alamb commented on code in PR #12536: URL: https://github.com/apache/datafusion/pull/12536#discussion_r1769531067
########## datafusion/expr-common/src/scalar.rs: ########## @@ -0,0 +1,98 @@ +// 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 arrow::{ + array::{Array, ArrayRef}, + datatypes::DataType, +}; +use datafusion_common::{exec_err, Result, ScalarValue}; + +#[derive(Clone, Debug)] +pub struct Scalar { + value: ScalarValue, + data_type: DataType, +} + +impl From<ScalarValue> for Scalar { + fn from(value: ScalarValue) -> Self { + Self { + data_type: value.data_type(), + value, + } + } +} + +impl PartialEq for Scalar { + fn eq(&self, other: &Self) -> bool { + self.value.eq(&other.value) + } +} + +impl Scalar { + pub fn try_from_array(array: &dyn Array, index: usize) -> Result<Self> { + let data_type = array.data_type().clone(); + let value = ScalarValue::try_from_array(array, index)?; + Ok(Self { value, data_type }) + } + + pub fn new_null_of(value: DataType) -> Result<Self> { + Ok(Self { + value: ScalarValue::try_from(&value)?, + data_type: value, + }) + } + + pub fn iter_to_array(scalars: impl IntoIterator<Item = Scalar>) -> Result<ArrayRef> { + let mut scalars = scalars.into_iter().peekable(); + + // figure out the type based on the first element + let data_type = match scalars.peek() { + None => return exec_err!("Empty iterator passed to Scalar::iter_to_array"), + Some(sv) => sv.data_type().clone(), + }; + + ScalarValue::iter_to_array_of_type(scalars.map(|scalar| scalar.value), &data_type) + } + + #[inline] + pub fn value(&self) -> &ScalarValue { Review Comment: We could potentially call this function `as_value` to hit that it was returning a reference and was cheap ########## datafusion/expr-common/src/scalar.rs: ########## @@ -0,0 +1,109 @@ +// 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 arrow::{ + array::{Array, ArrayRef}, + datatypes::DataType, +}; +use datafusion_common::{exec_err, DataFusionError, Result, ScalarValue}; + +#[derive(Clone, Debug)] +pub struct Scalar { + value: ScalarValue, + data_type: DataType, Review Comment: Another potential way to represent this idea would be to use an enum, perhaps, like ```rust pub enum Scalar { /// A ScalarValue (transitory) ScalarValue(ScalarValue), /// A logical String with associated Arrow physical typ String { value: Option<String>, data_type: DataType, }, } ``` I think we could modify this in the future as well ########## datafusion/expr-common/src/scalar.rs: ########## @@ -0,0 +1,109 @@ +// 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 arrow::{ + array::{Array, ArrayRef}, + datatypes::DataType, +}; +use datafusion_common::{exec_err, DataFusionError, Result, ScalarValue}; + +#[derive(Clone, Debug)] +pub struct Scalar { + value: ScalarValue, + data_type: DataType, +} + +impl From<ScalarValue> for Scalar { + fn from(value: ScalarValue) -> Self { + Self { + data_type: value.data_type(), + value, Review Comment: As I understood the idea, eventually the DataType of the scalar will be different than the underlying representation I 100% agree with the sentiment that this intent should be captured in code comments as it is very much non obvious from the code ########## datafusion/functions/src/encoding/inner.rs: ########## @@ -266,7 +266,7 @@ macro_rules! decode_to_array { impl Encoding { fn encode_scalar(self, value: Option<&[u8]>) -> ColumnarValue { - ColumnarValue::Scalar(match self { + ColumnarValue::from(match self { Review Comment: The switch from explicit use of a variant to a `From` clause is a nice change regardless, FWIW, and we could potentially break it out into its own PR -- This is an automated message from the Apache Git Service. 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