datafusion_spark/function/map/
map_from_entries.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use std::sync::Arc;
19
20use crate::function::map::utils::{
21    get_list_offsets, get_list_values, map_from_keys_values_offsets_nulls,
22    map_type_from_key_value_types,
23};
24use arrow::array::{Array, ArrayRef, NullBufferBuilder, StructArray};
25use arrow::buffer::NullBuffer;
26use arrow::datatypes::{DataType, Field, FieldRef};
27use datafusion_common::utils::take_function_args;
28use datafusion_common::{Result, exec_err, internal_err};
29use datafusion_expr::{
30    ColumnarValue, ReturnFieldArgs, ScalarFunctionArgs, ScalarUDFImpl, Signature,
31    Volatility,
32};
33use datafusion_functions::utils::make_scalar_function;
34
35/// Spark-compatible `map_from_entries` expression
36/// <https://spark.apache.org/docs/latest/api/sql/index.html#map_from_entries>
37#[derive(Debug, PartialEq, Eq, Hash)]
38pub struct MapFromEntries {
39    signature: Signature,
40}
41
42impl Default for MapFromEntries {
43    fn default() -> Self {
44        Self::new()
45    }
46}
47
48impl MapFromEntries {
49    pub fn new() -> Self {
50        Self {
51            signature: Signature::array(Volatility::Immutable),
52        }
53    }
54}
55
56impl ScalarUDFImpl for MapFromEntries {
57    fn name(&self) -> &str {
58        "map_from_entries"
59    }
60
61    fn signature(&self) -> &Signature {
62        &self.signature
63    }
64
65    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
66        internal_err!("return_field_from_args should be used instead")
67    }
68
69    fn return_field_from_args(&self, args: ReturnFieldArgs) -> Result<FieldRef> {
70        let [entries_field] = args.arg_fields else {
71            return exec_err!("map_from_entries: expected one argument");
72        };
73
74        let (entries_element_field, entries_element_type) =
75            match entries_field.data_type() {
76                DataType::List(field)
77                | DataType::LargeList(field)
78                | DataType::FixedSizeList(field, _) => {
79                    Ok((field.as_ref(), field.data_type()))
80                }
81                wrong_type => exec_err!(
82                    "map_from_entries: expected array<struct<key, value>>, got {:?}",
83                    wrong_type
84                ),
85            }?;
86
87        let (keys_type, values_type) = match entries_element_type {
88            DataType::Struct(fields) if fields.len() == 2 => {
89                Ok((fields[0].data_type(), fields[1].data_type()))
90            }
91            wrong_type => exec_err!(
92                "map_from_entries: expected array<struct<key, value>>, got {:?}",
93                wrong_type
94            ),
95        }?;
96
97        let map_type = map_type_from_key_value_types(keys_type, values_type);
98        let nullable = entries_field.is_nullable() || entries_element_field.is_nullable();
99
100        Ok(Arc::new(Field::new(self.name(), map_type, nullable)))
101    }
102
103    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
104        make_scalar_function(map_from_entries_inner, vec![])(&args.args)
105    }
106}
107
108fn map_from_entries_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
109    let [entries] = take_function_args("map_from_entries", args)?;
110    let entries_offsets = get_list_offsets(entries)?;
111    let entries_values = get_list_values(entries)?;
112
113    let (flat_keys, flat_values) =
114        match entries_values.as_any().downcast_ref::<StructArray>() {
115            Some(a) => Ok((a.column(0), a.column(1))),
116            None => exec_err!(
117                "map_from_entries: expected array<struct<key, value>>, got {:?}",
118                entries_values.data_type()
119            ),
120        }?;
121
122    let entries_with_nulls = entries_values.nulls().and_then(|entries_inner_nulls| {
123        let mut builder = NullBufferBuilder::new_with_len(0);
124        let mut cur_offset = entries_offsets
125            .first()
126            .map(|offset| *offset as usize)
127            .unwrap_or(0);
128
129        for next_offset in entries_offsets.iter().skip(1) {
130            let num_entries = *next_offset as usize - cur_offset;
131            builder.append(
132                entries_inner_nulls
133                    .slice(cur_offset, num_entries)
134                    .null_count()
135                    == 0,
136            );
137            cur_offset = *next_offset as usize;
138        }
139        builder.finish()
140    });
141
142    let res_nulls = NullBuffer::union(entries.nulls(), entries_with_nulls.as_ref());
143
144    map_from_keys_values_offsets_nulls(
145        flat_keys,
146        flat_values,
147        &entries_offsets,
148        &entries_offsets,
149        None,
150        res_nulls.as_ref(),
151    )
152}
153
154#[cfg(test)]
155mod tests {
156    use super::*;
157    use arrow::datatypes::Fields;
158
159    fn make_entries_field(array_nullable: bool, element_nullable: bool) -> FieldRef {
160        let struct_type = DataType::Struct(Fields::from(vec![
161            Field::new("key", DataType::Int32, false),
162            Field::new("value", DataType::Utf8, true),
163        ]));
164        Arc::new(Field::new(
165            "entries",
166            DataType::List(Arc::new(Field::new("item", struct_type, element_nullable))),
167            array_nullable,
168        ))
169    }
170
171    #[test]
172    fn test_map_from_entries_nullability_matches_input() {
173        let func = MapFromEntries::new();
174        let expected_type =
175            map_type_from_key_value_types(&DataType::Int32, &DataType::Utf8);
176
177        // Non-nullable array and elements => non-nullable result
178        let non_nullable_field = make_entries_field(false, false);
179        let result = func
180            .return_field_from_args(ReturnFieldArgs {
181                arg_fields: &[Arc::clone(&non_nullable_field)],
182                scalar_arguments: &[None],
183            })
184            .expect("should infer field");
185        assert!(!result.is_nullable());
186        assert_eq!(result.data_type(), &expected_type);
187
188        // Nullable elements should make result nullable even if array is non-nullable
189        let element_nullable_field = make_entries_field(false, true);
190        let result = func
191            .return_field_from_args(ReturnFieldArgs {
192                arg_fields: &[Arc::clone(&element_nullable_field)],
193                scalar_arguments: &[None],
194            })
195            .expect("should infer field");
196        assert!(result.is_nullable());
197        assert_eq!(result.data_type(), &expected_type);
198
199        // Nullable array should also yield nullable result
200        let array_nullable_field = make_entries_field(true, false);
201        let result = func
202            .return_field_from_args(ReturnFieldArgs {
203                arg_fields: &[Arc::clone(&array_nullable_field)],
204                scalar_arguments: &[None],
205            })
206            .expect("should infer field");
207        assert!(result.is_nullable());
208        assert_eq!(result.data_type(), &expected_type);
209    }
210}
datafusion_spark/function/map/map_from_entries.rs

datafusion_spark/function/map/
map_from_entries.rs
