negation.go

// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package searcher

import (
	"github.com/m3db/m3/src/m3ninx/index"
	"github.com/m3db/m3/src/m3ninx/postings"
	"github.com/m3db/m3/src/m3ninx/search"
)

type negationSearcher struct {
	searcher search.Searcher
}

// NewNegationSearcher returns a new searcher for finding documents which do not match a
// given query.
func NewNegationSearcher(s search.Searcher) (search.Searcher, error) {
	return &negationSearcher{
		searcher: s,
	}, nil
}

func (s *negationSearcher) Search(r index.Reader) (postings.List, error) {
	pl, err := r.MatchAll()
	if err != nil {
		return nil, err
	}

	sPl, err := s.searcher.Search(r)
	if err != nil {
		return nil, err
	}

	pl.Difference(sPl)
	return pl, nil
}