facet-xml-diff

Diff-aware XML serialization—render structural diffs as readable XML.

Overview

This crate renders diffs between facet values as XML with visual diff markers. It shows what changed between two values in a format that's easy to read, with proper alignment, colored output, and collapsing of unchanged regions.

Example

use facet::Facet;
use facet_diff::tree_diff;

#[derive(Facet)]
struct Rect {
    fill: String,
    x: i32,
    y: i32,
}

let old = Rect { fill: "red".into(), x: 10, y: 20 };
let new = Rect { fill: "blue".into(), x: 10, y: 20 };

let xml = facet_xml_diff::diff_to_string(&old, &new)?;

Output:

<rect
← fill="red"
→ fill="blue"
  x="10" y="20"
/>

Features

• Diff markers: ←/→ (or -/+) prefix lines to show old vs new values
• Value-only coloring: Only the changed values are colored, not the whole line
• Alignment: Attributes align properly for readability
• Collapsing: Long runs of unchanged content are collapsed with ...
• ANSI colors: Optional terminal colors for better visibility

Options

use facet_xml_diff::{DiffSerializeOptions, DiffSymbols, DiffTheme};

let options = DiffSerializeOptions {
    symbols: DiffSymbols::ascii(),  // Use -/+ instead of arrows
    theme: DiffTheme::default(),
    colors: true,
    indent: "  ",
    max_line_width: 80,
    collapse_threshold: 3,
    ..Default::default()
};

Use Cases

• Debugging configuration changes
• Displaying diffs in CLI tools
• Generating human-readable change logs
• Testing serialization by comparing expected vs actual output

Sponsors

Thanks to all individual sponsors:

...along with corporate sponsors:

...without whom this work could not exist.

Special thanks

The facet logo was drawn by Misiasart.

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.