README
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iterator
Adapters that drain a cursor-style Iterator (Next(any) bool + Count() int) into a slice, channel, or mapped result. Part of rosetta.
This is the legacy iteration interface, predating Go 1.23 range-over-func. For new code using iter.Seq, see ranges; reach for this package only when adapting a type that already implements the Iterator interface (e.g. a database cursor).
What matters here
Nextpopulates a value through a pointer, so theconstructor func() Tmust return a FRESH value each call.Slice,Channel, andMapcall the constructor once per element and pass&valuetoNext. If the constructor returns a shared/aliased value, every slice entry ends up pointing at the same mutated item. Allocate a new zero value each time.Channelspawns a goroutine that closes its output and runs until the iterator is exhausted. If the consumer stops reading early, the goroutine blocks forever (leak). UseChannelWithCanceland signal itscancelchannel to stop early.Slicepre-allocates capacity fromiterator.Count(). AnIteratorwhoseCount()lies (returns fewer than it yields) just causes a re-grow — correctness is fine, butCount()should be accurate for the allocation to help.
Documentation
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Overview ¶
Package iterator adapts cursor-style collections into slices, channels, and mapped results.
An Iterator yields values by filling in a pointer — Next(any) bool — which is the shape a database cursor naturally has. Slice, Channel, and Map drain one, calling a caller-supplied constructor once per element; that constructor must return a fresh value every time, because a shared value would leave every result aliasing the same item.
This is the legacy iteration interface, predating range-over-func. New code should prefer iter.Seq and the ranges package; reach for this one only to adapt a type that already implements Iterator.
Index ¶
- func Channel[T any](iterator Iterator, constructor func() T) chan T
- func ChannelWithCancel[T any](iterator Iterator, constructor func() T, cancel <-chan bool) chan T
- func Map[In any, Out any](it Iterator, fn func(In) Out) []Out
- func Slice[T any](iterator Iterator, constructor func() T) []T
- type Iterator
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Channel ¶
Channel converts an Iterator into a channel of items. You must include a constructor function that generates fully initialized values of the type you want to return. Deprecated: freeing up this namespace to use for new Go 1.23 range functions
func ChannelWithCancel ¶
ChannelWithCancel converts an Iterator into a channel of items. You must include a constructor function that generates fully initialized values of the type you want to return. Deprecated: freeing up this namespace to use for new Go 1.23 range functions
func Map ¶
Map converts an iterator into a slice of items. Deprecated: freeing up this namespace to use for new Go 1.23 range functions
Types ¶
type Iterator ¶
type Iterator interface {
// Next populates the provided value with the next item, and returns FALSE when the iterator is exhausted
Next(any) bool
// Count returns the total number of items available to this iterator
Count() int
}
Iterator interface allows callers to iterator over a large number of items in an array/slice Deprecated: freeing up this namespace to use for new Go 1.23 range functions
Source Files