29 lines
996 B
Rust
29 lines
996 B
Rust
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//! Constraint trait, and some common constraints.
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//!
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//! Note that all puzzle states visited during the solution search
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//! share the same set of constraints. This means that you cannot
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//! store additional information about the state (e.g. caches) in the
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//! constraint to reuse later.
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use ::{PuzzleSearch,Val,VarToken};
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/// Constraint trait.
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pub trait Constraint {
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/// Applied after a variable has been assigned.
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///
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/// Returns true if the search should continue with these variable
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/// assignments, or false if the constraint found a contradiction.
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fn on_assigned(&self, _search: &mut PuzzleSearch, _var: VarToken, _val: Val)
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-> bool {
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true
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}
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/// Applied after a variable's candidates has been modified.
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///
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/// Returns true if the search should continue with these variable
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/// assignments, or false if the constraint found a contradiction.
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fn on_updated(&self, _search: &mut PuzzleSearch) -> bool {
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true
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}
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}
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