andygrove commented on code in PR #15994: URL: https://github.com/apache/datafusion/pull/15994#discussion_r2082124914
########## datafusion/spark/src/function/string/char.rs: ########## @@ -0,0 +1,130 @@ +// 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. + +use std::{any::Any, sync::Arc}; + +use arrow::{ + array::{ArrayRef, StringArray}, + datatypes::{ + DataType, + DataType::{Int64, Utf8}, + }, +}; + +use datafusion_common::{cast::as_int64_array, exec_err, Result, ScalarValue}; +use datafusion_expr::{ + ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl, Signature, Volatility, +}; + +/// Spark-compatible `char` expression +/// <https://spark.apache.org/docs/latest/api/sql/index.html#char> +#[derive(Debug)] +pub struct SparkChar { + signature: Signature, +} + +impl Default for SparkChar { + fn default() -> Self { + Self::new() + } +} + +impl SparkChar { + pub fn new() -> Self { + Self { + signature: Signature::uniform(1, vec![Int64], Volatility::Immutable), + } + } +} + +impl ScalarUDFImpl for SparkChar { + fn as_any(&self) -> &dyn Any { + self + } + + fn name(&self) -> &str { + "char" + } + + fn signature(&self) -> &Signature { + &self.signature + } + + fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> { + Ok(Utf8) + } + + fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { + spark_chr(&args.args) + } +} + +/// Returns the ASCII character having the binary equivalent to the input expression. +/// E.g., chr(65) = 'A'. +/// Compatible with Apache Spark's Chr function +fn spark_chr(args: &[ColumnarValue]) -> Result<ColumnarValue> { + let array = args[0].clone(); + match array { + ColumnarValue::Array(array) => { + let array = chr(&[array])?; + Ok(ColumnarValue::Array(array)) + } + ColumnarValue::Scalar(ScalarValue::Int64(Some(value))) => { + if value < 0 { + Ok(ColumnarValue::Scalar(ScalarValue::Utf8(Some( + "".to_string(), + )))) + } else { + match core::char::from_u32((value % 256) as u32) { + Some(ch) => Ok(ColumnarValue::Scalar(ScalarValue::Utf8(Some( + ch.to_string(), + )))), + None => { + exec_err!("requested character was incompatible for encoding.") + } + } + } + } + _ => exec_err!("The argument must be an Int64 array or scalar."), + } +} + +fn chr(args: &[ArrayRef]) -> Result<ArrayRef> { + let integer_array = as_int64_array(&args[0])?; + + // first map is the iterator, second is for the `Option<_>` Review Comment: Thanks. I filed a tracking issue https://github.com/apache/datafusion/issues/16009 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
