Damien Neil d30e561d9e proto: add MarshalState, UnmarshalState
Add functions to the proto package which plumb through the fast-path state.

As a sample use case: A followup CL adds an Initialized field to
protoiface.UnmarshalOutput, permitting the unmarshaller to report back
when it can confirm that a message is fully initialized. We want to
preserve that information when an unmarshal operation threads through
the proto package (such as when unmarshaling extensions).

To allow these functions to be added as methods of MarshalOptions and
UnmarshalOptions rather than top-level functions, separate the options
from the input structs.

Also update options passed to fast-path methods to set AllowPartial and
Merge to reflect the expected behavior of those methods. (Always allow
partial, never merge.)

Change-Id: I482477b0c9340793be533e75a86d0bb88708716a
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/215877
Reviewed-by: Joe Tsai <joetsai@google.com>
2020-01-22 20:52:17 +00:00

102 lines
3.2 KiB
Go

// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package protoiface contains types referenced or implemented by messages.
//
// WARNING: This package should only be imported by message implementations.
// The functionality found in this package should be accessed through
// higher-level abstractions provided by the proto package.
package protoiface
import (
"google.golang.org/protobuf/internal/pragma"
"google.golang.org/protobuf/reflect/protoreflect"
)
// Methods is a set of optional fast-path implementations of various operations.
type Methods = struct {
pragma.NoUnkeyedLiterals
// Flags indicate support for optional features.
Flags SupportFlags
// Size returns the size in bytes of the wire-format encoding of m.
// MarshalAppend must be provided if a custom Size is provided.
Size func(m protoreflect.Message, opts MarshalOptions) int
// Marshal writes the wire-format encoding of m to the provided buffer.
// Size should be provided if a custom MarshalAppend is provided.
Marshal func(m protoreflect.Message, in MarshalInput, opts MarshalOptions) (MarshalOutput, error)
// Unmarshal parses the wire-format encoding of a message and merges the result to m.
Unmarshal func(m protoreflect.Message, in UnmarshalInput, opts UnmarshalOptions) (UnmarshalOutput, error)
// IsInitialized returns an error if any required fields in m are not set.
IsInitialized func(m protoreflect.Message) error
}
type SupportFlags = uint64
const (
// SupportMarshalDeterministic reports whether MarshalOptions.Deterministic is supported.
SupportMarshalDeterministic SupportFlags = 1 << iota
// SupportUnmarshalDiscardUnknown reports whether UnmarshalOptions.DiscardUnknown is supported.
SupportUnmarshalDiscardUnknown
)
// MarshalInput is input to the marshaler.
type MarshalInput = struct {
pragma.NoUnkeyedLiterals
Buf []byte // output is appended to this buffer
}
// MarshalOutput is output from the marshaler.
type MarshalOutput = struct {
pragma.NoUnkeyedLiterals
Buf []byte // contains marshaled message
}
// MarshalOptions configure the marshaler.
//
// This type is identical to the one in package proto.
type MarshalOptions = struct {
pragma.NoUnkeyedLiterals
AllowPartial bool // may be treated as true by method implementations
Deterministic bool
UseCachedSize bool
}
// UnmarshalInput is input to the unmarshaler.
type UnmarshalInput = struct {
pragma.NoUnkeyedLiterals
Buf []byte // input buffer
}
// UnmarshalOutput is output from the unmarshaler.
type UnmarshalOutput = struct {
pragma.NoUnkeyedLiterals
// Contents available for future expansion.
}
// UnmarshalOptions configures the unmarshaler.
//
// This type is identical to the one in package proto.
type UnmarshalOptions = struct {
pragma.NoUnkeyedLiterals
Merge bool // may be treated as true by method implementations
AllowPartial bool // may be treated as true by method implementations
DiscardUnknown bool
Resolver interface {
FindExtensionByName(field protoreflect.FullName) (protoreflect.ExtensionType, error)
FindExtensionByNumber(message protoreflect.FullName, field protoreflect.FieldNumber) (protoreflect.ExtensionType, error)
}
}