arrow_array/array/byte_view_array.rs
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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.
use crate::array::print_long_array;
use crate::builder::{ArrayBuilder, GenericByteViewBuilder};
use crate::iterator::ArrayIter;
use crate::types::bytes::ByteArrayNativeType;
use crate::types::{BinaryViewType, ByteViewType, StringViewType};
use crate::{Array, ArrayAccessor, ArrayRef, GenericByteArray, OffsetSizeTrait, Scalar};
use arrow_buffer::{ArrowNativeType, Buffer, NullBuffer, ScalarBuffer};
use arrow_data::{ArrayData, ArrayDataBuilder, ByteView};
use arrow_schema::{ArrowError, DataType};
use core::str;
use num::ToPrimitive;
use std::any::Any;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::sync::Arc;
use super::ByteArrayType;
/// [Variable-size Binary View Layout]: An array of variable length bytes views.
///
/// This array type is used to store variable length byte data (e.g. Strings, Binary)
/// and has efficient operations such as `take`, `filter`, and comparison.
///
/// [Variable-size Binary View Layout]: https://arrow.apache.org/docs/format/Columnar.html#variable-size-binary-view-layout
///
/// This is different from [`GenericByteArray`], which also stores variable
/// length byte data, as it represents strings with an offset and length. `take`
/// and `filter` like operations are implemented by manipulating the "views"
/// (`u128`) without modifying the bytes. Each view also stores an inlined
/// prefix which speed up comparisons.
///
/// # See Also
///
/// * [`StringViewArray`] for storing utf8 encoded string data
/// * [`BinaryViewArray`] for storing bytes
/// * [`ByteView`] to interpret `u128`s layout of the views.
///
/// [`ByteView`]: arrow_data::ByteView
///
/// # Use the [`eq`] kernel to compare the logical content.
///
/// Comparing two `GenericByteViewArray` using PartialEq compares by structure
/// (the `u128`s) and contents of the buffers, not by logical content. As there
/// are many different buffer layouts to represent the same data (e.g. different
/// offsets, different buffer sizes, etc) two arrays with the same data may not
/// compare equal.
///
/// To compare the logical content of two `GenericByteViewArray`s, use the [`eq`]
/// kernel.
///
/// [`eq`]: https://docs.rs/arrow/latest/arrow/compute/kernels/cmp/fn.eq.html
///
/// # Layout: "views" and buffers
///
/// A `GenericByteViewArray` stores variable length byte strings. An array of
/// `N` elements is stored as `N` fixed length "views" and a variable number
/// of variable length "buffers".
///
/// Each view is a `u128` value whose layout is different depending on the
/// length of the string stored at that location:
///
/// ```text
/// ┌──────┬────────────────────────┐
/// │length│ string value │
/// Strings (len <= 12) │ │ (padded with 0) │
/// └──────┴────────────────────────┘
/// 0 31 127
///
/// ┌───────┬───────┬───────┬───────┐
/// │length │prefix │ buf │offset │
/// Strings (len > 12) │ │ │ index │ │
/// └───────┴───────┴───────┴───────┘
/// 0 31 63 95 127
/// ```
///
/// * Strings with length <= 12 are stored directly in the view. See
/// [`Self::inline_value`] to access the inlined prefix from a short view.
///
/// * Strings with length > 12: The first four bytes are stored inline in the
/// view and the entire string is stored in one of the buffers. See [`ByteView`]
/// to access the fields of the these views.
///
/// As with other arrays, the optimized kernels in [`arrow_compute`] are likely
/// the easiest and fastest way to work with this data. However, it is possible
/// to access the views and buffers directly for more control.
