The errors about the implement of queue

[Jia-Baos]

// queue.rs

// 队列 #[derive(Debug)] struct Queue<T> { cap: usize, // 容量 data: Vec<T>, // 数据容器 }

impl<T> Queue<T> { fn new(size: usize) -> Self { Queue { cap: size, data: Vec::with_capacity(size), } }

// 判断是否有剩余空间、有则数据加入队列
fn enqueue(&mut self, val: T) -> Result<(), String> {
    if Self::size(&self) == self.cap {
        return Err("No space available".to_string());
    }
    self.data.insert(0, val);

    Ok(())
}

fn size(&self) -> usize {
    self.data.len()
}

}

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Because the function of "size(&self) " is a method belongs to one instance, so that we can't use the Self::size(&self) to obtain the size of self, the better choice is using self.size()......