arrow_array/array/
map_array.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
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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//
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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 crate::array::{get_offsets, print_long_array};
19use crate::iterator::MapArrayIter;
20use crate::{Array, ArrayAccessor, ArrayRef, ListArray, StringArray, StructArray, make_array};
21use arrow_buffer::{ArrowNativeType, Buffer, NullBuffer, OffsetBuffer, ToByteSlice};
22use arrow_data::{ArrayData, ArrayDataBuilder};
23use arrow_schema::{ArrowError, DataType, Field, FieldRef};
24use std::any::Any;
25use std::sync::Arc;
26
27/// An array of key-value maps
28///
29/// Keys should always be non-null, but values can be null.
30///
31/// [`MapArray`] is physically a [`ListArray`] of key values pairs stored as an `entries`
32/// [`StructArray`] with 2 child fields.
33///
34/// See [`MapBuilder`](crate::builder::MapBuilder) for how to construct a [`MapArray`]
35#[derive(Clone)]
36pub struct MapArray {
37    data_type: DataType,
38    nulls: Option<NullBuffer>,
39    /// The [`StructArray`] that is the direct child of this array
40    entries: StructArray,
41    /// The start and end offsets of each entry
42    value_offsets: OffsetBuffer<i32>,
43}
44
45impl MapArray {
46    /// Create a new [`MapArray`] from the provided parts
47    ///
48    /// See [`MapBuilder`](crate::builder::MapBuilder) for a higher-level interface
49    /// to construct a [`MapArray`]
50    ///
51    /// # Errors
52    ///
53    /// Errors if
54    ///
55    /// * `offsets.len() - 1 != nulls.len()`
56    /// * `offsets.last() > entries.len()`
57    /// * `field.is_nullable()`
58    /// * `entries.null_count() != 0`
59    /// * `entries.columns().len() != 2`
60    /// * `field.data_type() != entries.data_type()`
61    pub fn try_new(
62        field: FieldRef,
63        offsets: OffsetBuffer<i32>,
64        entries: StructArray,
65        nulls: Option<NullBuffer>,
66        ordered: bool,
67    ) -> Result<Self, ArrowError> {
68        let len = offsets.len() - 1; // Offsets guaranteed to not be empty
69        let end_offset = offsets.last().unwrap().as_usize();
70        // don't need to check other values of `offsets` because they are checked
71        // during construction of `OffsetBuffer`
72        if end_offset > entries.len() {
73            return Err(ArrowError::InvalidArgumentError(format!(
74                "Max offset of {end_offset} exceeds length of entries {}",
75                entries.len()
76            )));
77        }
78
79        if let Some(n) = nulls.as_ref() {
80            if n.len() != len {
81                return Err(ArrowError::InvalidArgumentError(format!(
82                    "Incorrect length of null buffer for MapArray, expected {len} got {}",
83                    n.len(),
84                )));
85            }
86        }
87        if field.is_nullable() || entries.null_count() != 0 {
88            return Err(ArrowError::InvalidArgumentError(
89                "MapArray entries cannot contain nulls".to_string(),
90            ));
91        }
92
93        if field.data_type() != entries.data_type() {
94            return Err(ArrowError::InvalidArgumentError(format!(
95                "MapArray expected data type {} got {} for {:?}",
96                field.data_type(),
97                entries.data_type(),
98                field.name()
99            )));
100        }
101
102        if entries.columns().len() != 2 {
103            return Err(ArrowError::InvalidArgumentError(format!(
104                "MapArray entries must contain two children, got {}",
105                entries.columns().len()
106            )));
107        }
108
109        Ok(Self {
110            data_type: DataType::Map(field, ordered),
111            nulls,
112            entries,
113            value_offsets: offsets,
114        })
115    }
116
117    /// Create a new [`MapArray`] from the provided parts
118    ///
119    /// See [`MapBuilder`](crate::builder::MapBuilder) for a higher-level interface
