jorgecarleitao commented on a change in pull request #8032: URL: https://github.com/apache/arrow/pull/8032#discussion_r476704869
########## File path: rust/datafusion/src/execution/physical_plan/functions.rs ########## @@ -0,0 +1,208 @@ +// 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. + +//! Declaration of built-in (scalar) functions. +//! This module contains built-in functions' enumeration and metadata. + +use super::{expressions::cast, PhysicalExpr}; +use crate::error::{ExecutionError, Result}; +use crate::execution::physical_plan::math_expressions; +use crate::execution::physical_plan::udf; +use arrow::{ + compute::kernels::length::length, + datatypes::{DataType, Schema}, +}; +use std::{fmt, str::FromStr, sync::Arc}; +use udf::ScalarUdf; + +/// Enum of all built-in scalar functions +#[derive(Debug, Clone, PartialEq, Eq)] +pub enum ScalarFunction { + /// sqrt + Sqrt, + /// sin + Sin, + /// cos + Cos, + /// tan + Tan, + /// asin + Asin, + /// acos + Acos, + /// atan + Atan, + /// exp + Exp, + /// log, also known as ln + Log, + /// log2 + Log2, + /// log10 + Log10, + /// floor + Floor, + /// ceil + Ceil, + /// round + Round, + /// trunc + Trunc, + /// abs + Abs, + /// signum + Signum, + /// length + Length, +} + +impl fmt::Display for ScalarFunction { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + // lowercase of the debug. + write!(f, "{}", format!("{:?}", self).to_lowercase()) + } +} + +impl FromStr for ScalarFunction { + type Err = ExecutionError; + fn from_str(name: &str) -> Result<ScalarFunction> { + Ok(match name { + "sqrt" => ScalarFunction::Sqrt, + "sin" => ScalarFunction::Sin, + "cos" => ScalarFunction::Cos, + "tan" => ScalarFunction::Tan, + "asin" => ScalarFunction::Asin, + "acos" => ScalarFunction::Acos, + "atan" => ScalarFunction::Atan, + "exp" => ScalarFunction::Exp, + "log" => ScalarFunction::Log, + "log2" => ScalarFunction::Log2, + "log10" => ScalarFunction::Log10, + "floor" => ScalarFunction::Floor, + "ceil" => ScalarFunction::Ceil, + "round" => ScalarFunction::Round, + "truc" => ScalarFunction::Trunc, + "abs" => ScalarFunction::Abs, + "signum" => ScalarFunction::Signum, + "length" => ScalarFunction::Length, + _ => { + return Err(ExecutionError::General(format!( + "There is no built-in function named {}", + name + ))) + } + }) + } +} + +/// Returns the datatype of the scalar function +pub fn return_type(fun: &ScalarFunction, arg_types: &Vec<DataType>) -> Result<DataType> { + if arg_types.len() != 1 { + // for now, every function expects a single argument, and thus this is enough + return Err(ExecutionError::General(format!( + "The function \"{}\" expected 1 argument, but received \"{}\"", + fun, + arg_types.len() + ))); + } + + // verify that this is a valid type for this function + coerce(fun, &arg_types[0])?; + + match fun { + ScalarFunction::Length => Ok(DataType::UInt32), + _ => Ok(DataType::Float64), + } +} + +/// Create a physical (function) expression. +pub fn function( + fun: &ScalarFunction, + args: Vec<Arc<dyn PhysicalExpr>>, + input_schema: &Schema, +) -> Result<Arc<dyn PhysicalExpr>> { + let fun_expr: ScalarUdf = Arc::new(match fun { + ScalarFunction::Sqrt => math_expressions::sqrt, + ScalarFunction::Sin => math_expressions::sin, + ScalarFunction::Cos => math_expressions::cos, + ScalarFunction::Tan => math_expressions::tan, + ScalarFunction::Asin => math_expressions::asin, + ScalarFunction::Acos => math_expressions::acos, + ScalarFunction::Atan => math_expressions::atan, + ScalarFunction::Exp => math_expressions::exp, + ScalarFunction::Log => math_expressions::ln, + ScalarFunction::Log2 => math_expressions::log2, + ScalarFunction::Log10 => math_expressions::log10, + ScalarFunction::Floor => math_expressions::floor, + ScalarFunction::Ceil => math_expressions::ceil, + ScalarFunction::Round => math_expressions::round, + ScalarFunction::Trunc => math_expressions::trunc, + ScalarFunction::Abs => math_expressions::abs, + ScalarFunction::Signum => math_expressions::signum, + ScalarFunction::Length => |args| Ok(Arc::new(length(args[0].as_ref())?)), + }); + let data_types = args + .iter() + .map(|e| e.data_type(input_schema)) + .collect::<Result<Vec<_>>>()?; + + // coerce type + // for now, this works only for 1 argument. + assert!(args.len() == 1); + assert!(data_types.len() == 1); + let new_type = coerce(fun, &data_types[0])?; + let args = vec![cast(args[0].clone(), input_schema, new_type)?]; Review comment: we have this coercion rule in another PR, which will expand this to multiple arguments. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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