56 lines
1.0 KiB
Go
56 lines
1.0 KiB
Go
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// it-range.go
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package expr
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import "io"
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type RangeIterator struct {
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start int64
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end int64
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step int64
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current int64
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index int
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}
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func NewRangeIterator(start, end, step int64) *RangeIterator {
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if step == 0 {
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panic("Range step must be not zero")
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}
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if step < 0 && start < end {
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panic("When the range's step is less than zero, start must be greater than end")
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}
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if step > 0 && start > end {
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panic("When the range's step is greater than zero, start must be less than end")
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}
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return &RangeIterator{start: start, end: end, step: step, current: start, index: 0}
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}
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func (it *RangeIterator) Reset() {
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it.index = 0
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it.current = it.start
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}
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func (it *RangeIterator) Next() (item any, err error) {
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if it.step > 0 {
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if it.current < it.end {
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item = it.current
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it.current += it.step
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it.index++
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} else {
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err = io.EOF
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}
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} else {
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if it.current > it.end {
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item = it.current
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it.current += it.step
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it.index++
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} else {
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err = io.EOF
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}
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}
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return
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}
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func (it *RangeIterator) Index() int {
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return it.index - 1
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}
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