add ProjectSliceToMap function

Author: Diaphteiros

pkg/collections/utils.go

@@ -1,10 +1,20 @@
 package collections
 
-// ProjectSlice takes a slice and a projection function and applies this function to each element of the slice.
+// ProjectSliceToSlice takes a slice and a projection function and applies this function to each element of the slice.
 // It returns a new slice containing the results of the projection.
 // The original slice is not modified.
 // If the projection function is nil, it returns nil.
+//
+// Deprecated: With the introduction of ProjectSliceToMap, this function has been replaced by ProjectSliceToSlice for better naming consistency.
 func ProjectSlice[X any, Y any](src []X, project func(X) Y) []Y {
+	return ProjectSliceToSlice(src, project)
+}
+
+// ProjectSliceToSlice takes a slice and a projection function and applies this function to each element of the slice.
+// It returns a new slice containing the results of the projection.
+// The original slice is not modified.
+// If the projection function is nil, it returns nil.
+func ProjectSliceToSlice[X any, Y any](src []X, project func(X) Y) []Y {
 	if project == nil {
 		return nil
 	}
@@ -15,6 +25,23 @@ func ProjectSlice[X any, Y any](src []X, project func(X) Y) []Y {
 	return res
 }
 
+// ProjectSliceToMap takes a slice and a projection function and applies this function to each element of the slice.
+// It returns a new map containing the results of the projection.
+// The original slice is not modified.
+// Note that the resulting map may be smaller if the projection function does not guarantee unique keys.
+// If the projection function is nil, it returns nil.
+func ProjectSliceToMap[X any, K comparable, V any](src []X, project func(X) (K, V)) map[K]V {
+	if project == nil {
+		return nil
+	}
+	res := make(map[K]V, len(src))
+	for _, x := range src {
+		k, v := project(x)
+		res[k] = v
+	}
+	return res
+}
+
 // ProjectMapToSlice takes a map and a projection function and applies this function to each key-value pair in the map.
 // It returns a new slice containing the results of the projection.
 // The original map is not modified.

pkg/collections/utils_test.go

@@ -12,27 +12,54 @@ import (
 
 var _ = Describe("Utils Tests", func() {
 
-	Context("ProjectSlice", func() {
+	Context("ProjectSliceToSlice", func() {
 
 		projectFunc := func(i int) int {
 			return i * 2
 		}
 
 		It("should use the projection function on each element of the slice", func() {
 			src := []int{1, 2, 3, 4}
-			projected := collections.ProjectSlice(src, projectFunc)
+			projected := collections.ProjectSliceToSlice(src, projectFunc)
 			Expect(projected).To(Equal([]int{2, 4, 6, 8}))
 			Expect(src).To(Equal([]int{1, 2, 3, 4}), "original slice should not be modified")
 		})
 
 		It("should return an empty slice for an empty or nil input slice", func() {
-			Expect(collections.ProjectSlice(nil, projectFunc)).To(BeEmpty())
-			Expect(collections.ProjectSlice([]int{}, projectFunc)).To(BeEmpty())
+			Expect(collections.ProjectSliceToSlice(nil, projectFunc)).To(BeEmpty())
+			Expect(collections.ProjectSliceToSlice([]int{}, projectFunc)).To(BeEmpty())
 		})
 
 		It("should return nil for a nil projection function", func() {
 			src := []int{1, 2, 3, 4}
-			projected := collections.ProjectSlice[int, int](src, nil)
+			projected := collections.ProjectSliceToSlice[int, int](src, nil)
+			Expect(projected).To(BeNil())
+			Expect(src).To(Equal([]int{1, 2, 3, 4}), "original slice should not be modified")
+		})
+
+	})
+
+	Context("ProjectSliceToMap", func() {
+
+		projectFunc := func(i int) (int, int) {
+			return i, i * 2
+		}
+
+		It("should use the projection function on each element of the slice", func() {
+			src := []int{1, 2, 3, 4}
+			projected := collections.ProjectSliceToMap(src, projectFunc)
+			Expect(projected).To(Equal(map[int]int{1: 2, 2: 4, 3: 6, 4: 8}))
+			Expect(src).To(Equal([]int{1, 2, 3, 4}), "original slice should not be modified")
+		})
+
+		It("should return an empty slice for an empty or nil input slice", func() {
+			Expect(collections.ProjectSliceToMap(nil, projectFunc)).To(BeEmpty())
+			Expect(collections.ProjectSliceToMap([]int{}, projectFunc)).To(BeEmpty())
+		})
+
+		It("should return nil for a nil projection function", func() {
+			src := []int{1, 2, 3, 4}
+			projected := collections.ProjectSliceToMap[int, int, int](src, nil)
 			Expect(projected).To(BeNil())
 			Expect(src).To(Equal([]int{1, 2, 3, 4}), "original slice should not be modified")
 		})