Editing while preserving source¶

Document<T> pairs a serde configuration with its original source. Parsing and writing an unchanged document preserves its bytes, including comments, units, annotations, includes, and fields the Rust type does not represent.

use ratslang::serde::Document;
use serde::{Deserialize, Serialize};

#[derive(Deserialize, Serialize)]
struct Show {
    drones: u32,
}

let source = "# How many drones fly.\ndrones = 120\nlights = TWINKLE\n";
let mut document = Document::<Show>::parse(source)?;
assert_eq!(document.to_source()?, source);
document.value.drones = 150;
let updated = document.to_source()?;
assert!(updated.starts_with(source));

Edits become trailing override assignments. This preserves earlier expressions, references, comments, and includes while allowing Ratslang's assignment semantics to produce the new value. The compiler verifies the resulting source before returning it. Annotations on changed values are retained.

source() returns the original text. to_source() produces the edited text. ratslang::to_string(&document) uses the same source-preserving path. Removing a represented field returns an error.

For file-level formatting, minimization, and renaming, use the CLI's source-preserving commands.