HaoYang670 commented on code in PR #2383:
URL: https://github.com/apache/arrow-rs/pull/2383#discussion_r940957037
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arrow/src/util/decimal.rs:
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@@ -18,21 +18,51 @@
//! Decimal related utils
use crate::datatypes::{
- DECIMAL128_MAX_PRECISION, DECIMAL128_MAX_SCALE, DECIMAL256_MAX_PRECISION,
- DECIMAL256_MAX_SCALE,
+ DataType, DECIMAL128_MAX_PRECISION, DECIMAL128_MAX_SCALE,
DECIMAL256_MAX_PRECISION,
+ DECIMAL256_MAX_SCALE, DECIMAL_DEFAULT_SCALE,
};
use crate::error::{ArrowError, Result};
use num::bigint::BigInt;
use num::Signed;
use std::cmp::{min, Ordering};
-pub trait BasicDecimal: PartialOrd + Ord + PartialEq + Eq {
- /// The bit-width of the internal representation.
- const BIT_WIDTH: usize;
- /// The maximum precision.
- const MAX_PRECISION: usize;
- /// The maximum scale.
- const MAX_SCALE: usize;
+#[derive(Debug)]
+pub struct BasicDecimal<const BYTE_WIDTH: usize> {
+ precision: usize,
+ scale: usize,
+ value: [u8; BYTE_WIDTH],
+}
+
+impl<const BYTE_WIDTH: usize> BasicDecimal<BYTE_WIDTH> {
+ #[allow(clippy::type_complexity)]
+ const _MAX_PRECISION_SCALE_CONSTRUCTOR_DEFAULT_TYPE: (
+ usize,
+ usize,
+ fn(usize, usize) -> DataType,
+ DataType,
+ ) = match BYTE_WIDTH {
+ 16 => (
+ DECIMAL128_MAX_PRECISION,
+ DECIMAL128_MAX_SCALE,
+ DataType::Decimal128,
+ DataType::Decimal128(DECIMAL128_MAX_PRECISION,
DECIMAL_DEFAULT_SCALE),
+ ),
+ 32 => (
+ DECIMAL256_MAX_PRECISION,
+ DECIMAL256_MAX_SCALE,
+ DataType::Decimal256,
+ DataType::Decimal256(DECIMAL256_MAX_PRECISION,
DECIMAL_DEFAULT_SCALE),
+ ),
+ _ => panic!("invalid byte width"),
Review Comment:
We could constrain the byte width here. When compile the constant items, the
compiler will give error if byte width != 16 or 32.
@viirya
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