///
/// For example
///
/// ```rust
/// # use arrow_array::StringViewArray;
/// # use arrow_array::Array;
/// use arrow_data::ByteView;
/// let array = StringViewArray::from(vec![
/// "hello",
/// "this string is longer than 12 bytes",
/// "this string is also longer than 12 bytes"
/// ]);
///
/// // ** Examine the first view (short string) **
/// assert!(array.is_valid(0)); // Check for nulls
/// let short_view: u128 = array.views()[0]; // "hello"
/// // get length of the string
/// let len = short_view as u32;
/// assert_eq!(len, 5); // strings less than 12 bytes are stored in the view
/// // SAFETY: `view` is a valid view
/// let value = unsafe {
/// StringViewArray::inline_value(&short_view, len as usize)
/// };
/// assert_eq!(value, b"hello");
///
/// // ** Examine the third view (long string) **
/// assert!(array.is_valid(12)); // Check for nulls
/// let long_view: u128 = array.views()[2]; // "this string is also longer than 12 bytes"
/// let len = long_view as u32;
/// assert_eq!(len, 40); // strings longer than 12 bytes are stored in the buffer
/// let view = ByteView::from(long_view); // use ByteView to access the fields
/// assert_eq!(view.length, 40);
/// assert_eq!(view.buffer_index, 0);
/// assert_eq!(view.offset, 35); // data starts after the first long string
/// // Views for long strings store a 4 byte prefix
/// let prefix = view.prefix.to_le_bytes();
/// assert_eq!(&prefix, b"this");
/// let value = array.value(2); // get the string value (see `value` implementation for how to access the bytes directly)
/// assert_eq!(value, "this string is also longer than 12 bytes");
/// ```
///
/// [`arrow_compute`]: https://docs.rs/arrow/latest/arrow/compute/index.html
///
/// Unlike [`GenericByteArray`], there are no constraints on the offsets other
/// than they must point into a valid buffer. However, they can be out of order,
/// non continuous and overlapping.
///
/// For example, in the following diagram, the strings "FishWasInTownToday" and
/// "CrumpleFacedFish" are both longer than 12 bytes and thus are stored in a
/// separate buffer while the string "LavaMonster" is stored inlined in the
/// view. In this case, the same bytes for "Fish" are used to store both strings.
///
/// [`ByteView`]: arrow_data::ByteView
///
/// ```text
/// ┌───┐
/// ┌──────┬──────┬──────┬──────┐ offset │...│
/// "FishWasInTownTodayYay" │ 21 │ Fish │ 0 │ 115 │─ ─ 103 │Mr.│
/// └──────┴──────┴──────┴──────┘ │ ┌ ─ ─ ─ ─ ▶ │Cru│
/// ┌──────┬──────┬──────┬──────┐ │mpl│
/// "CrumpleFacedFish" │ 16 │ Crum │ 0 │ 103 │─ ─│─ ─ ─ ┘ │eFa│
/// └──────┴──────┴──────┴──────┘ │ced│
/// ┌──────┬────────────────────┐ └ ─ ─ ─ ─ ─ ─ ─ ─ ▶│Fis│
/// "LavaMonster" │ 11 │ LavaMonster\0 │ │hWa│
/// └──────┴────────────────────┘ offset │sIn│
/// 115 │Tow│
/// │nTo│
/// │day│
/// u128 "views" │Yay│
/// buffer 0 │...│
/// └───┘
/// ```
pub struct GenericByteViewArray<T: ByteViewType + ?Sized> {
data_type: DataType,
views: ScalarBuffer<u128>,
buffers: Vec<Buffer>,
phantom: PhantomData<T>,
nulls: Option<NullBuffer>,
}
impl<T: ByteViewType + ?Sized> Clone for GenericByteViewArray<T> {
fn clone(&self) -> Self {
Self {
data_type: T::DATA_TYPE,
views: self.views.clone(),
buffers: self.buffers.clone(),
nulls: self.nulls.clone(),
phantom: Default::default(),
}
}
}
// PartialEq
impl<T: ByteViewType + ?Sized> PartialEq for GenericByteViewArray<T> {
fn eq(&self, other: &Self) -> bool {
other.data_type.eq(&self.data_type)
&& other.views.eq(&self.views)
&& other.buffers.eq(&self.buffers)
&& other.nulls.eq(&self.nulls)
}
}
impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
/// Create a new [`GenericByteViewArray`] from the provided parts, panicking on failure
///
/// # Panics
///
/// Panics if [`GenericByteViewArray::try_new`] returns an error
pub fn new(views: ScalarBuffer<u128>, buffers: Vec<Buffer>, nulls: Option<NullBuffer>) -> Self {
Self::try_new(views, buffers, nulls).unwrap()
}
/// Create a new [`GenericByteViewArray`] from the provided parts, returning an error on failure
///
/// # Errors
///
/// * `views.len() != nulls.len()`
/// * [ByteViewType::validate] fails
pub fn try_new(
views: ScalarBuffer<u128>,
buffers: Vec<Buffer>,
nulls: Option<NullBuffer>,
) -> Result<Self, ArrowError> {
T::validate(&views, &buffers)?;
if let Some(n) = nulls.as_ref() {
if n.len() != views.len() {
return Err(ArrowError::InvalidArgumentError(format!(
"Incorrect length of null buffer for {}ViewArray, expected {} got {}",
T::PREFIX,
