From aa609e4f470e96044f34f91ab2b85683b0ceff24 Mon Sep 17 00:00:00 2001
From: Masakazu Ohtsuka <o.masakazu@gmail.com>
Date: Fri, 26 Jul 2024 14:51:40 +0900
Subject: [PATCH] feat: add FromSlicePtr (#217)

* feat: add FromSlicePtr

* Update README.md

---------

Co-authored-by: Samuel Berthe <dev@samuel-berthe.fr>
---
 README.md                 | 19 +++++++++++++++++++
 type_manipulation.go      | 11 +++++++++++
 type_manipulation_test.go | 10 ++++++++++
 3 files changed, 40 insertions(+)

diff --git a/README.md b/README.md
index ea94a528..2d92c422 100644
--- a/README.md
+++ b/README.md
@@ -254,6 +254,7 @@ Type manipulation helpers:
 - [FromPtr](#fromptr)
 - [FromPtrOr](#fromptror)
 - [ToSlicePtr](#tosliceptr)
+- [FromSlicePtr](#fromsliceptr)
 - [ToAnySlice](#toanyslice)
 - [FromAnySlice](#fromanyslice)
 - [Empty](#empty)
@@ -2681,6 +2682,24 @@ ptr := lo.ToSlicePtr([]string{"hello", "world"})
 // []*string{"hello", "world"}
 ```
 
+### FromSlicePtr
+
+Returns a slice with the pointer values.
+Returns a zero value in case of a nil pointer element.
+
+```go
+str1 := "hello"
+str2 := "world"
+
+ptr := lo.FromSlicePtr[string]([]*string{&str1, &str2, nil})
+// []string{"hello", "world", ""}
+
+ptr := lo.Compact(
+    lo.FromSlicePtr[string]([]*string{&str1, &str2, nil}),
+)
+// []string{"hello", "world"}
+```
+
 ### ToAnySlice
 
 Returns a slice with all elements mapped to `any` type.
diff --git a/type_manipulation.go b/type_manipulation.go
index 3e965183..27fa6e75 100644
--- a/type_manipulation.go
+++ b/type_manipulation.go
@@ -58,6 +58,17 @@ func ToSlicePtr[T any](collection []T) []*T {
 	return result
 }
 
+// FromSlicePtr returns a slice with the pointer values.
+// Returns a zero value in case of a nil pointer element.
+func FromSlicePtr[T any](collection []*T) []T {
+	return Map(collection, func(x *T, _ int) T {
+		if x == nil {
+			return Empty[T]()
+		}
+		return *x
+	})
+}
+
 // ToAnySlice returns a slice with all elements mapped to `any` type
 func ToAnySlice[T any](collection []T) []any {
 	result := make([]any, len(collection))
diff --git a/type_manipulation_test.go b/type_manipulation_test.go
index 61e21f52..f0d2567f 100644
--- a/type_manipulation_test.go
+++ b/type_manipulation_test.go
@@ -121,6 +121,16 @@ func TestToSlicePtr(t *testing.T) {
 	is.Equal(result1, []*string{&str1, &str2})
 }
 
+func TestFromSlicePtr(t *testing.T) {
+	is := assert.New(t)
+
+	str1 := "foo"
+	str2 := "bar"
+	result1 := FromSlicePtr([]*string{&str1, &str2, nil})
+
+	is.Equal(result1, []string{str1, str2, ""})
+}
+
 func TestToAnySlice(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)