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65 lines
2.7 KiB
Go
65 lines
2.7 KiB
Go
/*
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Package iterator provides functions to work with Neo iterators.
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*/
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package iterator
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import "github.com/nspcc-dev/neo-go/pkg/interop/enumerator"
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// Iterator represents a Neo iterator, it's an opaque data structure that can
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// be properly created by Create or storage.Find. Unlike enumerators, iterators
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// range over key-value pairs, so it's convenient to use them for maps. This
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// structure is similar in function to Neo .net framework's Iterator.
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type Iterator struct{}
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// Create creates an iterator from the given items (array, struct or map). A new
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// iterator is set to point at element -1, so to access its first element you
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// need to call Next first. This function uses `Neo.Iterator.Create` syscall.
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func Create(items []interface{}) Iterator {
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return Iterator{}
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}
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// Concat concatenates two given iterators returning one that will range on
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// a first and then continue with b. Iterator positions are not reset for a
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// and b, so if any of them was already advanced by Next the resulting
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// Iterator will point at this new position and never go back to previous
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// key-value pairs. Concatenated iterators also remain completely independent
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// in results they return, so if both contain the same key you'll receive this
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// key twice when iterating. This function uses `Neo.Iterator.Concat` syscall.
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func Concat(a, b Iterator) Iterator {
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return Iterator{}
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}
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// Key returns iterator's key at current position. It's only valid to call after
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// successful Next call. This function uses `Neo.Iterator.Key` syscall.
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func Key(it Iterator) interface{} {
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return nil
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}
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// Keys returns Enumerator ranging over keys or the given Iterator. Note that
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// this Enumerator is actually directly tied to the underlying Iterator, so that
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// advancing it with Next will actually advance the Iterator too. This function
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// uses `Neo.Iterator.Keys` syscall.
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func Keys(it Iterator) enumerator.Enumerator {
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return enumerator.Enumerator{}
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}
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// Next advances the iterator returning true if it is was successful (and you
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// can use Key or Value) and false otherwise (and there are no more elements in
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// this Iterator). This function uses `Neo.Iterator.Next` syscall.
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func Next(it Iterator) bool {
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return true
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}
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// Value returns iterator's current value. It's only valid to call after
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// successful Next call. This function uses `Neo.Iterator.Value` syscall.
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func Value(it Iterator) interface{} {
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return nil
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}
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// Values returns Enumerator ranging over values or the given Iterator. Note that
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// this Enumerator is actually directly tied to the underlying Iterator, so that
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// advancing it with Next will actually advance the Iterator too. This function
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// uses `Neo.Iterator.Values` syscall.
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func Values(it Iterator) enumerator.Enumerator {
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return enumerator.Enumerator{}
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}
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