views.len(),
n.len(),
)));
}
}
Ok(Self {
data_type: T::DATA_TYPE,
views,
buffers,
nulls,
phantom: Default::default(),
})
}
/// Create a new [`GenericByteViewArray`] from the provided parts, without validation
///
/// # Safety
///
/// Safe if [`Self::try_new`] would not error
pub unsafe fn new_unchecked(
views: ScalarBuffer<u128>,
buffers: Vec<Buffer>,
nulls: Option<NullBuffer>,
) -> Self {
Self {
data_type: T::DATA_TYPE,
phantom: Default::default(),
views,
buffers,
nulls,
}
}
/// Create a new [`GenericByteViewArray`] of length `len` where all values are null
pub fn new_null(len: usize) -> Self {
Self {
data_type: T::DATA_TYPE,
views: vec![0; len].into(),
buffers: vec![],
nulls: Some(NullBuffer::new_null(len)),
phantom: Default::default(),
}
}
/// Create a new [`Scalar`] from `value`
pub fn new_scalar(value: impl AsRef<T::Native>) -> Scalar<Self> {
Scalar::new(Self::from_iter_values(std::iter::once(value)))
}
/// Creates a [`GenericByteViewArray`] based on an iterator of values without nulls
pub fn from_iter_values<Ptr, I>(iter: I) -> Self
where
Ptr: AsRef<T::Native>,
I: IntoIterator<Item = Ptr>,
{
let iter = iter.into_iter();
let mut builder = GenericByteViewBuilder::<T>::with_capacity(iter.size_hint().0);
for v in iter {
builder.append_value(v);
}
builder.finish()
}
/// Deconstruct this array into its constituent parts
pub fn into_parts(self) -> (ScalarBuffer<u128>, Vec<Buffer>, Option<NullBuffer>) {
(self.views, self.buffers, self.nulls)
}
/// Returns the views buffer
#[inline]
pub fn views(&self) -> &ScalarBuffer<u128> {
&self.views
}
/// Returns the buffers storing string data
#[inline]
pub fn data_buffers(&self) -> &[Buffer] {
&self.buffers
}
/// Returns the element at index `i`
/// # Panics
/// Panics if index `i` is out of bounds.
pub fn value(&self, i: usize) -> &T::Native {
assert!(
i < self.len(),
"Trying to access an element at index {} from a {}ViewArray of length {}",
i,
T::PREFIX,
self.len()
);
unsafe { self.value_unchecked(i) }
}
/// Returns the element at index `i` without bounds checking
///
/// # Safety
///
/// Caller is responsible for ensuring that the index is within the bounds
/// of the array
pub unsafe fn value_unchecked(&self, idx: usize) -> &T::Native {
let v = self.views.get_unchecked(idx);
let len = *v as u32;
let b = if len <= 12 {
Self::inline_value(v, len as usize)
} else {
let view = ByteView::from(*v);
let data = self.buffers.get_unchecked(view.buffer_index as usize);
let offset = view.offset as usize;
data.get_unchecked(offset..offset + len as usize)
};
T::Native::from_bytes_unchecked(b)
}
/// Returns the first `len` bytes the inline value of the view.
///
/// # Safety
/// - The `view` must be a valid element from `Self::views()` that adheres to the view layout.
/// - The `len` must be the length of the inlined value. It should never be larger than 12.
#[inline(always)]
pub unsafe fn inline_value(view: &u128, len: usize) -> &[u8] {
debug_assert!(len <= 12);
std::slice::from_raw_parts((view as *const u128 as *const u8).wrapping_add(4), len)
}
/// Constructs a new iterator for iterating over the values of this array
pub fn iter(&self) -> ArrayIter<&Self> {
ArrayIter::new(self)
}
/// Returns an iterator over the bytes of this array, including null values
pub fn bytes_iter(&self) -> impl Iterator<Item = &[u8]> {
self.views.iter().map(move |v| {
let len = *v as u32;
if len <= 12 {
unsafe { Self::inline_value(v, len as usize) }
} else {
let view = ByteView::from(*v);
let data = &self.buffers[view.buffer_index as usize];
let offset = view.offset as usize;
unsafe { data.get_unchecked(offset..offset + len as usize) }
}
})
}
/// Returns an iterator over the first `prefix_len` bytes of each array
/// element, including null values.
///
/// If `prefix_len` is larger than the element's length, the iterator will
/// return an empty slice (`&[]`).
pub fn prefix_bytes_iter(&self, prefix_len: usize) -> impl Iterator<Item = &[u8]> {
self.views().into_iter().map(move |v| {
let len = (*v as u32) as usize;
if len < prefix_len {
return &[] as &[u8];
}
if prefix_len <= 4 || len <= 12 {
unsafe { StringViewArray::inline_value(v, prefix_len) }
} else {
let view = ByteView::from(*v);
let data = unsafe {
self.data_buffers()
.get_unchecked(view.buffer_index as usize)
};
let offset = view.offset as usize;
unsafe { data.get_unchecked(offset..offset + prefix_len) }
}
})
}
/// Returns an iterator over the last `suffix_len` bytes of each array
/// element, including null values.
