Rusty Rules Lua Bindings

This crate provides Lua bindings for the rusty_rules crate, allowing you to create and evaluate rule-based conditions from within Lua scripts.

Overview

The library exposes two main types:

• Engine - The main rules engine for registering fetchers and compiling rules
• Rule - A compiled rule that can be evaluated against context data

Basic Usage

use mlua::prelude::*;

// Register the Engine type
let lua = Lua::new();
let engine = lua.create_proxy::<rusty_rules_lua::Engine>()?;
lua.globals().set("Engine", engine)?;

-- Create a new engine instance
local engine = Engine.new()

-- Register a simple fetcher that extracts values from context
engine:register_fetcher("user_attr", function(ctx, attr)
    return ctx.user[attr]
end)

-- Compile and evaluate a rule
local rule = engine:compile({["user_attr(role)"] = "admin"})
local result = rule:evaluate({user = {role = "admin"}})
-- `result` will be true

Advanced Features

Custom Matchers

You can specify custom matchers for different data types:

-- Register an IP address fetcher with IP matcher
engine:register_fetcher("client_ip", { matcher = "ip" }, function(ctx)
    return ctx.ip_address
end)

-- Use CIDR notation in rules
local rule = engine:compile({ client_ip = "192.168.1.0/24" })

Available matchers:

• "bool" - Boolean matching
• "ip" - IP address and CIDR range matching
• "number" - Numeric comparison
• "regex" or "re" - Regular expression matching
• "string" - String comparison

The default matcher (if unspecified) is a universal matcher for all types.

Raw Arguments

By default, fetcher arguments are split by whitespace and trimmed. You can disable this:

engine:register_fetcher("raw_fetcher", { raw_args = true }, function(ctx, arg)
    -- Single argument is passed as a string without modification
    return arg
end)

Rule Validation

When the validation feature is enabled, you can validate rules without compiling them:

local is_valid, error = engine:validate({
    ["get_value(key)"] = "expected_value"
})
-- `error` is: "Additional properties are not allowed ('get_value(key)' was unexpected)"

Validation check the rule structure against the json schema.

JSON Schema

Get the JSON schema for valid rule structures:

-- Returns JSON schema as a string
local schema = engine:json_schema()