code review 3608041: reflect: add ArrayType.Slice, ArrayValue.Slice

src/pkg/reflect/value.go

Index: src/pkg/reflect/value.go
===================================================================
--- a/src/pkg/reflect/value.go
+++ b/src/pkg/reflect/value.go
@@ -397,6 +397,7 @@
 	Len() int
 	Cap() int
 	Elem(i int) Value
+	Slice(beg, end int) *SliceValue
 	addr() addr
 }
 
@@ -456,6 +457,20 @@
 	return newValue(typ, p, v.canSet)
 }
 
+// Slice returns a slice of the array v.
+func (v *ArrayValue) Slice(beg, end int) *SliceValue {
+	cap := v.Cap()
+	if beg < 0 || end < beg || end > cap {
+		panic("slice index out of bounds")
+	}
+	typ := v.typ.(*ArrayType).Slice()
+	s := new(SliceHeader)
+	s.Data = uintptr(v.addr()) + uintptr(beg)*typ.Elem().Size()
+	s.Len = end - beg
+	s.Cap = cap - beg
+	return newValue(typ, addr(s), v.canSet).(*SliceValue)
+}
+
 /*
  * slice
  */