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moby--moby/vendor/github.com/ugorji/go/codec/helper_unsafe.go

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//+build unsafe
// Copyright (c) 2012-2015 Ugorji Nwoke. All rights reserved.
// Use of this source code is governed by a MIT license found in the LICENSE file.
package codec
import (
"unsafe"
)
// This file has unsafe variants of some helper methods.
type unsafeString struct {
Data uintptr
Len int
}
type unsafeBytes struct {
Data uintptr
Len int
Cap int
}
// stringView returns a view of the []byte as a string.
// In unsafe mode, it doesn't incur allocation and copying caused by conversion.
// In regular safe mode, it is an allocation and copy.
func stringView(v []byte) string {
if len(v) == 0 {
return ""
}
x := unsafeString{uintptr(unsafe.Pointer(&v[0])), len(v)}
return *(*string)(unsafe.Pointer(&x))
}
// bytesView returns a view of the string as a []byte.
// In unsafe mode, it doesn't incur allocation and copying caused by conversion.
// In regular safe mode, it is an allocation and copy.
func bytesView(v string) []byte {
if len(v) == 0 {
return zeroByteSlice
}
x := unsafeBytes{uintptr(unsafe.Pointer(&v)), len(v), len(v)}
return *(*[]byte)(unsafe.Pointer(&x))
}