From c570b99ea72fdead7c062008573689d08c5bfd65 Mon Sep 17 00:00:00 2001
From: tuannguyen <nguyenvantuan2391996@gmail.com>
Date: Tue, 8 Aug 2023 12:14:58 +0700
Subject: [PATCH] feat: Implement funk.Partition

---
 partition.go      | 48 +++++++++++++++++++++++++++++++++++++++++++++++
 partition_test.go | 43 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 91 insertions(+)
 create mode 100644 partition.go
 create mode 100644 partition_test.go

diff --git a/partition.go b/partition.go
new file mode 100644
index 0000000..ad7dc43
--- /dev/null
+++ b/partition.go
@@ -0,0 +1,48 @@
+package funk
+
+import (
+	"reflect"
+)
+
+// Partition separates the elements of the input array into two slices based on the predicate function.
+// It takes an array-like data structure and a predicate function that determines the Partition.
+// The predicate function should have the signature func(elementType) bool.
+// The function returns two new slices: one containing elements that satisfy the predicate,
+// and the other containing elements that do not satisfy the predicate.
+func Partition(in, predicate interface{}) interface{} {
+	if !IsCollection(in) {
+		panic("First parameter must be a collection")
+	}
+
+	if !IsFunction(predicate, 1, 1) {
+		panic("Second argument must be function")
+	}
+
+	inValue, funcValue := reflect.ValueOf(in), reflect.ValueOf(predicate)
+
+	funcType := funcValue.Type()
+
+	if funcType.Out(0).Kind() != reflect.Bool {
+		panic("Return argument should be a boolean")
+	}
+
+	result := reflect.MakeSlice(reflect.SliceOf(reflect.TypeOf(in)), 0, 0)
+	partitionOne, partitionTwo := reflect.MakeSlice(inValue.Type(), 0, 0), reflect.MakeSlice(inValue.Type(), 0, 0)
+
+	for i := 0; i < inValue.Len(); i++ {
+		element := inValue.Index(i)
+
+		res := funcValue.Call([]reflect.Value{reflect.ValueOf(element.Interface())})
+		if res[0].Interface().(bool) {
+			partitionOne = reflect.Append(partitionOne, element)
+		} else {
+			partitionTwo = reflect.Append(partitionTwo, element)
+		}
+	}
+
+	if partitionOne.Len() > 0 || partitionTwo.Len() > 0 {
+		result = reflect.Append(result, partitionOne, partitionTwo)
+	}
+
+	return result.Interface()
+}
diff --git a/partition_test.go b/partition_test.go
new file mode 100644
index 0000000..b6f326f
--- /dev/null
+++ b/partition_test.go
@@ -0,0 +1,43 @@
+package funk
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_partition_valid_int(t *testing.T) {
+	result := Partition([]int{1, 2, 3, 4}, func(n int) bool {
+		return n%2 == 0
+	})
+
+	assert.Equal(t, [][]int{{2, 4}, {1, 3}}, result)
+}
+
+func Test_partition_valid_float64(t *testing.T) {
+	result := Partition([]float64{1.1, 2.2, 3.3, 4.4}, func(n float64) bool {
+		return n > float64(2)
+	})
+
+	assert.Equal(t, [][]float64{{2.2, 3.3, 4.4}, {1.1}}, result)
+}
+
+func Test_partition_valid_string(t *testing.T) {
+	result := Partition([]string{"a", "b", "c"}, func(n string) bool {
+		return n > "a"
+	})
+
+	assert.Equal(t, [][]string{{"b", "c"}, {"a"}}, result)
+}
+
+func Test_partition_valid_struct(t *testing.T) {
+	type User struct {
+		Name string
+		Age  int
+	}
+	result := Partition([]*User{{Name: "Kakalot", Age: 26}, {Name: "Vegeta", Age: 27}, {Name: "Trunk", Age: 10}}, func(n *User) bool {
+		return n.Age%2 == 0
+	})
+
+	assert.Equal(t, [][]*User{{{Name: "Kakalot", Age: 26}, {Name: "Trunk", Age: 10}}, {{Name: "Vegeta", Age: 27}}}, result)
+}