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https://github.com/protocolbuffers/protobuf-go.git
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c6b7561199
Given a pointer to a Go struct (that is well-formed according to the v1 struct field layout), wrap the type such that it implements the v2 protoreflect.Message interface. Change-Id: I5987cad0d22e53970c613cdbbb1cfd4210897f69 Reviewed-on: https://go-review.googlesource.com/c/138897 Reviewed-by: Damien Neil <dneil@google.com>
50 lines
1.4 KiB
Go
50 lines
1.4 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !purego
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package impl
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import (
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"reflect"
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"unsafe"
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)
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// offset represents the offset to a struct field, accessible from a pointer.
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// The offset is the byte offset to the field from the start of the struct.
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type offset uintptr
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// offsetOf returns a field offset for the struct field.
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func offsetOf(f reflect.StructField) offset {
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return offset(f.Offset)
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}
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// pointer is a pointer to a message struct or field.
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type pointer struct{ p unsafe.Pointer }
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// pointerOfValue returns v as a pointer.
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func pointerOfValue(v reflect.Value) pointer {
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return pointer{p: unsafe.Pointer(v.Pointer())}
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}
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// pointerOfIface returns the pointer portion of an interface.
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func pointerOfIface(v *interface{}) pointer {
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type ifaceHeader struct {
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Type unsafe.Pointer
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Data unsafe.Pointer
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}
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return pointer{p: (*ifaceHeader)(unsafe.Pointer(v)).Data}
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}
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// apply adds an offset to the pointer to derive a new pointer
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// to a specified field. The current pointer must be pointing at a struct.
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func (p pointer) apply(f offset) pointer {
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return pointer{p: unsafe.Pointer(uintptr(p.p) + uintptr(f))}
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}
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// asType treats p as a pointer to an object of type t and returns the value.
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func (p pointer) asType(t reflect.Type) reflect.Value {
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return reflect.NewAt(t, p.p)
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}
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