1 // Copyright 2023 CUE Labs AG 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package ociregistry 16 17 // TODO(go1.23) when we can depend on Go 1.23, this should be: 18 // type Seq[T any] = iter.Seq2[T, error] 19 20 // Seq defines the type of an iterator sequence returned from 21 // the iterator functions. In general, a non-nil 22 // error means that the item is the last in the sequence. 23 type Seq[T any] func(yield func(T, error) bool) 24 25 func All[T any](it Seq[T]) (_ []T, _err error) { 26 xs := []T{} 27 // TODO(go1.23) for x, err := range it 28 it(func(x T, err error) bool { 29 if err != nil { 30 _err = err 31 return false 32 } 33 xs = append(xs, x) 34 return true 35 }) 36 return xs, _err 37 } 38 39 type sliceIter[T any] struct { 40 i int 41 xs []T 42 } 43 44 func SliceIter[T any](xs []T) Seq[T] { 45 return func(yield func(T, error) bool) { 46 for _, x := range xs { 47 if !yield(x, nil) { 48 return 49 } 50 } 51 } 52 } 53 54 // ErrorIter returns an iterator that has no 55 // items and always returns the given error. 56 func ErrorIter[T any](err error) Seq[T] { 57 return func(yield func(T, error) bool) { 58 yield(*new(T), err) 59 } 60 } 61