refactor(server): replace RangeByChunks with Go 1.23 iterators (#3292)

* refactor(server): replace RangeByChunks with Go 1.23 iterators

* chore: fix comments re: SQLITE_MAX_VARIABLE_NUMBER

* test: improve playqueue test

* refactor(server): don't create a new iterator when it is not required

utils/slice/slice.go

@@ -62,31 +62,7 @@ func Move[T any](slice []T, srcIndex int, dstIndex int) []T {
 	return Insert(Remove(slice, srcIndex), value, dstIndex)
 }
 
-func BreakUp[T any](items []T, chunkSize int) [][]T {
-	numTracks := len(items)
-	var chunks [][]T
-	for i := 0; i < numTracks; i += chunkSize {
-		end := i + chunkSize
-		if end > numTracks {
-			end = numTracks
-		}
-
-		chunks = append(chunks, items[i:end])
-	}
-	return chunks
-}
-
-func RangeByChunks[T any](items []T, chunkSize int, cb func([]T) error) error {
-	chunks := BreakUp(items, chunkSize)
-	for _, chunk := range chunks {
-		err := cb(chunk)
-		if err != nil {
-			return err
-		}
-	}
-	return nil
-}
-
+// LinesFrom returns a Seq that reads lines from the given reader
 func LinesFrom(reader io.Reader) iter.Seq[string] {
 	return func(yield func(string) bool) {
 		scanner := bufio.NewScanner(reader)
@@ -123,16 +99,17 @@ func scanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
 	return 0, nil, nil
 }
 
-func CollectChunks[T any](n int, it iter.Seq[T]) iter.Seq[[]T] {
+// CollectChunks collects chunks of n elements from the input sequence and return a Seq of chunks
+func CollectChunks[T any](it iter.Seq[T], n int) iter.Seq[[]T] {
 	return func(yield func([]T) bool) {
-		var s []T
+		s := make([]T, 0, n)
 		for x := range it {
 			s = append(s, x)
 			if len(s) >= n {
 				if !yield(s) {
 					return
 				}
-				s = nil
+				s = make([]T, 0, n)
 			}
 		}
 		if len(s) > 0 {
@@ -140,3 +117,14 @@ func CollectChunks[T any](n int, it iter.Seq[T]) iter.Seq[[]T] {
 		}
 	}
 }
+
+// SeqFunc returns a Seq that iterates over the slice with the given mapping function
+func SeqFunc[I, O any](s []I, f func(I) O) iter.Seq[O] {
+	return func(yield func(O) bool) {
+		for _, x := range s {
+			if !yield(f(x)) {
+				return
+			}
+		}
+	}
+}

utils/slice/slice_test.go

@@ -74,27 +74,6 @@ var _ = Describe("Slice Utils", func() {
 		})
 	})
 
-	Describe("BreakUp", func() {
-		It("returns no chunks if slice is empty", func() {
-			var s []string
-			chunks := slice.BreakUp(s, 10)
-			Expect(chunks).To(HaveLen(0))
-		})
-		It("returns the slice in one chunk if len < chunkSize", func() {
-			s := []string{"a", "b", "c"}
-			chunks := slice.BreakUp(s, 10)
-			Expect(chunks).To(HaveLen(1))
-			Expect(chunks[0]).To(HaveExactElements("a", "b", "c"))
-		})
-		It("breaks up the slice if len > chunkSize", func() {
-			s := []string{"a", "b", "c", "d", "e"}
-			chunks := slice.BreakUp(s, 3)
-			Expect(chunks).To(HaveLen(2))
-			Expect(chunks[0]).To(HaveExactElements("a", "b", "c"))
-			Expect(chunks[1]).To(HaveExactElements("d", "e"))
-		})
-	})
-
 	DescribeTable("LinesFrom",
 		func(path string, expected int) {
 			count := 0
@@ -112,14 +91,30 @@ var _ = Describe("Slice Utils", func() {
 
 	DescribeTable("CollectChunks",
 		func(input []int, n int, expected [][]int) {
-			result := [][]int{}
-			for chunks := range slice.CollectChunks[int](n, slices.Values(input)) {
+			var result [][]int
+			for chunks := range slice.CollectChunks(slices.Values(input), n) {
 				result = append(result, chunks)
 			}
 			Expect(result).To(Equal(expected))
 		},
-		Entry("returns empty slice for an empty input", []int{}, 1, [][]int{}),
+		Entry("returns empty slice (nil) for an empty input", []int{}, 1, nil),
 		Entry("returns the slice in one chunk if len < chunkSize", []int{1, 2, 3}, 10, [][]int{{1, 2, 3}}),
 		Entry("breaks up the slice if len > chunkSize", []int{1, 2, 3, 4, 5}, 3, [][]int{{1, 2, 3}, {4, 5}}),
 	)
+
+	Describe("SeqFunc", func() {
+		It("returns empty slice for an empty input", func() {
+			it := slice.SeqFunc([]int{}, func(v int) int { return v })
+
+			result := slices.Collect(it)
+			Expect(result).To(BeEmpty())
+		})
+
+		It("returns a new slice with mapped elements", func() {
+			it := slice.SeqFunc([]int{1, 2, 3, 4}, func(v int) string { return strconv.Itoa(v * 2) })
+
+			result := slices.Collect(it)
+			Expect(result).To(ConsistOf("2", "4", "6", "8"))
+		})
+	})
 })