60 lines
1.8 KiB
Go
60 lines
1.8 KiB
Go
package iterator
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import (
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"github.com/nspcc-dev/neo-go/pkg/core/interop"
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"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
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)
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type iterator interface {
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Next() bool
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Value() stackitem.Item
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}
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// Next advances the iterator, pushes true on success and false otherwise.
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func Next(ic *interop.Context) error {
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iop := ic.VM.Estack().Pop().Interop()
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arr := iop.Value().(iterator)
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ic.VM.Estack().PushItem(stackitem.Bool(arr.Next()))
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return nil
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}
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// Value returns current iterator value and depends on iterator type:
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// For slices the result is just value.
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// For maps the result is key-value pair packed in a struct.
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func Value(ic *interop.Context) error {
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iop := ic.VM.Estack().Pop().Interop()
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arr := iop.Value().(iterator)
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ic.VM.Estack().PushItem(arr.Value())
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return nil
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}
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// IsIterator returns whether stackitem implements iterator interface.
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func IsIterator(item stackitem.Item) bool {
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_, ok := item.Value().(iterator)
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return ok
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}
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// ValuesTruncated returns an array of up to `max` iterator values. The second
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// return parameter denotes whether iterator is truncated, i.e. has more values.
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// The provided iterator CAN NOT be reused in the subsequent calls to Values and
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// to ValuesTruncated.
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func ValuesTruncated(item stackitem.Item, max int) ([]stackitem.Item, bool) {
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result := Values(item, max)
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arr := item.Value().(iterator)
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return result, arr.Next()
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}
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// Values returns an array of up to `max` iterator values. The provided
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// iterator can safely be reused to retrieve the rest of its values in the
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// subsequent calls to Values and to ValuesTruncated.
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func Values(item stackitem.Item, max int) []stackitem.Item {
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var result []stackitem.Item
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arr := item.Value().(iterator)
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for max > 0 && arr.Next() {
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result = append(result, arr.Value())
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max--
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}
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return result
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}
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