go/src/internal/profile/filter.go

type TagMatch …

// FilterSamplesByTag removes all samples from the profile, except
// those that match focus and do not match the ignore regular
// expression.
func (p *Profile) FilterSamplesByTag(focus, ignore TagMatch) (fm, im bool) { … }

// focusedSample checks a sample against focus and ignore regexps.
// Returns whether the focus/ignore regexps match any tags.
func focusedSample(s *Sample, focus, ignore TagMatch) (fm, im bool) { … }