120    /// to construct a [`MapArray`]
121    ///
122    /// # Panics
123    ///
124    /// Panics if [`Self::try_new`] returns an error
125    pub fn new(
126        field: FieldRef,
127        offsets: OffsetBuffer<i32>,
128        entries: StructArray,
129        nulls: Option<NullBuffer>,
130        ordered: bool,
131    ) -> Self {
132        Self::try_new(field, offsets, entries, nulls, ordered).unwrap()
133    }
134
135    /// Deconstruct this array into its constituent parts
136    pub fn into_parts(
137        self,
138    ) -> (
139        FieldRef,
140        OffsetBuffer<i32>,
141        StructArray,
142        Option<NullBuffer>,
143        bool,
144    ) {
145        let (f, ordered) = match self.data_type {
146            DataType::Map(f, ordered) => (f, ordered),
147            _ => unreachable!(),
148        };
149        (f, self.value_offsets, self.entries, self.nulls, ordered)
150    }
151
152    /// Returns a reference to the offsets of this map
153    ///
154    /// Unlike [`Self::value_offsets`] this returns the [`OffsetBuffer`]
155    /// allowing for zero-copy cloning
156    #[inline]
157    pub fn offsets(&self) -> &OffsetBuffer<i32> {
158        &self.value_offsets
159    }
160
161    /// Returns a reference to the keys of this map
162    pub fn keys(&self) -> &ArrayRef {
163        self.entries.column(0)
164    }
165
166    /// Returns a reference to the values of this map
167    pub fn values(&self) -> &ArrayRef {
168        self.entries.column(1)
169    }
170
171    /// Returns a reference to the [`StructArray`] entries of this map
172    pub fn entries(&self) -> &StructArray {
173        &self.entries
174    }
175
176    /// Returns a reference to the fields of the [`StructArray`] that backs this map.
177    pub fn entries_fields(&self) -> (&Field, &Field) {
178        let fields = self.entries.fields().iter().collect::<Vec<_>>();
179        let fields = TryInto::<[&FieldRef; 2]>::try_into(fields)
180            .expect("Every map has a key and value field");
181
182        (fields[0].as_ref(), fields[1].as_ref())
183    }
184
185    /// Returns the data type of the map's keys.
186    pub fn key_type(&self) -> &DataType {
187        self.keys().data_type()
188    }
189
190    /// Returns the data type of the map's values.
191    pub fn value_type(&self) -> &DataType {
192        self.values().data_type()
193    }
194
195    /// Returns ith value of this map array.
196    ///
197    /// Note: This method does not check for nulls and the value is arbitrary
198    /// if [`is_null`](Self::is_null) returns true for the index.
199    ///
200    /// # Safety
201    /// Caller must ensure that the index is within the array bounds
202    pub unsafe fn value_unchecked(&self, i: usize) -> StructArray {
203        let end = *unsafe { self.value_offsets().get_unchecked(i + 1) };
204        let start = *unsafe { self.value_offsets().get_unchecked(i) };
205        self.entries
206            .slice(start.to_usize().unwrap(), (end - start).to_usize().unwrap())
207    }
208
209    /// Returns ith value of this map array.
210    ///
211    /// This is a [`StructArray`] containing two fields
212    ///
213    /// Note: This method does not check for nulls and the value is arbitrary
214    /// (but still well-defined) if [`is_null`](Self::is_null) returns true for the index.
215    ///
216    /// # Panics
217    /// Panics if index `i` is out of bounds
218    pub fn value(&self, i: usize) -> StructArray {
219        let end = self.value_offsets()[i + 1] as usize;
220        let start = self.value_offsets()[i] as usize;
221        self.entries.slice(start, end - start)
222    }
223
224    /// Returns the offset values in the offsets buffer
225    #[inline]
226    pub fn value_offsets(&self) -> &[i32] {
227        &self.value_offsets
228    }
229
230    /// Returns the length for value at index `i`.
231    #[inline]
232    pub fn value_length(&self, i: usize) -> i32 {
233        let offsets = self.value_offsets();
234        offsets[i + 1] - offsets[i]
235    }
236
237    /// Returns a zero-copy slice of this array with the indicated offset and length.
