tree a99653ab9034f3f5b7cfedb9547c4d64319657f3
parent 31610fd9139106e5b7432e3533ca1254bfa32433
author Joe Tsai <joetsai@digital-static.net> 1589244452 -0700
committer Joe Tsai <joetsai@digital-static.net> 1617318559 +0000

reflect: add protopath and protorange packages

The protopath package provides a means to programmatically represent
a sequence of protobuf reflection operations.
The protorange package traverses through a message and
calls a user-provided function as it iterates.

This feature sets the groundwork for the often requested feature
of being able to exclude certain fields when merging or serializing.

package protopath
    type Path []Step
    type Step struct{ ... }
        func Root(protoreflect.MessageDescriptor) Step
        func FieldAccess(protoreflect.FieldDescriptor) Step
        func UnknownAccess() Step
        func ListIndex(int) Step
        func MapIndex(protoreflect.MapKey) Step
        func AnyExpand(protoreflect.MessageDescriptor) Step
        func (Step) Kind() StepKind
        func (Step) FieldDescriptor() protoreflect.FieldDescriptor
        func (Step) MessageDescriptor() protoreflect.MessageDescriptor
        func (Step) ListIndex() int
        func (Step) MapIndex() protoreflect.MapKey
        func (Step) String() string
    type StepKind int
        const RootStep StepKind
        const FieldAccessStep StepKind
        const UnknownAccessStep StepKind
        const ListIndexStep StepKind
        const MapIndexStep StepKind
        const AnyExpandStep StepKind
    type Values struct {
        Path   Path
        Values []protoreflect.Value
    }
    func (Values) Index(int) (out struct{ ... })
    func (Values) Len() int
    func (Values) String() string

package protorange
    var Break error
    var Terminate error
    func Range(protoreflect.Message, func(protopath.Values) error) error
    type Options struct {
        Stable bool
        Resolver interface { ... }
    }
    func (Options) Range(m protoreflect.Message, push, pop func(protopath.Values) error) error

Change-Id: I29cbd5142fe169d78367d54a95d37801888b64f4
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/236540
Trust: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Damien Neil <dneil@google.com>