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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 std::ops::Deref;
use std::sync::Arc;
use crate::{ArrowError, DataType, Field, FieldRef, SchemaBuilder};
/// A cheaply cloneable, owned slice of [`FieldRef`]
///
/// Similar to `Arc<Vec<FieldRef>>` or `Arc<[FieldRef]>`
///
/// Can be constructed in a number of ways
///
/// ```
/// # use std::sync::Arc;
/// # use arrow_schema::{DataType, Field, Fields, SchemaBuilder};
/// // Can be constructed from Vec<Field>
/// Fields::from(vec![Field::new("a", DataType::Boolean, false)]);
/// // Can be constructed from Vec<FieldRef>
/// Fields::from(vec![Arc::new(Field::new("a", DataType::Boolean, false))]);
/// // Can be constructed from an iterator of Field
/// std::iter::once(Field::new("a", DataType::Boolean, false)).collect::<Fields>();
/// // Can be constructed from an iterator of FieldRef
/// std::iter::once(Arc::new(Field::new("a", DataType::Boolean, false))).collect::<Fields>();
/// ```
///
/// See [`SchemaBuilder`] for mutating or updating [`Fields`]
///
/// ```
/// # use arrow_schema::{DataType, Field, SchemaBuilder};
/// let mut builder = SchemaBuilder::new();
/// builder.push(Field::new("a", DataType::Boolean, false));
/// builder.push(Field::new("b", DataType::Boolean, false));
/// let fields = builder.finish().fields;
///
/// let mut builder = SchemaBuilder::from(&fields);
/// builder.remove(0);
/// let new = builder.finish().fields;
/// ```
///
/// [`SchemaBuilder`]: crate::SchemaBuilder
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "serde", serde(transparent))]
pub struct Fields(Arc<[FieldRef]>);
impl std::fmt::Debug for Fields {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.as_ref().fmt(f)
}
}
impl Fields {
/// Returns a new empty [`Fields`]
pub fn empty() -> Self {
Self(Arc::new([]))
}
/// Return size of this instance in bytes.
pub fn size(&self) -> usize {
self.iter()
.map(|field| field.size() + std::mem::size_of::<FieldRef>())
.sum()
}
/// Searches for a field by name, returning it along with its index if found
pub fn find(&self, name: &str) -> Option<(usize, &FieldRef)> {
self.0.iter().enumerate().find(|(_, b)| b.name() == name)
}
/// Check to see if `self` is a superset of `other`
///
/// In particular returns true if both have the same number of fields, and [`Field::contains`]
/// for each field across self and other
///
/// In other words, any record that conforms to `other` should also conform to `self`
pub fn contains(&self, other: &Fields) -> bool {
if Arc::ptr_eq(&self.0, &other.0) {
return true;
}
self.len() == other.len()
&& self
.iter()
.zip(other.iter())
.all(|(a, b)| Arc::ptr_eq(a, b) || a.contains(b))
}
/// Returns a copy of this [`Fields`] containing only those [`FieldRef`] passing a predicate
///
/// Performs a depth-first scan of [`Fields`] invoking `filter` for each [`FieldRef`]
/// containing no child [`FieldRef`], a leaf field, along with a count of the number
/// of such leaves encountered so far. Only [`FieldRef`] for which `filter`
/// returned `true` will be included in the result.
///
/// This can therefore be used to select a subset of fields from nested types
/// such as [`DataType::Struct`] or [`DataType::List`].
