Trait regex_syntax::hir::Visitor
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pub trait Visitor { type Output; type Err; fn finish(self) -> Result<Self::Output, Self::Err>; fn start(&mut self) { ... } fn visit_pre(&mut self, _hir: &Hir) -> Result<(), Self::Err> { ... } fn visit_post(&mut self, _hir: &Hir) -> Result<(), Self::Err> { ... } fn visit_alternation_in(&mut self) -> Result<(), Self::Err> { ... } }
A trait for visiting the high-level IR (HIR) in depth first order.
The principle aim of this trait is to enable callers to perform case analysis on a high-level intermediate representation of a regular expression without necessarily using recursion. In particular, this permits callers to do case analysis with constant stack usage, which can be important since the size of an HIR may be proportional to end user input.
Typical usage of this trait involves providing an implementation and then
running it using the visit
function.
Associated Types
Required Methods
fn finish(self) -> Result<Self::Output, Self::Err>
All implementors of Visitor
must provide a finish
method, which
yields the result of visiting the HIR or an error.
Provided Methods
fn start(&mut self)
This method is called before beginning traversal of the HIR.
fn visit_pre(&mut self, _hir: &Hir) -> Result<(), Self::Err>
This method is called on an Hir
before descending into child Hir
nodes.
fn visit_post(&mut self, _hir: &Hir) -> Result<(), Self::Err>
This method is called on an Hir
after descending all of its child
Hir
nodes.
fn visit_alternation_in(&mut self) -> Result<(), Self::Err>
This method is called between child nodes of an alternation.