Module syn::visit [−][src]
This is supported on crate feature
visit only.Expand description
Syntax tree traversal to walk a shared borrow of a syntax tree.
Each method of the Visit trait is a hook that can be overridden to
customize the behavior when visiting the corresponding type of node. By
default, every method recursively visits the substructure of the input
by invoking the right visitor method of each of its fields.
pub trait Visit<'ast> {
/* ... */
fn visit_expr_binary(&mut self, node: &'ast ExprBinary) {
visit_expr_binary(self, node);
}
/* ... */
}
pub fn visit_expr_binary<'ast, V>(v: &mut V, node: &'ast ExprBinary)
where
V: Visit<'ast> + ?Sized,
{
for attr in &node.attrs {
v.visit_attribute(attr);
}
v.visit_expr(&*node.left);
v.visit_bin_op(&node.op);
v.visit_expr(&*node.right);
}
/* ... */This module is available only if Syn is built with the "visit" feature.
Example
This visitor will print the name of every freestanding function in the syntax tree, including nested functions.
// [dependencies]
// quote = "1.0"
// syn = { version = "1.0", features = ["full", "visit"] }
use quote::quote;
use syn::visit::{self, Visit};
use syn::{File, ItemFn};
struct FnVisitor;
impl<'ast> Visit<'ast> for FnVisitor {
fn visit_item_fn(&mut self, node: &'ast ItemFn) {
println!("Function with name={}", node.sig.ident);
// Delegate to the default impl to visit any nested functions.
visit::visit_item_fn(self, node);
}
}
fn main() {
let code = quote! {
pub fn f() {
fn g() {}
}
};
let syntax_tree: File = syn::parse2(code).unwrap();
FnVisitor.visit_file(&syntax_tree);
}The 'ast lifetime on the input references means that the syntax tree
outlives the complete recursive visit call, so the visitor is allowed to
hold on to references into the syntax tree.
use quote::quote;
use syn::visit::{self, Visit};
use syn::{File, ItemFn};
struct FnVisitor<'ast> {
functions: Vec<&'ast ItemFn>,
}
impl<'ast> Visit<'ast> for FnVisitor<'ast> {
fn visit_item_fn(&mut self, node: &'ast ItemFn) {
self.functions.push(node);
visit::visit_item_fn(self, node);
}
}
fn main() {
let code = quote! {
pub fn f() {
fn g() {}
}
};
let syntax_tree: File = syn::parse2(code).unwrap();
let mut visitor = FnVisitor { functions: Vec::new() };
visitor.visit_file(&syntax_tree);
for f in visitor.functions {
println!("Function with name={}", f.sig.ident);
}
}Traits
Syntax tree traversal to walk a shared borrow of a syntax tree.
Functions
visit_abi
derive or fullvisit_angle_bracketed_generic_arguments
derive or fullvisit_arm
fullvisit_attr_style
derive or fullvisit_attribute
derive or fullvisit_bare_fn_arg
derive or fullvisit_bin_op
derive or fullvisit_binding
derive or fullvisit_block
fullvisit_bound_lifetimes
derive or fullvisit_const_param
derive or fullvisit_constraint
derive or fullvisit_data
derivevisit_data_enum
derivevisit_data_struct
derivevisit_data_union
derivevisit_derive_input
derivevisit_expr
derive or fullvisit_expr_array
fullvisit_expr_async
fullvisit_expr_await
fullvisit_expr_binary
derive or fullvisit_expr_block
fullvisit_expr_box
fullvisit_expr_break
fullvisit_expr_call
derive or fullvisit_expr_cast
derive or fullvisit_expr_field
derive or fullvisit_expr_group
fullvisit_expr_if
fullvisit_expr_index
derive or fullvisit_expr_let
fullvisit_expr_lit
derive or fullvisit_expr_loop
fullvisit_expr_macro
fullvisit_expr_match
fullvisit_expr_paren
derive or fullvisit_expr_path
derive or fullvisit_expr_range
fullvisit_expr_try
fullvisit_expr_tuple
fullvisit_expr_type
fullvisit_expr_unary
derive or fullvisit_expr_while
fullvisit_expr_yield
fullvisit_field
derive or fullvisit_field_pat
fullvisit_fields
derive or fullvisit_fields_named
derive or fullvisit_fields_unnamed
derive or fullvisit_file
fullvisit_fn_arg
fullvisit_generic_argument
derive or fullvisit_generic_param
derive or fullvisit_generics
derive or fullvisit_impl_item
fullvisit_index
derive or fullvisit_item
fullvisit_item_const
fullvisit_item_enum
fullvisit_item_fn
fullvisit_item_impl
fullvisit_item_macro
fullvisit_item_mod
fullvisit_item_trait
fullvisit_item_type
fullvisit_item_union
fullvisit_item_use
fullvisit_label
fullvisit_lifetime_def
derive or fullvisit_local
fullvisit_macro
derive or fullvisit_macro_delimiter
derive or fullvisit_member
derive or fullvisit_meta
derive or fullvisit_meta_list
derive or fullvisit_meta_name_value
derive or fullvisit_nested_meta
derive or fullvisit_parenthesized_generic_arguments
derive or fullvisit_pat
fullvisit_pat_box
fullvisit_pat_ident
fullvisit_pat_lit
fullvisit_pat_macro
fullvisit_pat_or
fullvisit_pat_path
fullvisit_pat_range
fullvisit_pat_rest
fullvisit_pat_slice
fullvisit_pat_struct
fullvisit_pat_tuple
fullvisit_pat_type
fullvisit_pat_wild
fullvisit_path
derive or fullvisit_path_arguments
derive or fullvisit_path_segment
derive or fullvisit_predicate_eq
derive or fullvisit_predicate_lifetime
derive or fullvisit_predicate_type
derive or fullvisit_qself
derive or fullvisit_receiver
fullvisit_return_type
derive or fullvisit_signature
fullvisit_stmt
fullvisit_trait_bound
derive or fullvisit_trait_bound_modifier
derive or fullvisit_trait_item
fullvisit_type
derive or fullvisit_type_array
derive or fullvisit_type_bare_fn
derive or fullvisit_type_group
derive or fullvisit_type_impl_trait
derive or fullvisit_type_infer
derive or fullvisit_type_macro
derive or fullvisit_type_never
derive or fullvisit_type_param
derive or fullvisit_type_param_bound
derive or fullvisit_type_paren
derive or fullvisit_type_path
derive or fullvisit_type_ptr
derive or fullvisit_type_reference
derive or fullvisit_type_slice
derive or fullvisit_type_trait_object
derive or fullvisit_type_tuple
derive or fullvisit_un_op
derive or fullvisit_use_glob
fullvisit_use_group
fullvisit_use_name
fullvisit_use_path
fullvisit_use_rename
fullvisit_use_tree
fullvisit_variadic
derive or fullvisit_variant
derive or fullvisit_vis_crate
derive or fullvisit_vis_public
derive or fullvisit_vis_restricted
derive or fullvisit_visibility
derive or fullvisit_where_clause
derive or fullvisit_where_predicate
derive or full