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fa02f4eaa6
This provides an implementation of the has, get, set, clear methods for each field in a message. The approach taken here is similar to the table-driven implementation in the current v1 proto package. The pointer_reflect.go and pointer_unsafe.go files are a simplified version of the same files in the v1 implementation. They provide a pointer abstraction that enables a high-efficiency approach in a non-purego environment. The unsafe fast-path is not implemented in this commit. This commit only implements the accessor methods for scalars using pure Go reflection. Change-Id: Icdf707e9d4e3385e55434f93b30a341a7680ae11 Reviewed-on: https://go-review.googlesource.com/135136 Reviewed-by: Damien Neil <dneil@google.com>
48 lines
1.3 KiB
Go
48 lines
1.3 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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"fmt"
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"reflect"
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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 field index into a struct.
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type offset []int
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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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if len(f.Index) != 1 {
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panic("embedded structs are not supported")
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}
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return f.Index
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}
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// pointer is an abstract representation of a pointer to a struct or field.
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type pointer struct{ v reflect.Value }
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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{v: v}
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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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// TODO: Handle unexported fields in an API that hides XXX fields?
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return pointer{v: p.v.Elem().FieldByIndex(f).Addr()}
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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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if p.v.Type().Elem() != t {
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panic(fmt.Sprintf("invalid type: got %v, want %v", p.v.Type(), t))
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}
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return p.v
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}
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