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17 | 17 |
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18 | 18 | //! Built-in functions module contains all the built-in functions definitions.
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19 | 19 |
|
20 |
| -use std::fmt; |
21 |
| -use std::str::FromStr; |
22 |
| - |
23 |
| -use crate::type_coercion::functions::data_types; |
24 |
| -use crate::utils; |
25 |
| -use crate::{Signature, Volatility}; |
26 |
| -use datafusion_common::{plan_datafusion_err, plan_err, DataFusionError, Result}; |
27 |
| - |
28 |
| -use arrow::datatypes::DataType; |
29 |
| - |
30 | 20 | use strum_macros::EnumIter;
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31 | 21 |
|
32 |
| -impl fmt::Display for BuiltInWindowFunction { |
33 |
| - fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
34 |
| - write!(f, "{}", self.name()) |
35 |
| - } |
36 |
| -} |
37 |
| - |
38 | 22 | /// A [window function] built in to DataFusion
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39 | 23 | ///
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40 | 24 | /// [Window Function]: https://en.wikipedia.org/wiki/Window_function_(SQL)
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41 | 25 | #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Hash, EnumIter)]
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42 | 26 | pub enum BuiltInWindowFunction {
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43 |
| - /// returns value evaluated at the row that is the first row of the window frame |
44 |
| - FirstValue, |
45 |
| - /// Returns value evaluated at the row that is the last row of the window frame |
46 |
| - LastValue, |
47 |
| - /// Returns value evaluated at the row that is the nth row of the window frame (counting from 1); returns null if no such row |
48 |
| - NthValue, |
49 |
| -} |
50 |
| - |
51 |
| -impl BuiltInWindowFunction { |
52 |
| - pub fn name(&self) -> &str { |
53 |
| - use BuiltInWindowFunction::*; |
54 |
| - match self { |
55 |
| - FirstValue => "first_value", |
56 |
| - LastValue => "last_value", |
57 |
| - NthValue => "NTH_VALUE", |
58 |
| - } |
59 |
| - } |
60 |
| -} |
61 |
| - |
62 |
| -impl FromStr for BuiltInWindowFunction { |
63 |
| - type Err = DataFusionError; |
64 |
| - fn from_str(name: &str) -> Result<BuiltInWindowFunction> { |
65 |
| - Ok(match name.to_uppercase().as_str() { |
66 |
| - "FIRST_VALUE" => BuiltInWindowFunction::FirstValue, |
67 |
| - "LAST_VALUE" => BuiltInWindowFunction::LastValue, |
68 |
| - "NTH_VALUE" => BuiltInWindowFunction::NthValue, |
69 |
| - _ => return plan_err!("There is no built-in window function named {name}"), |
70 |
| - }) |
71 |
| - } |
72 |
| -} |
73 |
| - |
74 |
| -/// Returns the datatype of the built-in window function |
75 |
| -impl BuiltInWindowFunction { |
76 |
| - pub fn return_type(&self, input_expr_types: &[DataType]) -> Result<DataType> { |
77 |
| - // Note that this function *must* return the same type that the respective physical expression returns |
78 |
| - // or the execution panics. |
79 |
| - |
80 |
| - // Verify that this is a valid set of data types for this function |
81 |
| - data_types(input_expr_types, &self.signature()) |
82 |
| - // Original errors are all related to wrong function signature |
83 |
| - // Aggregate them for better error message |
84 |
| - .map_err(|_| { |
85 |
| - plan_datafusion_err!( |
86 |
| - "{}", |
87 |
| - utils::generate_signature_error_msg( |
88 |
| - &format!("{self}"), |
89 |
| - self.signature(), |
90 |
| - input_expr_types, |
91 |
| - ) |
92 |
| - ) |
93 |
| - })?; |
94 |
| - |
95 |
| - match self { |
96 |
| - BuiltInWindowFunction::FirstValue |
97 |
| - | BuiltInWindowFunction::LastValue |
98 |
| - | BuiltInWindowFunction::NthValue => Ok(input_expr_types[0].clone()), |
99 |
| - } |
100 |
| - } |
101 |
| - |
102 |
| - /// The signatures supported by the built-in window function `fun`. |
103 |
| - pub fn signature(&self) -> Signature { |
104 |
| - // Note: The physical expression must accept the type returned by this function or the execution panics. |
105 |
| - match self { |
106 |
| - BuiltInWindowFunction::FirstValue | BuiltInWindowFunction::LastValue => { |
107 |
| - Signature::any(1, Volatility::Immutable) |
108 |
| - } |
109 |
| - BuiltInWindowFunction::NthValue => Signature::any(2, Volatility::Immutable), |
110 |
| - } |
111 |
| - } |
112 |
| -} |
113 |
| - |
114 |
| -#[cfg(test)] |
115 |
| -mod tests { |
116 |
| - use super::*; |
117 |
| - use strum::IntoEnumIterator; |
118 |
| - #[test] |
119 |
| - // Test for BuiltInWindowFunction's Display and from_str() implementations. |
120 |
| - // For each variant in BuiltInWindowFunction, it converts the variant to a string |
121 |
| - // and then back to a variant. The test asserts that the original variant and |
122 |
| - // the reconstructed variant are the same. This assertion is also necessary for |
123 |
| - // function suggestion. See https://github.com/apache/datafusion/issues/8082 |
124 |
| - fn test_display_and_from_str() { |
125 |
| - for func_original in BuiltInWindowFunction::iter() { |
126 |
| - let func_name = func_original.to_string(); |
127 |
| - let func_from_str = BuiltInWindowFunction::from_str(&func_name).unwrap(); |
128 |
| - assert_eq!(func_from_str, func_original); |
129 |
| - } |
130 |
| - } |
| 27 | + Stub, |
131 | 28 | }
|
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