rhai-analyzer

Static analysis utilities for Rhai scripts.

Why this exists

rhai-analyzer provides a way to extract information from a compiled rhai::AST without executing it. This is useful for:

Dependency Tracking: Identify which external variables or data paths a script depends on (e.g., input.value, settings.mode).
Schema Validation: Ensure a script only accesses allowed variables.
Optimization: Pre-calculate or pre-fetch data based on what the script is guaranteed (or likely) to access.

Features

Variable Path Extraction: Collects all unique, fully-qualified variable paths (e.g., user.profile.name) accessed in a script.
Local Variable Tracking: Identifies variables defined within the script (via let or loop iterations) to distinguish them from external dependencies.
String Comparison Analysis: Maps variable paths to the literal strings they are compared against (via == or !=).
Domain Agnostic: The analyzer doesn't make assumptions about your data model—it just reports what it finds.

Installation

Add via Cargo

cargo add rhai-analyzer

Manual Configuration

Add the following to your Cargo.toml:

[dependencies]
rhai-analyzer = "0.1.0"
rhai = "1.22.2"

Usage

1. Analyzing a Script

use rhai::Engine;
use rhai_analyzer::analyze_ast;

fn main() {
    let engine = Engine::new();
    let script = r#"
        if request.amount > 100 && user.role == "admin" {
            let status = "approved";
            print(status);
        }
    "#;

    let ast = engine.compile(script).unwrap();
    let result = analyze_ast(&ast);

    // Variables accessed in the script
    assert!(result.accessed_variables.contains("request.amount"));
    assert!(result.accessed_variables.contains("user.role"));

    // Local variables defined in the script
    assert!(result.local_variables.contains("status"));

    // String comparisons tracked
    let comparisons = result.string_comparisons.get("user.role").unwrap();
    assert!(comparisons.contains("admin"));
}

2. Result Data Structure

The analyze_ast function returns a ScriptAnalysisResult:

pub struct ScriptAnalysisResult {
    /// All unique, fully-qualified variable paths accessed in the script.
    pub accessed_variables: HashSet<String>,

    /// Local variables defined within the script via `let` or loops.
    pub local_variables: HashSet<String>,

    /// Maps a variable path to the set of string literals it is compared against.
    pub string_comparisons: HashMap<String, HashSet<String>>,
}

License

MIT license (http://opensource.org/licenses/MIT)

rhai-analyzer 0.1.0