238    pub fn slice(&self, offset: usize, length: usize) -> Self {
239        Self {
240            data_type: self.data_type.clone(),
241            nulls: self.nulls.as_ref().map(|n| n.slice(offset, length)),
242            entries: self.entries.clone(),
243            value_offsets: self.value_offsets.slice(offset, length),
244        }
245    }
246
247    /// constructs a new iterator
248    pub fn iter(&self) -> MapArrayIter<'_> {
249        MapArrayIter::new(self)
250    }
251}
252
253impl From<ArrayData> for MapArray {
254    fn from(data: ArrayData) -> Self {
255        Self::try_new_from_array_data(data)
256            .expect("Expected infallible creation of MapArray from ArrayData failed")
257    }
258}
259
260impl From<MapArray> for ArrayData {
261    fn from(array: MapArray) -> Self {
262        let len = array.len();
263        let builder = ArrayDataBuilder::new(array.data_type)
264            .len(len)
265            .nulls(array.nulls)
266            .buffers(vec![array.value_offsets.into_inner().into_inner()])
267            .child_data(vec![array.entries.to_data()]);
268
269        unsafe { builder.build_unchecked() }
270    }
271}
272
273impl MapArray {
274    fn try_new_from_array_data(data: ArrayData) -> Result<Self, ArrowError> {
275        if !matches!(data.data_type(), DataType::Map(_, _)) {
276            return Err(ArrowError::InvalidArgumentError(format!(
277                "MapArray expected ArrayData with DataType::Map got {}",
278                data.data_type()
279            )));
280        }
281
282        if data.buffers().len() != 1 {
283            return Err(ArrowError::InvalidArgumentError(format!(
284                "MapArray data should contain a single buffer only (value offsets), had {}",
285                data.len()
286            )));
287        }
288
289        if data.child_data().len() != 1 {
290            return Err(ArrowError::InvalidArgumentError(format!(
291                "MapArray should contain a single child array (values array), had {}",
292                data.child_data().len()
293            )));
294        }
295
296        let entries = data.child_data()[0].clone();
297
298        if let DataType::Struct(fields) = entries.data_type() {
299            if fields.len() != 2 {
300                return Err(ArrowError::InvalidArgumentError(format!(
301                    "MapArray should contain a struct array with 2 fields, have {} fields",
302                    fields.len()
303                )));
304            }
305        } else {
306            return Err(ArrowError::InvalidArgumentError(format!(
307                "MapArray should contain a struct array child, found {:?}",
308                entries.data_type()
309            )));
310        }
311        let entries = entries.into();
312
313        // SAFETY:
314        // ArrayData is valid, and verified type above
315        let value_offsets = unsafe { get_offsets(&data) };
316
317        Ok(Self {
318            data_type: data.data_type().clone(),
319            nulls: data.nulls().cloned(),
320            entries,
321            value_offsets,
322        })
323    }
324
325    /// Creates map array from provided keys, values and entry_offsets.
326    pub fn new_from_strings<'a>(
327        keys: impl Iterator<Item = &'a str>,
328        values: &dyn Array,
329        entry_offsets: &[u32],
330    ) -> Result<Self, ArrowError> {
331        let entry_offsets_buffer = Buffer::from(entry_offsets.to_byte_slice());
332        let keys_data = StringArray::from_iter_values(keys);
333
334        let keys_field = Arc::new(Field::new("keys", DataType::Utf8, false));
335        let values_field = Arc::new(Field::new(
336            "values",
337            values.data_type().clone(),
338            values.null_count() > 0,
339        ));
340
341        let entry_struct = StructArray::from(vec![
342            (keys_field, Arc::new(keys_data) as ArrayRef),
343            (values_field, make_array(values.to_data())),
344        ]);
345
346        let map_data_type = DataType::Map(
347            Arc::new(Field::new(
348                "entries",
349                entry_struct.data_type().clone(),
350                false,
351            )),
352            false,
353        );
354        let map_data = ArrayData::builder(map_data_type)
355            .len(entry_offsets.len() - 1)
356            .add_buffer(entry_offsets_buffer)
357            .add_child_data(entry_struct.into_data())
358            .build()?;
359
360        Ok(MapArray::from(map_data))
361    }
362}
363
364/// SAFETY: Correctly implements the contract of Arrow Arrays
365unsafe impl Array for MapArray {
366    fn as_any(&self) -> &dyn Any {
367        self
368    }
369
370    fn to_data(&self) -> ArrayData {
