. + * Falls back to binary comparison if the collation is binary. + */ + public final BiFunction<UTF8String, UTF8String, Boolean> equalsFunction; + + /** + * Binary collation implies that UTF8Strings are considered equal only if they are + * byte for byte equal. All accent or case-insensitive collations are considered non-binary. + */ + public final boolean isBinaryCollation; + + public Collation( + String collationName, + Collator collator, + Comparator<UTF8String> comparator, + String version, + ToLongFunction<UTF8String> hashFunction, + boolean isBinaryCollation) { + this.collationName = collationName; + this.collator = collator; + this.comparator = comparator; + this.version = version; + this.hashFunction = hashFunction; + this.isBinaryCollation = isBinaryCollation; + + if (isBinaryCollation) { + this.equalsFunction = UTF8String::equals; + } else { + this.equalsFunction = (s1, s2) -> this.comparator.compare(s1, s2) == 0; + } + } + + /** + * Constructor with comparators that are inherited from the given collator. + */ + public Collation( + String collationName, Collator collator, String version, boolean isBinaryCollation) { + this( + collationName, + collator, + (s1, s2) -> collator.compare(s1.toString(), s2.toString()), + version, + s -> (long)collator.getCollationKey(s.toString()).hashCode(), + isBinaryCollation); + } + } + + private final Collation[] collatorTable; + private final HashMap<String, Integer> collationNameToIdMap = new HashMap<>(); + + private CollationFactory() { + collatorTable = new Collation[4]; + + // Binary comparison. This is the default collation. + // No custom comparators will be used for this collation. + // Instead, we rely on byte for byte comparison. + collatorTable[0] = new Collation( + "UCS_BASIC", + null, + UTF8String::compareTo, + "1.0", + s -> (long)s.hashCode(), + true); + + // Case-insensitive UTF8 binary collation. + // TODO: Do in place comparisons instead of creating new strings. + collatorTable[1] = new Collation( + "UCS_BASIC_LCASE", + null, + Comparator.comparing(UTF8String::toLowerCase), "1.0", + (s) -> (long)s.toLowerCase().hashCode(), + false); + + // UNICODE case sensitive comparison (ROOT locale, in ICU). + collatorTable[2] = new Collation( + "UNICODE", Collator.getInstance(ULocale.ROOT), "153.120.0.0", true); + collatorTable[2].collator.setStrength(Collator.TERTIARY); + + + // UNICODE case-insensitive comparison (ROOT locale, in ICU + Secondary strength). + collatorTable[3] = new Collation( + "UNICODE_CI", Collator.getInstance(ULocale.ROOT), "153.120.0.0", false); + collatorTable[3].collator.setStrength(Collator.SECONDARY); + + for (int i = 0; i < collatorTable.length; i++) { + this.collationNameToIdMap.put(collatorTable[i].collationName, i); + } + } + + private static final CollationFactory instance = new CollationFactory(); + + /** + * Returns the collation id for the given collation name. + */ + public int collationNameToId(String collationName) throws SparkException { + String normalizedName = collationName.toUpperCase(); + if (collationNameToIdMap.containsKey(normalizedName)) { + return collationNameToIdMap.get(normalizedName); + } else { + throw new SparkException( + "COLLATION_INVALID_NAME", Collections.singletonMap("collationName", collationName)); + } + } + + public Collation fetchCollationInfo(int collationId) { Review Comment: maybe refactor the names of these two methods as well if to match the new class name -- This is an automated message from the Apache Git Service. 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