Trait bonsaidb_core::key::KeyVisitor

pub trait KeyVisitor {
    // Required methods
    fn visit_type(&mut self, kind: KeyKind);
    fn visit_other(&mut self, kind: impl Into<Cow<'static, str>>);
    fn visit_composite(&mut self, kind: CompositeKind, count: usize);
    fn visit_composite_attribute(
        &mut self,
        key: impl Into<Cow<'static, str>>,
        value: impl Into<KeyAttibuteValue>
    );
}

A Visitor for information about a KeyEncoding.

This trait is used in KeyEncoding::describe to report information about the type of data contained within the key. Using this information, generically interpreting the bytes of a key type can be possible as long as the key type uses CompositeKeyEncoder.

This trait is not something that most users will ever need to implement. Instead, KeyDescription::for_key()/KeyDescription::for_encoding() are built-in functions to retrieve the information reported by this trait in an easier-to-use interface.

Required Methods

fn visit_type(&mut self, kind: KeyKind)

Report that a basic key type is encoded next in this key.

fn visit_other(&mut self, kind: impl Into<Cow<'static, str>>)

Report that a custom type is encoded next as a single byte sequence in this key.

fn visit_composite(&mut self, kind: CompositeKind, count: usize)

Report that a composite type made up of count fields is encoded next in this key.

KeyVisitor implementations may panic if there are less than or more than count fields reported by either visit_type() or visit_composite().

fn visit_composite_attribute( &mut self, key: impl Into<Cow<'static, str>>, value: impl Into<KeyAttibuteValue> )

Report that the current composite type has extra metadata.

This can be used to encode const generic parameters that are helpful in interpretting the contents of a type. For example, LimitedResolutionTimestamp uses this function to report the TimeEpoch’s nanoseconds since the Unix epoch.

Object Safety

This trait is not object safe.

Implementors