ucd: Compress numeric values by joshuamegnauth54 · Pull Request #9794 · RustPython/RustPython

joshuamegnauth54 · 2026-11-10T18:30:08Z

RustPython currently stores numeric values in a flat table where each value is 16 bytes wide. Most of the actual values are repetitive and duplicated. The range itself is eight bytes wide.

To compress the ranges, I split the table into two. The first table stores the start character as an u32, a u16 offset for the end character, and a u16 index into the second table. The second table stores deduplicated values.

Closes #xxxx

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Summary

Compresses numeric values to save binary space and help cache locality for binary search.

Summary by CodeRabbit

Improvements
- Numeric, digit, and decimal lookups continue to respect the selected Unicode version, including differences between modern Unicode data and Unicode 3.2.0.
- Numeric lookups now consistently account for characters with differing numeric types and for characters that lack a numeric value in Unicode 3.2.0, preserving version-appropriate results.

chatgpt-codex-connector · 2026-11-10T18:30:19Z

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Walkthrough

Numeric value generation now creates deduplicated values and indexed ranges. Unicode 3.2 numeric-type differences include explicit no-value ranges. Runtime lookups use version-aware range searches for digit, decimal, and numeric.

Changes: Unicode Numeric Tables

Layer / File(s)	Summary
Generate indexed numeric ranges `crates/unicode/build.rs`	The generator deduplicates numeric values and emits indexed ranges. It also records Unicode 3.2 assigned ranges that have no numeric value. Slice writers now accept immutable slices.
Build Unicode 3.2 numeric-type differences `crates/unicode/build.rs`	Numeric-type differences are expanded per code point, combined with numeric-value and no-value differences, then recompressed into ranges with matching types.
Look up versioned numeric values `crates/unicode/src/data.rs`	A shared helper searches numeric ranges. Unicode 3.2 lookup checks its differences and membership before using modern values. `digit`, `decimal`, and `numeric` use the helper.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Refactor

Suggested reviewers: youknowone

Merge Risk: Minimal · previous review cf4dd

This change compresses the numeric value tables and keeps lookups correct for characters inside multi-character ranges. No remaining merge-blocking risk was found; the code was inspected but not run.

Pre-merge checks: 4

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title, "ucd: Compress numeric values," clearly and concisely describes the pull request's main change: compact numeric-value tables and reduced binary size.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Review comments at @crates/unicode/build.rs:
- Around line 626-631: Update the range insertion logic for ucd32_diffs to add
an entry for every code point from line.start through line.end, inclusive, so
exact-match lookups in numeric() find interior code points; singleton ranges
should continue to produce one entry.

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joshuamegnauth54 · 2026-11-10T20:04:43Z

This patch reduced numeric_value_3_2.rs to 28k from 42k. 😋

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chatgpt-codex-connector · 2026-11-11T01:41:01Z

+            values_latest.push((line.start, value));
+        } else {
+            for key in line.start..=line.end {
+                values_latest.push((key, value));


Retain ranges to avoid enlarging the numeric table

On 64-bit builds, both (u32, u32, f64) and (u32, f64) occupy 16 bytes because of f64 alignment, while the current vendored file has 1,980 records and this expansion emits 2,023 entries. NUMERIC_VALUES therefore grows by 688 bytes and occupies more cache lines, which is the opposite of this change's stated compression goal; retain the ranges or use a representation that actually eliminates the padding.

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youknowone · 2026-11-11T01:45:08Z

 }

+#[expect(unused)]
+fn write_slice_flat_display(


why do these exist if it is unused?

I was refactoring a lot but wanted to silence clippy. 😅 I think I need to work on this patch more anyway so I'll remove it when I undraft.

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RustPython currently stores numeric values in a flat table where each value is 16 bytes wide. Most of the actual values are repetitive and duplicated. The range itself is eight bytes wide. To compress the ranges, I split the table into two. The first table stores the start character as an u32, a u16 offset for the end character, and a u16 index into the second table. The second table stores deduplicated values.

chatgpt-codex-connector · 2026-11-12T01:25:23Z

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chatgpt-codex-connector Bot reviewed Nov 10, 2026

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Comment thread crates/unicode/build.rs Resolved

joshuamegnauth54 force-pushed the ucd-single-items branch from af32496 to c1571de Compare November 10, 2026 18:51

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joshuamegnauth54 marked this pull request as draft November 11, 2026 01:58

joshuamegnauth54 marked this pull request as ready for review November 11, 2026 19:53

joshuamegnauth54 force-pushed the ucd-single-items branch from 6968f5a to cf4dd50 Compare November 11, 2026 19:53

joshuamegnauth54 force-pushed the ucd-single-items branch from cf4dd50 to d19f681 Compare November 12, 2026 01:25

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