feat: adding LastOrEmpty and LastOr (#474)

samber · Jun 27, 2024 · 5aa64ef · 5aa64ef
1 parent a94098f
commit 5aa64ef
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diff --git a/README.md b/README.md
@@ -222,10 +222,12 @@ Supported search helpers:
 - [Max](#max)
 - [MaxBy](#maxby)
 - [Latest](#latest)
-- [Last](#last)
 - [First](#first)
 - [FirstOrEmpty](#FirstOrEmpty)
 - [FirstOr](#FirstOr)
+- [Last](#last)
+- [LastOrEmpty](#LastOrEmpty)
+- [LastOr](#LastOr)
 - [Nth](#nth)
 - [Sample](#sample)
 - [Samples](#samples)
@@ -2238,14 +2240,6 @@ latest := lo.Latest([]time.Time{time.Now(), time.Time{}})
 // 2023-04-01 01:02:03 +0000 UTC
 ```
 
-### Last
-
-Returns the last element of a collection or error if empty.
-
-```go
-last, err := lo.Last([]int{1, 2, 3})
-// 3
-```
 ### First
 
 Returns the first element of a collection and check for availability of the first element.
@@ -2257,6 +2251,7 @@ first, ok := lo.First([]int{1, 2, 3})
 first, ok := lo.First([]int{})
 // 0, false
 ```
+
 ### FirstOrEmpty
 
 Returns the first element of a collection or zero value if empty.
@@ -2280,6 +2275,43 @@ first := lo.FirstOr([]int{}, 31)
 // 31
 ```
 
+### Last
+
+Returns the last element of a collection or error if empty.
+
+```go
+last, ok := lo.Last([]int{1, 2, 3})
+// 3
+// true
+
+last, ok := lo.Last([]int{})
+// 0
+// false
+```
+
+### FirstOrEmpty
+
+Returns the first element of a collection or zero value if empty.
+
+```go
+last := lo.LastOrEmpty([]int{1, 2, 3})
+// 3
+
+last := lo.LastOrEmpty([]int{})
+// 0
+```
+### FirstOr
+
+Returns the first element of a collection or the fallback value if empty.
+
+```go
+last := lo.LastOr([]int{1, 2, 3}, 245)
+// 3
+
+last := lo.LastOr([]int{}, 31)
+// 31
+```
+
 ### Nth
 
 Returns the element at index `nth` of collection. If `nth` is negative, the nth element from the end is returned. An error is returned when nth is out of slice bounds.

diff --git a/find.go b/find.go
@@ -355,39 +355,55 @@ func Latest(times ...time.Time) time.Time {
 	return max
 }
 
-// Last returns the last element of a collection or error if empty.
-func Last[T any](collection []T) (T, error) {
+// First returns the first element of a collection and check for availability of the first element.
+func First[T any](collection []T) (T, bool) {
 	length := len(collection)
 
 	if length == 0 {
 		var t T
-		return t, fmt.Errorf("last: cannot extract the last element of an empty slice")
+		return t, false
 	}
 
-	return collection[length-1], nil
+	return collection[0], true
 }
 
-// Returns the first element of a collection and check for availability of the first element.
-func First[T any](collection []T) (T, bool) {
+// FirstOrEmpty returns the first element of a collection or zero value if empty.
+func FirstOrEmpty[T any](collection []T) T {
+	i, _ := First(collection)
+	return i
+}
+
+// FirstOr returns the first element of a collection or the fallback value if empty.
+func FirstOr[T any](collection []T, fallback T) T {
+	i, ok := First(collection)
+	if !ok {
+		return fallback
+	}
+
+	return i
+}
+
+// Last returns the last element of a collection or error if empty.
+func Last[T any](collection []T) (T, bool) {
 	length := len(collection)
 
 	if length == 0 {
 		var t T
 		return t, false
 	}
 
-	return collection[0], true
+	return collection[length-1], true
 }
 
-// Returns the first element of a collection or zero value if empty.
-func FirstOrEmpty[T any](collection []T) T {
-	i, _ := First(collection)
+// Returns the last element of a collection or zero value if empty.
+func LastOrEmpty[T any](collection []T) T {
+	i, _ := Last(collection)
 	return i
 }
 
-// Returns the first element of a collection or the fallback value if empty.
-func FirstOr[T any](collection []T, fallback T) T {
-	i, ok := First(collection)
+// LastOr returns the last element of a collection or the fallback value if empty.
+func LastOr[T any](collection []T, fallback T) T {
+	i, ok := Last(collection)
 	if !ok {
 		return fallback
 	}

diff --git a/find_test.go b/find_test.go
@@ -359,19 +359,6 @@ func TestLatest(t *testing.T) {
 	is.Equal(result2, time.Time{})
 }
 
-func TestLast(t *testing.T) {
-	t.Parallel()
-	is := assert.New(t)
-
-	result1, err1 := Last([]int{1, 2, 3})
-	result2, err2 := Last([]int{})
-
-	is.Equal(result1, 3)
-	is.Equal(err1, nil)
-	is.Equal(result2, 0)
-	is.Equal(err2, fmt.Errorf("last: cannot extract the last element of an empty slice"))
-}
-
 func TestFirst(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)
@@ -411,6 +398,45 @@ func TestFirstOr(t *testing.T) {
 	is.Equal(result3, "test")
 }
 
+func TestLast(t *testing.T) {
+	t.Parallel()
+	is := assert.New(t)
+
+	result1, ok1 := Last([]int{1, 2, 3})
+	result2, ok2 := Last([]int{})
+
+	is.Equal(result1, 3)
+	is.True(ok1)
+	is.Equal(result2, 0)
+	is.False(ok2)
+}
+
+func TestLastOrEmpty(t *testing.T) {
+	t.Parallel()
+	is := assert.New(t)
+
+	result1 := LastOrEmpty([]int{1, 2, 3})
+	result2 := LastOrEmpty([]int{})
+	result3 := LastOrEmpty([]string{})
+
+	is.Equal(result1, 3)
+	is.Equal(result2, 0)
+	is.Equal(result3, "")
+}
+
+func TestLastOr(t *testing.T) {
+	t.Parallel()
+	is := assert.New(t)
+
+	result1 := LastOr([]int{1, 2, 3}, 63)
+	result2 := LastOr([]int{}, 23)
+	result3 := LastOr([]string{}, "test")
+
+	is.Equal(result1, 3)
+	is.Equal(result2, 23)
+	is.Equal(result3, "test")
+}
+
 func TestNth(t *testing.T) {
 	t.Parallel()
 	is := assert.New(t)