Popping and pushing from the end of a linked list is constant time. This
documentation is already there for popping and pushing from the front.
@bors: r+ 38fe8d2 rollup
Remove `tokenstream::Delimited`.
Because it's an extra type layer that doesn't really help; in a couple
of places it actively gets in the way, and overall removing it makes the
code nicer. It does, however, move `tokenstream::TokenTree` further away
from the `TokenTree` in `quote.rs`.
More importantly, this change reduces the size of `TokenStream` from 48
bytes to 40 bytes on x86-64, which is enough to slightly reduce
instruction counts on numerous benchmarks, the best by 1.5%.
Note that `open_tt` and `close_tt` have gone from being methods on
`Delimited` to associated methods of `TokenTree`.
Because it's an extra type layer that doesn't really help; in a couple
of places it actively gets in the way, and overall removing it makes the
code nicer. It does, however, move `tokenstream::TokenTree` further away
from the `TokenTree` in `quote.rs`.
More importantly, this change reduces the size of `TokenStream` from 48
bytes to 40 bytes on x86-64, which is enough to slightly reduce
instruction counts on numerous benchmarks, the best by 1.5%.
Note that `open_tt` and `close_tt` have gone from being methods on
`Delimited` to associated methods of `TokenTree`.
This commit also fixes up lifetimes a bit:
- Renames `'a` as `'p` when used with `Matrix` and `Pattern`, for
consistency.
- Removes some unnecessary `'p` lifetimes on some function arguments.
- Adds some missing lifetime parameters.
slice: tweak concat & join
- use `sum` instead of `fold` (readability)
- adjust the capacity for `join` - the number of separators is `n - 1`, not `n`; proof:
```
fn main() {
let a = [[1, 2], [4, 5]];
let v = a.join(&3);
assert_ne!(v.len(), v.capacity()); // len is 5, capacity is 6
}
```
Update the book to fix some edition-related bugs
I'd love to have this included in a point release if one happens, but the changes aren't worth doing a point release on their own IMO. I'd definitely like to see this backported to beta.
The most urgent changes included here are:
- Chapter 19.6, on macros (including the macro changes that just stabilized), [is cut off](https://github.com/rust-lang/book/issues/1668) because of an ill-placed newline in a comment that [pulldown-cmark interprets incorrectly](https://github.com/raphlinus/pulldown-cmark/issues/124).
- [The `Cargo.toml` shown in the Guessing Game example in Chapter 2 (and one in Chapter 14) doesn't have `edition="2018"`](https://github.com/rust-lang/book/pull/1671), which can be confusing depending on whether the readers have it in theirs or not, think they should remove it if they have it, and the rest of the chapter assumes it's there and the code doesn't compile if you don't have it.
- The redirects implemented as part of only shipping the 2018 edition of the book sometimes lead to [having to click through 2 redirect pages](https://github.com/rust-lang/book/pull/1667) when it could be just one.
There are other small corrections included that were made since the last time the book was updated, but those aren't urgent.
cc @steveklabnik