371        self.clone().into_data()
372    }
373
374    fn into_data(self) -> ArrayData {
375        self.into()
376    }
377
378    fn data_type(&self) -> &DataType {
379        &self.data_type
380    }
381
382    fn slice(&self, offset: usize, length: usize) -> ArrayRef {
383        Arc::new(self.slice(offset, length))
384    }
385
386    fn len(&self) -> usize {
387        self.value_offsets.len() - 1
388    }
389
390    fn is_empty(&self) -> bool {
391        self.value_offsets.len() <= 1
392    }
393
394    fn shrink_to_fit(&mut self) {
395        if let Some(nulls) = &mut self.nulls {
396            nulls.shrink_to_fit();
397        }
398        self.entries.shrink_to_fit();
399        self.value_offsets.shrink_to_fit();
400    }
401
402    fn offset(&self) -> usize {
403        0
404    }
405
406    fn nulls(&self) -> Option<&NullBuffer> {
407        self.nulls.as_ref()
408    }
409
410    fn logical_null_count(&self) -> usize {
411        // More efficient that the default implementation
412        self.null_count()
413    }
414
415    fn get_buffer_memory_size(&self) -> usize {
416        let mut size = self.entries.get_buffer_memory_size();
417        size += self.value_offsets.inner().inner().capacity();
418        if let Some(n) = self.nulls.as_ref() {
419            size += n.buffer().capacity();
420        }
421        size
422    }
423
424    fn get_array_memory_size(&self) -> usize {
425        let mut size = std::mem::size_of::<Self>() + self.entries.get_array_memory_size();
426        size += self.value_offsets.inner().inner().capacity();
427        if let Some(n) = self.nulls.as_ref() {
428            size += n.buffer().capacity();
429        }
430        size
431    }
432}
433
434impl ArrayAccessor for &MapArray {
435    type Item = StructArray;
436
437    fn value(&self, index: usize) -> Self::Item {
438        MapArray::value(self, index)
439    }
440
441    unsafe fn value_unchecked(&self, index: usize) -> Self::Item {
442        MapArray::value(self, index)
443    }
444}
445
446impl std::fmt::Debug for MapArray {
447    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
448        write!(f, "MapArray\n[\n")?;
449        print_long_array(self, f, |array, index, f| {
450            std::fmt::Debug::fmt(&array.value(index), f)
451        })?;
452        write!(f, "]")
453    }
454}
455
456impl From<MapArray> for ListArray {
457    fn from(value: MapArray) -> Self {
458        let field = match value.data_type() {
459            DataType::Map(field, _) => field,
460            _ => unreachable!("This should be a map type."),
461        };
462        let data_type = DataType::List(field.clone());
463        let builder = value.into_data().into_builder().data_type(data_type);
464        let array_data = unsafe { builder.build_unchecked() };
465
466        ListArray::from(array_data)
467    }
468}
469
470#[cfg(test)]
471mod tests {
472    use crate::cast::AsArray;
473    use crate::types::UInt32Type;
474    use crate::{Int32Array, UInt32Array};
475    use arrow_schema::Fields;
476
477    use super::*;
478
479    fn create_from_buffers() -> MapArray {
480        // Construct key and values
481        let keys_data = ArrayData::builder(DataType::Int32)
482            .len(8)
483            .add_buffer(Buffer::from([0, 1, 2, 3, 4, 5, 6, 7].to_byte_slice()))
484            .build()
485            .unwrap();
486        let values_data = ArrayData::builder(DataType::UInt32)
487            .len(8)
488            .add_buffer(Buffer::from(
489                [0u32, 10, 20, 30, 40, 50, 60, 70].to_byte_slice(),
490            ))
491            .build()
492            .unwrap();
493
494        // Construct a buffer for value offsets, for the nested array:
495        //  [[0, 1, 2], [3, 4, 5], [6, 7]]
496        let entry_offsets = Buffer::from([0, 3, 6, 8].to_byte_slice());
497
498        let keys = Arc::new(Field::new("keys", DataType::Int32, false));
499        let values = Arc::new(Field::new("values", DataType::UInt32, false));
500        let entry_struct = StructArray::from(vec![
501            (keys, make_array(keys_data)),
502            (values, make_array(values_data)),
503        ]);
504
505        // Construct a map array from the above two
506        let map_data_type = DataType::Map(
507            Arc::new(Field::new(
508                "entries",
509                entry_struct.data_type().clone(),
510                false,
511            )),
512            false,
513        );
514        let map_data = ArrayData::builder(map_data_type)
515            .len(3)
516            .add_buffer(entry_offsets)
517            .add_child_data(entry_struct.into_data())
518            .build()
519            .unwrap();
520        MapArray::from(map_data)
521    }
522
523    #[test]
