peridot/vendor/github.com/sourcegraph/conc/iter/map.go

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package iter
import (
"sync"
"github.com/sourcegraph/conc/internal/multierror"
)
// Mapper is an Iterator with a result type R. It can be used to configure
// the behaviour of Map and MapErr. The zero value is safe to use with
// reasonable defaults.
//
// Mapper is also safe for reuse and concurrent use.
type Mapper[T, R any] Iterator[T]
// Map applies f to each element of input, returning the mapped result.
//
// Map always uses at most runtime.GOMAXPROCS goroutines. For a configurable
// goroutine limit, use a custom Mapper.
func Map[T, R any](input []T, f func(*T) R) []R {
return Mapper[T, R]{}.Map(input, f)
}
// Map applies f to each element of input, returning the mapped result.
//
// Map uses up to the configured Mapper's maximum number of goroutines.
func (m Mapper[T, R]) Map(input []T, f func(*T) R) []R {
res := make([]R, len(input))
Iterator[T](m).ForEachIdx(input, func(i int, t *T) {
res[i] = f(t)
})
return res
}
// MapErr applies f to each element of the input, returning the mapped result
// and a combined error of all returned errors.
//
// Map always uses at most runtime.GOMAXPROCS goroutines. For a configurable
// goroutine limit, use a custom Mapper.
func MapErr[T, R any](input []T, f func(*T) (R, error)) ([]R, error) {
return Mapper[T, R]{}.MapErr(input, f)
}
// MapErr applies f to each element of the input, returning the mapped result
// and a combined error of all returned errors.
//
// Map uses up to the configured Mapper's maximum number of goroutines.
func (m Mapper[T, R]) MapErr(input []T, f func(*T) (R, error)) ([]R, error) {
var (
res = make([]R, len(input))
errMux sync.Mutex
errs error
)
Iterator[T](m).ForEachIdx(input, func(i int, t *T) {
var err error
res[i], err = f(t)
if err != nil {
errMux.Lock()
// TODO: use stdlib errors once multierrors land in go 1.20
errs = multierror.Join(errs, err)
errMux.Unlock()
}
})
return res, errs
}