Struct Traces 

pub struct Traces { /* private fields */ }

The interning table for expansion traces.

Implementations

impl Traces

pub fn new() -> Traces

An empty table.

pub fn push(&mut self, macro_name: Symbol, at: Span, outer: TraceId) -> TraceId

Records that macro_name, invoked at at, was reached from outer.

The result is the trace the tokens it produces should carry. Expansion works outermost macro first, so the chain above a step is always already interned by the time the step is, and the list grows inwards.

pub fn step(&self, id: TraceId) -> Option<Step>

One step, or None for TraceId::NONE.

pub fn chain(&self, id: TraceId) -> Vec<Step>

The chain from the outermost macro inwards, which is the order a reader wants it.

The list points the other way, because a step can only be interned once the chain above it exists, so this walks it and reverses. Chains are a handful of steps long in the worst real case, so the allocation is not worth avoiding.

Trait Implementations

impl Debug for Traces

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

Formats the value using the given formatter.

impl Default for Traces

fn default() -> Traces

Returns the “default value” for a type.