http_body/
size_hint.rs

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1use std::u64;
2
3/// A `Body` size hint
4///
5/// The default implementation returns:
6///
7/// * 0 for `lower`
8/// * `None` for `upper`.
9#[derive(Debug, Default, Clone)]
10pub struct SizeHint {
11    lower: u64,
12    upper: Option<u64>,
13}
14
15impl SizeHint {
16    /// Returns a new `SizeHint` with default values
17    #[inline]
18    pub fn new() -> SizeHint {
19        SizeHint::default()
20    }
21
22    /// Returns a new `SizeHint` with both upper and lower bounds set to the
23    /// given value.
24    #[inline]
25    pub fn with_exact(value: u64) -> SizeHint {
26        SizeHint {
27            lower: value,
28            upper: Some(value),
29        }
30    }
31
32    /// Returns the lower bound of data that the `Body` will yield before
33    /// completing.
34    #[inline]
35    pub fn lower(&self) -> u64 {
36        self.lower
37    }
38
39    /// Set the value of the `lower` hint.
40    ///
41    /// # Panics
42    ///
43    /// The function panics if `value` is greater than `upper`.
44    #[inline]
45    pub fn set_lower(&mut self, value: u64) {
46        assert!(value <= self.upper.unwrap_or(u64::MAX));
47        self.lower = value;
48    }
49
50    /// Returns the upper bound of data the `Body` will yield before
51    /// completing, or `None` if the value is unknown.
52    #[inline]
53    pub fn upper(&self) -> Option<u64> {
54        self.upper
55    }
56
57    /// Set the value of the `upper` hint value.
58    ///
59    /// # Panics
60    ///
61    /// This function panics if `value` is less than `lower`.
62    #[inline]
63    pub fn set_upper(&mut self, value: u64) {
64        assert!(value >= self.lower, "`value` is less than than `lower`");
65
66        self.upper = Some(value);
67    }
68
69    /// Returns the exact size of data that will be yielded **if** the
70    /// `lower` and `upper` bounds are equal.
71    #[inline]
72    pub fn exact(&self) -> Option<u64> {
73        if Some(self.lower) == self.upper {
74            self.upper
75        } else {
76            None
77        }
78    }
79
80    /// Set the value of the `lower` and `upper` bounds to exactly the same.
81    #[inline]
82    pub fn set_exact(&mut self, value: u64) {
83        self.lower = value;
84        self.upper = Some(value);
85    }
86}
http_body/size_hint.rs

http_body/
size_hint.rs
