tustvold commented on code in PR #5318: URL: https://github.com/apache/arrow-rs/pull/5318#discussion_r1465595120
########## arrow-json/src/writer/encoder.rs: ########## @@ -0,0 +1,436 @@ +// 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 arrow_array::cast::AsArray; +use arrow_array::types::*; +use arrow_array::*; +use arrow_buffer::{ArrowNativeType, NullBuffer, OffsetBuffer, ScalarBuffer}; +use arrow_cast::display::{ArrayFormatter, FormatOptions}; +use arrow_schema::{ArrowError, DataType, FieldRef}; +use half::f16; +use lexical_core::FormattedSize; +use serde::Serializer; +use std::io::Write; + +#[derive(Debug, Clone, Default)] +pub struct EncoderOptions { + pub explicit_nulls: bool, +} + +pub trait Encoder { + fn encode(&mut self, idx: usize, out: &mut Vec<u8>); +} + +pub fn make_encoder<'a>( + array: &'a dyn Array, + options: &EncoderOptions, +) -> Result<Box<dyn Encoder + 'a>, ArrowError> { + let (encoder, nulls) = make_encoder_impl(array, options)?; + assert!(nulls.is_none(), "root cannot be nullable"); + Ok(encoder) +} + +fn make_encoder_impl<'a>( + array: &'a dyn Array, + options: &EncoderOptions, +) -> Result<(Box<dyn Encoder + 'a>, Option<NullBuffer>), ArrowError> { + macro_rules! primitive_helper { + ($t:ty) => {{ + let array = array.as_primitive::<$t>(); + let nulls = array.nulls().cloned(); + (Box::new(PrimitiveEncoder::new(array)) as _, nulls) + }}; + } + + Ok(downcast_integer! { + array.data_type() => (primitive_helper), + DataType::Float16 => primitive_helper!(Float16Type), + DataType::Float32 => primitive_helper!(Float32Type), + DataType::Float64 => primitive_helper!(Float64Type), + DataType::Boolean => { + let array = array.as_boolean(); + (Box::new(BooleanEncoder(array.clone())), array.nulls().cloned()) + } + DataType::Null => (Box::new(NullEncoder), array.logical_nulls()), + DataType::Utf8 => { + let array = array.as_string::<i32>(); + (Box::new(StringEncoder(array.clone())) as _, array.nulls().cloned()) + } + DataType::LargeUtf8 => { + let array = array.as_string::<i64>(); + (Box::new(StringEncoder(array.clone())) as _, array.nulls().cloned()) + } + DataType::List(_) => { + let array = array.as_list::<i32>(); + (Box::new(ListEncoder::try_new(array, options)?) as _, array.nulls().cloned()) + } + DataType::LargeList(_) => { + let array = array.as_list::<i64>(); + (Box::new(ListEncoder::try_new(array, options)?) as _, array.nulls().cloned()) + } + + DataType::Dictionary(_, _) => downcast_dictionary_array! { + array => (Box::new(DictionaryEncoder::try_new(array, options)?) as _, array.logical_nulls()), + _ => unreachable!() + } + + DataType::Map(_, _) => { + let array = array.as_map(); + (Box::new(MapEncoder::try_new(array, options)?) as _, array.nulls().cloned()) + } + + DataType::Struct(fields) => { + let array = array.as_struct(); + let encoders = fields.iter().zip(array.columns()).map(|(field, array)| { + let (encoder, nulls) = make_encoder_impl(array, options)?; + Ok(FieldEncoder{ + field: field.clone(), + encoder, nulls + }) + }).collect::<Result<Vec<_>, ArrowError>>()?; + + let encoder = StructArrayEncoder{ + encoders, + explicit_nulls: options.explicit_nulls, + }; + (Box::new(encoder) as _, array.nulls().cloned()) + } + d => match d.is_temporal() { + true => { + // Note: the implementation of Encoder for ArrayFormatter assumes it does not produce + // characters that would need to be escaped within a JSON string, e.g. `'"'`. + // If support for user-provided format specifications is added, this assumption + // may need to be revisited + let options = FormatOptions::new().with_display_error(true); + let formatter = ArrayFormatter::try_new(array, &options)?; + (Box::new(formatter) as _, array.nulls().cloned()) + } + false => return Err(ArrowError::InvalidArgumentError(format!("JSON Writer does not support data type: {d}"))), + } + }) +} + +fn encode_string(s: &str, out: &mut Vec<u8>) { + let mut serializer = serde_json::Serializer::new(out); + serializer.serialize_str(s).unwrap(); +} + +struct FieldEncoder<'a> { + field: FieldRef, + encoder: Box<dyn Encoder + 'a>, + nulls: Option<NullBuffer>, +} + +struct StructArrayEncoder<'a> { + encoders: Vec<FieldEncoder<'a>>, + explicit_nulls: bool, +} + +impl<'a> Encoder for StructArrayEncoder<'a> { + fn encode(&mut self, idx: usize, out: &mut Vec<u8>) { + out.push(b'{'); + let mut is_first = true; + for field_encoder in &mut self.encoders { + let is_null = field_encoder.nulls.as_ref().is_some_and(|n| n.is_null(idx)); + if is_null && !self.explicit_nulls { + continue; + } + + if !is_first { + out.push(b','); + } + is_first = false; + + encode_string(field_encoder.field.name(), out); + out.push(b':'); + + match is_null { + true => out.extend_from_slice(b"null"), + false => field_encoder.encoder.encode(idx, out), + } + } + out.push(b'}'); + } +} + +trait PrimitiveEncode: ArrowNativeType { + type Buffer; + + // Workaround https://github.com/rust-lang/rust/issues/61415 + fn init_buffer() -> Self::Buffer; + + fn encode(self, buf: &mut Self::Buffer) -> &[u8]; +} + +macro_rules! integer_encode { + ($($t:ty),*) => { + $( + impl PrimitiveEncode for $t { + type Buffer = [u8; Self::FORMATTED_SIZE]; + + fn init_buffer() -> Self::Buffer { + [0; Self::FORMATTED_SIZE] + } + + fn encode(self, buf: &mut Self::Buffer) -> &[u8] { + lexical_core::write(self, buf) + } + } + )* + }; +} +integer_encode!(i8, i16, i32, i64, u8, u16, u32, u64); + +macro_rules! float_encode { + ($($t:ty),*) => { + $( + impl PrimitiveEncode for $t { + type Buffer = [u8; Self::FORMATTED_SIZE]; + + fn init_buffer() -> Self::Buffer { + [0; Self::FORMATTED_SIZE] + } + + fn encode(self, buf: &mut Self::Buffer) -> &[u8] { + if self.is_infinite() || self.is_nan() { + b"null" + } else { + lexical_core::write(self, buf) + } + } + } + )* + }; +} +float_encode!(f32, f64); + +impl PrimitiveEncode for f16 { + type Buffer = <f64 as PrimitiveEncode>::Buffer; Review Comment: Because the formulation of PrimitiveEncoder expects fixed size buffers... Having peeked at f16's display impl, it converts to f32 in order to print and to parse, so will update this to likewise -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
