feat: Implement Spark unhex #342
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| // 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. | ||
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| use std::sync::Arc; | ||
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| use arrow_array::OffsetSizeTrait; | ||
| use arrow_schema::DataType; | ||
| use datafusion::logical_expr::ColumnarValue; | ||
| use datafusion_common::{cast::as_generic_string_array, exec_err, DataFusionError, ScalarValue}; | ||
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| /// Helper function to convert a hex digit to a binary value. | ||
| fn unhex_digit(c: u8) -> Result<u8, DataFusionError> { | ||
| match c { | ||
| b'0'..=b'9' => Ok(c - b'0'), | ||
| b'A'..=b'F' => Ok(10 + c - b'A'), | ||
| b'a'..=b'f' => Ok(10 + c - b'a'), | ||
| _ => Err(DataFusionError::Execution( | ||
| "Input to unhex_digit is not a valid hex digit".to_string(), | ||
| )), | ||
| } | ||
| } | ||
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| /// Convert a hex string to binary and store the result in `result`. Returns an error if the input | ||
| /// is not a valid hex string. | ||
| fn unhex(hex_str: &str, result: &mut Vec<u8>) -> Result<(), DataFusionError> { | ||
| let bytes = hex_str.as_bytes(); | ||
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| let mut i = 0; | ||
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| if (bytes.len() & 0x01) != 0 { | ||
| let v = unhex_digit(bytes[0])?; | ||
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| result.push(v); | ||
| i += 1; | ||
| } | ||
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| while i < bytes.len() { | ||
| let first = unhex_digit(bytes[i])?; | ||
| let second = unhex_digit(bytes[i + 1])?; | ||
| result.push((first << 4) | second); | ||
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| i += 2; | ||
| } | ||
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| Ok(()) | ||
| } | ||
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| fn spark_unhex_inner<T: OffsetSizeTrait>( | ||
| array: &ColumnarValue, | ||
| fail_on_error: bool, | ||
| ) -> Result<ColumnarValue, DataFusionError> { | ||
| match array { | ||
| ColumnarValue::Array(array) => { | ||
| let string_array = as_generic_string_array::<T>(array)?; | ||
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| let mut encoded = Vec::new(); | ||
| let mut builder = arrow::array::BinaryBuilder::new(); | ||
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| for item in string_array.iter() { | ||
| if let Some(s) = item { | ||
| if unhex(s, &mut encoded).is_ok() { | ||
| builder.append_value(encoded.as_slice()); | ||
| encoded.clear(); | ||
| } else if fail_on_error { | ||
| return exec_err!("Input to unhex is not a valid hex string: {s}"); | ||
| } else { | ||
| builder.append_null(); | ||
|
There was a problem hiding this comment. If There was a problem hiding this comment. All good, thank you very much for looking. I think you're right in that there was a bug, which should be fixed and tested in c5c3fcd. |
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| } | ||
| } else { | ||
| builder.append_null(); | ||
| } | ||
| } | ||
| Ok(ColumnarValue::Array(Arc::new(builder.finish()))) | ||
| } | ||
| ColumnarValue::Scalar(ScalarValue::Utf8(Some(string))) => { | ||
| let mut encoded = Vec::new(); | ||
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| if unhex(string, &mut encoded).is_ok() { | ||
| Ok(ColumnarValue::Scalar(ScalarValue::Binary(Some(encoded)))) | ||
| } else if fail_on_error { | ||
| exec_err!("Input to unhex is not a valid hex string: {string}") | ||
| } else { | ||
| Ok(ColumnarValue::Scalar(ScalarValue::Binary(None))) | ||
| } | ||
| } | ||
| ColumnarValue::Scalar(ScalarValue::Utf8(None)) => { | ||
| Ok(ColumnarValue::Scalar(ScalarValue::Binary(None))) | ||
| } | ||
| _ => { | ||
| exec_err!( | ||
| "The first argument must be a string scalar or array, but got: {:?}", | ||
| array | ||
| ) | ||
| } | ||
| } | ||
| } | ||
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| pub(super) fn spark_unhex(args: &[ColumnarValue]) -> Result<ColumnarValue, DataFusionError> { | ||
| if args.len() > 2 { | ||
| return exec_err!("unhex takes at most 2 arguments, but got: {}", args.len()); | ||
| } | ||
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| let val_to_unhex = &args[0]; | ||
| let fail_on_error = if args.len() == 2 { | ||
