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package tensor
// A Slice represents a slicing operation for a Tensor.
type Slice interface {
Start() int
End() int
Step() int
}
type rs struct {
start, end, step int
}
func (s rs) Start() int { return s.start }
func (s rs) End() int { return s.end }
func (s rs) Step() int { return s.step }
// makeRS creates a ranged slice. It takes an optional step param.
func makeRS(start, end int, opts ...int) rs {
step := 1
if len(opts) > 0 {
step = opts[0]
}
return rs{
start: start,
end: end,
step: step,
}
}
// ss is a single slice, representing this: [start:start+1:0]
type ss int
func (s ss) Start() int { return int(s) }
func (s ss) End() int { return int(s) + 1 }
func (s ss) Step() int { return 0 }
// sli is slice. It's named sli to prevent confusion over naming
type sli struct {
start, end, step int
}
// S creates a Slice.
// end is optional. It should be passed in as the first param of the optionals.
// step is optional. It should be passed in as the second param of the optionals.
//
// Default end is start+1. Default step is 1, unless end == step+1, then it defaults to 0
func S(start int, opt ...int) Slice {
var end, step int
if len(opt) > 0 {
end = opt[0]
} else {
end = start + 1
}
step = 1
if len(opt) > 1 {
step = opt[1]
} else if end == start+1 {
step = 0
}
return &sli{
start: start,
end: end,
step: step,
}
}
func (s *sli) Start() int { return s.start }
func (s *sli) End() int { return s.end }
func (s *sli) Step() int { return s.step }
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