///
/// Note that for [`StringViewArray`] the last bytes may start in the middle
/// of a UTF-8 codepoint, and thus may not be a valid `&str`.
///
/// If `suffix_len` is larger than the element's length, the iterator will
/// return an empty slice (`&[]`).
pub fn suffix_bytes_iter(&self, suffix_len: usize) -> impl Iterator<Item = &[u8]> {
self.views().into_iter().map(move |v| {
let len = (*v as u32) as usize;
if len < suffix_len {
return &[] as &[u8];
}
if len <= 12 {
unsafe { &StringViewArray::inline_value(v, len)[len - suffix_len..] }
} else {
let view = ByteView::from(*v);
let data = unsafe {
self.data_buffers()
.get_unchecked(view.buffer_index as usize)
};
let offset = view.offset as usize;
unsafe { data.get_unchecked(offset + len - suffix_len..offset + len) }
}
})
}
/// Returns a zero-copy slice of this array with the indicated offset and length.
pub fn slice(&self, offset: usize, length: usize) -> Self {
Self {
data_type: T::DATA_TYPE,
views: self.views.slice(offset, length),
buffers: self.buffers.clone(),
nulls: self.nulls.as_ref().map(|n| n.slice(offset, length)),
phantom: Default::default(),
}
}
/// Returns a "compacted" version of this array
///
/// The original array will *not* be modified
///
/// # Garbage Collection
///
/// Before GC:
/// ```text
/// ┌──────┐
/// │......│
/// │......│
/// ┌────────────────────┐ ┌ ─ ─ ─ ▶ │Data1 │ Large buffer
/// │ View 1 │─ ─ ─ ─ │......│ with data that
/// ├────────────────────┤ │......│ is not referred
/// │ View 2 │─ ─ ─ ─ ─ ─ ─ ─▶ │Data2 │ to by View 1 or
/// └────────────────────┘ │......│ View 2
/// │......│
/// 2 views, refer to │......│
/// small portions of a └──────┘
/// large buffer
/// ```
///
/// After GC:
///
/// ```text
/// ┌────────────────────┐ ┌─────┐ After gc, only
/// │ View 1 │─ ─ ─ ─ ─ ─ ─ ─▶ │Data1│ data that is
/// ├────────────────────┤ ┌ ─ ─ ─ ▶ │Data2│ pointed to by
/// │ View 2 │─ ─ ─ ─ └─────┘ the views is
/// └────────────────────┘ left
///
///
/// 2 views
/// ```
/// This method will compact the data buffers by recreating the view array and only include the data
/// that is pointed to by the views.
///
/// Note that it will copy the array regardless of whether the original array is compact.
/// Use with caution as this can be an expensive operation, only use it when you are sure that the view
/// array is significantly smaller than when it is originally created, e.g., after filtering or slicing.
///
/// Note: this function does not attempt to canonicalize / deduplicate values. For this
/// feature see [`GenericByteViewBuilder::with_deduplicate_strings`].
pub fn gc(&self) -> Self {
let mut builder = GenericByteViewBuilder::<T>::with_capacity(self.len());
for v in self.iter() {
builder.append_option(v);
}
builder.finish()
}
/// Compare two [`GenericByteViewArray`] at index `left_idx` and `right_idx`
///
/// Comparing two ByteView types are non-trivial.
/// It takes a bit of patience to understand why we don't just compare two &[u8] directly.
///
/// ByteView types give us the following two advantages, and we need to be careful not to lose them:
/// (1) For string/byte smaller than 12 bytes, the entire data is inlined in the view.
/// Meaning that reading one array element requires only one memory access
/// (two memory access required for StringArray, one for offset buffer, the other for value buffer).
///
/// (2) For string/byte larger than 12 bytes, we can still be faster than (for certain operations) StringArray/ByteArray,
/// thanks to the inlined 4 bytes.
/// Consider equality check:
/// If the first four bytes of the two strings are different, we can return false immediately (with just one memory access).
///
/// If we directly compare two &[u8], we materialize the entire string (i.e., make multiple memory accesses), which might be unnecessary.
/// - Most of the time (eq, ord), we only need to look at the first 4 bytes to know the answer,
/// e.g., if the inlined 4 bytes are different, we can directly return unequal without looking at the full string.