| match &args[1] { | ||
| ColumnarValue::Scalar(ScalarValue::Boolean(Some(fail_on_error))) => *fail_on_error, | ||
| _ => { | ||
| return exec_err!( | ||
| "The second argument must be boolean scalar, but got: {:?}", | ||
| args[1] | ||
| ); | ||
| } | ||
| } | ||
| } else { | ||
| false | ||
| }; | ||
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| match val_to_unhex.data_type() { | ||
| DataType::Utf8 => spark_unhex_inner::<i32>(val_to_unhex, fail_on_error), | ||
| DataType::LargeUtf8 => spark_unhex_inner::<i64>(val_to_unhex, fail_on_error), | ||
| other => exec_err!( | ||
| "The first argument must be a Utf8 or LargeUtf8: {:?}", | ||
| other | ||
| ), | ||
| } | ||
| } | ||
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| #[cfg(test)] | ||
| mod test { | ||
| use std::sync::Arc; | ||
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| use arrow_array::make_array; | ||
| use arrow_data::ArrayData; | ||
| use datafusion::logical_expr::ColumnarValue; | ||
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| use super::unhex; | ||
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| #[test] | ||
| fn test_spark_unhex_null() -> Result<(), Box<dyn std::error::Error>> { | ||
| let input = ArrayData::new_null(&arrow_schema::DataType::Utf8, 2); | ||
| let output = ArrayData::new_null(&arrow_schema::DataType::Binary, 2); | ||
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| let input = ColumnarValue::Array(Arc::new(make_array(input))); | ||
| let expected = ColumnarValue::Array(Arc::new(make_array(output))); | ||
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| let result = super::spark_unhex(&[input])?; | ||
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| match (result, expected) { | ||
| (ColumnarValue::Array(result), ColumnarValue::Array(expected)) => { | ||
| assert_eq!(*result, *expected); | ||
| Ok(()) | ||
| } | ||
| _ => Err("Unexpected result type".into()), | ||
| } | ||
| } | ||
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| #[test] | ||
| fn test_unhex_valid() -> Result<(), Box<dyn std::error::Error>> { | ||
| let mut result = Vec::new(); | ||
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| unhex("537061726B2053514C", &mut result)?; | ||
|
There was a problem hiding this comment. Could we also have a test for the case where the input is padded? |
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| let result_str = std::str::from_utf8(&result)?; | ||
| assert_eq!(result_str, "Spark SQL"); | ||
| result.clear(); | ||
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| unhex("1C", &mut result)?; | ||
| assert_eq!(result, vec![28]); | ||
| result.clear(); | ||
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| unhex("737472696E67", &mut result)?; | ||
| assert_eq!(result, "string".as_bytes()); | ||
| result.clear(); | ||
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| unhex("1", &mut result)?; | ||
| assert_eq!(result, vec![1]); | ||
| result.clear(); | ||
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| Ok(()) | ||
| } | ||
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| #[test] | ||
| fn test_odd_length() -> Result<(), Box<dyn std::error::Error>> { | ||
| let mut result = Vec::new(); | ||
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| unhex("A1B", &mut result)?; | ||
| assert_eq!(result, vec![10, 27]); | ||
| result.clear(); | ||
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| unhex("0A1B", &mut result)?; | ||
| assert_eq!(result, vec![10, 27]); | ||
| result.clear(); | ||
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| Ok(()) | ||
| } | ||
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| #[test] | ||
| fn test_unhex_empty() { | ||
| let mut result = Vec::new(); | ||
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| // Empty hex string | ||
| unhex("", &mut result).unwrap(); | ||
| assert!(result.is_empty()); | ||
| } | ||
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| #[test] | ||
| fn test_unhex_invalid() { | ||
| let mut result = Vec::new(); | ||
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| // Invalid hex strings | ||
| assert!(unhex("##", &mut result).is_err()); | ||
| assert!(unhex("G123", &mut result).is_err()); | ||
| assert!(unhex("hello", &mut result).is_err()); | ||
| assert!(unhex("\0", &mut result).is_err()); | ||
| } | ||
| } | ||
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Unrelated, but more idiomatic IMO