github.com/m3db/m3@v1.5.0/src/m3ninx/index/segment/mem/iterator.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package mem
    22  
    23  import (
    24  	"github.com/m3db/m3/src/m3ninx/postings"
    25  )
    26  
    27  // boundedPostingsIterator wraps a normal postings iterator but only returns IDs
    28  // within a given range.
    29  type boundedPostingsIterator struct {
    30  	postings.Iterator
    31  	curr   postings.ID
    32  	limits readerDocRange
    33  }
    34  
    35  func newBoundedPostingsIterator(it postings.Iterator, limits readerDocRange) postings.Iterator {
    36  	return &boundedPostingsIterator{
    37  		Iterator: it,
    38  		limits:   limits,
    39  	}
    40  }
    41  
    42  func (it *boundedPostingsIterator) Next() bool {
    43  	for {
    44  		if !it.Iterator.Next() {
    45  			return false
    46  		}
    47  
    48  		curr := it.Iterator.Current()
    49  		// We are not assuming that the posting IDs are ordered otherwise we could return
    50  		// false immediately when we exceed the end of the range.
    51  		if curr < it.limits.startInclusive || curr >= it.limits.endExclusive {
    52  			continue
    53  		}
    54  
    55  		it.curr = curr
    56  		return true
    57  	}
    58  }
    59  
    60  func (it *boundedPostingsIterator) Current() postings.ID {
    61  	return it.curr
    62  }