polars_core/chunked_array/object/
registry.rs

1//! This is a heap allocated utility that can be used to register an object type.
2//!
3//! That object type will know its own generic type parameter `T` and callers can simply
4//! send `&Any` values and don't have to know the generic type themselves.
5use std::any::Any;
6use std::fmt::{Debug, Formatter};
7use std::ops::Deref;
8use std::sync::{Arc, LazyLock, RwLock};
9
10use arrow::array::ArrayRef;
11use arrow::array::builder::ArrayBuilder;
12use arrow::datatypes::ArrowDataType;
13use polars_utils::pl_str::PlSmallStr;
14
15use crate::chunked_array::object::builder::ObjectChunkedBuilder;
16use crate::datatypes::AnyValue;
17use crate::prelude::{ListBuilderTrait, ObjectChunked, PolarsObject};
18use crate::series::{IntoSeries, Series};
19
20/// Takes a `name` and `capacity` and constructs a new builder.
21pub type BuilderConstructor =
22    Box<dyn Fn(PlSmallStr, usize) -> Box<dyn AnonymousObjectBuilder> + Send + Sync>;
23pub type ObjectConverter = Arc<dyn Fn(AnyValue) -> Box<dyn Any> + Send + Sync>;
24
25pub struct ObjectRegistry {
26    /// A function that creates an object builder
27    pub builder_constructor: BuilderConstructor,
28    // A function that converts AnyValue to Box<dyn Any> of the object type
29    object_converter: Option<ObjectConverter>,
30    pub physical_dtype: ArrowDataType,
31}
32
33impl Debug for ObjectRegistry {
34    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
35        write!(f, "object-registry")
36    }
37}
38
39static GLOBAL_OBJECT_REGISTRY: LazyLock<RwLock<Option<ObjectRegistry>>> =
40    LazyLock::new(Default::default);
41
42/// This trait can be registered, after which that global registration
43/// can be used to materialize object types
44pub trait AnonymousObjectBuilder: ArrayBuilder {
45    fn as_array_builder(self: Box<Self>) -> Box<dyn ArrayBuilder>;
46
47    /// # Safety
48    /// Expect `ObjectArray<T>` arrays.
49    unsafe fn from_chunks(self: Box<Self>, chunks: Vec<ArrayRef>) -> Series;
50
51    /// Append a `null` value.
52    fn append_null(&mut self);
53
54    /// Append a `T` of [`ObjectChunked<T>`][ObjectChunked<T>] made generic via the [`Any`] trait.
55    ///
56    /// [ObjectChunked<T>]: crate::chunked_array::object::ObjectChunked
57    fn append_value(&mut self, value: &dyn Any);
58
59    fn append_option(&mut self, value: Option<&dyn Any>) {
60        match value {
61            None => self.append_null(),
62            Some(v) => self.append_value(v),
63        }
64    }
65
66    /// Take the current state and materialize as a [`Series`]
67    /// the builder should not be used after that.
68    fn to_series(&mut self) -> Series;
69
70    fn get_list_builder(
71        &self,
72        name: PlSmallStr,
73        values_capacity: usize,
74        list_capacity: usize,
75    ) -> Box<dyn ListBuilderTrait>;
76}
77
78impl<T: PolarsObject> AnonymousObjectBuilder for ObjectChunkedBuilder<T> {
79    /// # Safety
80    /// Expects `ObjectArray<T>` arrays.
81    unsafe fn from_chunks(self: Box<Self>, chunks: Vec<ArrayRef>) -> Series {
82        ObjectChunked::<T>::new_with_compute_len(Arc::new(self.field().clone()), chunks)
83            .into_series()
84    }
85
86    fn as_array_builder(self: Box<Self>) -> Box<dyn ArrayBuilder> {
87        self
88    }
89
90    fn append_null(&mut self) {
91        self.append_null()
92    }
93
94    fn append_value(&mut self, value: &dyn Any) {
95        let value = value.downcast_ref::<T>().unwrap();
96        self.append_value(value.clone())
97    }
98
99    fn to_series(&mut self) -> Series {
100        let builder = std::mem::take(self);
101        builder.finish().into_series()
102    }
103    fn get_list_builder(
104        &self,
105        name: PlSmallStr,
106        values_capacity: usize,
107        list_capacity: usize,
108    ) -> Box<dyn ListBuilderTrait> {
109        Box::new(super::extension::list::ExtensionListBuilder::<T>::new(
110            name,
111            values_capacity,
112            list_capacity,
113        ))
114    }
115}
116
117pub fn register_object_builder(
118    builder_constructor: BuilderConstructor,
119    object_converter: ObjectConverter,
120    physical_dtype: ArrowDataType,
121) {
122    let reg = GLOBAL_OBJECT_REGISTRY.deref();
123    let mut reg = reg.write().unwrap();
124
125    *reg = Some(ObjectRegistry {
126        builder_constructor,
127        object_converter: Some(object_converter),
128        physical_dtype,
129    })
130}
131
132#[cold]
133pub fn get_object_physical_type() -> ArrowDataType {
134    let reg = GLOBAL_OBJECT_REGISTRY.read().unwrap();
135    let reg = reg.as_ref().unwrap();
136    reg.physical_dtype.clone()
137}
138
139pub fn get_object_builder(name: PlSmallStr, capacity: usize) -> Box<dyn AnonymousObjectBuilder> {
140    let reg = GLOBAL_OBJECT_REGISTRY.read().unwrap();
141    let reg = reg.as_ref().unwrap();
142    (reg.builder_constructor)(name, capacity)
143}
144
145pub fn get_object_converter() -> ObjectConverter {
146    let reg = GLOBAL_OBJECT_REGISTRY.read().unwrap();
147    let reg = reg.as_ref().unwrap();
148    reg.object_converter.as_ref().unwrap().clone()
149}
polars_core/chunked_array/object/registry.rs

polars_core/chunked_array/object/
registry.rs
