list: add DeleteIf method (#50)

DeleteIf delete all satisfying f(data[i]), returns count of removed elements

datastructure/list/list.go

@@ -163,6 +163,31 @@ func (l *List[T]) DeleteAt(index int) {
 	l.data = data
 }
 
+// DeleteIf delete all satisfying f(data[i]), returns count of removed elements
+func (l *List[T]) DeleteIf(f func(T) bool) int {
+	data := l.data
+	size := len(data)
+
+	var c int
+	for index := 0; index < len(data); index++ {
+		if !f(data[index]) {
+			continue
+		}
+		if index == size-1 {
+			data = append(data[:index])
+		} else {
+			data = append(data[:index], data[index+1:]...)
+			index--
+		}
+		c++
+	}
+
+	if c > 0 {
+		l.data = data
+	}
+	return c
+}
+
 // UpdateAt update value of list at index, index shoud between 0 and list size -1
 func (l *List[T]) UpdateAt(index int, value T) {
 	data := l.data

datastructure/list/list_test.go

@@ -331,3 +331,17 @@ func BenchmarkSubSlice(b *testing.B) {
 		list.SubList(2, 5)
 	}
 }
+
+func TestDeleteIf(t *testing.T) {
+	assert := internal.NewAssert(t, "TestDeleteIf")
+
+	list := NewList([]int{1, 1, 1, 1, 2, 3, 1, 1, 4, 1, 1, 1, 1, 1, 1})
+
+	count := list.DeleteIf(func(a int) bool { return a == 1 })
+	assert.Equal([]int{2, 3, 4}, list.Data())
+	assert.Equal(12, count)
+
+	count = list.DeleteIf(func(a int) bool { return a == 5 })
+	assert.Equal([]int{2, 3, 4}, list.Data())
+	assert.Equal(0, count)
+}

docs/datastructure/list.md

@@ -47,6 +47,7 @@ import (
 - [Union](#Union)
 - [Intersection](#Intersection)
 - [SubList](#SubList)
+- [DeleteIf](#DeleteIf)
 
 <div STYLE="page-break-after: always;"></div>
 
@@ -820,4 +821,33 @@ func main() {
 
     fmt.Println(l.SubList(2, 5)) // []int{3, 4, 5}
 }
-```
+```
+
+
+
+
+### <span id="DeleteIf">DeleteIf</span>
+<p>DeleteIf delete all satisfying f(data[i]), returns count of removed elements</p>
+
+<b>Signature:</b>
+
+```go
+func (l *List[T]) DeleteIf(f func(T) bool) int
+```
+<b>Example:</b>
+
+```go
+package main
+
+import (
+    "fmt"
+    list "github.com/duke-git/lancet/v2/datastructure/list"
+)
+
+func main() {
+	l := list.NewList([]int{1, 1, 1, 1, 2, 3, 1, 1, 4, 1, 1, 1, 1, 1, 1})
+
+	fmt.Println(l.DeleteIf(func(a int) bool { return a == 1 })) // 12 
+	fmt.Println(l.Data()) // []int{2, 3, 4}
+}
+```