com.hazelcast.org.apache.calcite.sql2rel.InitializerContext Maven / Gradle / Ivy
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* 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 com.hazelcast.org.apache.calcite.sql2rel;
import com.hazelcast.org.apache.calcite.rel.type.RelDataType;
import com.hazelcast.org.apache.calcite.rex.RexBuilder;
import com.hazelcast.org.apache.calcite.rex.RexNode;
import com.hazelcast.org.apache.calcite.sql.SqlNode;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParseException;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParser;
/**
* Provides context for {@link InitializerExpressionFactory} methods.
*/
public interface InitializerContext {
RexBuilder getRexBuilder();
/**
* Parse a column computation expression for a table. Usually this expression is declared
* in the create table statement, i.e.
*
* create table t(
* a int not null,
* b varchar(5) as (my_udf(a)) virtual,
* c int not null as (a + 1)
* );
*
*
* You can use the string format expression "my_udf(a)" and "a + 1"
* as the initializer expression of column b and c.
*
*
Calcite doesn't really need this now because the DDL nodes
* can be executed directly from {@code SqlNode}s, but we still provide the way
* to initialize from a SQL-like string, because a string can be used to persist easily and
* the column expressions are important part of the table metadata.
*
* @param config parse config
* @param expr the SQL-style column expression
* @return a {@code SqlNode} instance
*/
default SqlNode parseExpression(SqlParser.Config config, String expr) {
SqlParser parser = SqlParser.create(expr, config);
try {
return parser.parseExpression();
} catch (SqlParseException e) {
throw new RuntimeException("Failed to parse expression " + expr, e);
}
}
/**
* Validate the expression with a base table row type. The expression may reference the fields
* of the row type defines.
*
* @param rowType the table row type
* @param expr the expression
* @return a validated {@code SqlNode}, usually it transforms
* from a {@code SqlUnresolvedFunction} to a resolved one
*/
SqlNode validateExpression(RelDataType rowType, SqlNode expr);
/**
* Converts a {@code SqlNode} to {@code RexNode}.
*
*
Caution that the {@code SqlNode} must be validated,
* you can use {@link #validateExpression} to validate if the {@code SqlNode}
* is un-validated.
*
* @param expr the expression of sql node to convert
* @return a converted {@code RexNode} instance
*/
RexNode convertExpression(SqlNode expr);
}