Files
bun.sh/bench/runner.mjs
SUZUKI Sosuke 44df912d37 Add Bun.wrapAnsi() for text wrapping with ANSI escape code preservation (#26061)
## Summary

Adds `Bun.wrapAnsi()`, a native implementation of the popular
[wrap-ansi](https://www.npmjs.com/package/wrap-ansi) npm package for
wrapping text with ANSI escape codes.

## API

```typescript
Bun.wrapAnsi(string: string, columns: number, options?: WrapAnsiOptions): string

interface WrapAnsiOptions {
  hard?: boolean;              // default: false - Break words longer than columns
  wordWrap?: boolean;          // default: true - Wrap at word boundaries
  trim?: boolean;              // default: true - Trim leading/trailing whitespace
  ambiguousIsNarrow?: boolean; // default: true - Treat ambiguous-width chars as narrow
}
```

## Features

- Wraps text to fit within specified column width
- Preserves ANSI escape codes (SGR colors/styles)
- Supports OSC 8 hyperlinks
- Respects Unicode display widths (full-width characters, emoji)
- Normalizes `\r\n` to `\n`

## Implementation Details

The implementation closes and reopens ANSI codes around line breaks for
robust terminal compatibility. This differs slightly from the npm
package in edge cases but produces visually equivalent output.

### Behavioral Differences from npm wrap-ansi

1. **ANSI code preservation**: Bun always maintains complete ANSI escape
sequences. The npm version can output malformed codes (missing ESC
character) in certain edge cases with `wordWrap: false, trim: false`.

2. **Newline ANSI handling**: Bun closes and reopens ANSI codes around
newlines for robustness. The npm version sometimes keeps them spanning
across newlines. The visual output is equivalent.

## Tests

- 27 custom tests covering basic functionality, ANSI codes, Unicode, and
options
- 23 tests ported from the npm package (MIT licensed, credited in file
header)
- All 50 tests pass

