github.com/egonelbre/exp@v0.0.0-20240430123955-ed1d3aa93911/niterator/onearrrev/iterator.go (about)

     1  package onearrrev
     2  
     3  import (
     4  	"io"
     5  
     6  	"github.com/egonelbre/exp/niterator/shape"
     7  )
     8  
     9  type Index struct {
    10  	Track  uint32
    11  	Shape  uint32
    12  	Stride uint32
    13  }
    14  
    15  type Iterator struct {
    16  	*shape.AP
    17  
    18  	Track     []Index
    19  	NextIndex uint32
    20  	Done      bool
    21  }
    22  
    23  func NewIterator(ap *shape.AP) *Iterator {
    24  	track := make([]Index, len(ap.Shape))
    25  	for i := range ap.Shape {
    26  		track[3-i].Track = uint32(ap.Shape[i])
    27  		track[3-i].Shape = uint32(ap.Shape[i])
    28  		track[3-i].Stride = uint32(ap.Stride[i])
    29  	}
    30  
    31  	return &Iterator{
    32  		AP:    ap,
    33  		Track: track,
    34  	}
    35  }
    36  
    37  func (it *Iterator) IsDone() bool {
    38  	return it.Done
    39  }
    40  
    41  func (it *Iterator) Next() (int, error) {
    42  	if it.Done {
    43  		return 0, io.EOF
    44  	}
    45  
    46  	next := it.NextIndex
    47  	result := next
    48  	track := it.Track
    49  	for i := range track {
    50  		x := &track[i]
    51  		x.Track--
    52  		if x.Track > 0 {
    53  			next += x.Stride
    54  			it.NextIndex = next
    55  			return int(result), nil
    56  		}
    57  		x.Track = x.Shape
    58  		next -= (x.Shape - 1) * x.Stride
    59  	}
    60  
    61  	it.Done = true
    62  	it.NextIndex = next
    63  	return int(result), nil
    64  }