1 // Licensed to the Apache Software Foundation (ASF) under one 2 // or more contributor license agreements. See the NOTICE file 3 // distributed with this work for additional information 4 // regarding copyright ownership. The ASF licenses this file 5 // to you under the Apache License, Version 2.0 (the 6 // "License"); you may not use this file except in compliance 7 // with the License. You may obtain a copy of the License at 8 // 9 // http://www.apache.org/licenses/LICENSE-2.0 10 // 11 // Unless required by applicable law or agreed to in writing, 12 // software distributed under the License is distributed on an 13 // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 14 // KIND, either express or implied. See the License for the 15 // specific language governing permissions and limitations 16 // under the License. 17 18 //! Variable provider 19 20 use crate::error::Result; 21 use crate::scalar::ScalarValue; 22 23 /// Variable type, system/user defined 24 #[derive(Debug, Clone, PartialEq, Eq, Hash)] 25 pub enum VarType { 26 /// System variable, like @@version 27 System, 28 /// User defined variable, like @name 29 UserDefined, 30 } 31 32 /// A var provider for @variable 33 pub trait VarProvider { 34 /// Get variable value get_value(&self, var_names: Vec<String>) -> Result<ScalarValue>35 fn get_value(&self, var_names: Vec<String>) -> Result<ScalarValue>; 36 } 37