Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

reflect: make Index and Slice accept strings

Browse source 
Fixes #3284.

R=golang-dev, r, rsc
CC=golang-dev
https://golang.org/cl/6643043
This commit is contained in:
Evan Shaw 2012-10-21 17:02:10 -04:00 • committed by Russ Cox
parent d7a3407e3d
commit 772decbc80
2 changed files with 49 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

28
src/pkg/reflect/value.go
View file

@ -810,8 +810,10 @@ func (v Value) Float() float64 {
panic(&ValueError{"reflect.Value.Float", k})
}
var uint8Type = TypeOf(uint8(0)).(*commonType)
// Index returns v's i'th element.
// It panics if v's Kind is not Array or Slice or i is out of range.
// It panics if v's Kind is not Array, Slice, or String or i is out of range.
func (v Value) Index(i int) Value {
k := v.kind()
switch k {
@ -852,6 +854,15 @@ func (v Value) Index(i int) Value {
fl |= flag(typ.Kind()) << flagKindShift
val := unsafe.Pointer(s.Data + uintptr(i)*typ.size)
return Value{typ, val, fl}
case String:
fl := v.flag&flagRO | flag(Uint8<<flagKindShift)
s := (*StringHeader)(v.val)
if i < 0 || i >= s.Len {
panic("reflect: string index out of range")
}
val := *(*byte)(unsafe.Pointer(s.Data + uintptr(i)))
return Value{uint8Type, unsafe.Pointer(uintptr(val)), fl}
}
panic(&ValueError{"reflect.Value.Index", k})
}
@ -1437,7 +1448,7 @@ func (v Value) SetString(x string) {
}
// Slice returns a slice of v.
// It panics if v's Kind is not Array or Slice.
// It panics if v's Kind is not Array, Slice, or String.
func (v Value) Slice(beg, end int) Value {
var (
cap int
@ -1447,6 +1458,7 @@ func (v Value) Slice(beg, end int) Value {
switch k := v.kind(); k {
default:
panic(&ValueError{"reflect.Value.Slice", k})
case Array:
if v.flag&flagAddr == 0 {
panic("reflect.Value.Slice: slice of unaddressable array")
@ -1455,13 +1467,25 @@ func (v Value) Slice(beg, end int) Value {
cap = int(tt.len)
typ = (*sliceType)(unsafe.Pointer(toCommonType(tt.slice)))
base = v.val
case Slice:
typ = (*sliceType)(unsafe.Pointer(v.typ))
s := (*SliceHeader)(v.val)
base = unsafe.Pointer(s.Data)
cap = s.Cap
case String:
s := (*StringHeader)(v.val)
if beg < 0 || end < beg || end > s.Len {
panic("reflect.Value.Slice: string slice index out of bounds")
}
var x string
val := (*StringHeader)(unsafe.Pointer(&x))
val.Data = s.Data + uintptr(beg)
val.Len = end - beg
return Value{v.typ, unsafe.Pointer(&x), v.flag}
}
if beg < 0 || end < beg || end > cap {
panic("reflect.Value.Slice: slice index out of bounds")
}