list: Add LastIndexOfFunc and IndexOfFunc method (#48)

* LastIndexOfFunc returns the index of the last occurrence of the value in this list satisfying f(data[i])
* IndexOfFunc returns the first index satisfying f(v)

datastructure/list/list.go

@@ -58,6 +58,34 @@ func (l *List[T]) LastIndexOf(value T) int {
 	return index
 }
 
+// IndexOfFunc returns the first index satisfying f(v)
+// if not found return -1
+func (l *List[T]) IndexOfFunc(f func(T) bool) int {
+	index := -1
+	data := l.data
+	for i, v := range data {
+		if f(v) {
+			index = i
+			break
+		}
+	}
+	return index
+}
+
+// LastIndexOfFunc returns the index of the last occurrence of the value in this list satisfying f(data[i])
+// if not found return -1
+func (l *List[T]) LastIndexOfFunc(f func(T) bool) int {
+	index := -1
+	data := l.data
+	for i := len(data) - 1; i >= 0; i-- {
+		if f(data[i]) {
+			index = i
+			break
+		}
+	}
+	return index
+}
+
 // Contain checks if the value in the list or not
 func (l *List[T]) Contain(value T) bool {
 	data := l.data

datastructure/list/list_test.go

@@ -36,6 +36,17 @@ func TestIndexOf(t *testing.T) {
 	assert.Equal(-1, i)
 }
 
+func TestIndexOfFunc(t *testing.T) {
+	assert := internal.NewAssert(t, "TestIndexOf")
+
+	list := NewList([]int{1, 2, 3})
+	i := list.IndexOfFunc(func(a int) bool { return a == 1 })
+	assert.Equal(0, i)
+
+	i = list.IndexOfFunc(func(a int) bool { return a == 4 })
+	assert.Equal(-1, i)
+}
+
 func TestLastIndexOf(t *testing.T) {
 	assert := internal.NewAssert(t, "TestIndexOf")
 
@@ -53,6 +64,23 @@ func TestLastIndexOf(t *testing.T) {
 	assert.Equal(0, i)
 }
 
+func TestLastIndexOfFunc(t *testing.T) {
+	assert := internal.NewAssert(t, "TestIndexOf")
+
+	list := NewList([]int{1, 2, 3, 3, 3, 3, 4, 5, 6, 9})
+	i := list.LastIndexOfFunc(func(a int) bool { return a == 3 })
+	assert.Equal(5, i)
+
+	i = list.LastIndexOfFunc(func(a int) bool { return a == 10 })
+	assert.Equal(-1, i)
+
+	i = list.LastIndexOfFunc(func(a int) bool { return a == 4 })
+	assert.Equal(6, i)
+
+	i = list.LastIndexOfFunc(func(a int) bool { return a == 1 })
+	assert.Equal(0, i)
+}
+
 func TestContain(t *testing.T) {
 	assert := internal.NewAssert(t, "TestContain")