Struct AssignmentBuilder

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pub struct AssignmentBuilder { /* private fields */ }

Expand description

Fluent builder for bipartite assignment COPs.

Construct via assignment() (preferred) or Default::default. All setters consume self and return self, allowing chained configuration. The terminal AssignmentBuilder::solve call validates the configuration, materializes the underlying Csp<CostFiniteDomain>, runs branch-and-bound, and returns an AssignmentSolution (or an AssignmentError on mis-configuration / infeasibility).

Implementations§

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impl AssignmentBuilder

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pub fn rows(self, n: usize) -> Self

Set the number of source rows.

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pub fn cols(self, n: usize) -> Self

Set the number of target columns.

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pub fn cost(self, f: impl Fn(usize, usize) -> f64) -> Self

Eagerly populate the row-major cost matrix.

Calls f(i, k) exactly once per (row, col) cell during this method, stores the result in an internal Vec<f64>, and returns self. No closure is retained, which keeps the builder Send + Sync even when constructed from non-'static captures.

§Panics

Panics if AssignmentBuilder::rows or AssignmentBuilder::cols has not been called yet — both dimensions are required to know how to walk f.

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pub fn row_group(self, f: impl Fn(usize) -> u8) -> Self

Tag each row with a u8 group identifier.

Rows in different groups are placed in independent AllDifferentExcept scopes, and a row may only be assigned to a column whose group identifier matches. Omitting the call (or supplying |_| 0) puts every row in a single group, which is the standard bipartite-assignment shape.

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pub fn col_group(self, f: impl Fn(usize) -> u8) -> Self

Tag each column with a u8 group identifier.

See AssignmentBuilder::row_group for the semantics.

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pub fn pin(self, row: usize, col: i32) -> Self

Hard-pin row row to column col.

col may be SENTINEL to force the row unmatched. Multiple pins are accumulated; conflicting pins on the same row are detected at AssignmentBuilder::solve time as AssignmentError::Infeasible.

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pub fn unmatch_penalty(self, penalty: f64) -> Self

Set the per-row cost paid when a row is assigned to SENTINEL (left unmatched).

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pub fn node_budget(self, budget: Option<u64>) -> Self

Override the underlying branch-and-bound node budget.

Passing None here is not the same as never calling this method: None requests an unbounded search, while the default (no call) installs a 1_000_000 node guard so a pathological problem cannot hang the caller. See crate::SolveConfig::node_budget.

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