InitFuncs assigns late-bound functions to the func map.

InterpolateFields replaces all occurrences of field modifiers in the given string with values extracted from the event.

NewFuncMap returns the template func map populated with some useful template functions that can be used in rule actions.

NewRules produces a fresh rules engine instance.

ErrNoFields signals an error that happens when the filter is declared without any fields.

ErrPsNil indicates the process state associated with the event is not initialized.

Rules stores the compiled filter groups and for each incoming event, it applies the corresponding filtering policies to the event, dropping the event or passing it accordingly.

Filter is the main interface for the filter engine implementors.