| /* |
| * 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; |
| |
| import org.apache.calcite.adapter.java.JavaTypeFactory; |
| import org.apache.calcite.linq4j.QueryProvider; |
| import org.apache.calcite.linq4j.tree.Expressions; |
| import org.apache.calcite.linq4j.tree.ParameterExpression; |
| import org.apache.calcite.schema.SchemaPlus; |
| import org.apache.calcite.sql.advise.SqlAdvisor; |
| |
| import com.google.common.base.CaseFormat; |
| |
| import java.lang.reflect.Modifier; |
| import java.util.TimeZone; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * Runtime context allowing access to the tables in a database. |
| */ |
| public interface DataContext { |
| ParameterExpression ROOT = |
| Expressions.parameter(Modifier.FINAL, DataContext.class, "root"); |
| |
| /** |
| * Returns a sub-schema with a given name, or null. |
| */ |
| SchemaPlus getRootSchema(); |
| |
| /** |
| * Returns the type factory. |
| */ |
| JavaTypeFactory getTypeFactory(); |
| |
| /** |
| * Returns the query provider. |
| */ |
| QueryProvider getQueryProvider(); |
| |
| /** |
| * Returns a context variable. |
| * |
| * <p>Supported variables include: "sparkContext", "currentTimestamp", |
| * "localTimestamp".</p> |
| * |
| * @param name Name of variable |
| */ |
| Object get(String name); |
| |
| /** Variable that may be asked for in a call to {@link DataContext#get}. */ |
| enum Variable { |
| UTC_TIMESTAMP("utcTimestamp", Long.class), |
| |
| /** The time at which the current statement started executing. In |
| * milliseconds after 1970-01-01 00:00:00, UTC. Required. */ |
| CURRENT_TIMESTAMP("currentTimestamp", Long.class), |
| |
| /** The time at which the current statement started executing. In |
| * milliseconds after 1970-01-01 00:00:00, in the time zone of the current |
| * statement. Required. */ |
| LOCAL_TIMESTAMP("localTimestamp", Long.class), |
| |
| /** The Spark engine. Available if Spark is on the class path. */ |
| SPARK_CONTEXT("sparkContext", Object.class), |
| |
| /** A mutable flag that indicates whether user has requested that the |
| * current statement be canceled. Cancellation may not be immediate, but |
| * implementations of relational operators should check the flag fairly |
| * frequently and cease execution (e.g. by returning end of data). */ |
| CANCEL_FLAG("cancelFlag", AtomicBoolean.class), |
| |
| /** Advisor that suggests completion hints for SQL statements. */ |
| SQL_ADVISOR("sqlAdvisor", SqlAdvisor.class), |
| |
| /** Time zone in which the current statement is executing. Required; |
| * defaults to the time zone of the JVM if the connection does not specify a |
| * time zone. */ |
| TIME_ZONE("timeZone", TimeZone.class); |
| |
| public final String camelName; |
| public final Class clazz; |
| |
| Variable(String camelName, Class clazz) { |
| this.camelName = camelName; |
| this.clazz = clazz; |
| assert camelName.equals( |
| CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, name())); |
| } |
| |
| /** Returns the value of this variable in a given data context. */ |
| public <T> T get(DataContext dataContext) { |
| //noinspection unchecked |
| return (T) clazz.cast(dataContext.get(camelName)); |
| } |
| } |
| } |
| |
| // End DataContext.java |