github.com/m3db/m3@v1.5.0/src/m3ninx/postings/range_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 postings
    22  
    23  import "errors"
    24  
    25  var (
    26  	errRangerIterClosed = errors.New("iterator has already been closed")
    27  )
    28  
    29  type rangeIter struct {
    30  	startInclusive ID
    31  	endExclusive   ID
    32  	closed         bool
    33  	started        bool
    34  }
    35  
    36  // NewRangeIterator returns a new Iterator over the specified range.
    37  func NewRangeIterator(startInclusive, endExclusive ID) Iterator {
    38  	return &rangeIter{
    39  		startInclusive: startInclusive,
    40  		endExclusive:   endExclusive,
    41  	}
    42  }
    43  
    44  func (r *rangeIter) Next() bool {
    45  	if r.closed {
    46  		return false
    47  	}
    48  	if r.started {
    49  		r.startInclusive++
    50  	}
    51  	r.started = true
    52  	return r.startInclusive < r.endExclusive
    53  }
    54  
    55  func (r *rangeIter) Current() ID {
    56  	return r.startInclusive
    57  }
    58  
    59  func (r *rangeIter) Err() error {
    60  	return nil
    61  }
    62  
    63  func (r *rangeIter) Close() error {
    64  	if r.closed {
    65  		return errRangerIterClosed
    66  	}
    67  	r.closed = true
    68  	return nil
    69  }