Trait regex_syntax::ast::Visitor
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[src]
pub trait Visitor { type Output; type Err; fn finish(self) -> Result<Self::Output, Self::Err>; fn start(&mut self) { ... } fn visit_pre(&mut self, _ast: &Ast) -> Result<(), Self::Err> { ... } fn visit_post(&mut self, _ast: &Ast) -> Result<(), Self::Err> { ... } fn visit_alternation_in(&mut self) -> Result<(), Self::Err> { ... } fn visit_class_set_item_pre(
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err> { ... } fn visit_class_set_item_post(
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err> { ... } fn visit_class_set_binary_op_pre(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err> { ... } fn visit_class_set_binary_op_post(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err> { ... } fn visit_class_set_binary_op_in(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err> { ... } }
A trait for visiting an abstract syntax tree (AST) in depth first order.
The principle aim of this trait is to enable callers to perform case analysis on an abstract syntax tree 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 abstract syntax tree may be proportional to end user input.
Typical usage of this trait involves providing an implementation and then
running it using the visit
function.
Note that the abstract syntax tree for a regular expression is quite
complex. Unless you specifically need it, you might be able to use the
much simpler
high-level intermediate representation
and its
corresponding Visitor
trait
instead.
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 AST or an error.
Provided Methods
fn start(&mut self)
This method is called before beginning traversal of the AST.
fn visit_pre(&mut self, _ast: &Ast) -> Result<(), Self::Err>
This method is called on an Ast
before descending into child Ast
nodes.
fn visit_post(&mut self, _ast: &Ast) -> Result<(), Self::Err>
This method is called on an Ast
after descending all of its child
Ast
nodes.
fn visit_alternation_in(&mut self) -> Result<(), Self::Err>
This method is called between child nodes of an
Alternation
.
fn visit_class_set_item_pre(
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err>
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err>
This method is called on every
ClassSetItem
before descending into child nodes.
fn visit_class_set_item_post(
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err>
&mut self,
_ast: &ClassSetItem
) -> Result<(), Self::Err>
This method is called on every
ClassSetItem
after descending into child nodes.
fn visit_class_set_binary_op_pre(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
This method is called on every
ClassSetBinaryOp
before descending into child nodes.
fn visit_class_set_binary_op_post(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
This method is called on every
ClassSetBinaryOp
after descending into child nodes.
fn visit_class_set_binary_op_in(
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
&mut self,
_ast: &ClassSetBinaryOp
) -> Result<(), Self::Err>
This method is called between the left hand and right hand child nodes
of a ClassSetBinaryOp
.