tokio_buf/
size_hint.rs

1use std::u64;
2
3/// A `BufStream` size hint
4///
5/// The default implementation returns:
6///
7/// * 0 for `available`
8/// * 0 for `lower`
9/// * `None` for `upper`.
10#[derive(Debug, Default, Clone)]
11pub struct SizeHint {
12    lower: u64,
13    upper: Option<u64>,
14}
15
16impl SizeHint {
17    /// Returns a new `SizeHint` with default values
18    pub fn new() -> SizeHint {
19        SizeHint::default()
20    }
21
22    /// Returns the lower bound of data that the `BufStream` will yield before
23    /// completing.
24    pub fn lower(&self) -> u64 {
25        self.lower
26    }
27
28    /// Set the value of the `lower` hint.
29    ///
30    /// # Panics
31    ///
32    /// The function panics if `value` is greater than `upper`.
33    pub fn set_lower(&mut self, value: u64) {
34        assert!(value <= self.upper.unwrap_or(u64::MAX));
35        self.lower = value;
36    }
37
38    /// Returns the upper bound of data the `BufStream` will yield before
39    /// completing, or `None` if the value is unknown.
40    pub fn upper(&self) -> Option<u64> {
41        self.upper
42    }
43
44    /// Set the value of the `upper` hint value.
45    ///
46    /// # Panics
47    ///
48    /// This function panics if `value` is less than `lower`.
49    pub fn set_upper(&mut self, value: u64) {
50        // There is no need to check `available` as that is guaranteed to be
51        // less than or equal to `lower`.
52        assert!(value >= self.lower, "`value` is less than than `lower`");
53
54        self.upper = Some(value);
55    }
56}
tokio_buf/size_hint.rs

tokio_buf/
size_hint.rs
