danny0405 commented on a change in pull request #1181: [CALCITE-3016] Add sql dialect table operator factory to support all … URL: https://github.com/apache/calcite/pull/1181#discussion_r278395006
########## File path: core/src/main/java/org/apache/calcite/sql/fun/SqlDialectOperatorTableFactory.java ########## @@ -0,0 +1,247 @@ +/* + * 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.calcite.sql.fun; + +import org.apache.calcite.rel.type.RelDataType; +import org.apache.calcite.rel.type.RelDataTypeFactory; +import org.apache.calcite.sql.SqlFunction; +import org.apache.calcite.sql.SqlFunctionCategory; +import org.apache.calcite.sql.SqlIdentifier; +import org.apache.calcite.sql.SqlKind; +import org.apache.calcite.sql.SqlOperator; +import org.apache.calcite.sql.SqlOperatorTable; +import org.apache.calcite.sql.SqlSyntax; +import org.apache.calcite.sql.type.OperandTypes; +import org.apache.calcite.sql.type.ReturnTypes; +import org.apache.calcite.sql.type.SqlReturnTypeInference; +import org.apache.calcite.sql.type.SqlTypeTransforms; +import org.apache.calcite.sql.util.ListSqlOperatorTable; +import org.apache.calcite.sql.validate.SqlNameMatcher; +import org.apache.calcite.util.Util; + +import com.google.common.base.Preconditions; + +import java.lang.reflect.Field; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +import static org.apache.calcite.sql.fun.SqlDialect.Dialect; + +/** + * Operator table factory for multiple sql dialects. You can use method + * {@link #getOperatorTable} to fetch dialect specific operator table. + * + * <p>If you want to extend the sql dialect, add the sql dialect in {@link SqlDialect}, + * if the sql dialect already exists, and you want to add a sql function, annotate the function + * with the specific sql dialects that function belongs. + */ +public class SqlDialectOperatorTableFactory { + + //~ Instance fields -------------------------------------------------------- + + // The singleton SqlDialectOperatorTableFactory instance. + private static SqlDialectOperatorTableFactory instance = null; + + // Flag to indicate if this operator table has been initialized. + private boolean initialized = false; + + // A container holding the operators for all the sql dialects. + private final Map<Dialect, ListSqlOperatorTable> dialectSqlOperatorTableMapping = + new HashMap<>(); + + /** Return type inference for {@code DECODE}. */ + protected static final SqlReturnTypeInference DECODE_RETURN_TYPE = + opBinding -> { + final List<RelDataType> list = new ArrayList<>(); + for (int i = 1, n = opBinding.getOperandCount(); i < n; i++) { + if (i < n - 1) { + ++i; + } + list.add(opBinding.getOperandType(i)); + } + final RelDataTypeFactory typeFactory = opBinding.getTypeFactory(); + RelDataType type = typeFactory.leastRestrictive(list); + if (opBinding.getOperandCount() % 2 == 1) { + type = typeFactory.createTypeWithNullability(type, true); + } + return type; + }; + + /** The "DECODE(v, v1, result1, [v2, result2, ...], resultN)" function. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction DECODE = + new SqlFunction("DECODE", SqlKind.DECODE, DECODE_RETURN_TYPE, null, + OperandTypes.VARIADIC, SqlFunctionCategory.SYSTEM); + + /** The "NVL(value, value)" function. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction NVL = + new SqlFunction("NVL", SqlKind.NVL, + ReturnTypes.cascade(ReturnTypes.LEAST_RESTRICTIVE, + SqlTypeTransforms.TO_NULLABLE_ALL), + null, OperandTypes.SAME_SAME, SqlFunctionCategory.SYSTEM); + + /** The "LTRIM(string)" function. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction LTRIM = + new SqlFunction("LTRIM", SqlKind.LTRIM, + ReturnTypes.cascade(ReturnTypes.ARG0, SqlTypeTransforms.TO_NULLABLE, + SqlTypeTransforms.TO_VARYING), null, + OperandTypes.STRING, SqlFunctionCategory.STRING); + + /** The "RTRIM(string)" function. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction RTRIM = + new SqlFunction("RTRIM", SqlKind.RTRIM, + ReturnTypes.cascade(ReturnTypes.ARG0, SqlTypeTransforms.TO_NULLABLE, + SqlTypeTransforms.TO_VARYING), null, + OperandTypes.STRING, SqlFunctionCategory.STRING); + + /** Oracle's "SUBSTR(string, position [, substringLength ])" function. + * + * <p>It has similar semantics to standard SQL's + * {@link SqlStdOperatorTable#SUBSTRING} function but different syntax. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction SUBSTR = + new SqlFunction("SUBSTR", SqlKind.OTHER_FUNCTION, + ReturnTypes.ARG0_NULLABLE_VARYING, null, null, + SqlFunctionCategory.STRING); + + /** The "GREATEST(value, value)" function. */ + @SqlDialect(dialects = {Dialect.ORACLE}) + public static final SqlFunction GREATEST = + new SqlFunction("GREATEST", SqlKind.GREATEST, + ReturnTypes.cascade(ReturnTypes.LEAST_RESTRICTIVE, + SqlTypeTransforms.TO_NULLABLE), null, + OperandTypes.SAME_VARIADIC, SqlFunctionCategory.SYSTEM); + Review comment: Then i think we should keep a different field name for them, after all, these two sql function should never be put into one sql parse context ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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