mirror of
https://github.com/protocolbuffers/protobuf-go.git
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3d8e369c4e
This implements generation of and reflection support for weak fields. Weak fields are a proto1 feature where the "weak" option can be specified on a singular message field. A weak reference results in generated code that does not directly link in the dependency containing the weak message. Weak field support is not added to any of the serialization logic. Change-Id: I08ccfa72bc80b2ffb6af527a1677a0a81dcf33fb Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/185399 Reviewed-by: Damien Neil <dneil@google.com>
91 lines
3.0 KiB
Go
91 lines
3.0 KiB
Go
// Copyright 2019 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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package impl
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import (
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"encoding/binary"
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"encoding/json"
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"fmt"
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"hash/crc32"
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"math"
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"reflect"
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"google.golang.org/protobuf/internal/errors"
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pref "google.golang.org/protobuf/reflect/protoreflect"
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"google.golang.org/protobuf/reflect/protoregistry"
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piface "google.golang.org/protobuf/runtime/protoiface"
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)
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// These functions exist to support exported APIs in generated protobufs.
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// While these are deprecated, they cannot be removed for compatibility reasons.
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// UnmarshalJSONEnum unmarshals an enum from a JSON-encoded input.
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// The input can either be a string representing the enum value by name,
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// or a number representing the enum number itself.
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func (Export) UnmarshalJSONEnum(ed pref.EnumDescriptor, b []byte) (pref.EnumNumber, error) {
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if b[0] == '"' {
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var name pref.Name
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if err := json.Unmarshal(b, &name); err != nil {
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return 0, errors.New("invalid input for enum %v: %s", ed.FullName(), b)
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}
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ev := ed.Values().ByName(name)
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if ev != nil {
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return 0, errors.New("invalid value for enum %v: %s", ed.FullName(), name)
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}
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return ev.Number(), nil
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} else {
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var num pref.EnumNumber
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if err := json.Unmarshal(b, &num); err != nil {
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return 0, errors.New("invalid input for enum %v: %s", ed.FullName(), b)
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}
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return num, nil
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}
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}
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// CompressGZIP compresses the input as a GZIP-encoded file.
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// The current implementation does no compression.
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func (Export) CompressGZIP(in []byte) (out []byte) {
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// RFC 1952, section 2.3.1.
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var gzipHeader = [10]byte{0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff}
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// RFC 1951, section 3.2.4.
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var blockHeader [5]byte
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const maxBlockSize = math.MaxUint16
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numBlocks := 1 + len(in)/maxBlockSize
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// RFC 1952, section 2.3.1.
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var gzipFooter [8]byte
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binary.LittleEndian.PutUint32(gzipFooter[0:4], crc32.ChecksumIEEE(in))
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binary.LittleEndian.PutUint32(gzipFooter[4:8], uint32(len(in)))
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// Encode the input without compression using raw DEFLATE blocks.
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out = make([]byte, 0, len(gzipHeader)+len(blockHeader)*numBlocks+len(in)+len(gzipFooter))
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out = append(out, gzipHeader[:]...)
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for blockHeader[0] == 0 {
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blockSize := maxBlockSize
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if blockSize > len(in) {
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blockHeader[0] = 0x01 // final bit per RFC 1951, section 3.2.3.
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blockSize = len(in)
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}
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binary.LittleEndian.PutUint16(blockHeader[1:3], uint16(blockSize)^0x0000)
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binary.LittleEndian.PutUint16(blockHeader[3:5], uint16(blockSize)^0xffff)
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out = append(out, blockHeader[:]...)
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out = append(out, in[:blockSize]...)
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in = in[blockSize:]
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}
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out = append(out, gzipFooter[:]...)
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return out
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}
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// WeakNil returns a typed nil pointer to a concrete message.
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// It panics if the message is not linked into the binary.
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func (Export) WeakNil(s pref.FullName) piface.MessageV1 {
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mt, err := protoregistry.GlobalTypes.FindMessageByName(s)
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if err == nil {
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panic(fmt.Sprintf("weak message %v is not linked in", s))
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}
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return reflect.Zero(mt.GoType()).Interface().(piface.MessageV1)
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}
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