viirya commented on code in PR #3749: URL: https://github.com/apache/arrow-rs/pull/3749#discussion_r1118368762
########## arrow-data/src/data/bytes.rs: ########## @@ -0,0 +1,288 @@ +// 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::data::types::{BytesType, OffsetType}; +use arrow_buffer::buffer::{NullBuffer, ScalarBuffer}; +use arrow_buffer::{ArrowNativeType, Buffer}; +use arrow_schema::DataType; +use std::marker::PhantomData; + +mod private { + use super::*; + + pub trait BytesSealed { + /// Create from bytes without performing any validation + /// + /// # Safety + /// + /// If `str`, `b` must be a valid UTF-8 sequence + unsafe fn from_bytes_unchecked(b: &[u8]) -> &Self; + + /// Downcast [`ArrayDataBytes`] to `[ArrayDataBytesOffset`] + fn downcast_ref(data: &ArrayDataBytes) -> Option<&ArrayDataBytesOffset<Self>> + where + Self: Bytes; + + /// Downcast [`ArrayDataBytes`] to `[ArrayDataBytesOffset`] + fn downcast(data: ArrayDataBytes) -> Option<ArrayDataBytesOffset<Self>> + where + Self: Bytes; + + /// Cast [`ArrayDataBytesOffset`] to [`ArrayDataBytes`] + fn upcast(v: ArrayDataBytesOffset<Self>) -> ArrayDataBytes + where + Self: Bytes; + } + + pub trait BytesOffsetSealed { + /// Downcast [`ArrayDataBytesOffset`] to `[BytesArrayData`] + fn downcast_ref<B: Bytes + ?Sized>( + data: &ArrayDataBytesOffset<B>, + ) -> Option<&BytesArrayData<Self, B>> + where + Self: BytesOffset; + + /// Downcast [`ArrayDataBytesOffset`] to `[BytesArrayData`] + fn downcast<B: Bytes + ?Sized>( + data: ArrayDataBytesOffset<B>, + ) -> Option<BytesArrayData<Self, B>> + where + Self: BytesOffset; + + /// Cast [`BytesArrayData`] to [`ArrayDataBytesOffset`] + fn upcast<B: Bytes + ?Sized>( + v: BytesArrayData<Self, B>, + ) -> ArrayDataBytesOffset<B> + where + Self: BytesOffset; + } +} + +/// Types backed by a variable length slice of bytes +pub trait Bytes: private::BytesSealed { + const TYPE: BytesType; +} + +impl Bytes for [u8] { + const TYPE: BytesType = BytesType::Binary; +} + +impl private::BytesSealed for [u8] { + unsafe fn from_bytes_unchecked(b: &[u8]) -> &Self { + b + } + + fn downcast_ref(data: &ArrayDataBytes) -> Option<&ArrayDataBytesOffset<Self>> { + match data { + ArrayDataBytes::Binary(v) => Some(v), + ArrayDataBytes::Utf8(_) => None, + } + } + + fn downcast(data: ArrayDataBytes) -> Option<ArrayDataBytesOffset<Self>> { + match data { + ArrayDataBytes::Binary(v) => Some(v), + ArrayDataBytes::Utf8(_) => None, + } + } + + fn upcast(v: ArrayDataBytesOffset<Self>) -> ArrayDataBytes { + ArrayDataBytes::Binary(v) + } +} + +impl Bytes for str { + const TYPE: BytesType = BytesType::Utf8; +} + +impl private::BytesSealed for str { + unsafe fn from_bytes_unchecked(b: &[u8]) -> &Self { + std::str::from_utf8_unchecked(b) + } + + fn downcast_ref(data: &ArrayDataBytes) -> Option<&ArrayDataBytesOffset<Self>> { + match data { + ArrayDataBytes::Binary(_) => None, + ArrayDataBytes::Utf8(v) => Some(v), + } + } + + fn downcast(data: ArrayDataBytes) -> Option<ArrayDataBytesOffset<Self>> { + match data { + ArrayDataBytes::Binary(_) => None, + ArrayDataBytes::Utf8(v) => Some(v), + } + } + + fn upcast(v: ArrayDataBytesOffset<Self>) -> ArrayDataBytes { + ArrayDataBytes::Utf8(v) + } +} + +/// Types of offset used by variable length byte