spark VariableSubstitution 源码
spark VariableSubstitution 代码
文件路径：/sql/core/src/main/scala/org/apache/spark/sql/internal/VariableSubstitution.scala
/*
* 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.internal
import org.apache.spark.internal.config._
import org.apache.spark.sql.catalyst.SQLConfHelper
/**
* A helper class that enables substitution using syntax like
* `${var}`, `${system:var}` and `${env:var}`.
*
* Variable substitution is controlled by `SQLConf.variableSubstituteEnabled`.
*/
class VariableSubstitution extends SQLConfHelper {
private val provider = new ConfigProvider {
override def get(key: String): Option[String] = Option(conf.getConfString(key, ""))
}
private val reader = new ConfigReader(provider)
.bind("spark", provider)
.bind("sparkconf", provider)
.bind("hivevar", provider)
.bind("hiveconf", provider)
/**
* Given a query, does variable substitution and return the result.
*/
def substitute(input: String): String = {
if (conf.variableSubstituteEnabled) {
reader.substitute(input)
} else {
input
}
}
}
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