The test is reduced from a doc test, but making it separate ensures that
(1) unrelated changes to the docs won't leave this case uncovered, and
(2) the nature of any future failures will be more obvious to whoever
sees the tree on fire as a result.
`std::bigint` contains the following code.
```rust
borrow = *elem << (uint::bits - n_bits);
```
The code above contains a bug that the value of the right operand of the shift operator exceeds the size of the left operand,
because sizeof(*elem) == 32, and 0 <= n_bits < 32 in 64bit architecture.
If `--opt-level` option is not given to rustc, the code above runs as if the right operand is `(uint::bits - n_bits) % 32`,
but if --opt-level is given, `borrow` is always zero.
I wonder why this bug is not catched in the libstd's testsuite (I try the `rustc --test --opt-level=2 bigint.rs` before fixing the bug,
but the unittest passes normally.)
This pull request also removes the implicit vector copies in `bigint.rs`.
This replaces the wrapper around the runtime RNG with a pure Rust implementation of the same algorithm. This is much faster (up to 5x), and is hopefully safer.
There is still (a little) room for optimisation: testing by summing 100,000,000 random `u32`s indicates this is about ~~40-50%~~ 10% slower than the pure C implementation (running as standalone executable, not in the runtime).
(Only 6d50d55 is part of this PR, the first two are from #6058, but are required for the rt rng to be correct to compare against in the tests.)
This replaces the wrapper around the runtime RNG with a pure Rust
implementation of the same algorithm. This is faster (up to 5x), and
is hopefully safer.
There is still much room for optimisation: testing by summing 100,000,000
random `u32`s indicates this is about 40-50% slower than the pure C
implementation (running as standalone executable, not in the runtime).
As discussed on issue #4819, I have created four new traits: `Algebraic`, `Trigonometric`, `Exponential` and `Hyperbolic`, and moved the appropriate methods into them from `Real`.
~~~rust
pub trait Algebraic {
fn pow(&self, n: Self) -> Self;
fn sqrt(&self) -> Self;
fn rsqrt(&self) -> Self;
fn cbrt(&self) -> Self;
fn hypot(&self, other: Self) -> Self;
}
pub trait Trigonometric {
fn sin(&self) -> Self;
fn cos(&self) -> Self;
fn tan(&self) -> Self;
fn asin(&self) -> Self;
fn acos(&self) -> Self;
fn atan(&self) -> Self;
fn atan2(&self, other: Self) -> Self;
}
pub trait Exponential {
fn exp(&self) -> Self;
fn exp2(&self) -> Self;
fn expm1(&self) -> Self;
fn log(&self) -> Self;
fn log2(&self) -> Self;
fn log10(&self) -> Self;
}
pub trait Hyperbolic: Exponential {
fn sinh(&self) -> Self;
fn cosh(&self) -> Self;
fn tanh(&self) -> Self;
}
~~~
There was some discussion over whether we should shorten the names, for example `Trig` and `Exp`. No abbreviations have been agreed on yet, but this could be considered in the future.
Additionally, `Integer::divisible_by` has been renamed to `Integer::is_multiple_of`.
One of the tests seems to have no current equivalent that's similar. Please let me know if that's incorrect, and I'll try fixing it instead of deleting it. I suppose a struct could be used instead of `any` and `match type`, but it seems like the original intent of the test was to exercise `match type`
After discussions on IRC and #4819, we have decided to revert this change. This is due to the traits expressing different ideas and because hyperbolic functions are not trivially implementable from exponential functions for floating-point types.
The Hyperbolic Functions are trivially implemented in terms of `exp`, so it's simpler to group them the Exponential trait. In the future these would have default implementations.
r? @pcwalton
A month's worth of parser cleanup here. Much of this is new comments and renaming. A number of these commits also remove unneeded code. Probably the biggest refactor here is splitting "parse_item_or_view_item" into two functions; it turns out that the only overlap between items in foreign modules and items in regular modules was macros, so this refactor should make things substantially easier for future maintenance.
borrow = *elem << (uint::bits - n_bits);
The code above contains a bug that the value of the right operand of the shift operator exceeds the size of the left operand,
because sizeof(*elem) == 32, and 0 <= n_bits < 32 in 64bit architecture.
If `--opt-level` option is not given to rustc, the code above runs as if the right operand is `(uint::bits - n_bits) % 32`,
but if --opt-level is given, `borrow` is always zero.
I wonder why this bug is not catched in the libstd's testsuite (I try the `rustc --test --opt-level=2 bigint.rs` before fixing the bug,
but the unittest passes normally.)
The existing adaptors like `map` in the `iter` module are very flawed because they only work for `BaseIter` implementations. There are many internal iterator implementations in the standard library like the set methods (`difference`, `symmetric_difference`, `intersection`, `union`) and the `range` functions that only share the `for` loop protocol in common.
The internal iterator adaptors should be implemented to work on any implementation of that protocol, rather than just a method called `each` taking `&self`.
This just moves `iter.rs` to `old_iter.rs` and begins work on documenting and implementing a nicer module.
