Module syn::visit_mut [−][src]
This is supported on crate feature
visit-mut only.Expand description
Syntax tree traversal to mutate an exclusive borrow of a syntax tree in place.
Each method of the VisitMut trait is a hook that can be overridden
to customize the behavior when mutating 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 VisitMut {
/* ... */
fn visit_expr_binary_mut(&mut self, node: &mut ExprBinary) {
visit_expr_binary_mut(self, node);
}
/* ... */
}
pub fn visit_expr_binary_mut<V>(v: &mut V, node: &mut ExprBinary)
where
V: VisitMut + ?Sized,
{
for attr in &mut node.attrs {
v.visit_attribute_mut(attr);
}
v.visit_expr_mut(&mut *node.left);
v.visit_bin_op_mut(&mut node.op);
v.visit_expr_mut(&mut *node.right);
}
/* ... */This module is available only if Syn is built with the "visit-mut"
feature.
Example
This mut visitor replace occurrences of u256 suffixed integer literals
like 999u256 with a macro invocation bigint::u256!(999).
// [dependencies]
// quote = "1.0"
// syn = { version = "1.0", features = ["full", "visit-mut"] }
use quote::quote;
use syn::visit_mut::{self, VisitMut};
use syn::{parse_quote, Expr, File, Lit, LitInt};
struct BigintReplace;
impl VisitMut for BigintReplace {
fn visit_expr_mut(&mut self, node: &mut Expr) {
if let Expr::Lit(expr) = &node {
if let Lit::Int(int) = &expr.lit {
if int.suffix() == "u256" {
let digits = int.base10_digits();
let unsuffixed: LitInt = syn::parse_str(digits).unwrap();
*node = parse_quote!(bigint::u256!(#unsuffixed));
return;
}
}
}
// Delegate to the default impl to visit nested expressions.
visit_mut::visit_expr_mut(self, node);
}
}
fn main() {
let code = quote! {
fn main() {
let _ = 999u256;
}
};
let mut syntax_tree: File = syn::parse2(code).unwrap();
BigintReplace.visit_file_mut(&mut syntax_tree);
println!("{}", quote!(#syntax_tree));
}Traits
Syntax tree traversal to mutate an exclusive borrow of a syntax tree in place.
Functions
visit_abi_mut
derive or fullvisit_angle_bracketed_generic_arguments_mut
derive or fullvisit_arm_mut
fullvisit_attr_style_mut
derive or fullvisit_attribute_mut
derive or fullvisit_bare_fn_arg_mut
derive or fullvisit_bin_op_mut
derive or fullvisit_binding_mut
derive or fullvisit_block_mut
fullvisit_bound_lifetimes_mut
derive or fullvisit_const_param_mut
derive or fullvisit_constraint_mut
derive or fullvisit_data_enum_mut
derivevisit_data_mut
derivevisit_data_struct_mut
derivevisit_data_union_mut
derivevisit_derive_input_mut
derivevisit_expr_binary_mut
derive or fullvisit_expr_call_mut
derive or fullvisit_expr_cast_mut
derive or fullvisit_expr_field_mut
derive or fullvisit_expr_index_mut
derive or fullvisit_expr_lit_mut
derive or fullvisit_expr_mut
derive or fullvisit_expr_paren_mut
derive or fullvisit_expr_path_mut
derive or fullvisit_expr_unary_mut
derive or fullvisit_field_mut
derive or fullvisit_fields_mut
derive or fullvisit_fields_named_mut
derive or fullvisit_fields_unnamed_mut
derive or fullvisit_file_mut
fullvisit_fn_arg_mut
fullvisit_generic_argument_mut
derive or fullvisit_generic_param_mut
derive or fullvisit_generics_mut
derive or fullvisit_index_mut
derive or fullvisit_item_mut
fullvisit_label_mut
fullvisit_lifetime_def_mut
derive or fullvisit_local_mut
fullvisit_macro_delimiter_mut
derive or fullvisit_macro_mut
derive or fullvisit_member_mut
derive or fullvisit_meta_list_mut
derive or fullvisit_meta_mut
derive or fullvisit_meta_name_value_mut
derive or fullvisit_nested_meta_mut
derive or fullvisit_parenthesized_generic_arguments_mut
derive or fullvisit_pat_mut
fullvisit_pat_or_mut
fullvisit_path_arguments_mut
derive or fullvisit_path_mut
derive or fullvisit_path_segment_mut
derive or fullvisit_predicate_eq_mut
derive or fullvisit_predicate_lifetime_mut
derive or fullvisit_predicate_type_mut
derive or fullvisit_qself_mut
derive or fullvisit_return_type_mut
derive or fullvisit_stmt_mut
fullvisit_trait_bound_modifier_mut
derive or fullvisit_trait_bound_mut
derive or fullvisit_type_array_mut
derive or fullvisit_type_bare_fn_mut
derive or fullvisit_type_group_mut
derive or fullvisit_type_impl_trait_mut
derive or fullvisit_type_infer_mut
derive or fullvisit_type_macro_mut
derive or fullvisit_type_mut
derive or fullvisit_type_never_mut
derive or fullvisit_type_param_bound_mut
derive or fullvisit_type_param_mut
derive or fullvisit_type_paren_mut
derive or fullvisit_type_path_mut
derive or fullvisit_type_ptr_mut
derive or fullvisit_type_reference_mut
derive or fullvisit_type_slice_mut
derive or fullvisit_type_trait_object_mut
derive or fullvisit_type_tuple_mut
derive or fullvisit_un_op_mut
derive or fullvisit_variadic_mut
derive or fullvisit_variant_mut
derive or fullvisit_vis_crate_mut
derive or fullvisit_vis_public_mut
derive or fullvisit_vis_restricted_mut
derive or fullvisit_visibility_mut
derive or fullvisit_where_clause_mut
derive or fullvisit_where_predicate_mut
derive or full