datafusion_functions/math/
iszero.rs

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
18use std::any::Any;
19use std::sync::Arc;
20
21use arrow::array::{ArrayRef, AsArray, BooleanArray};
22use arrow::datatypes::DataType::{Boolean, Float32, Float64};
23use arrow::datatypes::{DataType, Float32Type, Float64Type};
24
25use datafusion_common::{exec_err, Result};
26use datafusion_expr::TypeSignature::Exact;
27use datafusion_expr::{
28    ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature,
29    Volatility,
30};
31use datafusion_macros::user_doc;
32
33use crate::utils::make_scalar_function;
34
35#[user_doc(
36    doc_section(label = "Math Functions"),
37    description = "Returns true if a given number is +0.0 or -0.0 otherwise returns false.",
38    syntax_example = "iszero(numeric_expression)",
39    sql_example = r#"```sql
40> SELECT iszero(0);
41+------------+
42| iszero(0)  |
43+------------+
44| true       |
45+------------+
46```"#,
47    standard_argument(name = "numeric_expression", prefix = "Numeric")
48)]
49#[derive(Debug, PartialEq, Eq, Hash)]
50pub struct IsZeroFunc {
51    signature: Signature,
52}
53
54impl Default for IsZeroFunc {
55    fn default() -> Self {
56        IsZeroFunc::new()
57    }
58}
59
60impl IsZeroFunc {
61    pub fn new() -> Self {
62        use DataType::*;
63        Self {
64            signature: Signature::one_of(
65                vec![Exact(vec![Float32]), Exact(vec![Float64])],
66                Volatility::Immutable,
67            ),
68        }
69    }
70}
71
72impl ScalarUDFImpl for IsZeroFunc {
73    fn as_any(&self) -> &dyn Any {
74        self
75    }
76
77    fn name(&self) -> &str {
78        "iszero"
79    }
80
81    fn signature(&self) -> &Signature {
82        &self.signature
83    }
84
85    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
86        Ok(Boolean)
87    }
88
89    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
90        make_scalar_function(iszero, vec![])(&args.args)
91    }
92
93    fn documentation(&self) -> Option<&Documentation> {
94        self.doc()
95    }
96}
97
98/// Iszero SQL function
99pub fn iszero(args: &[ArrayRef]) -> Result<ArrayRef> {
100    match args[0].data_type() {
101        Float64 => Ok(Arc::new(BooleanArray::from_unary(
102            args[0].as_primitive::<Float64Type>(),
103            |x| x == 0.0,
104        )) as ArrayRef),
105
106        Float32 => Ok(Arc::new(BooleanArray::from_unary(
107            args[0].as_primitive::<Float32Type>(),
108            |x| x == 0.0,
109        )) as ArrayRef),
110
111        other => exec_err!("Unsupported data type {other:?} for function iszero"),
112    }
113}
114
115#[cfg(test)]
116mod test {
117    use std::sync::Arc;
118
119    use arrow::array::{ArrayRef, Float32Array, Float64Array};
120
121    use datafusion_common::cast::as_boolean_array;
122
123    use crate::math::iszero::iszero;
124
125    #[test]
126    fn test_iszero_f64() {
127        let args: Vec<ArrayRef> =
128            vec![Arc::new(Float64Array::from(vec![1.0, 0.0, 3.0, -0.0]))];
129
130        let result = iszero(&args).expect("failed to initialize function iszero");
131        let booleans =
132            as_boolean_array(&result).expect("failed to initialize function iszero");
133
134        assert_eq!(booleans.len(), 4);
135        assert!(!booleans.value(0));
136        assert!(booleans.value(1));
137        assert!(!booleans.value(2));
138        assert!(booleans.value(3));
139    }
140
141    #[test]
142    fn test_iszero_f32() {
143        let args: Vec<ArrayRef> =
144            vec![Arc::new(Float32Array::from(vec![1.0, 0.0, 3.0, -0.0]))];
145
146        let result = iszero(&args).expect("failed to initialize function iszero");
147        let booleans =
148            as_boolean_array(&result).expect("failed to initialize function iszero");
149
150        assert_eq!(booleans.len(), 4);
151        assert!(!booleans.value(0));
152        assert!(booleans.value(1));
153        assert!(!booleans.value(2));
154        assert!(booleans.value(3));
155    }
156}
datafusion_functions/math/iszero.rs

datafusion_functions/math/
iszero.rs
