Enum ScopeEntry

enum ScopeEntry {
    Backref(usize),
    Rootref,
    Scope(Scopes, Reason),
    Named(usize, Reason),
}

ScopeEntry is a description of what we know of a scope’s type and its connection to other scopes.

It is used both to look up a scope’s type, and to propagate knowledge about that type backward to the scope’s source. For example if this is a Rootref, and we find out that this is a Character, then root must be a Character too.

Variants

Backref(usize)

Backref is for when the current scope is made with prev or this. It counts as a scope in the chain, for purposes of prev and such, but any updates to it (such as narrowing of scope types) need to be propagated back to the real origin of that scope.

The backref number is 0 for ‘this’, 1 for ‘prev’

Rootref

A Rootref is for when the current scope is made with root. Most of the time, we also start with this being a Rootref.

Scope(Scopes, Reason)

Token is the token that’s the reason why we think the Scopes value is what it is. It’s usually the token that was the cause of the latest narrowing.

Named(usize, Reason)

The current scope takes its value from a named scope. The usize is an index into the ScopeContext::named vector.

Implementations

impl ScopeEntry

fn deduce<T: Into<Token>>(token: T) -> ScopeEntry

Trait Implementations

impl Clone for ScopeEntry

fn clone(&self) -> ScopeEntry

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ScopeEntry

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.