我试图使用一个泛型类型
以下是我的结构体定义:
假设我有一个变量
以下是上下文中的代码片段以及与之相关的Playground直链:
生成以下错误信息:
R
,并保留 Read
类型边界,以便可以访问 Read
trait,并进而支持 bytes()
方法。具体来说,我希望将 std::io::Cursor
与此相关联。以下是我的结构体定义:
struct Parse<'parse, R: Read + BufRead + 'parse> {
tokens: Vec<Token>,
source: Cursor<&'parse mut R>,
}
假设我有一个变量
parser
,它是Parse
的一个实例,我想调用parser.source.bytes()
方法。尽管在R
周围有注释,但编译器告诉我R
未满足std::io::Read
trait限制。以下是上下文中的代码片段以及与之相关的Playground直链:
// using Cursor because it tracks position internally
use std::io::{Cursor, Read, BufRead};
struct Token {
start: usize,
end: usize,
}
struct Parse<'parse, R: Read + BufRead + 'parse> {
tokens: Vec<Token>,
source: Cursor<&'parse mut R>,
}
impl<'parse, R: Read + BufRead + 'parse> Parse <'parse, R> {
fn new(source: &'parse mut R) -> Self {
Parse {
tokens: vec!(),
source: Cursor::new(source),
}
}
fn parse_primitive(&mut self) -> std::io::Result<Token> {
let start = self.source.position();
let bytes = self.source.bytes(); // <- error raised here
// dummy work
for _ in 0..3 {
let byte = bytes.next().unwrap().unwrap()
}
let end = self.source.position();
Ok(Token { start: start as usize, end: end as usize})
}
}
fn main() {
//...
}
生成以下错误信息:
error[E0599]: no method named `bytes` found for type `std::io::Cursor<&'parse mut R>` in the current scope
--> src/main.rs:24:33
|
24 | let bytes = self.source.bytes();
| ^^^^^
|
= note: the method `bytes` exists but the following trait bounds were not satisfied:
`std::io::Cursor<&mut R> : std::io::Read`
`&mut std::io::Cursor<&'parse mut R> : std::io::Read`
感谢您的帮助!
AsRef<[u8]>
。 - Peter Hallbytes()
会消耗游标。 - Peter Hall