Goldfish-RE

Reactive and Embeddable rules engine library written in pure Go!.

This rules engine has been thought to trigger automatically an event each time that a condition from your ruleset has been satisfied by some updated fact into a context.

The evaluation algorithm is RETE-based with focus on evaluation and memory using a Trie struct to improve its performance.

Data types

The rule engines expose different data types to work with:

• String: This is a well known string type
• Number: A number is a representation of an integer value. In this case is a wrapper for a int64 data type
• Float: Floats are also numeric types. They represent the decimal numbers implemented as float64
• Boolean: The boolean are useful to assert a condition as true or false
• Date: Represents a time.Time data type

Key concepts

• Fact: A fact is a representatioon of a variable that stores a value.
  • Each fact represents an object's attribute, like User.birthday
  • Each fact only can be defined as one of the supported types: String Number Float Boolean Date
• Term: A term represents one side of a condition, could be a fact or could be a discrete value.
• Condition: The condition is a boolean sentence which after its evaluation the result can be true or false.
  • Ex. User.birthday > 1984-10-22
  • A condition must have a Fact term as left term.
    • Not valid: 2000 >= Trip.miles
    • Valid: Trip.miles <= 2000
• Rule: The rule is a collection of conditions under the operator All or Any
  • All: The rule will be valid (true) when all contained conditions are true after its evaluation
  • Any: The rule will be valid (true) when at least one contained condition is true after its evaluation
• RuleSet: The ruleset is a group of rules defined by the user. The ruleset exposes a context were the facts are registered and evaluated on each rule into the ruleset when a change happens
• Context: A context groups the facts involved on the rule activation that belongs to a ruleset.