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values.go
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values.go
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package seq
import "github.com/kamstrup/fn/opt"
type valuesSeq[T any] struct {
seq Seq[opt.Opt[T]]
}
// ValuesOf returns a seq that lazily converts opts into their wrapped values, stopping at the first error.
func ValuesOf[T any](opts Seq[opt.Opt[T]]) Seq[T] {
return valuesSeq[T]{seq: opts}
}
func (v valuesSeq[T]) ForEach(f Func1[T]) opt.Opt[T] {
var (
val T
loopErr error
)
res := v.seq.ForEach(func(o opt.Opt[T]) {
if loopErr == nil { // only do something if we didn't already see an error
val, loopErr = o.Return()
if loopErr == nil {
f(val)
}
} // else: skip remaining items
})
if resErr := res.Error(); resErr != nil {
return opt.ErrorOf[T](resErr)
} else if loopErr != nil && loopErr != opt.ErrEmpty {
return opt.ErrorOf[T](loopErr)
}
return opt.Zero[T]()
}
func (v valuesSeq[T]) ForEachIndex(f Func2[int, T]) opt.Opt[T] {
i := 0
return v.ForEach(func(t T) {
f(i, t)
i++
})
}
func (v valuesSeq[T]) Len() (int, bool) {
return v.seq.Len() // FIXME: length could be shorter if there is an error opt
}
func (v valuesSeq[T]) ToSlice() Slice[T] {
var arr []T
if sz, ok := v.Len(); ok {
arr = make([]T, 0, sz)
}
v.ForEach(func(t T) {
arr = append(arr, t)
})
return arr
}
func (v valuesSeq[T]) Limit(n int) Seq[T] {
return LimitOf[T](v, n)
}
func (v valuesSeq[T]) Take(n int) (Slice[T], Seq[T]) {
i := 0
return v.TakeWhile(func(t T) bool {
if i < n {
i++
return true
}
return false
})
}
func (v valuesSeq[T]) TakeWhile(pred Predicate[T]) (Slice[T], Seq[T]) {
var (
arr []T
head opt.Opt[T]
tail Seq[T]
)
for head, tail = v.First(); ; head, tail = tail.First() {
t, err := head.Return()
if err != nil {
return arr, ErrorOf[T](err)
} else if pred(t) {
arr = append(arr, t)
} else {
return arr, PrependOf(t, tail)
}
}
return arr, tail
}
func (v valuesSeq[T]) Skip(n int) Seq[T] {
var (
head opt.Opt[T]
tail Seq[T]
)
for head, tail = v.First(); n > 0; head, tail = tail.First() {
n--
if err := head.Error(); err != nil {
return ErrorOf[T](err)
}
}
return tail
}
func (v valuesSeq[T]) Where(pred Predicate[T]) Seq[T] {
return WhereOf[T](v, pred)
}
func (v valuesSeq[T]) While(pred Predicate[T]) Seq[T] {
return WhileOf[T](v, pred)
}
func (v valuesSeq[T]) First() (opt.Opt[T], Seq[T]) {
fst, tail := v.seq.First() // note: fst is an Opt[Opt[T]]
optT, err := fst.Return()
if err != nil {
return opt.ErrorOf[T](err), ErrorOf[T](err)
}
return optT, valuesSeq[T]{seq: tail}
}
func (v valuesSeq[T]) Map(funcMap FuncMap[T, T]) Seq[T] {
return MappingOf[T, T](v, funcMap)
}