http_body/
size_hint.rs

1/// A `Body` size hint
2///
3/// The default implementation returns:
4///
5/// * 0 for `lower`
6/// * `None` for `upper`.
7#[derive(Debug, Default, Clone)]
8pub struct SizeHint {
9    lower: u64,
10    upper: Option<u64>,
11}
12
13impl SizeHint {
14    /// Returns a new `SizeHint` with default values
15    #[inline]
16    pub fn new() -> SizeHint {
17        SizeHint::default()
18    }
19
20    /// Returns a new `SizeHint` with both upper and lower bounds set to the
21    /// given value.
22    #[inline]
23    pub fn with_exact(value: u64) -> SizeHint {
24        SizeHint {
25            lower: value,
26            upper: Some(value),
27        }
28    }
29
30    /// Returns the lower bound of data that the `Body` will yield before
31    /// completing.
32    #[inline]
33    pub fn lower(&self) -> u64 {
34        self.lower
35    }
36
37    /// Set the value of the `lower` hint.
38    ///
39    /// # Panics
40    ///
41    /// The function panics if `value` is greater than `upper`.
42    #[inline]
43    pub fn set_lower(&mut self, value: u64) {
44        assert!(value <= self.upper.unwrap_or(u64::MAX));
45        self.lower = value;
46    }
47
48    /// Returns the upper bound of data the `Body` will yield before
49    /// completing, or `None` if the value is unknown.
50    #[inline]
51    pub fn upper(&self) -> Option<u64> {
52        self.upper
53    }
54
55    /// Set the value of the `upper` hint value.
56    ///
57    /// # Panics
58    ///
59    /// This function panics if `value` is less than `lower`.
60    #[inline]
61    pub fn set_upper(&mut self, value: u64) {
62        assert!(value >= self.lower, "`value` is less than than `lower`");
63
64        self.upper = Some(value);
65    }
66
67    /// Returns the exact size of data that will be yielded **if** the
68    /// `lower` and `upper` bounds are equal.
69    #[inline]
70    pub fn exact(&self) -> Option<u64> {
71        if Some(self.lower) == self.upper {
72            self.upper
73        } else {
74            None
75        }
76    }
77
78    /// Set the value of the `lower` and `upper` bounds to exactly the same.
79    #[inline]
80    pub fn set_exact(&mut self, value: u64) {
81        self.lower = value;
82        self.upper = Some(value);
83    }
84}
http_body/size_hint.rs

http_body/
size_hint.rs
