Trait Visitor 

pub trait Visitor<'arena, 'src> {
    type Break;

    // Provided methods
    fn visit_program(
        &mut self,
        program: &Program<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_stmt(
        &mut self,
        stmt: &Stmt<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_block(
        &mut self,
        block: &Block<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_expr(
        &mut self,
        expr: &Expr<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_param(
        &mut self,
        param: &Param<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_arg(&mut self, arg: &Arg<'arena, 'src>) -> ControlFlow<Self::Break> { ... }
    fn visit_class_member(
        &mut self,
        member: &ClassMember<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_enum_member(
        &mut self,
        member: &EnumMember<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_property_hook(
        &mut self,
        hook: &PropertyHook<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_type_hint(
        &mut self,
        type_hint: &TypeHint<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_attribute(
        &mut self,
        attribute: &Attribute<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_catch_clause(
        &mut self,
        catch: &CatchClause<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_match_arm(
        &mut self,
        arm: &MatchArm<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_closure_use_var(
        &mut self,
        _var: &ClosureUseVar<'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_trait_use(
        &mut self,
        trait_use: &TraitUseDecl<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_trait_adaptation(
        &mut self,
        adaptation: &TraitAdaptation<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_name(
        &mut self,
        _name: &Name<'arena, 'src>,
    ) -> ControlFlow<Self::Break> { ... }
    fn visit_comment(
        &mut self,
        _comment: &Comment<'src>,
    ) -> ControlFlow<Self::Break> { ... }
}

Visitor trait for immutable AST traversal.

All methods return ControlFlow<Self::Break>:

• ControlFlow::Continue(()) — keep walking.
• ControlFlow::Break(value) — stop the entire traversal immediately; value is returned by the call that started the walk. Use type Break = (); when there is nothing to return.

Default implementations recursively walk child nodes, so implementors only need to override the node types they care about.

To skip a subtree, override the method and return Continue(()) without calling the corresponding walk_* function.

Example

use php_ast::visitor::{Visitor, walk_expr};
use php_ast::ast::*;
use std::ops::ControlFlow;

struct VarCounter { count: usize }

impl<'arena, 'src> Visitor<'arena, 'src> for VarCounter {
    type Break = ();
    fn visit_expr(&mut self, expr: &Expr<'arena, 'src>) -> ControlFlow<()> {
        if matches!(&expr.kind, ExprKind::Variable(_)) {
            self.count += 1;
        }
        walk_expr(self, expr)
    }
}

Required Associated Types

type Break

Value carried by ControlFlow::Break when a visit stops the walk early; use () to stop without a result.

Provided Methods

fn visit_program( &mut self, program: &Program<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits the root program node.

fn visit_stmt(&mut self, stmt: &Stmt<'arena, 'src>) -> ControlFlow<Self::Break>

Visits a statement.

fn visit_block( &mut self, block: &Block<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a block of statements.

fn visit_expr(&mut self, expr: &Expr<'arena, 'src>) -> ControlFlow<Self::Break>

Visits an expression.

fn visit_param( &mut self, param: &Param<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a function parameter.

fn visit_arg(&mut self, arg: &Arg<'arena, 'src>) -> ControlFlow<Self::Break>

Visits a call argument.

fn visit_class_member( &mut self, member: &ClassMember<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a class-like member.

fn visit_enum_member( &mut self, member: &EnumMember<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits an enum member.

fn visit_property_hook( &mut self, hook: &PropertyHook<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a property hook (get/set).

fn visit_type_hint( &mut self, type_hint: &TypeHint<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a type hint.

fn visit_attribute( &mut self, attribute: &Attribute<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits an attribute.

fn visit_catch_clause( &mut self, catch: &CatchClause<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a catch clause.

fn visit_match_arm( &mut self, arm: &MatchArm<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a match arm.

fn visit_closure_use_var( &mut self, _var: &ClosureUseVar<'src>, ) -> ControlFlow<Self::Break>

Visits a closure use variable.

fn visit_trait_use( &mut self, trait_use: &TraitUseDecl<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a use Trait; declaration.

fn visit_trait_adaptation( &mut self, adaptation: &TraitAdaptation<'arena, 'src>, ) -> ControlFlow<Self::Break>

Visits a trait insteadof/as adaptation.

fn visit_name(&mut self, _name: &Name<'arena, 'src>) -> ControlFlow<Self::Break>

Visits a name reference.

fn visit_comment( &mut self, _comment: &Comment<'src>, ) -> ControlFlow<Self::Break>

Called for each comment when driven by walk_comments.

Comments live in ParseResult::comments separately from AST nodes. Use walk_comments to drive this hook.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<'arena, 'src, V: ScopeVisitor<'arena, 'src>> Visitor<'arena, 'src> for ScopeWalker<'src, V>

type Break = <V as ScopeVisitor<'arena, 'src>>::Break