Enum BalancedBoundary 

pub enum BalancedBoundary {
    Transparent,
    Opaque,
}

What a balanced read (read_balanced) does when it exhausts a mouth before the braces balance.

Perl has no such distinction: Gullet.pm L465-472 reads $$self{mouth} ->readToken() — the current mouth only — and lasts at the boundary, so every Perl mouth is Opaque. Rust crosses the boundary for token-level injections, which is a deliberate surpass-Perl divergence (xint, see read_balanced) and must stay narrow: crossing from a mouth that is its own input lets one runaway argument swallow everything after it.

Variants

Transparent

The mouth is a token-level continuation of the enclosing stream (\scantokens, RawTeX): its } may legitimately live in the parent, so a balanced read drains it and resumes there.

Opaque

The mouth is a self-contained input. A balanced read stops at its end, as Perl always does — an unbalanced argument loses the rest of this mouth and nothing more.

Trait Implementations

impl Clone for BalancedBoundary

fn clone(&self) -> BalancedBoundary

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for BalancedBoundary

impl Debug for BalancedBoundary

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

Formats the value using the given formatter.

impl Eq for BalancedBoundary

impl PartialEq for BalancedBoundary

fn eq(&self, other: &BalancedBoundary) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for BalancedBoundary