524    fn test_map_array() {
525        // Construct key and values
526        let key_data = ArrayData::builder(DataType::Int32)
527            .len(8)
528            .add_buffer(Buffer::from([0, 1, 2, 3, 4, 5, 6, 7].to_byte_slice()))
529            .build()
530            .unwrap();
531        let value_data = ArrayData::builder(DataType::UInt32)
532            .len(8)
533            .add_buffer(Buffer::from(
534                [0u32, 10, 20, 0, 40, 0, 60, 70].to_byte_slice(),
535            ))
536            .null_bit_buffer(Some(Buffer::from(&[0b11010110])))
537            .build()
538            .unwrap();
539
540        // Construct a buffer for value offsets, for the nested array:
541        //  [[0, 1, 2], [3, 4, 5], [6, 7]]
542        let entry_offsets = Buffer::from([0, 3, 6, 8].to_byte_slice());
543
544        let keys_field = Arc::new(Field::new("keys", DataType::Int32, false));
545        let values_field = Arc::new(Field::new("values", DataType::UInt32, true));
546        let entry_struct = StructArray::from(vec![
547            (keys_field.clone(), make_array(key_data)),
548            (values_field.clone(), make_array(value_data.clone())),
549        ]);
550
551        // Construct a map array from the above two
552        let map_data_type = DataType::Map(
553            Arc::new(Field::new(
554                "entries",
555                entry_struct.data_type().clone(),
556                false,
557            )),
558            false,
559        );
560        let map_data = ArrayData::builder(map_data_type)
561            .len(3)
562            .add_buffer(entry_offsets)
563            .add_child_data(entry_struct.into_data())
564            .build()
565            .unwrap();
566        let map_array = MapArray::from(map_data);
567
568        assert_eq!(value_data, map_array.values().to_data());
569        assert_eq!(&DataType::UInt32, map_array.value_type());
570        assert_eq!(3, map_array.len());
571        assert_eq!(0, map_array.null_count());
572        assert_eq!(6, map_array.value_offsets()[2]);
573        assert_eq!(2, map_array.value_length(2));
574
575        let key_array = Arc::new(Int32Array::from(vec![0, 1, 2])) as ArrayRef;
576        let value_array =
577            Arc::new(UInt32Array::from(vec![None, Some(10u32), Some(20)])) as ArrayRef;
578        let struct_array = StructArray::from(vec![
579            (keys_field.clone(), key_array),
580            (values_field.clone(), value_array),
581        ]);
582        assert_eq!(
583            struct_array,
584            StructArray::from(map_array.value(0).into_data())
585        );
586        assert_eq!(
587            &struct_array,
588            unsafe { map_array.value_unchecked(0) }
589                .as_any()
590                .downcast_ref::<StructArray>()
591                .unwrap()
592        );
593        for i in 0..3 {
594            assert!(map_array.is_valid(i));
595            assert!(!map_array.is_null(i));
596        }
597
598        // Now test with a non-zero offset
599        let map_array = map_array.slice(1, 2);
600
601        assert_eq!(value_data, map_array.values().to_data());
602        assert_eq!(&DataType::UInt32, map_array.value_type());
603        assert_eq!(2, map_array.len());
604        assert_eq!(0, map_array.null_count());
605        assert_eq!(6, map_array.value_offsets()[1]);
606        assert_eq!(2, map_array.value_length(1));
607
608        let key_array = Arc::new(Int32Array::from(vec![3, 4, 5])) as ArrayRef;
609        let value_array = Arc::new(UInt32Array::from(vec![None, Some(40), None])) as ArrayRef;
610        let struct_array =
611            StructArray::from(vec![(keys_field, key_array), (values_field, value_array)]);
612        assert_eq!(
613            &struct_array,
614            map_array
615                .value(0)
616                .as_any()
617                .downcast_ref::<StructArray>()
618                .unwrap()
619        );
620        assert_eq!(
621            &struct_array,
622            unsafe { map_array.value_unchecked(0) }
623                .as_any()
624                .downcast_ref::<StructArray>()
625                .unwrap()
626        );
627    }
628
629    #[test]
630    #[ignore = "Test fails because slice of <list<struct>> is still buggy"]
631    fn test_map_array_slice() {
632        let map_array = create_from_buffers();
633
634        let sliced_array = map_array.slice(1, 2);
635        assert_eq!(2, sliced_array.len());
636        assert_eq!(1, sliced_array.offset());
637        let sliced_array_data = sliced_array.to_data();
638        for array_data in sliced_array_data.child_data() {
639            assert_eq!(array_data.offset(), 1);
640        }
641
642        // Check offset and length for each non-null value.