///
/// # Order check flow
/// (1) if both string are smaller than 12 bytes, we can directly compare the data inlined to the view.
/// (2) if any of the string is larger than 12 bytes, we need to compare the full string.
/// (2.1) if the inlined 4 bytes are different, we can return the result immediately.
/// (2.2) o.w., we need to compare the full string.
///
/// # Safety
/// The left/right_idx must within range of each array
pub unsafe fn compare_unchecked(
left: &GenericByteViewArray<T>,
left_idx: usize,
right: &GenericByteViewArray<T>,
right_idx: usize,
) -> std::cmp::Ordering {
let l_view = left.views().get_unchecked(left_idx);
let l_len = *l_view as u32;
let r_view = right.views().get_unchecked(right_idx);
let r_len = *r_view as u32;
if l_len <= 12 && r_len <= 12 {
let l_data = unsafe { GenericByteViewArray::<T>::inline_value(l_view, l_len as usize) };
let r_data = unsafe { GenericByteViewArray::<T>::inline_value(r_view, r_len as usize) };
return l_data.cmp(r_data);
}
// one of the string is larger than 12 bytes,
// we then try to compare the inlined data first
let l_inlined_data = unsafe { GenericByteViewArray::<T>::inline_value(l_view, 4) };
let r_inlined_data = unsafe { GenericByteViewArray::<T>::inline_value(r_view, 4) };
if r_inlined_data != l_inlined_data {
return l_inlined_data.cmp(r_inlined_data);
}
// unfortunately, we need to compare the full data
let l_full_data: &[u8] = unsafe { left.value_unchecked(left_idx).as_ref() };
let r_full_data: &[u8] = unsafe { right.value_unchecked(right_idx).as_ref() };
l_full_data.cmp(r_full_data)
}
}
impl<T: ByteViewType + ?Sized> Debug for GenericByteViewArray<T> {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(f, "{}ViewArray\n[\n", T::PREFIX)?;
print_long_array(self, f, |array, index, f| {
std::fmt::Debug::fmt(&array.value(index), f)
})?;
write!(f, "]")
}
}
impl<T: ByteViewType + ?Sized> Array for GenericByteViewArray<T> {
fn as_any(&self) -> &dyn Any {
self
}
fn to_data(&self) -> ArrayData {
self.clone().into()
}
fn into_data(self) -> ArrayData {
self.into()
}
fn data_type(&self) -> &DataType {
&self.data_type
}
fn slice(&self, offset: usize, length: usize) -> ArrayRef {
Arc::new(self.slice(offset, length))
}
fn len(&self) -> usize {
self.views.len()
}
fn is_empty(&self) -> bool {
self.views.is_empty()
}
fn offset(&self) -> usize {
0
}
fn nulls(&self) -> Option<&NullBuffer> {
self.nulls.as_ref()
}
fn get_buffer_memory_size(&self) -> usize {
let mut sum = self.buffers.iter().map(|b| b.capacity()).sum::<usize>();
sum += self.views.inner().capacity();
if let Some(x) = &self.nulls {
sum += x.buffer().capacity()
}
sum
}
fn get_array_memory_size(&self) -> usize {
std::mem::size_of::<Self>() + self.get_buffer_memory_size()
}
}
impl<'a, T: ByteViewType + ?Sized> ArrayAccessor for &'a GenericByteViewArray<T> {
type Item = &'a T::Native;
fn value(&self, index: usize) -> Self::Item {
GenericByteViewArray::value(self, index)
}
unsafe fn value_unchecked(&self, index: usize) -> Self::Item {
GenericByteViewArray::value_unchecked(self, index)
}
}
impl<'a, T: ByteViewType + ?Sized> IntoIterator for &'a GenericByteViewArray<T> {
type Item = Option<&'a T::Native>;
type IntoIter = ArrayIter<Self>;
fn into_iter(self) -> Self::IntoIter {
ArrayIter::new(self)
}
}
impl<T: ByteViewType + ?Sized> From<ArrayData> for GenericByteViewArray<T> {
fn from(value: ArrayData) -> Self {
let views = value.buffers()[0].clone();
let views = ScalarBuffer::new(views, value.offset(), value.len());
let buffers = value.buffers()[1..].to_vec();
Self {
data_type: T::DATA_TYPE,
views,
buffers,
nulls: value.nulls().cloned(),
phantom: Default::default(),
}
}
}
/// Efficiently convert a [`GenericByteArray`] to a [`GenericByteViewArray`]
///
/// For example this method can convert a [`StringArray`] to a
/// [`StringViewArray`].
