40 lines
1.3 KiB
Rust
40 lines
1.3 KiB
Rust
//! Diff misc.
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use common::*;
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#[derive(Debug,Clone,PartialEq,Eq)]
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/// Diff type for specifying a change (or not).
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pub enum Diff<T> where T: Eq {
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/// Both sides are the same.
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Same,
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/// Left (pre, source) side doesn't include value, right side (post, destination) does.
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Born(T),
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/// Both sides include data; it chaged value between them.
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Changed(T, T),
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/// Left (pre, source) side does include value, right side (post, destination) does not.
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Died(T),
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}
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impl<T> Diff<T> where T: Eq {
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/// Construct new object with given `pre` and `post`.
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pub fn new(pre: T, post: T) -> Self { if pre == post { Diff::Same } else { Diff::Changed(pre, post) } }
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/// Get the before value, if there is one.
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pub fn pre(&self) -> Option<&T> { match *self { Diff::Died(ref x) | Diff::Changed(ref x, _) => Some(x), _ => None } }
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/// Get the after value, if there is one.
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pub fn post(&self) -> Option<&T> { match *self { Diff::Born(ref x) | Diff::Changed(_, ref x) => Some(x), _ => None } }
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/// Determine whether there was a change or not.
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pub fn is_same(&self) -> bool { match *self { Diff::Same => true, _ => false }}
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}
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#[derive(PartialEq,Eq,Clone,Copy)]
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/// Boolean type for clean/dirty status.
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pub enum Filth {
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/// Data has not been changed.
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Clean,
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/// Data has been changed.
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Dirty,
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}
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