apache_datasketches/cpc/
builder.rs

1use crate::error::SketchError;
2
3/// Builder for [`crate::cpc::CpcSketch`], mirroring upstream's
4/// `cpc_sketch_alloc` constructor. `lg_k` defaults to `11`
5/// (`cpc_constants::DEFAULT_LG_K`). The seed is never exposed — every
6/// sketch built by this crate always uses upstream's `DEFAULT_SEED`.
7#[derive(Debug, Clone, Copy)]
8pub struct CpcSketchBuilder {
9    lg_k: u8,
10}
11
12impl Default for CpcSketchBuilder {
13    fn default() -> Self {
14        Self { lg_k: 11 }
15    }
16}
17
18impl CpcSketchBuilder {
19    /// Creates a new builder with the default `lg_k` (`11`).
20    pub fn new() -> Self {
21        Self::default()
22    }
23
24    /// Sets the base-2 log of the number of bins in the sketch (`4..=26`).
25    pub fn lg_k(mut self, lg_k: u8) -> Self {
26        self.lg_k = lg_k;
27        self
28    }
29
30    /// Builds the sketch. Returns [`SketchError::InvalidConfig`] if `lg_k`
31    /// is out of range.
32    pub fn build(self) -> Result<super::CpcSketch, SketchError> {
33        super::CpcSketch::from_lg_k(self.lg_k)
34    }
35}
36
37/// Builder for [`crate::cpc::CpcUnion`], mirroring upstream's
38/// `cpc_union_alloc` constructor. `lg_k` defaults to `11`
39/// (`cpc_constants::DEFAULT_LG_K`). The seed is never exposed, same as
40/// [`CpcSketchBuilder`].
41#[derive(Debug, Clone, Copy)]
42pub struct CpcUnionBuilder {
43    lg_k: u8,
44}
45
46impl Default for CpcUnionBuilder {
47    fn default() -> Self {
48        Self { lg_k: 11 }
49    }
50}
51
52impl CpcUnionBuilder {
53    /// Creates a new builder with the default `lg_k` (`11`).
54    pub fn new() -> Self {
55        Self::default()
56    }
57
58    /// Sets the base-2 log of the number of bins in the union (`4..=26`).
59    pub fn lg_k(mut self, lg_k: u8) -> Self {
60        self.lg_k = lg_k;
61        self
62    }
63
64    /// Builds the union. Returns [`SketchError::InvalidConfig`] if `lg_k`
65    /// is out of range.
66    pub fn build(self) -> Result<super::CpcUnion, SketchError> {
67        super::CpcUnion::from_lg_k(self.lg_k)
68    }
69}
apache_datasketches/cpc/builder.rs

apache_datasketches/cpc/
builder.rs