///
/// If the offsets are all less than u32::MAX, the new [`GenericByteViewArray`]
/// is built without copying the underlying string data (views are created
/// directly into the existing buffer)
///
/// [`StringArray`]: crate::StringArray
impl<FROM, V> From<&GenericByteArray<FROM>> for GenericByteViewArray<V>
where
FROM: ByteArrayType,
FROM::Offset: OffsetSizeTrait + ToPrimitive,
V: ByteViewType<Native = FROM::Native>,
{
fn from(byte_array: &GenericByteArray<FROM>) -> Self {
let offsets = byte_array.offsets();
let can_reuse_buffer = match offsets.last() {
Some(offset) => offset.as_usize() < u32::MAX as usize,
None => true,
};
if can_reuse_buffer {
// build views directly pointing to the existing buffer
let len = byte_array.len();
let mut views_builder = GenericByteViewBuilder::<V>::with_capacity(len);
let str_values_buf = byte_array.values().clone();
let block = views_builder.append_block(str_values_buf);
for (i, w) in offsets.windows(2).enumerate() {
let offset = w[0].as_usize();
let end = w[1].as_usize();
let length = end - offset;
if byte_array.is_null(i) {
views_builder.append_null();
} else {
// Safety: the input was a valid array so it valid UTF8 (if string). And
// all offsets were valid
unsafe {
views_builder.append_view_unchecked(block, offset as u32, length as u32)
}
}
}
assert_eq!(views_builder.len(), len);
views_builder.finish()
} else {
// Otherwise, create a new buffer for large strings
// TODO: the original buffer could still be used
// by making multiple slices of u32::MAX length
GenericByteViewArray::<V>::from_iter(byte_array.iter())
}
}
}
impl<T: ByteViewType + ?Sized> From<GenericByteViewArray<T>> for ArrayData {
fn from(mut array: GenericByteViewArray<T>) -> Self {
let len = array.len();
array.buffers.insert(0, array.views.into_inner());
let builder = ArrayDataBuilder::new(T::DATA_TYPE)
.len(len)
.buffers(array.buffers)
.nulls(array.nulls);
unsafe { builder.build_unchecked() }
}
}
impl<'a, Ptr, T> FromIterator<&'a Option<Ptr>> for GenericByteViewArray<T>
where
Ptr: AsRef<T::Native> + 'a,
T: ByteViewType + ?Sized,
{
fn from_iter<I: IntoIterator<Item = &'a Option<Ptr>>>(iter: I) -> Self {
iter.into_iter()
.map(|o| o.as_ref().map(|p| p.as_ref()))
.collect()
}
}
impl<Ptr, T: ByteViewType + ?Sized> FromIterator<Option<Ptr>> for GenericByteViewArray<T>
where
Ptr: AsRef<T::Native>,
{
fn from_iter<I: IntoIterator<Item = Option<Ptr>>>(iter: I) -> Self {
let iter = iter.into_iter();
let mut builder = GenericByteViewBuilder::<T>::with_capacity(iter.size_hint().0);
builder.extend(iter);
builder.finish()
}
}
/// A [`GenericByteViewArray`] of `[u8]`
///
/// See [`GenericByteViewArray`] for format and layout details.
///
/// # Example
/// ```
/// use arrow_array::BinaryViewArray;
/// let array = BinaryViewArray::from_iter_values(vec![b"hello" as &[u8], b"world", b"lulu", b"large payload over 12 bytes"]);
/// assert_eq!(array.value(0), b"hello");
/// assert_eq!(array.value(3), b"large payload over 12 bytes");
/// ```
pub type BinaryViewArray = GenericByteViewArray<BinaryViewType>;
impl BinaryViewArray {
/// Convert the [`BinaryViewArray`] to [`StringViewArray`]
/// If items not utf8 data, validate will fail and error returned.
pub fn to_string_view(self) -> Result<StringViewArray, ArrowError> {
StringViewType::validate(self.views(), self.data_buffers())?;
unsafe { Ok(self.to_string_view_unchecked()) }
}
/// Convert the [`BinaryViewArray`] to [`StringViewArray`]
/// # Safety
/// Caller is responsible for ensuring that items in array are utf8 data.
pub unsafe fn to_string_view_unchecked(self) -> StringViewArray {
StringViewArray::new_unchecked(self.views, self.buffers, self.nulls)
}
}
impl From<Vec<&[u8]>> for BinaryViewArray {
fn from(v: Vec<&[u8]>) -> Self {
Self::from_iter_values(v)
}
}
impl From<Vec<Option<&[u8]>>> for BinaryViewArray {
fn from(v: Vec<Option<&[u8]>>) -> Self {
v.into_iter().collect()
}
}
/// A [`GenericByteViewArray`] that stores utf8 data
///
/// See [`GenericByteViewArray`] for format and layout details.
