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591dd5d9
编写于
3月 16, 2018
作者:
A
Aleksey Kladov
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差异文件
Add Iterator::find_map
上级
14ac1b5f
变更
3
隐藏空白更改
内联
并排
Showing
3 changed file
with
60 addition
and
0 deletion
+60
-0
src/libcore/iter/iterator.rs
src/libcore/iter/iterator.rs
+32
-0
src/libcore/tests/iter.rs
src/libcore/tests/iter.rs
+27
-0
src/libcore/tests/lib.rs
src/libcore/tests/lib.rs
+1
-0
未找到文件。
src/libcore/iter/iterator.rs
浏览文件 @
591dd5d9
...
...
@@ -1745,6 +1745,38 @@ fn find<P>(&mut self, mut predicate: P) -> Option<Self::Item> where
})
.break_value
()
}
/// Applies function to the elements of iterator and returns
/// the first non-none result.
///
/// `iter.find_map(f)` is equivalent to `iter.filter_map(f).next()`.
///
///
/// # Examples
///
/// ```
/// #![feature(iterator_find_map)]
/// let a = ["lol", "NaN", "2", "5"];
///
/// let mut first_number = a.iter().find_map(|s| s.parse().ok());
///
/// assert_eq!(first_number, Some(2));
/// ```
#[inline]
#[unstable(feature
=
"iterator_find_map"
,
reason
=
"unstable new API"
,
issue
=
"49602"
)]
fn
find_map
<
B
,
F
>
(
&
mut
self
,
mut
f
:
F
)
->
Option
<
B
>
where
Self
:
Sized
,
F
:
FnMut
(
Self
::
Item
)
->
Option
<
B
>
,
{
self
.try_for_each
(
move
|
x
|
{
match
f
(
x
)
{
Some
(
x
)
=>
LoopState
::
Break
(
x
),
None
=>
LoopState
::
Continue
(()),
}
})
.break_value
()
}
/// Searches for an element in an iterator, returning its index.
///
/// `position()` takes a closure that returns `true` or `false`. It applies
...
...
src/libcore/tests/iter.rs
浏览文件 @
591dd5d9
...
...
@@ -1146,6 +1146,33 @@ fn test_find() {
assert
!
(
v
.iter
()
.find
(|
&&
x
|
x
%
12
==
0
)
.is_none
());
}
#[test]
fn
test_find_map
()
{
let
xs
:
&
[
isize
]
=
&
[];
assert_eq!
(
xs
.iter
()
.find_map
(
half_if_even
),
None
);
let
xs
:
&
[
isize
]
=
&
[
3
,
5
];
assert_eq!
(
xs
.iter
()
.find_map
(
half_if_even
),
None
);
let
xs
:
&
[
isize
]
=
&
[
4
,
5
];
assert_eq!
(
xs
.iter
()
.find_map
(
half_if_even
),
Some
(
2
));
let
xs
:
&
[
isize
]
=
&
[
3
,
6
];
assert_eq!
(
xs
.iter
()
.find_map
(
half_if_even
),
Some
(
3
));
let
xs
:
&
[
isize
]
=
&
[
1
,
2
,
3
,
4
,
5
,
6
,
7
];
let
mut
iter
=
xs
.iter
();
assert_eq!
(
iter
.find_map
(
half_if_even
),
Some
(
1
));
assert_eq!
(
iter
.find_map
(
half_if_even
),
Some
(
2
));
assert_eq!
(
iter
.find_map
(
half_if_even
),
Some
(
3
));
assert_eq!
(
iter
.next
(),
Some
(
&
7
));
fn
half_if_even
(
x
:
&
isize
)
->
Option
<
isize
>
{
if
x
%
2
==
0
{
Some
(
x
/
2
)
}
else
{
None
}
}
}
#[test]
fn
test_position
()
{
let
v
=
&
[
1
,
3
,
9
,
27
,
103
,
14
,
11
];
...
...
src/libcore/tests/lib.rs
浏览文件 @
591dd5d9
...
...
@@ -49,6 +49,7 @@
#![feature(atomic_nand)]
#![feature(reverse_bits)]
#![feature(inclusive_range_fields)]
#![feature(iterator_find_map)]
extern
crate
core
;
extern
crate
test
;
...
...
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