[−][src]Trait chalk_ir::visit::VisitResult

pub trait VisitResult: Sized {
    fn new() -> Self;

    fn return_early(&self) -> bool;

    fn combine(self, other: Self) -> Self;

    fn and_then(self, op: impl FnOnce() -> Self) -> Self { ... }
}

A "result type" that can be returned from a visitor. Visitors pick an appropriate result type depending on what sort of operation they are doing. A common choice is FindAny, which indicates that the visitor is searching for something and that the visitor should stop once it is found.

Required methods

fn new() -> Self

fn return_early(&self) -> bool

Returns true if this result is "complete" and we can stop visiting any further parts of the term. This is used by FindAny, for example, to stop the search after a match has been found.

fn combine(self, other: Self) -> Self

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Provided methods

fn and_then(self, op: impl FnOnce() -> Self) -> Self

Convenience helper for use in writing Visitor impls. Returns self if return_early() is true, but otherwise combines self with the result of invoking op.

If you have a struct with two fields, foo and bar, you can thus write code like

ⓘThis example is not tested
self.foo.visit_with(visitor, outer_binder)
    .and_then(|| self.bar.visit_with(visitor, outer_binder))

and bar will only be visited if necessary.

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Implementations on Foreign Types

impl VisitResult for ()[src]

Unit type for a visitor indicates a "side-effecting" visitor that should visit an entire term.

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Implementors

impl VisitResult for FindAny[src]

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