[英]How do I resolve the lifetime issues in this code?
pub struct Map<'a, F, I, O>
where F: Fn(I) -> O {
parser: &'a Parser<'a>,
mapper: F,
phantomDataI: PhantomData<I>,
phantomDataO: PhantomData<O>
}
impl<'a, F, I, O> Map<'a, F, I, O>
where F: Fn(I) -> O {
fn new(parser: &'a Parser, mapper: F) -> Map<'a, F, I, O> {
Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
}
}
When I compile this I get an error...当我编译这个时,我收到一个错误...
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
--> src\combinator\mod.rs:123:9
|
123 | Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
| ^^^
|
note: first, the lifetime cannot outlive the lifetime 'a as defined on the impl at 120:1...
--> src\combinator\mod.rs:120:1
|
120 | / impl<'a, F, I, O> Map<'a, F, I, O>
121 | | where F: Fn(I) -> O {
122 | | fn new(parser: &'a Parser, mapper: F) -> Map<'a, F, I, O> {
123 | | Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
124 | | }
125 | | }
| |_^
note: ...so that expression is assignable (expected combinator::Map<'a, _, _, _>, found combinator::Map<'_, _, _, _>)
--> src\combinator\mod.rs:123:9
|
123 | Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: but, the lifetime must be valid for the anonymous lifetime #1 defined on the method body at 122:5...
--> src\combinator\mod.rs:122:5
|
122 | / fn new(parser: &'a Parser, mapper: F) -> Map<'a, F, I, O> {
123 | | Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
124 | | }
| |_____^
note: ...so that types are compatible (expected combinator::Parser<'_>, found combinator::Parser<'_>)
--> src\combinator\mod.rs:123:15
|
123 | Map { parser, mapper, phantomDataI: PhantomData, phantomDataO: PhantomData }
| ^^^^^^
I don't understand why this line is occuring我不明白为什么会出现这条线
expression is assignable (expected combinator::Map<'a, _, _, _>, found combinator::Map<'_, _, _, _>)
Do I need to change my lifetime specifiers somehow?我是否需要以某种方式更改我的生命周期说明符?
new
签名中的Parser
需要'a
生命周期参数:
fn new(parser: &'a Parser<'a>, mapper: F) -> Map<'a, F, I, O>
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