/Users/andrewlamb/Software/datafusion/datafusion/expr/src/var_provider.rs
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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 arrow::datatypes::DataType; |
21 | | use datafusion_common::{Result, 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` and `@@variable` runtime values. |
33 | | pub trait VarProvider: std::fmt::Debug { |
34 | | /// Get variable value |
35 | | fn get_value(&self, var_names: Vec<String>) -> Result<ScalarValue>; |
36 | | |
37 | | /// Return the type of the given variable |
38 | | fn get_type(&self, var_names: &[String]) -> Option<DataType>; |
39 | | } |
40 | | |
41 | 0 | pub fn is_system_variables(variable_names: &[String]) -> bool { |
42 | 0 | !variable_names.is_empty() && variable_names[0].get(0..2) == Some("@@") |
43 | 0 | } |
44 | | |
45 | | #[cfg(test)] |
46 | | mod test { |
47 | | use super::*; |
48 | | |
49 | | #[test] |
50 | | fn test_is_system_variables() { |
51 | | assert!(!is_system_variables(&["N".into(), "\"\"".into()])); |
52 | | assert!(is_system_variables(&["@@D".into(), "F".into(), "J".into()])); |
53 | | assert!(!is_system_variables(&[ |
54 | | "J".into(), |
55 | | "@@F".into(), |
56 | | "K".into() |
57 | | ])); |
58 | | assert!(!is_system_variables(&[])); |
59 | | assert!(is_system_variables(&[ |
60 | | "@@longvariablenamethatIdontknowhwyanyonewoulduse".into() |
61 | | ])); |
62 | | assert!(!is_system_variables(&["@F".into()])); |
63 | | } |
64 | | } |