syncthing/vendor/github.com/gogo/protobuf/plugin/description/description.go

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// Protocol Buffers for Go with Gadgets
//
// Copyright (c) 2013, The GoGo Authors. All rights reserved.
// http://github.com/gogo/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/*
The description (experimental) plugin generates a Description method for each message.
The Description method returns a populated google_protobuf.FileDescriptorSet struct.
This contains the description of the files used to generate this message.
It is enabled by the following extensions:
- description
- description_all
The description plugin also generates a test given it is enabled using one of the following extensions:
- testgen
- testgen_all
Let us look at:
github.com/gogo/protobuf/test/example/example.proto
Btw all the output can be seen at:
github.com/gogo/protobuf/test/example/*
The following message:
message B {
option (gogoproto.description) = true;
optional A A = 1 [(gogoproto.nullable) = false, (gogoproto.embed) = true];
repeated bytes G = 2 [(gogoproto.customtype) = "github.com/gogo/protobuf/test/custom.Uint128", (gogoproto.nullable) = false];
}
given to the description plugin, will generate the following code:
func (this *B) Description() (desc *google_protobuf.FileDescriptorSet) {
return ExampleDescription()
}
and the following test code:
func TestDescription(t *testing9.T) {
ExampleDescription()
}
The hope is to use this struct in some way instead of reflect.
This package is subject to change, since a use has not been figured out yet.
*/
package description
import (
"bytes"
"compress/gzip"
"fmt"
"github.com/gogo/protobuf/gogoproto"
"github.com/gogo/protobuf/proto"
descriptor "github.com/gogo/protobuf/protoc-gen-gogo/descriptor"
"github.com/gogo/protobuf/protoc-gen-gogo/generator"
)
type plugin struct {
*generator.Generator
generator.PluginImports
}
func NewPlugin() *plugin {
return &plugin{}
}
func (p *plugin) Name() string {
return "description"
}
func (p *plugin) Init(g *generator.Generator) {
p.Generator = g
}
func (p *plugin) Generate(file *generator.FileDescriptor) {
used := false
localName := generator.FileName(file)
p.PluginImports = generator.NewPluginImports(p.Generator)
descriptorPkg := p.NewImport("github.com/gogo/protobuf/protoc-gen-gogo/descriptor")
protoPkg := p.NewImport("github.com/gogo/protobuf/proto")
gzipPkg := p.NewImport("compress/gzip")
bytesPkg := p.NewImport("bytes")
ioutilPkg := p.NewImport("io/ioutil")
for _, message := range file.Messages() {
if !gogoproto.HasDescription(file.FileDescriptorProto, message.DescriptorProto) {
continue
}
if message.DescriptorProto.GetOptions().GetMapEntry() {
continue
}
used = true
ccTypeName := generator.CamelCaseSlice(message.TypeName())
p.P(`func (this *`, ccTypeName, `) Description() (desc *`, descriptorPkg.Use(), `.FileDescriptorSet) {`)
p.In()
p.P(`return `, localName, `Description()`)
p.Out()
p.P(`}`)
}
if used {
p.P(`func `, localName, `Description() (desc *`, descriptorPkg.Use(), `.FileDescriptorSet) {`)
p.In()
//Don't generate SourceCodeInfo, since it will create too much code.
ss := make([]*descriptor.SourceCodeInfo, 0)
for _, f := range p.Generator.AllFiles().GetFile() {
ss = append(ss, f.SourceCodeInfo)
f.SourceCodeInfo = nil
}
b, err := proto.Marshal(p.Generator.AllFiles())
if err != nil {
panic(err)
}
for i, f := range p.Generator.AllFiles().GetFile() {
f.SourceCodeInfo = ss[i]
}
p.P(`d := &`, descriptorPkg.Use(), `.FileDescriptorSet{}`)
var buf bytes.Buffer
w, _ := gzip.NewWriterLevel(&buf, gzip.BestCompression)
w.Write(b)
w.Close()
b = buf.Bytes()
p.P("var gzipped = []byte{")
p.In()
p.P("// ", len(b), " bytes of a gzipped FileDescriptorSet")
for len(b) > 0 {
n := 16
if n > len(b) {
n = len(b)
}
s := ""
for _, c := range b[:n] {
s += fmt.Sprintf("0x%02x,", c)
}
p.P(s)
b = b[n:]
}
p.Out()
p.P("}")
p.P(`r := `, bytesPkg.Use(), `.NewReader(gzipped)`)
p.P(`gzipr, err := `, gzipPkg.Use(), `.NewReader(r)`)
p.P(`if err != nil {`)
p.In()
p.P(`panic(err)`)
p.Out()
p.P(`}`)
p.P(`ungzipped, err := `, ioutilPkg.Use(), `.ReadAll(gzipr)`)
p.P(`if err != nil {`)
p.In()
p.P(`panic(err)`)
p.Out()
p.P(`}`)
p.P(`if err := `, protoPkg.Use(), `.Unmarshal(ungzipped, d); err != nil {`)
p.In()
p.P(`panic(err)`)
p.Out()
p.P(`}`)
p.P(`return d`)
p.Out()
p.P(`}`)
}
}
func init() {
generator.RegisterPlugin(NewPlugin())
}