Predicator
Predicator is a safe (does not eval code), admin or business user facing predicate engine. It turns a string predicate like "score > 600 or (score > 580 and monthly_income > 9000)" along with a supplied context into a true or false. This predicate can be stored as an attribute of a model (ex: an Offer model could store a predicate indicating if it is available to a customer).
Usage
Simple usage:
const Predicator = require('predicator');
// Compile a list of instructions which a Predicator Evaluator can execute
Predicator.compile('score >= 600 or (score > 580 and income > 9000)');
// [
// [ 'load', 'score' ],
// [ 'to_int' ],
// [ 'lit', 600 ],
// [ 'compare', 'GTE' ],
// [ 'jtrue', 11 ],
// [ 'load', 'score' ],
// [ 'to_int' ],
// [ 'lit', 580 ],
// [ 'compare', 'GT' ],
// [ 'jfalse', 5 ],
// [ 'load', 'income' ],
// [ 'to_int' ],
// [ 'lit', 9000 ],
// [ 'compare', 'GT' ]
// ]
// Evaluation
Predicator.evaluate('score >= 600 or (score > 580 and income > 9000)', {score: 600}); // true
Predicator.evaluate('score >= 600 or (score > 580 and income > 9000)', {score: 590}); // false
Predicator.evaluate('score >= 600 or (score > 580 and income > 9000)', {score: 590, income: 10000}); // trueContributing
Bug reports and pull requests are welcome on GitHub at https://github.com/riddler/predicator-js. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
License
The library is available as open source under the terms of the MIT License.