datafusion_functions/math/

abs.rs

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! math expressions

use std::sync::Arc;

use arrow::array::{
    ArrayRef, Decimal32Array, Decimal64Array, Decimal128Array, Decimal256Array,
    Float16Array, Float32Array, Float64Array, Int8Array, Int16Array, Int32Array,
    Int64Array,
};
use arrow::datatypes::DataType;
use arrow::error::ArrowError;
use datafusion_common::{Result, not_impl_err, utils::take_function_args};
use datafusion_expr::interval_arithmetic::Interval;
use datafusion_expr::sort_properties::{ExprProperties, SortProperties};
use datafusion_expr::{
    ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature,
    Volatility,
};
use datafusion_macros::user_doc;
use num_traits::sign::Signed;

type MathArrayFunction = fn(&ArrayRef) -> Result<ArrayRef>;

#[macro_export]
macro_rules! make_abs_function {
    ($ARRAY_TYPE:ident) => {{
        |input: &ArrayRef| {
            let array = downcast_named_arg!(&input, "abs arg", $ARRAY_TYPE);
            let res: $ARRAY_TYPE = array.unary(|x| x.abs());
            Ok(Arc::new(res) as ArrayRef)
        }
    }};
}

#[macro_export]
macro_rules! make_try_abs_function {
    ($ARRAY_TYPE:ident) => {{
        |input: &ArrayRef| {
            let array = downcast_named_arg!(&input, "abs arg", $ARRAY_TYPE);
            let res: $ARRAY_TYPE = array.try_unary(|x| {
                x.checked_abs().ok_or_else(|| {
                    ArrowError::ComputeError(format!(
                        "{} overflow on abs({})",
                        stringify!($ARRAY_TYPE),
                        x
                    ))
                })
            })
            .and_then(|v| Ok(v.with_data_type(input.data_type().clone())))?; // maintain decimal's precision and scale
            Ok(Arc::new(res) as ArrayRef)
        }
    }};
}

#[macro_export]
macro_rules! make_wrapping_abs_function {
    ($ARRAY_TYPE:ident) => {{
        |input: &ArrayRef| {
            let array = downcast_named_arg!(&input, "abs arg", $ARRAY_TYPE);
            let res: $ARRAY_TYPE = array
                .unary(|x| x.wrapping_abs())
                .with_data_type(input.data_type().clone());
            Ok(Arc::new(res) as ArrayRef)
        }
    }};
}

/// Abs SQL function
/// Return different implementations based on input datatype to reduce branches during execution
fn create_abs_function(input_data_type: &DataType) -> Result<MathArrayFunction> {
    match input_data_type {
        DataType::Float16 => Ok(make_abs_function!(Float16Array)),
        DataType::Float32 => Ok(make_abs_function!(Float32Array)),
        DataType::Float64 => Ok(make_abs_function!(Float64Array)),

        // Types that may overflow, such as abs(-128_i8).
        DataType::Int8 => Ok(make_try_abs_function!(Int8Array)),
        DataType::Int16 => Ok(make_try_abs_function!(Int16Array)),
        DataType::Int32 => Ok(make_try_abs_function!(Int32Array)),
        DataType::Int64 => Ok(make_try_abs_function!(Int64Array)),

        // Types of results are the same as the input.
        DataType::Null
        | DataType::UInt8
        | DataType::UInt16
        | DataType::UInt32
        | DataType::UInt64 => Ok(|input: &ArrayRef| Ok(Arc::clone(input))),

        // Decimal types
        DataType::Decimal32(_, _) => Ok(make_wrapping_abs_function!(Decimal32Array)),
        DataType::Decimal64(_, _) => Ok(make_wrapping_abs_function!(Decimal64Array)),
        DataType::Decimal128(_, _) => Ok(make_wrapping_abs_function!(Decimal128Array)),
        DataType::Decimal256(_, _) => Ok(make_wrapping_abs_function!(Decimal256Array)),

        other => not_impl_err!("Unsupported data type {other:?} for function abs"),
    }
}
#[user_doc(
    doc_section(label = "Math Functions"),
    description = "Returns the absolute value of a number.",
    syntax_example = "abs(numeric_expression)",
    sql_example = r#"```sql
> SELECT abs(-5);
+----------+
| abs(-5)  |
+----------+
| 5        |
+----------+
```"#,
    standard_argument(name = "numeric_expression", prefix = "Numeric")
)]
#[derive(Debug, PartialEq, Eq, Hash)]
pub struct AbsFunc {
    signature: Signature,
}

impl Default for AbsFunc {
    fn default() -> Self {
        Self::new()
    }
}

impl AbsFunc {
    pub fn new() -> Self {
        Self {
            signature: Signature::numeric(1, Volatility::Immutable),
        }
    }
}

impl ScalarUDFImpl for AbsFunc {
    fn name(&self) -> &str {
        "abs"
    }

    fn signature(&self) -> &Signature {
        &self.signature
    }

    fn return_type(&self, arg_types: &[DataType]) -> Result<DataType> {
        Ok(arg_types[0].clone())
    }

    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
        let args = ColumnarValue::values_to_arrays(&args.args)?;
        let [input] = take_function_args(self.name(), args)?;

        let input_data_type = input.data_type();
        let abs_fun = create_abs_function(input_data_type)?;

        abs_fun(&input).map(ColumnarValue::Array)
    }

    fn output_ordering(&self, input: &[ExprProperties]) -> Result<SortProperties> {
        // Non-decreasing for x ≥ 0 and symmetrically non-increasing for x ≤ 0.
        let arg = &input[0];
        let range = &arg.range;
        let zero_point = Interval::make_zero(&range.lower().data_type())?;

        if range.gt_eq(&zero_point)? == Interval::TRUE {
            Ok(arg.sort_properties)
        } else if range.lt_eq(&zero_point)? == Interval::TRUE {
            Ok(-arg.sort_properties)
        } else {
            Ok(SortProperties::Unordered)
        }
    }

    fn documentation(&self) -> Option<&Documentation> {
        self.doc()
    }
}