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Formatter (#51)

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Enforce consistent formatting use `dprint`
This commit is contained in:
Luca Palmieri
2024-05-24 17:00:03 +02:00
committed by GitHub
parent 537118574b
commit 99591a715e
157 changed files with 1057 additions and 1044 deletions
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book/src/06_ticket_management/16_btreemap.md
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@@ -1,20 +1,20 @@
# Ordering
By moving from a `Vec` to a `HashMap` we have improved the performance of our ticket management system,
and simplified our code in the process.
It's not all roses, though. When iterating over a `Vec`-backed store, we could be sure that the tickets
would be returned in the order they were added.
and simplified our code in the process.\
It's not all roses, though. When iterating over a `Vec`-backed store, we could be sure that the tickets
would be returned in the order they were added.\
That's not the case with a `HashMap`: you can iterate over the tickets, but the order is random.
We can recover a consistent ordering by switching from a `HashMap` to a `BTreeMap`.
## `BTreeMap`
A `BTreeMap` guarantees that entries are sorted by their keys.
A `BTreeMap` guarantees that entries are sorted by their keys.\
This is useful when you need to iterate over the entries in a specific order, or if you need to
perform range queries (e.g. "give me all tickets with an id between 10 and 20").
Just like `HashMap`, you won't find trait bounds on the definition of `BTreeMap`.
Just like `HashMap`, you won't find trait bounds on the definition of `BTreeMap`.
But you'll find trait bounds on its methods. Let's look at `insert`:
```rust
@@ -34,7 +34,7 @@ impl<K, V> BTreeMap<K, V> {
## `Ord`
The `Ord` trait is used to compare values.
The `Ord` trait is used to compare values.\
While `PartialEq` is used to compare for equality, `Ord` is used to compare for ordering.
It's defined in `std::cmp`:
@@ -45,8 +45,8 @@ pub trait Ord: Eq + PartialOrd {
}
```
The `cmp` method returns an `Ordering` enum, which can be one
of `Less`, `Equal`, or `Greater`.
The `cmp` method returns an `Ordering` enum, which can be one
of `Less`, `Equal`, or `Greater`.\
`Ord` requires that two other traits are implemented: `Eq` and `PartialOrd`.
## `PartialOrd`
@@ -60,9 +60,9 @@ pub trait PartialOrd: PartialEq {
}
```
`PartialOrd::partial_cmp` returns an `Option`—it is not guaranteed that two values can
be compared.
For example, `f32` doesn't implement `Ord` because `NaN` values are not comparable,
`PartialOrd::partial_cmp` returns an `Option`—it is not guaranteed that two values can
be compared.\
For example, `f32` doesn't implement `Ord` because `NaN` values are not comparable,
the same reason why `f32` doesn't implement `Eq`.
## Implementing `Ord` and `PartialOrd`
@@ -79,4 +79,4 @@ struct TicketId(u64);
If you choose (or need) to implement them manually, be careful:
- `Ord` and `PartialOrd` must be consistent with `Eq` and `PartialEq`.
- `Ord` and `PartialOrd` must be consistent with each other.
- `Ord` and `PartialOrd` must be consistent with each other.