The Zipper

Crates.io

The Zipper is a Rust library designed to provide efficient and ergonomic utilities for working with data structures using the zipper pattern. This library simplifies navigation and modification of complex data structures while maintaining immutability.

HUET G. The Zipper. Journal of Functional Programming. 1997;7(5):549-554. doi:10.1017/S0956796897002864

Features

Easy-to-use API for zipper-based data manipulation.
Supports various data structures like trees and lists.
Lightweight and performant.
Code coverage is 100%.

Installation

Add the following to your Cargo.toml:

[dependencies]
the_zipper = "0.1.2"

Usage

use the_zipper::Location;

fn main() {
    let tree = Tree::Section(vec![Tree::Item("a"), Tree::Item("+"), Tree::Item("b")]);

    let location = Location::new(tree);

    let location = location.go_down().unwrap();
    assert_eq!(location.cursor, Tree::Item("a"));

    let location = location.go_right().unwrap();
    assert_eq!(location.cursor, Tree::Item("+"));

    let location = location.go_left().unwrap();
    assert_eq!(location.cursor, Tree::Item("a"));

    let location = location.insert_right(Tree::Item(".")).unwrap();
    assert_eq!(
        location,
        Location {
            cursor: Tree::Item("a"),
            path: Path::Node {
                left: vec![],
                right: vec![Tree::Item("."), Tree::Item("+"), Tree::Item("b")],
                path: Path::Node {
                    left: vec![],
                    right: vec![Tree::Section(vec![
                        Tree::Item("a"),
                        Tree::Item("+"),
                        Tree::Item("b")
                    ])],
                    path: Path::Top.into()
                }
                .into()
            }
            .into()
        }
        .into()
    );
}

Links

F# Implementation

License