nevi-me commented on a change in pull request #491: URL: https://github.com/apache/arrow-rs/pull/491#discussion_r679472996
########## File path: arrow/src/array/array_map.rs ########## @@ -0,0 +1,380 @@ +// 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; +use std::fmt; +use std::mem; + +use super::make_array; +use super::{ + array::print_long_array, raw_pointer::RawPtrBox, Array, ArrayData, ArrayRef, +}; +use crate::datatypes::{ArrowNativeType, DataType}; +use crate::error::ArrowError; + +/// A nested array type where each record is a key-value map. +/// Keys should always be non-null, but values can be null. +/// +/// [MapArray] is physically a [ListArray] that has a [StructArray] +/// with 2 child fields. +pub struct MapArray { + data: ArrayData, + values: ArrayRef, + value_offsets: RawPtrBox<i32>, +} + +impl MapArray { + #[cfg(feature = "experimental-api")] + /// Returns a reference to the keys of this map. + pub fn keys(&self) -> ArrayRef { + make_array(self.values.data().child_data()[0].clone()) + } + + #[cfg(feature = "experimental-api")] + /// Returns a reference to the values of this map. + pub fn values(&self) -> ArrayRef { + make_array(self.values.data().child_data()[1].clone()) + } + + #[cfg(feature = "experimental-api")] + /// Returns the data type of the map's keys. + pub fn key_type(&self) -> DataType { + self.values.data().child_data()[0].data_type().clone() + } + + #[cfg(feature = "experimental-api")] + /// Returns the data type of the map's values. + pub fn value_type(&self) -> DataType { + self.values.data().child_data()[1].data_type().clone() + } + + /// Returns ith value of this map array. + /// # Safety + /// Caller must ensure that the index is within the array bounds + pub unsafe fn value_unchecked(&self, i: usize) -> ArrayRef { + let end = *self.value_offsets().get_unchecked(i + 1); + let start = *self.value_offsets().get_unchecked(i); + self.values + .slice(start.to_usize().unwrap(), (end - start).to_usize().unwrap()) + } + + /// Returns ith value of this map array. + pub fn value(&self, i: usize) -> ArrayRef { + let end = self.value_offsets()[i + 1] as usize; + let start = self.value_offsets()[i] as usize; + self.values.slice(start, end - start) + } + + /// Returns the offset values in the offsets buffer + #[inline] + pub fn value_offsets(&self) -> &[i32] { + // Soundness + // pointer alignment & location is ensured by RawPtrBox + // buffer bounds/offset is ensured by the ArrayData instance. + unsafe { + std::slice::from_raw_parts( + self.value_offsets.as_ptr().add(self.data.offset()), + self.len() + 1, + ) + } + } + + /// Returns the length for value at index `i`. + #[inline] + pub fn value_length(&self, i: usize) -> i32 { + let offsets = self.value_offsets(); + offsets[i + 1] - offsets[i] + } +} + +impl From<ArrayData> for MapArray { + fn from(data: ArrayData) -> Self { + Self::try_new_from_array_data(data) + .expect("Expected infallable creation of MapArray from ArrayData failed") + } +} + +impl MapArray { + fn try_new_from_array_data(data: ArrayData) -> Result<Self, ArrowError> { + if data.buffers().len() != 1 { + return Err(ArrowError::InvalidArgumentError( + format!("MapArray data should contain a single buffer only (value offsets), had {}", + data.len()))); + } + + if data.child_data().len() != 1 { + return Err(ArrowError::InvalidArgumentError(format!( + "MapArray should contain a single child array (values array), had {}", + data.child_data().len() + ))); + } + + let entries = data.child_data()[0].clone(); + + if let DataType::Struct(fields) = entries.data_type() { + if fields.len() != 2 { + return Err(ArrowError::InvalidArgumentError(format!( + "MapArray should contain a struct array with 2 fields, have {} fields", + fields.len() + ))); + } + } else { + return Err(ArrowError::InvalidArgumentError(format!( + "MapArray should contain a struct array child, found {:?