diffogus

This crate provides a flexible and customizable framework for computing differences ("diffs") between various types of data structures in Rust. The core functionality is built around the traits [diff::Diffable] and [diff::Changeable], which allow you to determine changes between two instances of a type and represent those changes in a structured way.

Overview

The crate supports diffing primitive types (e.g., integers, floats, strings), as well as collections like HashMap, Vec, and Option. It can be extended to handle custom types by implementing the [diff::Diffable] trait.

The result of a diff operation can be serialized into formats such as JSON, provided the serde feature is enabled.

Traits

• [diff::Changeable] - A trait for types that can report whether they have changed.
• [diff::Diffable] - A trait for types that can compute a difference with another instance of the same type.

Supported Types

By default, this crate implements [diff::Diffable] for most types.

Full list of types:

• Primitive types: u8, u16, u32, u64, i8, i16, i32, i64, f32, f64, bool, and String.
• Collections: HashMap<K, V>, Vec<T>.
• Containers: Option<T>.

Features

• serde: Enables support for serializing diff results using serde.
• derive: Enables support for [Diff] derive macro.

Usage

Basic Diffing

Here's a simple example that shows how to compute a diff between two integers:

use diffogus::diff::{Diffable, PrimitiveDiff};

let a = 5;
let b = 10;
let diff = a.diff(&b);

match diff {
    PrimitiveDiff::Changed { old, new } => {
        println!("Value changed from {} to {}", old, new);
    },
    PrimitiveDiff::Unchanged => {
        println!("No change detected.");
    }
}

Diffing more complex data structures

You can also compute diffs on more complex structures such as HashMap or Vec.

use diffogus::diff::{Diffable, HashMapDiff, CollectionDiffEntry};
use std::collections::HashMap;

let mut map1 = HashMap::new();
map1.insert("key1".to_string(), 1);
map1.insert("key2".to_string(), 2);

let mut map2 = HashMap::new();
map2.insert("key1".to_string(), 1);
map2.insert("key2".to_string(), 3);
map2.insert("key3".to_string(), 4);

let diff = map1.diff(&map2);

for (key, diff_entry) in diff.0 {
    match diff_entry {
        CollectionDiffEntry::Added(new_val) => println!("{} was added with value {}", key, new_val),
        CollectionDiffEntry::Removed(old_val) => println!("{} was removed with value {}", key, old_val),
        CollectionDiffEntry::Changed(changed_val) => println!("{} changed", key),
        CollectionDiffEntry::Unchanged => println!("{} did not change", key),
    }
}

Serde Integration

If you want to serialize the diff result (e.g., to JSON), enable the serde feature:

[dependencies]
diffogus = { version = "0.1", features = ["serde"] }

Example usage:

use diffogus::diff::{Diffable, HashMapDiff};
use serde_json;
use std::collections::HashMap;

let mut map1 = HashMap::new();
map1.insert("key1".to_string(), 1);

let mut map2 = HashMap::new();
map2.insert("key1".to_string(), 2);

let diff = map1.diff(&map2);
let serialized = serde_json::to_string(&diff).unwrap();

println!("Serialized diff: {}", serialized);

Derive macro

If you want to implement [diff::Diffable] and related traits you can do that very easily by enabling derive feature:

[dependencies]
diffogus = { version = "0.1", features = ["derive"] }

Example usage:

use diffogus::diff::{Diffable, PrimitiveDiff};
use diffogus_derive::Diff;

#[derive(Debug, Clone, Diff)]
struct MyStruct {
    id: u32,
    name: String,
}

let a = MyStruct { id: 0, name: "Joe".into() };
let b = MyStruct { id: 0, name: "Doe".into() };

let diff = a.diff(&b);
// Now do whatever you want with this diff.