Struct proptest::sample::Index [−][src]
pub struct Index(_);
A stand-in for an index into a slice or similar collection or conceptually similar things.
At the lowest level, Index
is a mechanism for generating usize
values
in the range [0..N), for some N whose value is not known until it is
needed. (Contrast with using 0..N
itself as a strategy, where you need to
know N when you define the strategy.)
For any upper bound, the actual index produced by an Index
is the same no
matter how many times it is used. Different upper bounds will produce
different but not independent values.
Shrinking will cause the index to binary search through the underlying collection(s) it is used to sample.
Note that Index
cannot currently be used as a slice index (e.g.,
slice[index]
) due to the trait coherence rules.
Example
If the collection itself being indexed is itself generated by a strategy,
you can make separately define that strategy and a strategy generating one
or more Index
es and then join the two after input generation, avoiding a
call to prop_flat_map()
.
#[macro_use] extern crate proptest; use proptest::prelude::*; proptest! { #[test] fn my_test( names in prop::collection::vec("[a-z]+", 10..20), indices in prop::collection::vec(any::<prop::sample::Index>(), 5..10) ) { // We now have Vec<String> of ten to twenty names, and a Vec<Index> // of five to ten indices and can combine them however we like. for index in &indices { println!("Accessing item by index: {}", names[index.index(names.len())]); println!("Accessing item by convenience method: {}", index.get(&names)); } // Test stuff... } }
Methods
impl Index
[src]
impl Index
pub fn index(&self, size: usize) -> usize
[src]
pub fn index(&self, size: usize) -> usize
Return the real index that would be used to index a collection of size size
.
Panics
Panics if size == 0
.
ⓘImportant traits for &'a mut Ipub fn get<'a, T>(&self, slice: &'a [T]) -> &'a T
[src]
pub fn get<'a, T>(&self, slice: &'a [T]) -> &'a T
Return a reference to the element in slice
that this Index
refers to.
A shortcut for &slice[index.index(slice.len())]
.
ⓘImportant traits for &'a mut Ipub fn get_mut<'a, T>(&self, slice: &'a mut [T]) -> &'a mut T
[src]
pub fn get_mut<'a, T>(&self, slice: &'a mut [T]) -> &'a mut T
Return a mutable reference to the element in slice
that this Index
refers to.
A shortcut for &mut slice[index.index(slice.len())]
.
Trait Implementations
impl Arbitrary for Index
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impl Arbitrary for Index
type Parameters = ()
The type of parameters that [arbitrary_with
] accepts for configuration of the generated [Strategy
]. Parameters must implement [Default
]. Read more
type Strategy = IndexStrategy
The type of [Strategy
] used to generate values of type Self
. Read more
fn arbitrary_with(_: ()) -> IndexStrategy
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fn arbitrary_with(_: ()) -> IndexStrategy
Generates a [Strategy
] for producing arbitrary values of type the implementing type (Self
). The strategy is passed the arguments given in args. Read more
fn arbitrary() -> Self::Strategy
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fn arbitrary() -> Self::Strategy
Generates a [Strategy
] for producing arbitrary values of type the implementing type (Self
). Read more
impl Clone for Index
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impl Clone for Index
fn clone(&self) -> Index
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fn clone(&self) -> Index
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
impl Copy for Index
[src]
impl Copy for Index
impl Debug for Index
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impl Debug for Index