///
/// # Example
/// ```
/// use arrow_array::StringViewArray;
/// let array = StringViewArray::from_iter_values(vec!["hello", "world", "lulu", "large payload over 12 bytes"]);
/// assert_eq!(array.value(0), "hello");
/// assert_eq!(array.value(3), "large payload over 12 bytes");
/// ```
pub type StringViewArray = GenericByteViewArray<StringViewType>;
impl StringViewArray {
/// Convert the [`StringViewArray`] to [`BinaryViewArray`]
pub fn to_binary_view(self) -> BinaryViewArray {
unsafe { BinaryViewArray::new_unchecked(self.views, self.buffers, self.nulls) }
}
/// Returns true if all data within this array is ASCII
pub fn is_ascii(&self) -> bool {
// Alternative (but incorrect): directly check the underlying buffers
// (1) Our string view might be sparse, i.e., a subset of the buffers,
// so even if the buffer is not ascii, we can still be ascii.
// (2) It is quite difficult to know the range of each buffer (unlike StringArray)
// This means that this operation is quite expensive, shall we cache the result?
// i.e. track `is_ascii` in the builder.
self.iter().all(|v| match v {
Some(v) => v.is_ascii(),
None => true,
})
}
}
impl From<Vec<&str>> for StringViewArray {
fn from(v: Vec<&str>) -> Self {
Self::from_iter_values(v)
}
}
impl From<Vec<Option<&str>>> for StringViewArray {
fn from(v: Vec<Option<&str>>) -> Self {
v.into_iter().collect()
}
}
impl From<Vec<String>> for StringViewArray {
fn from(v: Vec<String>) -> Self {
Self::from_iter_values(v)
}
}
impl From<Vec<Option<String>>> for StringViewArray {
fn from(v: Vec<Option<String>>) -> Self {
v.into_iter().collect()
}
}
#[cfg(test)]
mod tests {
use crate::builder::{BinaryViewBuilder, StringViewBuilder};
use crate::{Array, BinaryViewArray, StringViewArray};
use arrow_buffer::{Buffer, ScalarBuffer};
use arrow_data::ByteView;
#[test]
fn try_new_string() {
let array = StringViewArray::from_iter_values(vec![
"hello",
"world",
"lulu",
"large payload over 12 bytes",
]);
assert_eq!(array.value(0), "hello");
assert_eq!(array.value(3), "large payload over 12 bytes");
}
#[test]
fn try_new_binary() {
let array = BinaryViewArray::from_iter_values(vec![
b"hello".as_slice(),
b"world".as_slice(),
b"lulu".as_slice(),
b"large payload over 12 bytes".as_slice(),
]);
assert_eq!(array.value(0), b"hello");
assert_eq!(array.value(3), b"large payload over 12 bytes");
}
#[test]
fn try_new_empty_string() {
// test empty array
let array = {
let mut builder = StringViewBuilder::new();
builder.finish()
};
assert!(array.is_empty());
}
#[test]
fn try_new_empty_binary() {
// test empty array
let array = {
let mut builder = BinaryViewBuilder::new();
builder.finish()
};
assert!(array.is_empty());
}
#[test]
fn test_append_string() {
// test builder append
let array = {
let mut builder = StringViewBuilder::new();
builder.append_value("hello");
builder.append_null();
builder.append_option(Some("large payload over 12 bytes"));
builder.finish()
};
assert_eq!(array.value(0), "hello");
assert!(array.is_null(1));
assert_eq!(array.value(2), "large payload over 12 bytes");
}
#[test]
fn test_append_binary() {
// test builder append
let array = {
let mut builder = BinaryViewBuilder::new();
builder.append_value(b"hello");
builder.append_null();
builder.append_option(Some(b"large payload over 12 bytes"));
builder.finish()
};
assert_eq!(array.value(0), b"hello");
assert!(array.is_null(1));
assert_eq!(array.value(2), b"large payload over 12 bytes");
}
#[test]
fn test_in_progress_recreation() {
let array = {
// make a builder with small block size.
