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api.go
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api.go
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// Package seq2 provides helpers for “range-over-func” feature introduced in go 1.22.
package seq2
import (
"iter"
"github.com/m4gshm/gollections/map_/resolv"
)
// Of creates an index/value pairs iterator over the elements.
func Of[T any](elements ...T) iter.Seq2[int, T] {
return func(yield func(int, T) bool) {
for i, v := range elements {
if ok := yield(i, v); !ok {
break
}
}
}
}
// OfMap creates an key/value pairs iterator over the elements map.
func OfMap[K comparable, V any](elements map[K]V) iter.Seq2[K, V] {
return func(yield func(K, V) bool) {
for k, v := range elements {
if ok := yield(k, v); !ok {
break
}
}
}
}
// Filter creates a rangefunc that iterates only those elements for which the 'filter' function returns true.
func Filter[K, V any](seq iter.Seq2[K, V], filter func(K, V) bool) iter.Seq2[K, V] {
if seq == nil {
return func(_ func(K, V) bool) {}
}
return func(consumer func(K, V) bool) {
seq(func(k K, v V) bool {
if filter(k, v) {
return consumer(k, v)
}
return true
})
}
}
// Convert creates a rangefunc that applies the 'converter' function to each iterable element.
func Convert[Kfrom, Vfrom, Kto, Vto any](seq iter.Seq2[Kfrom, Vfrom], converter func(Kfrom, Vfrom) (Kto, Vto)) iter.Seq2[Kto, Vto] {
if seq == nil {
return func(_ func(Kto, Vto) bool) {}
}
return func(consumer func(Kto, Vto) bool) {
seq(func(k Kfrom, v Vfrom) bool {
return consumer(converter(k, v))
})
}
}
// Values converts a key/value pairs iterator to an iterator of just values.
func Values[K, V any](seq iter.Seq2[K, V]) iter.Seq[V] {
if seq == nil {
return func(_ func(V) bool) {}
}
return func(yield func(V) bool) {
seq(func(_ K, v V) bool {
return yield(v)
})
}
}
// Keys converts a key/value pairs iterator to an iterator of just keys.
func Keys[K, V any](seq iter.Seq2[K, V]) iter.Seq[K] {
if seq == nil {
return func(_ func(K) bool) {}
}
return func(yield func(K) bool) {
seq(func(k K, _ V) bool {
return yield(k)
})
}
}
// Slice collects the elements of the 'seq' sequence into a new slice.
func Slice[T any](seq iter.Seq2[T, error]) ([]T, error) {
return SliceCap(seq, 0)
}
// SliceCap collects the elements of the 'seq' sequence into a new slice with predefined capacity.
func SliceCap[T any](seq iter.Seq2[T, error], cap int) (out []T, e error) {
if seq == nil {
return nil, nil
}
if cap > 0 {
out = make([]T, 0, cap)
}
return Append(seq, out)
}
// Append collects the elements of the 'seq' sequence into the specified 'out' slice.
func Append[T any, TS ~[]T](seq iter.Seq2[T, error], out TS) (TS, error) {
if seq == nil {
return nil, nil
}
var errOur error
seq(func(v T, e error) bool {
if e != nil {
errOur = e
return false
}
out = append(out, v)
return true
})
return out, errOur
}
// Group converts the elements of the 'seq' sequence into a new map, extracting a key for each element applying the converter 'keyExtractor'.
func Group[K comparable, V any](seq iter.Seq2[K, V]) map[K][]V {
return MapResolv(seq, resolv.Slice[K, V])
}
// Map collects key\value elements into a new map by iterating over the elements.
func Map[K comparable, V any](seq iter.Seq2[K, V]) map[K]V {
return MapResolv(seq, resolv.First[K, V])
}
// MapResolv collects key\value elements into a new map by iterating over the elements with resolving of duplicated key values.
func MapResolv[K comparable, V, VR any](seq iter.Seq2[K, V], resolver func(bool, K, VR, V) VR) map[K]VR {
return AppendMapResolv(seq, resolver, nil)
}
// MapResolvOrder collects key\value elements into a new map by iterating over the elements with resolving of duplicated key values.
// Returns a slice with the keys ordered by the time they were added and the resolved key\value map.
func MapResolvOrder[K comparable, V, VR any](seq iter.Seq2[K, V], resolver func(bool, K, VR, V) VR) ([]K, map[K]VR) {
return AppendMapResolvOrder(seq, resolver, nil, nil)
}
// AppendMapResolv collects key\value elements into the 'dest' map by iterating over the elements with resolving of duplicated key values.
func AppendMapResolv[K comparable, V, VR any](seq iter.Seq2[K, V], resolver func(bool, K, VR, V) VR, dest map[K]VR) map[K]VR {
if seq == nil {
return nil
}
if dest == nil {
dest = map[K]VR{}
}
seq(func(k K, v V) bool {
exists, ok := dest[k]
dest[k] = resolver(ok, k, exists, v)
return true
})
return dest
}
// AppendMapResolvOrder collects key\value elements into the 'dest' map by iterating over the elements with resolving of duplicated key values
// Additionaly populates the 'order' slice by the keys ordered by the time they were added and the resolved key\value map.
func AppendMapResolvOrder[K comparable, V, VR any](seq iter.Seq2[K, V], resolver func(bool, K, VR, V) VR, order []K, dest map[K]VR) ([]K, map[K]VR) {
if seq == nil {
return nil, nil
}
if dest == nil {
dest = map[K]VR{}
}
seq(func(k K, v V) bool {
exists, ok := dest[k]
dest[k] = resolver(ok, k, exists, v)
if !ok {
order = append(order, k)
}
return true
})
return order, dest
}