toml_edit

Module visit

Source
Expand description

Document tree traversal to walk a shared borrow of a document tree.

Each method of the Visit 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 Visit<'doc> {
    /* ... */

    fn visit_item(&mut self, i: &'doc Item) {
        visit_item(self, i);
    }

    /* ... */
}

pub fn visit_item<'doc, V>(v: &mut V, node: &'doc Item)
where
    V: Visit<'doc> + ?Sized,
{
    match node {
        Item::None => {}
        Item::Value(value) => v.visit_value(value),
        Item::Table(table) => v.visit_table(table),
        Item::ArrayOfTables(array) => v.visit_array_of_tables(array),
    }
}

The API is modeled after syn::visit.

§Examples

This visitor stores every string in the document.

use toml_edit::visit::*;

#[derive(Default)]
struct StringCollector<'doc> {
    strings: Vec<&'doc str>,
}

impl<'doc> Visit<'doc> for StringCollector<'doc> {
    fn visit_string(&mut self, node: &'doc Formatted<String>) {
         self.strings.push(node.value().as_str());
    }
}

let input = r#"
laputa = "sky-castle"
the-force = { value = "surrounds-you" }
"#;

let mut document: DocumentMut = input.parse().unwrap();
let mut visitor = StringCollector::default();
visitor.visit_document(&document);

assert_eq!(visitor.strings, vec!["sky-castle", "surrounds-you"]);

For a more complex example where the visitor has internal state, see examples/visit.rs on GitHub.

Traits§

  • Visit
    Document tree traversal to mutate an exclusive borrow of a document tree in-place.

Functions§