jlens-core

A JSONata engine in Rust, with evaluation audits. It is the language core of jlens.

• Complete JSONata 2.2. Every operator and built-in function. It passes 1,688 of the 1,690 cases of the official test suite; the other two are documented.
• Explainable. evaluate_audited records which comparisons passed or failed, which items filters rejected and which values were bound. Labels in ordinary comments (/** @label "Minimum total" */) name the checks.
• Tooling-ready. Recovering parsing, a public syntax tree with spans, a function catalog, and stable error codes.
• Safe to embed. Timeouts and depth limits. Deep recursion fails with an error instead of overflowing the stack. Compiled expressions are Send + Sync.

use jlens_core::{Bindings, Expression};
use serde_json::json;

let expr = Expression::compile("$sum(items[type = $kind].(price * qty))")?;
let order = json!({"items": [
    {"type": "book", "price": 12.5, "qty": 2},
    {"type": "pen", "price": 1.5, "qty": 10}
]});
let total = expr.evaluate(Some(&order), &Bindings::new().var("kind", "book"))?;
assert_eq!(total, Some(json!(25)));

Documentation

• The API reference.
• The jlens book: a language reference, and guides to the crate, auditing and performance (docs/ in the repository).
• jlens-schema adds schema inference and editor support (completion, diagnostics, hover).
• jlens-cli is the jlens command.

License

MIT. Parts are ported from jsonata-js, also MIT; see LICENSE.