643        let sliced_map_array = sliced_array.as_any().downcast_ref::<MapArray>().unwrap();
644        assert_eq!(3, sliced_map_array.value_offsets()[0]);
645        assert_eq!(3, sliced_map_array.value_length(0));
646        assert_eq!(6, sliced_map_array.value_offsets()[1]);
647        assert_eq!(2, sliced_map_array.value_length(1));
648
649        // Construct key and values
650        let keys_data = ArrayData::builder(DataType::Int32)
651            .len(5)
652            .add_buffer(Buffer::from([3, 4, 5, 6, 7].to_byte_slice()))
653            .build()
654            .unwrap();
655        let values_data = ArrayData::builder(DataType::UInt32)
656            .len(5)
657            .add_buffer(Buffer::from([30u32, 40, 50, 60, 70].to_byte_slice()))
658            .build()
659            .unwrap();
660
661        // Construct a buffer for value offsets, for the nested array:
662        //  [[3, 4, 5], [6, 7]]
663        let entry_offsets = Buffer::from([0, 3, 5].to_byte_slice());
664
665        let keys = Arc::new(Field::new("keys", DataType::Int32, false));
666        let values = Arc::new(Field::new("values", DataType::UInt32, false));
667        let entry_struct = StructArray::from(vec![
668            (keys, make_array(keys_data)),
669            (values, make_array(values_data)),
670        ]);
671
672        // Construct a map array from the above two
673        let map_data_type = DataType::Map(
674            Arc::new(Field::new(
675                "entries",
676                entry_struct.data_type().clone(),
677                false,
678            )),
679            false,
680        );
681        let expected_map_data = ArrayData::builder(map_data_type)
682            .len(2)
683            .add_buffer(entry_offsets)
684            .add_child_data(entry_struct.into_data())
685            .build()
686            .unwrap();
687        let expected_map_array = MapArray::from(expected_map_data);
688
689        assert_eq!(&expected_map_array, sliced_map_array)
690    }
691
692    #[test]
693    #[should_panic(expected = "index out of bounds: the len is ")]
694    fn test_map_array_index_out_of_bound() {
695        let map_array = create_from_buffers();
696
697        map_array.value(map_array.len());
698    }
699
700    #[test]
701    #[should_panic(expected = "MapArray expected ArrayData with DataType::Map got Dictionary")]
702    fn test_from_array_data_validation() {
703        // A DictionaryArray has similar buffer layout to a MapArray
704        // but the meaning of the values differs
705        let struct_t = DataType::Struct(Fields::from(vec![
706            Field::new("keys", DataType::Int32, true),
707            Field::new("values", DataType::UInt32, true),
708        ]));
709        let dict_t = DataType::Dictionary(Box::new(DataType::Int32), Box::new(struct_t));
710        let _ = MapArray::from(ArrayData::new_empty(&dict_t));
711    }
712
713    #[test]
714    fn test_new_from_strings() {
715        let keys = vec!["a", "b", "c", "d", "e", "f", "g", "h"];
716        let values_data = UInt32Array::from(vec![0u32, 10, 20, 30, 40, 50, 60, 70]);
717
718        // Construct a buffer for value offsets, for the nested array:
719        //  [[a, b, c], [d, e, f], [g, h]]
720        let entry_offsets = [0, 3, 6, 8];
721
722        let map_array =
723            MapArray::new_from_strings(keys.clone().into_iter(), &values_data, &entry_offsets)
724                .unwrap();
725
726        assert_eq!(
727            &values_data,
728            map_array.values().as_primitive::<UInt32Type>()
729        );
730        assert_eq!(&DataType::UInt32, map_array.value_type());
731        assert_eq!(3, map_array.len());
732        assert_eq!(0, map_array.null_count());
733        assert_eq!(6, map_array.value_offsets()[2]);
734        assert_eq!(2, map_array.value_length(2));
735
736        let key_array = Arc::new(StringArray::from(vec!["a", "b", "c"])) as ArrayRef;