}", + entries.data_type() + ))); + } + + let values = make_array(entries); + let value_offsets = data.buffers()[0].as_ptr(); + + let value_offsets = unsafe { RawPtrBox::<i32>::new(value_offsets) }; + unsafe { + if (*value_offsets.as_ptr().offset(0)) != 0 { + return Err(ArrowError::InvalidArgumentError(String::from( + "offsets do not start at zero", + ))); + } + } + Ok(Self { + data, + values, + value_offsets, + }) + } +} + +impl Array for MapArray { + fn as_any(&self) -> &Any { + self + } + + fn data(&self) -> &ArrayData { + &self.data + } + + /// Returns the total number of bytes of memory occupied by the buffers owned by this [MapArray]. + fn get_buffer_memory_size(&self) -> usize { + self.data.get_buffer_memory_size() + } + + /// Returns the total number of bytes of memory occupied physically by this [MapArray]. + fn get_array_memory_size(&self) -> usize { + self.data.get_array_memory_size() + mem::size_of_val(self) + } +} + +impl fmt::Debug for MapArray { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + write!(f, "MapArray\n[\n")?; + print_long_array(self, f, |array, index, f| { + fmt::Debug::fmt(&array.value(index), f) + })?; + write!(f, "]") + } +} + +#[cfg(test)] +mod tests { + use std::sync::Arc; + + use crate::{ + array::ArrayData, + array::{Int32Array, StructArray, UInt32Array}, + buffer::Buffer, + datatypes::Field, + datatypes::ToByteSlice, + }; + + use super::*; + + fn create_from_buffers() -> MapArray { + // Construct key and values + let keys_data = ArrayData::builder(DataType::Int32) + .len(8) + .add_buffer(Buffer::from(&[0, 1, 2, 3, 4, 5, 6, 7].to_byte_slice())) + .build(); + let values_data = ArrayData::builder(DataType::UInt32) + .len(8) + .add_buffer(Buffer::from(&[0u32, 1, 2, 3, 4, 5, 6, 7].to_byte_slice())) + .build(); + + // Construct a buffer for value offsets, for the nested array: + // [[0, 1, 2], [3, 4, 5], [6, 7]] + let entry_offsets = Buffer::from(&[0, 3, 6, 8].to_byte_slice()); + + let keys = Field::new("keys", DataType::Int32, false); + let values = Field::new("values", DataType::UInt32, false); + let entry_struct = StructArray::from(vec![ + (keys, make_array(keys_data)), + (values, make_array(values_data)), + ]); + + // Construct a map array from the above two + let map_data_type = DataType::Map( + Box::new(Field::new( + "entries", + entry_struct.data_type().clone(), + true, + )), + false, + ); + let map_data = ArrayData::builder(map_data_type) + .len(3) + .add_buffer(entry_offsets) + .add_child_data(entry_struct.data().clone()) + .build(); + MapArray::from(map_data) + } + + #[test] + fn test_map_array() { + // Construct key and values + let key_data = ArrayData::builder(DataType::Int32) + .len(8) + .add_buffer(Buffer::from(&[0, 1, 2, 3, 4, 5, 6, 7].to_byte_slice())) + .build(); + let value_data = ArrayData::builder(DataType::UInt32) + .len(8) + .add_buffer(Buffer::from(&[0u32, 1, 2, 3, 4, 5, 6, 7].to_byte_slice())) + .build(); + + // Construct a buffer for value offsets, for the nested array: + // [[0, 1, 2], [3, 4, 5], [6, 7]] + let entry_offsets = Buffer::from(&[0, 3, 6, 8].to_byte_slice()); + + let keys_field = Field::new("keys", DataType::Int32, false); + let values_field = Field::new("values", DataType::UInt32, false); + let entry_struct = StructArray::from(vec![ + (keys_field.clone(), make_array(key_data)), + (values_field.clone(), make_array(value_data.clone())), + ]); + + // Construct a map array from the above two + let map_data_type = DataType::Map( + Box::new(Field::new( + "entries", + entry_struct.data_type().clone(), + true, + )), + false, + ); + let map_data = ArrayData::builder(map_data_type) + .len(3) + .add_buffer(entry_offsets) + .add_child_data(entry_struct.data().clone()) + .build(); + let map_array = MapArray::from(map_data); Review comment: I've made some slight differences between the two functions to test null values on the one map -- This is an automated message from the Apache Git Service. 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