forked from grafana/loki
/
step_evaluator.go
54 lines (44 loc) · 1.06 KB
/
step_evaluator.go
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package logql
import (
"errors"
"github.com/prometheus/prometheus/promql"
)
// StepEvaluator evaluate a single step of a query.
type StepEvaluator interface {
// while Next returns a promql.Value, the only acceptable types are Scalar and Vector.
Next() (ok bool, ts int64, vec promql.Vector)
// Close all resources used.
Close() error
// Reports any error
Error() error
}
type stepEvaluator struct {
fn func() (bool, int64, promql.Vector)
close func() error
err func() error
}
func newStepEvaluator(fn func() (bool, int64, promql.Vector), close func() error, err func() error) (StepEvaluator, error) {
if fn == nil {
return nil, errors.New("nil step evaluator fn")
}
if close == nil {
close = func() error { return nil }
}
if err == nil {
err = func() error { return nil }
}
return &stepEvaluator{
fn: fn,
close: close,
err: err,
}, nil
}
func (e *stepEvaluator) Next() (bool, int64, promql.Vector) {
return e.fn()
}
func (e *stepEvaluator) Close() error {
return e.close()
}
func (e *stepEvaluator) Error() error {
return e.err()
}