package slices

import (
	"container/list"
)

// Deref returns a slice containing all dereferenced values of s.
// The returned slice will be a dereferenced and continuous block of memory.
// Nil pointers are ignored.
func Deref[T any](s []*T) []T {
	out := make([]T, 0, len(s))
	Each(s, func(v *T) {
		if v != nil {
			out = append(out, *v)
		}
	})
	return out
}

// ToList returns a list.List containing all values of s
func ToList[T any](s []T) *list.List {
	l := list.New()
	Each(s, func(value T) { l.PushBack(value) })
	return l
}

// ToMap returns a map containing all values of s.
// The map key-value pairs are determined by mapper
func ToMap[T any, K comparable, V any](s []T, mapper func(T) (K, V)) map[K]V {
	m := map[K]V{}
	Each(s, func(value T) {
		k, v := mapper(value)
		m[k] = v
	})
	return m
}

// ToStructMap returns a struct{} map containing all values of s as keys.
// It is a shorthand for ToMap(s, func(value T) (T, struct{}) { return value, struct{}{} })
func ToStructMap[T comparable](s []T) map[T]struct{} {
	return ToMap(s, func(value T) (T, struct{}) { return value, struct{}{} })
}