use std::u64;
#[derive(Debug, Default, Clone)]
pub struct SizeHint {
lower: u64,
upper: Option<u64>,
}
impl SizeHint {
#[inline]
pub fn new() -> SizeHint {
SizeHint::default()
}
#[inline]
pub fn with_exact(value: u64) -> SizeHint {
SizeHint {
lower: value,
upper: Some(value),
}
}
#[inline]
pub fn lower(&self) -> u64 {
self.lower
}
#[inline]
pub fn set_lower(&mut self, value: u64) {
assert!(value <= self.upper.unwrap_or(u64::MAX));
self.lower = value;
}
#[inline]
pub fn upper(&self) -> Option<u64> {
self.upper
}
#[inline]
pub fn set_upper(&mut self, value: u64) {
assert!(value >= self.lower, "`value` is less than than `lower`");
self.upper = Some(value);
}
#[inline]
pub fn exact(&self) -> Option<u64> {
if Some(self.lower) == self.upper {
self.upper
} else {
None
}
}
#[inline]
pub fn set_exact(&mut self, value: u64) {
self.lower = value;
self.upper = Some(value);
}
}