| cmp.rs |
|
4642 |
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| either.rs |
|
1468 |
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| impls.rs |
|
9017 |
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| lib.rs |
This crate defines [`Writeable`], a trait representing an object that can be written to a
sink implementing `std::fmt::Write`. It is an alternative to `std::fmt::Display` with the
addition of a function indicating the number of bytes to be written.
`Writeable` improves upon `std::fmt::Display` in two ways:
1. More efficient, since the sink can pre-allocate bytes.
2. Smaller code, since the format machinery can be short-circuited.
This crate also exports [`TryWriteable`], a writeable that supports a custom error.
# Benchmarks
The benchmarks to generate the following data can be found in the `benches` directory.
| Case | `Writeable` | `Display` |
|---|---|---|
| Create string from single-string message (139 chars) | 15.642 ns | 19.251 ns |
| Create string from complex message | 35.830 ns | 89.478 ns |
| Write complex message to buffer | 57.336 ns | 64.408 ns |
# Examples
```
use std::fmt;
use writeable::assert_writeable_eq;
use writeable::LengthHint;
use writeable::Writeable;
struct WelcomeMessage<'s> {
pub name: &'s str,
}
impl<'s> Writeable for WelcomeMessage<'s> {
fn write_to<W: fmt::Write + ?Sized>(&self, sink: &mut W) -> fmt::Result {
sink.write_str("Hello, ")?;
sink.write_str(self.name)?;
sink.write_char('!')?;
Ok(())
}
fn writeable_length_hint(&self) -> LengthHint {
// "Hello, " + '!' + length of name
LengthHint::exact(8 + self.name.len())
}
}
let message = WelcomeMessage { name: "Alice" };
assert_writeable_eq!(&message, "Hello, Alice!");
// Types implementing `Writeable` are recommended to also implement `fmt::Display`.
// This can be simply done by redirecting to the `Writeable` implementation:
writeable::impl_display_with_writeable!(WelcomeMessage<'_>);
assert_eq!(message.to_string(), "Hello, Alice!");
```
[`ICU4X`]: ../icu/index.html |
17453 |
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| ops.rs |
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7877 |
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| parts_write_adapter.rs |
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2979 |
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| testing.rs |
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2252 |
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| to_string_or_borrow.rs |
|
7206 |
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| try_writeable.rs |
|
15210 |
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