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pub trait Source {
    fn visit<'kvs>(
        &'kvs self,
        visitor: &mut dyn Visitor<'kvs>
    ) -> Result<(), Error>; fn get<'v>(&'v self, key: Key<'_>) -> Option<Value<'v>> { ... }
fn count(&self) -> usize { ... } }
Expand description

A source of key-value pairs.

The source may be a single pair, a set of pairs, or a filter over a set of pairs. Use the Visitor trait to inspect the structured data in a source.

Required methods

Visit key-value pairs.

A source doesn’t have to guarantee any ordering or uniqueness of key-value pairs. If the given visitor returns an error then the source may early-return with it, even if there are more key-value pairs.

Implementation notes

A source should yield the same key-value pairs to a subsequent visitor unless that visitor itself fails.

Provided methods

Get the value for a given key.

If the key appears multiple times in the source then which key is returned is implementation specific.

Implementation notes

A source that can provide a more efficient implementation of this method should override it.

Count the number of key-value pairs that can be visited.

Implementation notes

A source that knows the number of key-value pairs upfront may provide a more efficient implementation.

A subsequent call to visit should yield the same number of key-value pairs to the visitor, unless that visitor fails part way through.

Implementations on Foreign Types

Implementors