fast_whitespace_collapse

fast_whitespace_collapse is a high-performance Rust crate for collapsing consecutive spaces and tabs into a single space.

Uses SIMD (u8x16) via the wide crate for efficient processing.
Automatically falls back to a scalar implementation if SIMD is unavailable.

Features

• Collapses multiple spaces and tabs into a single space.
• Preserves newlines and non-whitespace characters.
• Uses SIMD (u8x16) when supported to process 16 bytes at a time.
• Falls back to a fast scalar implementation if SIMD is unavailable.
• Ensures valid UTF-8 output.
• SIMD requires AVX2, SSE2, or NEON instruction sets.

Installation

Add this to your Cargo.toml:

[dependencies]
fast_whitespace_collapse = "0.1.0"

Or run the following command:

cargo add fast_whitespace_collapse

Controlling SIMD Support

By default, SIMD acceleration is enabled. You can control it via Cargo features:

🔹 Disable SIMD for Embedded Targets

cargo build --no-default-features

🔹 Explicitly Enable SIMD

cargo build --features simd-optimized

Usage

use fast_whitespace_collapse::collapse_whitespace;

let input = "This   is \t  a   test.";
let output = collapse_whitespace(input);
assert_eq!(output, "This is a test.");

Performance

• Processes text using SIMD (u8x16), handling 16 bytes in parallel.
• Falls back to scalar processing when SIMD is unavailable.
• Handles large inputs efficiently while maintaining valid UTF-8 output.

Benchmark Results

Comparison with Other Approaches

Method	Time
Regex approach	11.289 µs
collapse crate	1.2624 µs
Iterative approach	629.60 ns
Iterative bytes	428.00 ns
fast_whitespace_collapse crate	388.73 ns

🚀 fast_whitespace_collapse outperforms other methods, achieving the lowest execution time.

📌 Benchmark executed on Apple M1 Pro (NEON SIMD enabled).

🔹 Run Your Own Benchmark

cargo bench

Compatibility

fast_whitespace_collapse supports multiple architectures:

• x86_64: Uses SIMD (SSE2, AVX2) for maximum performance.
• ARM (aarch64, M1/M2/M3): Uses NEON SIMD.
• Other: Falls back to a scalar implementation.

Examples

Basic Usage

use fast_whitespace_collapse::collapse_whitespace;

assert_eq!(collapse_whitespace("Hello    world"), "Hello world");
assert_eq!(collapse_whitespace("   Trim   spaces   " ), "Trim spaces");
assert_eq!(collapse_whitespace("Tabs\t\tconverted"), "Tabs converted");

Unicode Support

assert_eq!(collapse_whitespace("こんにちは  世界"), "こんにちは 世界"); // Japanese
assert_eq!(collapse_whitespace("你好  世界"), "你好 世界"); // Chinese
assert_eq!(collapse_whitespace("😀  😃  😄"), "😀 😃 😄"); // Emojis

Handling Newlines

assert_eq!(collapse_whitespace("Line1\n   Line2\nLine3"), "Line1\n Line2\nLine3");

Tests

Run tests with:

cargo test

License

This project is licensed under the MIT License.