datafusion_functions/datetime/
current_date.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;
19
20use arrow::datatypes::DataType;
21use arrow::datatypes::DataType::Date32;
22use chrono::{Datelike, NaiveDate};
23
24use datafusion_common::{internal_err, Result, ScalarValue};
25use datafusion_expr::simplify::{ExprSimplifyResult, SimplifyInfo};
26use datafusion_expr::{
27    ColumnarValue, Documentation, Expr, ScalarUDFImpl, Signature, Volatility,
28};
29use datafusion_macros::user_doc;
30
31#[user_doc(
32    doc_section(label = "Time and Date Functions"),
33    description = r#"
34Returns the current UTC date.
35
36The `current_date()` return value is determined at query time and will return the same date, no matter when in the query plan the function executes.
37"#,
38    syntax_example = "current_date()"
39)]
40#[derive(Debug)]
41pub struct CurrentDateFunc {
42    signature: Signature,
43    aliases: Vec<String>,
44}
45
46impl Default for CurrentDateFunc {
47    fn default() -> Self {
48        Self::new()
49    }
50}
51
52impl CurrentDateFunc {
53    pub fn new() -> Self {
54        Self {
55            signature: Signature::nullary(Volatility::Stable),
56            aliases: vec![String::from("today")],
57        }
58    }
59}
60
61/// Create an implementation of `current_date()` that always returns the
62/// specified current date.
63///
64/// The semantics of `current_date()` require it to return the same value
65/// wherever it appears within a single statement. This value is
66/// chosen during planning time.
67impl ScalarUDFImpl for CurrentDateFunc {
68    fn as_any(&self) -> &dyn Any {
69        self
70    }
71
72    fn name(&self) -> &str {
73        "current_date"
74    }
75
76    fn signature(&self) -> &Signature {
77        &self.signature
78    }
79
80    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
81        Ok(Date32)
82    }
83
84    fn invoke_with_args(
85        &self,
86        _args: datafusion_expr::ScalarFunctionArgs,
87    ) -> Result<ColumnarValue> {
88        internal_err!(
89            "invoke should not be called on a simplified current_date() function"
90        )
91    }
92
93    fn aliases(&self) -> &[String] {
94        &self.aliases
95    }
96
97    fn simplify(
98        &self,
99        _args: Vec<Expr>,
100        info: &dyn SimplifyInfo,
101    ) -> Result<ExprSimplifyResult> {
102        let now_ts = info.execution_props().query_execution_start_time;
103        let days = Some(
104            now_ts.num_days_from_ce()
105                - NaiveDate::from_ymd_opt(1970, 1, 1)
106                    .unwrap()
107                    .num_days_from_ce(),
108        );
109        Ok(ExprSimplifyResult::Simplified(Expr::Literal(
110            ScalarValue::Date32(days),
111        )))
112    }
113
114    fn documentation(&self) -> Option<&Documentation> {
115        self.doc()
116    }
117}
datafusion_functions/datetime/current_date.rs

datafusion_functions/datetime/
current_date.rs