///
/// ```
/// # use arrow_schema::{DataType, Field, Fields};
/// let fields = Fields::from(vec![
/// Field::new("a", DataType::Int32, true), // Leaf 0
/// Field::new("b", DataType::Struct(Fields::from(vec![
/// Field::new("c", DataType::Float32, false), // Leaf 1
/// Field::new("d", DataType::Float64, false), // Leaf 2
/// Field::new("e", DataType::Struct(Fields::from(vec![
/// Field::new("f", DataType::Int32, false), // Leaf 3
/// Field::new("g", DataType::Float16, false), // Leaf 4
/// ])), true),
/// ])), false)
/// ]);
/// let filtered = fields.filter_leaves(|idx, _| [0, 2, 3, 4].contains(&idx));
/// let expected = Fields::from(vec![
/// Field::new("a", DataType::Int32, true),
/// Field::new("b", DataType::Struct(Fields::from(vec![
/// Field::new("d", DataType::Float64, false),
/// Field::new("e", DataType::Struct(Fields::from(vec![
/// Field::new("f", DataType::Int32, false),
/// Field::new("g", DataType::Float16, false),
/// ])), true),
/// ])), false)
/// ]);
/// assert_eq!(filtered, expected);
/// ```
pub fn filter_leaves<F: FnMut(usize, &FieldRef) -> bool>(&self, mut filter: F) -> Self {
fn filter_field<F: FnMut(&FieldRef) -> bool>(
f: &FieldRef,
filter: &mut F,
) -> Option<FieldRef> {
use DataType::*;
let v = match f.data_type() {
Dictionary(_, v) => v.as_ref(), // Key must be integer
RunEndEncoded(_, v) => v.data_type(), // Run-ends must be integer
d => d,
};
let d = match v {
List(child) => List(filter_field(child, filter)?),
LargeList(child) => LargeList(filter_field(child, filter)?),
Map(child, ordered) => Map(filter_field(child, filter)?, *ordered),
FixedSizeList(child, size) => FixedSizeList(filter_field(child, filter)?, *size),
Struct(fields) => {
let filtered: Fields = fields
.iter()
.filter_map(|f| filter_field(f, filter))
.collect();
if filtered.is_empty() {
return None;
}
Struct(filtered)
}
Union(fields, mode) => {
let filtered: UnionFields = fields
.iter()
.filter_map(|(id, f)| Some((id, filter_field(f, filter)?)))
.collect();
if filtered.is_empty() {
return None;
}
Union(filtered, *mode)
}
_ => return filter(f).then(|| f.clone()),
};
let d = match f.data_type() {
Dictionary(k, _) => Dictionary(k.clone(), Box::new(d)),
RunEndEncoded(v, f) => {
RunEndEncoded(v.clone(), Arc::new(f.as_ref().clone().with_data_type(d)))
}
_ => d,
};
Some(Arc::new(f.as_ref().clone().with_data_type(d)))
}
let mut leaf_idx = 0;
let mut filter = |f: &FieldRef| {
let t = filter(leaf_idx, f);
leaf_idx += 1;
t
};
self.0
.iter()
.filter_map(|f| filter_field(f, &mut filter))
.collect()
}
/// Remove a field by index and return it.
///
/// # Panic
///
/// Panics if `index` is out of bounds.
///
/// # Example
/// ```
/// use arrow_schema::{DataType, Field, Fields};
/// let mut fields = Fields::from(vec![
/// Field::new("a", DataType::Boolean, false),
/// Field::new("b", DataType::Int8, false),
/// Field::new("c", DataType::Utf8, false),
/// ]);
/// assert_eq!(fields.len(), 3);
/// assert_eq!(fields.remove(1), Field::new("b", DataType::Int8, false).into());
/// assert_eq!(fields.len(), 2);
/// ```
#[deprecated(note = "Use SchemaBuilder::remove")]
#[doc(hidden)]
pub fn remove(&mut self, index: usize) -> FieldRef {
let mut builder = SchemaBuilder::from(Fields::from(&*self.0));
let field = builder.remove(index);
*self = builder.finish().fields;
field
}
}
impl Default for Fields {
fn default() -> Self {
Self::empty()
}
}
impl FromIterator<Field> for Fields {
