AdamGS commented on code in PR #23631:
URL: https://github.com/apache/datafusion/pull/23631#discussion_r3602037403
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datafusion/common/src/scalar/consts.rs:
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@@ -54,3 +57,60 @@ pub(super) const NEGATIVE_FRAC_PI_2_LOWER_F32: f32 =
// Next f64 value below -π/2 (lower bound)
pub(super) const NEGATIVE_FRAC_PI_2_LOWER_F64: f64 =
(-std::f64::consts::FRAC_PI_2).next_down();
+
+// Generate lookup table for 1 values of decimals (1, 10, 100, etc.)
+macro_rules! decimal_ones_lut {
+ () => {{
+ let mut values = [1; _];
+ let mut i = 1;
+ while i < values.len() {
+ values[i] = values[i - 1] * 10;
+ i += 1;
+ }
+ values
+ }};
+}
+
+// 1, 10, 100 values meant to be indexed by scale. We omit handling for
MAX_SCALE
+// itself (we don't go to MAX_SCALE + 1) since we can't represent a 1 value at
+// that scale.
+pub(super) const DECIMAL32_ONES: [i32; Decimal32Type::MAX_SCALE as usize] =
+ decimal_ones_lut!();
+pub(super) const DECIMAL64_ONES: [i64; Decimal64Type::MAX_SCALE as usize] =
+ decimal_ones_lut!();
+pub(super) const DECIMAL128_ONES: [i128; Decimal128Type::MAX_SCALE as usize] =
+ decimal_ones_lut!();
+pub(super) const DECIMAL256_ONES: [i256; Decimal256Type::MAX_SCALE as usize] =
{
+ // This code was generated by codex and frankly I don't know how it works,
+ // but the test below verifies it outputs the correct values so ¯\_(ツ)_/¯
+ //
+ // This is mainly a shortcut for not needing to manually list out each
value
+ // anyway.
+ let mut values = [i256::ONE; _];
Review Comment:
I think this is basically const mul? I also ran into that recently
elsewhere, so figured I'll make a PR -
https://github.com/apache/arrow-rs/pull/10363
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