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63 lines
1.3 KiB
Go
63 lines
1.3 KiB
Go
2 years ago
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package operation
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import (
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"github.com/aziis98/cabret"
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)
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func init() {
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registerType("slice", &Slice{})
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}
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// Slice is a [cabret.ListOperation] will return a slice of the incoming items.
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// Both indices can be negative and will wrap around the items list.
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// For example "&Slice{From: -1, To: 0}" will reverse the incoming items list.
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type Slice struct {
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From, To int
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}
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// Configure will configure this operation
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//
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// from: <start index> # inclusive, optional and defaults to the start
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// to: <end index> # exclusive, optional and defaults to the end
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func (op *Slice) Configure(options map[string]any) error {
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var err error
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op.From, err = getKey(options, "from", 0)
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if err != nil {
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return err
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}
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op.To, err = getKey(options, "to", -1)
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if err != nil {
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return err
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}
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return nil
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}
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func (op *Slice) ProcessList(items []cabret.Content) ([]cabret.Content, error) {
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from := op.From
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to := op.To
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if to < 0 {
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to = to + len(items) + 1
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}
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if from < 0 {
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reverse(items)
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from = from + len(items) + 1
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from, to = to, from
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}
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return items[from:to], nil
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}
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//
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// utilities
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//
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// reverse taken from this answer https://stackoverflow.com/questions/28058278/how-do-i-reverse-a-slice-in-go
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func reverse[S ~[]E, E any](s S) {
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for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
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s[i], s[j] = s[j], s[i]
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}
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}
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