let mut builder = StringViewBuilder::new().with_fixed_block_size(14);
builder.append_value("large payload over 12 bytes");
builder.append_option(Some("another large payload over 12 bytes that double than the first one, so that we can trigger the in_progress in builder re-created"));
builder.finish()
};
assert_eq!(array.value(0), "large payload over 12 bytes");
assert_eq!(array.value(1), "another large payload over 12 bytes that double than the first one, so that we can trigger the in_progress in builder re-created");
assert_eq!(2, array.buffers.len());
}
#[test]
#[should_panic(expected = "Invalid buffer index at 0: got index 3 but only has 1 buffers")]
fn new_with_invalid_view_data() {
let v = "large payload over 12 bytes";
let view = ByteView::new(13, &v.as_bytes()[0..4])
.with_buffer_index(3)
.with_offset(1);
let views = ScalarBuffer::from(vec![view.into()]);
let buffers = vec![Buffer::from_slice_ref(v)];
StringViewArray::new(views, buffers, None);
}
#[test]
#[should_panic(
expected = "Encountered non-UTF-8 data at index 0: invalid utf-8 sequence of 1 bytes from index 0"
)]
fn new_with_invalid_utf8_data() {
let v: Vec<u8> = vec![
// invalid UTF8
0xf0, 0x80, 0x80, 0x80, // more bytes to make it larger than 12
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
];
let view = ByteView::new(v.len() as u32, &v[0..4]);
let views = ScalarBuffer::from(vec![view.into()]);
let buffers = vec![Buffer::from_slice_ref(v)];
StringViewArray::new(views, buffers, None);
}
#[test]
#[should_panic(expected = "View at index 0 contained non-zero padding for string of length 1")]
fn new_with_invalid_zero_padding() {
let mut data = [0; 12];
data[0] = b'H';
data[11] = 1; // no zero padding
let mut view_buffer = [0; 16];
view_buffer[0..4].copy_from_slice(&1u32.to_le_bytes());
view_buffer[4..].copy_from_slice(&data);
let view = ByteView::from(u128::from_le_bytes(view_buffer));
let views = ScalarBuffer::from(vec![view.into()]);
let buffers = vec![];
StringViewArray::new(views, buffers, None);
}
#[test]
#[should_panic(expected = "Mismatch between embedded prefix and data")]
fn test_mismatch_between_embedded_prefix_and_data() {
let input_str_1 = "Hello, Rustaceans!";
let input_str_2 = "Hallo, Rustaceans!";
let length = input_str_1.len() as u32;
assert!(input_str_1.len() > 12);
let mut view_buffer = [0; 16];
view_buffer[0..4].copy_from_slice(&length.to_le_bytes());
view_buffer[4..8].copy_from_slice(&input_str_1.as_bytes()[0..4]);
view_buffer[8..12].copy_from_slice(&0u32.to_le_bytes());
view_buffer[12..].copy_from_slice(&0u32.to_le_bytes());
let view = ByteView::from(u128::from_le_bytes(view_buffer));
let views = ScalarBuffer::from(vec![view.into()]);
let buffers = vec![Buffer::from_slice_ref(input_str_2.as_bytes())];
StringViewArray::new(views, buffers, None);
}
#[test]
fn test_gc() {
let test_data = [
Some("longer than 12 bytes"),
Some("short"),
Some("t"),
Some("longer than 12 bytes"),
None,
Some("short"),
];
let array = {
let mut builder = StringViewBuilder::new().with_fixed_block_size(8); // create multiple buffers
test_data.into_iter().for_each(|v| builder.append_option(v));
builder.finish()
};
assert!(array.buffers.len() > 1);
fn check_gc(to_test: &StringViewArray) {
let gc = to_test.gc();
assert_ne!(to_test.data_buffers().len(), gc.data_buffers().len());
to_test.iter().zip(gc.iter()).for_each(|(a, b)| {
assert_eq!(a, b);
});
assert_eq!(to_test.len(), gc.len());
}
check_gc(&array);
check_gc(&array.slice(1, 3));
check_gc(&array.slice(2, 1));
check_gc(&array.slice(2, 2));
check_gc(&array.slice(3, 1));
}
#[test]
fn test_eq() {
let test_data = [
Some("longer than 12 bytes"),
None,
Some("short"),
Some("again, this is longer than 12 bytes"),
];
let array1 = {
let mut builder = StringViewBuilder::new().with_fixed_block_size(8);
test_data.into_iter().for_each(|v| builder.append_option(v));
builder.finish()
};
let array2 = {
// create a new array with the same data but different layout
let mut builder = StringViewBuilder::new().with_fixed_block_size(100);
test_data.into_iter().for_each(|v| builder.append_option(v));
builder.finish()
};
assert_eq!(array1, array1.clone());
assert_eq!(array2, array2.clone());
assert_ne!(array1, array2);
}
}