Struct ModifierChain 

pub struct ModifierChain<T> { /* private fields */ }

A composed chain of OpFieldModifier<T> — the moral equivalent of upstream NB Java’s specialized LongFunction<S>.

Built once in the dispenser initializer; called per cycle on the critical path. Carries an optional ModifierTraceSink for cross-cutting observation; the sink hot-path is gated lazily (see Self::apply).

Implementations

impl<T: 'static> ModifierChain<T>

pub fn new( op_label: impl Into<String>, active: Vec<Box<dyn OpFieldModifier<T>>>, event_sink: Option<Arc<dyn ModifierTraceSink>>, ) -> Self

Construct a chain. active MUST already exclude inactive modifiers; the caller (typically a per-adapter builder like build_cql_modifier_chain) is responsible for dropping None results from parent.lookup(...) so this vec contains only modifiers the user actually bound.

pub fn is_empty(&self) -> bool

True when the user did not bind any universal field for this op. Lets the caller skip the apply call entirely on a fully-default path — the most common case in practice.

pub fn len(&self) -> usize

Number of active modifiers. For diagnostics / tests.

pub fn op_label(&self) -> &str

The op label this chain was built for. Used by sinks for event correlation.

pub fn apply(&self, target: &mut T)

Critical-path entry. Apply every active modifier to the target.

Two arms:

• No sink installed: tight loop over active. No closure construction, no JSON serialization, no virtual dispatch beyond each modifier’s own apply.
• Sink installed: after each apply, the sink is handed a &dyn Fn() -> serde_json::Value that the sink may or may not invoke. JSON serialization is paid only when the sink actually wants the value (e.g. trace-router has at least one subscriber to this adapter’s traces).

Trait Implementations

impl<T: 'static> Debug for ModifierChain<T>

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

Formats the value using the given formatter.