fn from_iter<T: IntoIterator<Item = Field>>(iter: T) -> Self {
iter.into_iter().map(Arc::new).collect()
}
}
impl FromIterator<FieldRef> for Fields {
fn from_iter<T: IntoIterator<Item = FieldRef>>(iter: T) -> Self {
Self(iter.into_iter().collect())
}
}
impl From<Vec<Field>> for Fields {
fn from(value: Vec<Field>) -> Self {
value.into_iter().collect()
}
}
impl From<Vec<FieldRef>> for Fields {
fn from(value: Vec<FieldRef>) -> Self {
Self(value.into())
}
}
impl From<&[FieldRef]> for Fields {
fn from(value: &[FieldRef]) -> Self {
Self(value.into())
}
}
impl<const N: usize> From<[FieldRef; N]> for Fields {
fn from(value: [FieldRef; N]) -> Self {
Self(Arc::new(value))
}
}
impl Deref for Fields {
type Target = [FieldRef];
fn deref(&self) -> &Self::Target {
self.0.as_ref()
}
}
impl<'a> IntoIterator for &'a Fields {
type Item = &'a FieldRef;
type IntoIter = std::slice::Iter<'a, FieldRef>;
fn into_iter(self) -> Self::IntoIter {
self.0.iter()
}
}
/// A cheaply cloneable, owned collection of [`FieldRef`] and their corresponding type ids
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "serde", serde(transparent))]
pub struct UnionFields(Arc<[(i8, FieldRef)]>);
impl std::fmt::Debug for UnionFields {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
self.0.as_ref().fmt(f)
}
}
impl UnionFields {
/// Create a new [`UnionFields`] with no fields
pub fn empty() -> Self {
Self(Arc::from([]))
}
/// Create a new [`UnionFields`] from a [`Fields`] and array of type_ids
///
/// See <https://arrow.apache.org/docs/format/Columnar.html#union-layout>
///
/// ```
/// use arrow_schema::{DataType, Field, UnionFields};
/// // Create a new UnionFields with type id mapping
/// // 1 -> DataType::UInt8
/// // 3 -> DataType::Utf8
/// UnionFields::new(
/// vec![1, 3],
/// vec![
/// Field::new("field1", DataType::UInt8, false),
/// Field::new("field3", DataType::Utf8, false),
/// ],
/// );
/// ```
pub fn new<F, T>(type_ids: T, fields: F) -> Self
where
F: IntoIterator,
F::Item: Into<FieldRef>,
T: IntoIterator<Item = i8>,
{
let fields = fields.into_iter().map(Into::into);
let mut set = 0_u128;
type_ids
.into_iter()
.map(|idx| {
let mask = 1_u128 << idx;
if (set & mask) != 0 {
panic!("duplicate type id: {}", idx);
} else {
set |= mask;
}
idx
})
.zip(fields)
.collect()
}
/// Return size of this instance in bytes.
pub fn size(&self) -> usize {
self.iter()
.map(|(_, field)| field.size() + std::mem::size_of::<(i8, FieldRef)>())
.sum()
}
/// Returns the number of fields in this [`UnionFields`]
pub fn len(&self) -> usize {
self.0.len()
}
/// Returns `true` if this is empty
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Returns an iterator over the fields and type ids in this [`UnionFields`]
///
/// Note: the iteration order is not guaranteed
pub fn iter(&self) -> impl Iterator<Item = (i8, &FieldRef)> + '_ {
self.0.iter().map(|(id, f)| (*id, f))
}
/// Merge this field into self if it is compatible.
///
/// See [`Field::try_merge`]
pub(crate) fn try_merge(&mut self, other: &Self) -> Result<(), ArrowError> {
// TODO: This currently may produce duplicate type IDs (#3982)
let mut output: Vec<_> = self.iter().map(|(id, f)| (id, f.clone())).collect();
for (field_type_id, from_field) in other.iter() {
let mut is_new_field = true;
for (self_type_id, self_field) in output.iter_mut() {
if from_field == self_field {
// If the nested fields in two unions are the same, they must have same
// type id.