arrays +pub trait BytesOffset: private::BytesOffsetSealed + ArrowNativeType { + const TYPE: OffsetType; +} + +impl BytesOffset for i32 { + const TYPE: OffsetType = OffsetType::Small; +} + +impl private::BytesOffsetSealed for i32 { + fn downcast_ref<B: Bytes + ?Sized>( + data: &ArrayDataBytesOffset<B>, + ) -> Option<&BytesArrayData<Self, B>> { + match data { + ArrayDataBytesOffset::Small(v) => Some(v), + ArrayDataBytesOffset::Large(_) => None, + } + } + + fn downcast<B: Bytes + ?Sized>( + data: ArrayDataBytesOffset<B>, + ) -> Option<BytesArrayData<Self, B>> { + match data { + ArrayDataBytesOffset::Small(v) => Some(v), + ArrayDataBytesOffset::Large(_) => None, + } + } + + fn upcast<B: Bytes + ?Sized>(v: BytesArrayData<Self, B>) -> ArrayDataBytesOffset<B> { + ArrayDataBytesOffset::Small(v) + } +} + +impl BytesOffset for i64 { + const TYPE: OffsetType = OffsetType::Large; +} + +impl private::BytesOffsetSealed for i64 { + fn downcast_ref<B: Bytes + ?Sized>( + data: &ArrayDataBytesOffset<B>, + ) -> Option<&BytesArrayData<Self, B>> { + match data { + ArrayDataBytesOffset::Small(_) => None, + ArrayDataBytesOffset::Large(v) => Some(v), + } + } + + fn downcast<B: Bytes + ?Sized>( + data: ArrayDataBytesOffset<B>, + ) -> Option<BytesArrayData<Self, B>> { + match data { + ArrayDataBytesOffset::Small(_) => None, + ArrayDataBytesOffset::Large(v) => Some(v), + } + } + + fn upcast<B: Bytes + ?Sized>(v: BytesArrayData<Self, B>) -> ArrayDataBytesOffset<B> { + ArrayDataBytesOffset::Large(v) + } +} + +/// An enumeration of the types of [`ArrayDataBytesOffset`] +pub enum ArrayDataBytes { + Binary(ArrayDataBytesOffset<[u8]>), + Utf8(ArrayDataBytesOffset<str>), +} + +impl ArrayDataBytes { + /// Downcast this [`ArrayDataBytes`] to the corresponding [`BytesArrayData`] + pub fn downcast_ref<O: BytesOffset, B: Bytes + ?Sized>( + &self, + ) -> Option<&BytesArrayData<O, B>> { + O::downcast_ref(B::downcast_ref(self)?) + } + + /// Downcast this [`ArrayDataBytes`] to the corresponding [`BytesArrayData`] + pub fn downcast<O: BytesOffset, B: Bytes + ?Sized>( + self, + ) -> Option<BytesArrayData<O, B>> { + O::downcast(B::downcast(self)?) + } +} + +/// An enumeration of the types of [`BytesArrayData`] +pub enum ArrayDataBytesOffset<B: Bytes + ?Sized> { + Small(BytesArrayData<i32, B>), + Large(BytesArrayData<i64, B>), +} + +impl<O: BytesOffset, B: Bytes + ?Sized> From<BytesArrayData<O, B>> for ArrayDataBytes { + fn from(value: BytesArrayData<O, B>) -> Self { + B::upcast(O::upcast(value)) + } +} + +/// ArrayData for arrays of [`Bytes`] +pub struct BytesArrayData<O: BytesOffset, B: Bytes + ?Sized> { + data_type: DataType, + nulls: Option<NullBuffer>, + offsets: ScalarBuffer<O>, + values: Buffer, + phantom: PhantomData<B>, +} + +impl<O: BytesOffset, B: Bytes> BytesArrayData<O, B> { + /// Creates a new [`BytesArrayData`] + /// + /// # Safety + /// + /// - Each consecutive window of `offsets` must identify a valid slice of `values` + /// - `nulls.len() == offsets.len() + 1` + /// - `data_type` must be valid for this layout + pub unsafe fn new_unchecked( Review Comment: Do we need a way to validate it like a `validate` function? -- This is an automated message from the Apache Git Service. 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