This patch adds an implementation of the Iterator::size_hint() trait
function so that the compiler can optimize allocations on the collecting
side of the iterator better.
From the trait function docs:
> size_hint() is primarily intended to be used for optimizations such
> as reserving space for the elements of the iterator, but must not be
> trusted to e.g., omit bounds checks in unsafe code. An incorrect
> implementation of size_hint() should not lead to memory safety
> violations.
Source: https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html#method.size_hint
And:
> Vec may use any or none of the following strategies, depending on the
> supplied iterator:
>
> * preallocate based on Iterator::size_hint() and panic if the number
> of items is outside the provided lower/upper bounds
Source: https://doc.rust-lang.org/stable/std/iter/trait.FromIterator.html
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Matthias Beyer
Lorenz Leutgeb