if *self_type_id != field_type_id {
return Err(ArrowError::SchemaError(
format!("Fail to merge schema field '{}' because the self_type_id = {} does not equal field_type_id = {}",
self_field.name(), self_type_id, field_type_id)
));
}
is_new_field = false;
break;
}
}
if is_new_field {
output.push((field_type_id, from_field.clone()))
}
}
*self = output.into_iter().collect();
Ok(())
}
}
impl FromIterator<(i8, FieldRef)> for UnionFields {
fn from_iter<T: IntoIterator<Item = (i8, FieldRef)>>(iter: T) -> Self {
// TODO: Should this validate type IDs are unique (#3982)
Self(iter.into_iter().collect())
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::UnionMode;
#[test]
fn test_filter() {
let floats = Fields::from(vec![
Field::new("a", DataType::Float32, false),
Field::new("b", DataType::Float32, false),
]);
let fields = Fields::from(vec![
Field::new("a", DataType::Int32, true),
Field::new("floats", DataType::Struct(floats.clone()), true),
Field::new("b", DataType::Int16, true),
Field::new(
"c",
DataType::Dictionary(Box::new(DataType::Int32), Box::new(DataType::Utf8)),
false,
),
Field::new(
"d",
DataType::Dictionary(
Box::new(DataType::Int32),
Box::new(DataType::Struct(floats.clone())),
),
false,
),
Field::new_list(
"e",
Field::new("floats", DataType::Struct(floats.clone()), true),
true,
),
Field::new_fixed_size_list("f", Field::new("item", DataType::Int32, false), 3, false),
Field::new_map(
"g",
"entries",
Field::new("keys", DataType::LargeUtf8, false),
Field::new("values", DataType::Int32, true),
false,
false,
),
Field::new(
"h",
DataType::Union(
UnionFields::new(
vec![1, 3],
vec![
Field::new("field1", DataType::UInt8, false),
Field::new("field3", DataType::Utf8, false),
],
),
UnionMode::Dense,
),
true,
),
Field::new(
"i",
DataType::RunEndEncoded(
Arc::new(Field::new("run_ends", DataType::Int32, false)),
Arc::new(Field::new("values", DataType::Struct(floats.clone()), true)),
),
false,
),
]);
let floats_a = DataType::Struct(vec![floats[0].clone()].into());
let r = fields.filter_leaves(|idx, _| idx == 0 || idx == 1);
assert_eq!(r.len(), 2);
assert_eq!(r[0], fields[0]);
assert_eq!(r[1].data_type(), &floats_a);
let r = fields.filter_leaves(|_, f| f.name() == "a");
assert_eq!(r.len(), 5);
assert_eq!(r[0], fields[0]);
assert_eq!(r[1].data_type(), &floats_a);
assert_eq!(
r[2].data_type(),
&DataType::Dictionary(Box::new(DataType::Int32), Box::new(floats_a.clone()))
);
assert_eq!(
r[3].as_ref(),
&Field::new_list("e", Field::new("floats", floats_a.clone(), true), true)
);
assert_eq!(
r[4].as_ref(),
&Field::new(
"i",
DataType::RunEndEncoded(
Arc::new(Field::new("run_ends", DataType::Int32, false)),
Arc::new(Field::new("values", floats_a.clone(), true)),
),
false,
)
);
let r = fields.filter_leaves(|_, f| f.name() == "floats");
assert_eq!(r.len(), 0);
let r = fields.filter_leaves(|idx, _| idx == 9);
assert_eq!(r.len(), 1);
assert_eq!(r[0], fields[6]);
let r = fields.filter_leaves(|idx, _| idx == 10 || idx == 11);
assert_eq!(r.len(), 1);
assert_eq!(r[0], fields[7]);
let union = DataType::Union(
UnionFields::new(vec![1], vec![Field::new("field1", DataType::UInt8, false)]),
UnionMode::Dense,
);
let r = fields.filter_leaves(|idx, _| idx == 12);
assert_eq!(r.len(), 1);
assert_eq!(r[0].data_type(), &union);
let r = fields.filter_leaves(|idx, _| idx == 14 || idx == 15);
assert_eq!(r.len(), 1);
assert_eq!(r[0], fields[9]);
}
}