## Benchmark

<!-- Benchmark results will be added -->
```
$ cd /Users/sosuke/code/bun/bench && ../build/release/bun snippets/wrap-ansi.js
clk: ~3.82 GHz
cpu: Apple M4 Max
runtime: bun 1.3.7 (arm64-darwin)

benchmark                    avg (min … max) p75   p99    (min … top 1%)
-------------------------------------------- -------------------------------
Short text (45 chars) - npm    25.81 µs/iter  21.71 µs  █
                      (16.79 µs … 447.38 µs) 110.96 µs ▆█▃▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁
Short text (45 chars) - Bun   685.55 ns/iter 667.00 ns    █
                       (459.00 ns … 2.16 ms)   1.42 µs ▁▁▁█▃▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁

summary
  Short text (45 chars) - Bun
   37.65x faster than Short text (45 chars) - npm

-------------------------------------------- -------------------------------
Medium text (810 chars) - npm 568.12 µs/iter 578.00 µs  ▄▅█▆▆▃
                     (525.25 µs … 944.71 µs) 700.75 µs ▄██████▆▅▄▃▃▂▂▂▁▁▁▁▁▁
Medium text (810 chars) - Bun  11.22 µs/iter  11.28 µs                     █
                       (11.04 µs … 11.46 µs)  11.33 µs █▁▁▁██▁█▁▁▁▁█▁█▁▁█▁▁█

summary
  Medium text (810 chars) - Bun
   50.62x faster than Medium text (810 chars) - npm

-------------------------------------------- -------------------------------
Long text (8100 chars) - npm    7.66 ms/iter   7.76 ms     ▂▂▅█   ▅
                         (7.31 ms … 8.10 ms)   8.06 ms ▃▃▄▃█████▇▇███▃▆▆▆▄▁▃
Long text (8100 chars) - Bun  112.14 µs/iter 113.50 µs        █
                     (102.50 µs … 146.04 µs) 124.92 µs ▁▁▁▁▁▁██▇▅█▃▂▂▂▂▁▁▁▁▁

summary
  Long text (8100 chars) - Bun
   68.27x faster than Long text (8100 chars) - npm

-------------------------------------------- -------------------------------
Colored short - npm            28.46 µs/iter  28.56 µs              █
                       (27.90 µs … 29.34 µs)  28.93 µs ▆▁▆▁▁▆▁▁▆▆▆▁▆█▁▁▁▁▁▁▆
Colored short - Bun           861.64 ns/iter 867.54 ns         ▂  ▇█▄▂
                     (839.68 ns … 891.12 ns) 882.04 ns ▃▅▄▅▆▆▇▆██▇████▆▃▅▅▅▂

summary
  Colored short - Bun
   33.03x faster than Colored short - npm

-------------------------------------------- -------------------------------
Colored medium - npm          557.84 µs/iter 562.63 µs      ▂▃█▄
                     (508.08 µs … 911.92 µs) 637.96 µs ▁▁▁▂▄█████▅▂▂▁▁▁▁▁▁▁▁
Colored medium - Bun           14.91 µs/iter  14.94 µs ██  ████ ██ █      ██
                       (14.77 µs … 15.17 µs)  15.06 µs ██▁▁████▁██▁█▁▁▁▁▁▁██

summary
  Colored medium - Bun
   37.41x faster than Colored medium - npm

-------------------------------------------- -------------------------------
Colored long - npm              7.84 ms/iter   7.90 ms       █  ▅
                         (7.53 ms … 8.38 ms)   8.19 ms ▂▂▂▄▃▆██▇██▇▃▂▃▃▃▄▆▂▂
Colored long - Bun            176.73 µs/iter 175.42 µs       █
                       (162.50 µs … 1.37 ms) 204.46 µs ▁▁▂▄▇██▅▂▂▂▁▁▁▁▁▁▁▁▁▁

summary
  Colored long - Bun
   44.37x faster than Colored long - npm

-------------------------------------------- -------------------------------
Hard wrap long - npm            8.05 ms/iter   8.12 ms       ▃ ▇█
                         (7.67 ms … 8.53 ms)   8.50 ms ▄▁▁▁▃▄█████▄▃▂▆▄▃▂▂▂▂
Hard wrap long - Bun          111.85 µs/iter 112.33 µs         ▇█
                     (101.42 µs … 145.42 µs) 123.88 µs ▁▁▁▁▁▁▁████▄▃▂▂▂▁▁▁▁▁

summary
  Hard wrap long - Bun
   72.01x faster than Hard wrap long - npm

-------------------------------------------- -------------------------------
Hard wrap colored - npm         8.82 ms/iter   8.92 ms   ▆ ██
                         (8.55 ms … 9.47 ms)   9.32 ms ▆▆████▆▆▄▆█▄▆▄▄▁▃▁▃▄▃
Hard wrap colored - Bun       174.38 µs/iter 175.54 µs   █ ▂
                     (165.75 µs … 210.25 µs) 199.50 µs ▁▃█▆███▃▂▃▂▂▂▂▂▁▁▁▁▁▁

summary
  Hard wrap colored - Bun
   50.56x faster than Hard wrap colored - npm

-------------------------------------------- -------------------------------
Japanese (full-width) - npm    51.00 µs/iter  52.67 µs    █▂   █▄
                      (40.71 µs … 344.88 µs)  66.13 µs ▁▁▃██▄▃▅██▇▄▃▄▃▂▂▁▁▁▁
Japanese (full-width) - Bun     7.46 µs/iter   7.46 µs       █
                        (6.50 µs … 34.92 µs)   9.38 µs ▁▁▁▁▁██▆▂▁▂▁▁▁▁▁▁▁▁▁▁

summary
  Japanese (full-width) - Bun
   6.84x faster than Japanese (full-width) - npm

-------------------------------------------- -------------------------------
Emoji text - npm              173.63 µs/iter 222.17 µs   █
                     (129.42 µs … 527.25 µs) 249.58 µs ▁▃█▆▃▃▃▁▁▁▁▁▁▁▂▄▆▄▂▂▁
Emoji text - Bun                9.42 µs/iter   9.47 µs           ██
                         (9.32 µs … 9.52 µs)   9.50 µs █▁▁███▁▁█▁██▁▁▁▁██▁▁█

summary
  Emoji text - Bun
   18.44x faster than Emoji text - npm

-------------------------------------------- -------------------------------
Hyperlink (OSC 8) - npm       208.00 µs/iter 254.25 µs   █
                     (169.58 µs … 542.17 µs) 281.00 µs ▁▇█▃▃▂▂▂▁▁▁▁▁▁▁▃▃▅▃▂▁
Hyperlink (OSC 8) - Bun         6.00 µs/iter   6.06 µs      █           ▄
                         (5.88 µs … 6.11 µs)   6.10 µs ▅▅▅▁▅█▅▁▅▁█▁▁▅▅▅▅█▅▁█

summary
  Hyperlink (OSC 8) - Bun
   34.69x faster than Hyperlink (OSC 8) - npm

-------------------------------------------- -------------------------------
No trim long - npm              8.32 ms/iter   8.38 ms  █▇
                        (7.61 ms … 13.67 ms)  11.74 ms ▃████▄▂▃▂▂▃▁▁▁▁▁▁▁▁▁▂
No trim long - Bun             93.92 µs/iter  94.42 µs           █▂
                      (82.75 µs … 162.38 µs) 103.83 µs ▁▁▁▁▁▁▁▁▄███▄▃▂▂▁▁▁▁▁

summary
  No trim long - Bun
   88.62x faster than No trim long - npm
```

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
2026-01-16 16:12:23 -08:00

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