add SliceWrapper

ds/slice/slice_wrapper.go

@@ -0,0 +1,73 @@
+package slice
+
+import "reflect"
+
+//SliceWrapper wraps a slice in order to provide functions related to iterators
+type SliceWrapper struct {
+	slice      interface{}
+	sliceValue reflect.Value
+	itemType   reflect.Type
+}
+
+// New creates a SliceWrapper
+func NewSliceWrapper(slice interface{}, itemType reflect.Type) *SliceWrapper {
+	return &SliceWrapper{
+		slice:      slice,
+		sliceValue: reflect.ValueOf(slice),
+		itemType:   itemType,
+	}
+}
+
+func (s *SliceWrapper) Attach(newSlice interface{}) {
+	if reflect.ValueOf(newSlice).Kind() == s.sliceValue.Kind() {
+		s.slice = newSlice
+		s.sliceValue = reflect.ValueOf(newSlice)
+	}
+}
+
+// Len returns the length of s
+func (s *SliceWrapper) Len() int {
+	return s.sliceValue.Len()
+}
+
+// At returns the value at position
+func (s *SliceWrapper) At(position int) interface{} {
+	if position < 0 || position >= s.Len() {
+		return nil
+	}
+	return s.sliceValue.Index(position).Interface()
+}
+
+// Set sets value at position
+func (s *SliceWrapper) Set(position int, val interface{}) {
+	if position < 0 || position >= s.Len() {
+		return
+	}
+	s.sliceValue.Index(position).Set(reflect.ValueOf(val))
+}
+
+// Begin returns the first iterator of s
+func (s *SliceWrapper) Begin() *SliceIterator {
+	return s.First()
+}
+
+// End returns the end iterator of s
+func (s *SliceWrapper) End() *SliceIterator {
+	return &SliceIterator{s: s,
+		position: s.Len(),
+	}
+}
+
+// First returns the first iterator of s
+func (s *SliceWrapper) First() *SliceIterator {
+	return &SliceIterator{s: s,
+		position: 0,
+	}
+}
+
+// Last returns the last iterator of s
+func (s *SliceWrapper) Last() *SliceIterator {
+	return &SliceIterator{s: s,
+		position: s.Len(),
+	}
+}

ds/slice/slice_wrapper_test.go

@@ -0,0 +1,52 @@
+package slice
+
+import (
+	"github.com/liyue201/gostl/algorithm/sort"
+	"github.com/stretchr/testify/assert"
+	"reflect"
+	"testing"
+)
+
+func TestSliceWrapper(t *testing.T) {
+	type User struct {
+		age  int
+		name string
+	}
+
+	a := make([]*User, 0)
+	a = append(a, &User{age: 2, name: "zzz"})
+	a = append(a, &User{age: 5, name: "nnn"})
+	a = append(a, &User{age: 2, name: "aaa"})
+
+	sw := NewSliceWrapper(a, reflect.TypeOf(&User{}))
+
+	assert.Equal(t, 3, sw.Len())
+
+	sort.Sort(sw.Begin(), sw.End(), func(a, b interface{}) int {
+		ua := a.(*User)
+		ub := b.(*User)
+		if ua.age < ub.age {
+			return -1
+		}
+		if ua.age > ub.age {
+			return 1
+		}
+		if ua.name < ub.name {
+			return -1
+		}
+		if ua.name > ub.name {
+			return 1
+		}
+		return 0
+	})
+	for i := range a {
+		t.Logf("%+v\n", a[i])
+		assert.Equal(t, a[i], sw.At(i))
+		if i > 0 {
+			assert.LessOrEqual(t, a[i-1].age, a[i].age)
+			if a[i-1].age == a[i].age {
+				assert.LessOrEqual(t, a[i-1].name, a[i].name)
+			}
+		}
+	}
+}