737        let value_array = Arc::new(UInt32Array::from(vec![0u32, 10, 20])) as ArrayRef;
738        let keys_field = Arc::new(Field::new("keys", DataType::Utf8, false));
739        let values_field = Arc::new(Field::new("values", DataType::UInt32, false));
740        let struct_array =
741            StructArray::from(vec![(keys_field, key_array), (values_field, value_array)]);
742        assert_eq!(
743            struct_array,
744            StructArray::from(map_array.value(0).into_data())
745        );
746        assert_eq!(
747            &struct_array,
748            unsafe { map_array.value_unchecked(0) }
749                .as_any()
750                .downcast_ref::<StructArray>()
751                .unwrap()
752        );
753        for i in 0..3 {
754            assert!(map_array.is_valid(i));
755            assert!(!map_array.is_null(i));
756        }
757    }
758
759    #[test]
760    fn test_try_new() {
761        let offsets = OffsetBuffer::new(vec![0, 1, 4, 5].into());
762        let fields = Fields::from(vec![
763            Field::new("key", DataType::Int32, false),
764            Field::new("values", DataType::Int32, false),
765        ]);
766        let columns = vec![
767            Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5])) as _,
768            Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5])) as _,
769        ];
770
771        let entries = StructArray::new(fields.clone(), columns, None);
772        let field = Arc::new(Field::new("entries", DataType::Struct(fields), false));
773
774        MapArray::new(field.clone(), offsets.clone(), entries.clone(), None, false);
775
776        let nulls = NullBuffer::new_null(3);
777        MapArray::new(field.clone(), offsets, entries.clone(), Some(nulls), false);
778
779        let nulls = NullBuffer::new_null(3);
780        let offsets = OffsetBuffer::new(vec![0, 1, 2, 4, 5].into());
781        let err = MapArray::try_new(
782            field.clone(),
783            offsets.clone(),
784            entries.clone(),
785            Some(nulls),
786            false,
787        )
788        .unwrap_err();
789
790        assert_eq!(
791            err.to_string(),
792            "Invalid argument error: Incorrect length of null buffer for MapArray, expected 4 got 3"
793        );
794
795        let err = MapArray::try_new(field, offsets.clone(), entries.slice(0, 2), None, false)
796            .unwrap_err();
797
798        assert_eq!(
799            err.to_string(),
800            "Invalid argument error: Max offset of 5 exceeds length of entries 2"
801        );
802
803        let field = Arc::new(Field::new("element", DataType::Int64, false));
804        let err = MapArray::try_new(field, offsets.clone(), entries, None, false)
805            .unwrap_err()
806            .to_string();
807
808        assert!(
809            err.starts_with("Invalid argument error: MapArray expected data type Int64 got Struct"),
810            "{err}"
811        );
812
813        let fields = Fields::from(vec![
814            Field::new("a", DataType::Int32, false),
815            Field::new("b", DataType::Int32, false),
816            Field::new("c", DataType::Int32, false),
817        ]);
818        let columns = vec![
819            Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5])) as _,
820            Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5])) as _,
821            Arc::new(Int32Array::from(vec![1, 2, 3, 4, 5])) as _,
822        ];
823
824        let s = StructArray::new(fields.clone(), columns, None);
825        let field = Arc::new(Field::new("entries", DataType::Struct(fields), false));
826        let err = MapArray::try_new(field, offsets, s, None, false).unwrap_err();
827
828        assert_eq!(
829            err.to_string(),
830            "Invalid argument error: MapArray entries must contain two children, got 3"
831        );
832    }
833}
arrow_array/array/map_array.rs

arrow_array/array/
map_array.rs
