72 lines
1.7 KiB
Rust
72 lines
1.7 KiB
Rust
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use core::fmt::Debug;
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/// Helper for caching a value when the value is optionally present in the 'unused' state.
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#[derive(Clone, Debug)]
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pub enum Cached<T: Clone + Debug> {
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Empty,
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Unused(T),
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Used(T),
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}
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impl<T: Clone + Debug> Cached<T> {
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pub fn get(&self) -> Option<&T> {
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match self {
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Self::Empty | Self::Unused(_) => None,
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Self::Used(t) => Some(t),
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}
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}
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pub fn get_mut(&mut self) -> Option<&mut T> {
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match self {
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Self::Empty | Self::Unused(_) => None,
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Self::Used(t) => Some(t),
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}
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}
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pub fn is_unused(&self) -> bool {
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match self {
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Self::Empty | Self::Unused(_) => true,
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Self::Used(_) => false,
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}
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}
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pub fn is_used(&self) -> bool {
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match self {
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Self::Empty | Self::Unused(_) => false,
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Self::Used(_) => true,
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}
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}
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pub fn take_unused(&mut self) -> Option<T> {
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if matches!(*self, Self::Unused(_)) {
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let Self::Unused(val) = std::mem::replace(self, Self::Empty) else {
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unreachable!()
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};
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Some(val)
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} else {
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None
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}
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}
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pub fn take_used(&mut self) -> Option<T> {
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if matches!(*self, Self::Used(_)) {
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let Self::Used(val) = std::mem::replace(self, Self::Empty) else {
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unreachable!()
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};
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Some(val)
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} else {
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None
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}
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}
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pub fn set_unused(&mut self) {
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if matches!(*self, Self::Used(_)) {
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*self = Self::Unused(self.take_used().unwrap());
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}
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}
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pub fn set_used(&mut self, val: T) {
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*self = Self::Used(val);
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}
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}
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