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TODO

Empyre

Rule Engine written in Python.

Why? Why not.

Why the name? Good 'ol nerdy Star Wars reference in which the Empire rules the galaxy.

Concepts

Context

The provided data against which Empyre will check Rules/Matchers.

Matcher

A condition to be evaluated against the Context, defined by:

  • path: a json-path used to retrieve data from the Context
  • value: a value that will be matched against the path-retrieved value(s)
  • op: the Operator that will be used to perform the matching between the above
  • comp: a Comparator telling if the evaluation should produce True or False
  • transform: an optional callable to modify the Context values before the match
  • matchers: a list of Matchers to be used with the and/or Operators

Comparator

The expectation for a matcher to match or not. Can be either is or not.

Operator

The matching operation performed by a Matcher.

Available operators are of different kinds: logical, comparison, membership and regex.

Logical

To be used with Matcher's child Matchers

  • and_: all the child matchers should be True
  • or_: at least one child matcher should be True

Comparison

A comparison between the context-extracted value (left hand) and the Matcher value (right hand):

  • eq: equivalent to ==
  • gt: equivalent to >
  • lt: equivalent to <
  • ge: equivalent to >=
  • le: equivalent to <=

Membership

Checks that the context-extracted value is present in the Matcher value

  • in_

Regex

Check for a regex match of the Matcher's value against the context-extracted values

  • re

Outcome

The output returned is all defined Matchers match. Can be of 4 kinds:

  • VALUE: a fixed value
  • DATA: a dynamic/nested container of values, either extracted from the context or fixed
  • EVENT: a DATA outcome with a fixed identifier
  • RULE: another Rule to be evaluated, for complex chains of evaluations

Rule

Represents a set of Matchers to be evaluated against the context that eventually produces a set of Outcomes. Defined by:

  • matchers: a list of Matchers
  • op: the and_/or_ condition to extract matcher's expected results
  • comp: a Comparator for the op's result