| lib.rs |
Efficiently insert line endings.
If you have a buffer full of data and want to insert any sort of regularly-spaced separator,
this will do it with a minimum of data copying. Commonly, this is to insert `\n` (see `lf()`) or `\r\n` (`crlf()`), but
any byte sequence can be used.
1. Pick a line ending. For single byte separators, see `ByteLineEnding`, or for two bytes, `TwoByteLineEnding`. For
arbitrary byte slices, use `SliceLineEnding`.
2. Call `line_wrap`.
3. Your data has been rearranged in place with the specified line ending inserted.
# Examples
```
use line_wrap::*;
// suppose we have 80 bytes of data in a buffer and we want to wrap as per MIME.
// Buffer is large enough to hold line endings.
let mut data = vec![0; 82];
assert_eq!(2, line_wrap(&mut data, 80, 76, &crlf()));
// first line of zeroes
let mut expected_data = vec![0; 76];
// line ending
expected_data.extend_from_slice(b"\r\n");
// next line
expected_data.extend_from_slice(&[0, 0, 0, 0]);
assert_eq!(expected_data, data);
```
# Performance
On an i7 6850k:
- 10 byte input, 1 byte line length takes ~60ns (~160MiB/s)
- 100 byte input, 10 byte lines takes ~60ns (~1.6GiB/s)
- Startup costs dominate at these small lengths
- 1,000 byte input, 100 byte lines takes ~65ns (~15GiB/s)
- 10,000 byte input, 100 byte lines takes ~550ns (~17GiB/s)
- In general, `SliceLineEncoding` is about 75% the speed of the fixed-length impls.
Naturally, try `cargo +nightly bench` on your hardware to get more representative data. |
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