| // 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 onlyone plugin generates code for the onlyone extension. |
| All fields must be nullable and only one of the fields may be set, like a union. |
| Two methods are generated |
| |
| GetValue() interface{} |
| |
| and |
| |
| SetValue(v interface{}) (set bool) |
| |
| These provide easier interaction with a onlyone. |
| |
| The onlyone extension is not called union as this causes compile errors in the C++ generated code. |
| There can only be one ;) |
| |
| It is enabled by the following extensions: |
| |
| - onlyone |
| - onlyone_all |
| |
| The onlyone plugin also generates a test given it is enabled using one of the following extensions: |
| |
| - testgen |
| - testgen_all |
| |
| Lets 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 U { |
| option (gogoproto.onlyone) = true; |
| optional A A = 1; |
| optional B B = 2; |
| } |
| |
| given to the onlyone plugin, will generate code which looks a lot like this: |
| |
| func (this *U) GetValue() interface{} { |
| if this.A != nil { |
| return this.A |
| } |
| if this.B != nil { |
| return this.B |
| } |
| return nil |
| } |
| |
| func (this *U) SetValue(value interface{}) bool { |
| switch vt := value.(type) { |
| case *A: |
| this.A = vt |
| case *B: |
| this.B = vt |
| default: |
| return false |
| } |
| return true |
| } |
| |
| and the following test code: |
| |
| func TestUUnion(t *testing.T) { |
| popr := math_rand.New(math_rand.NewSource(time.Now().UnixNano())) |
| p := NewPopulatedU(popr) |
| v := p.GetValue() |
| msg := &U{} |
| if !msg.SetValue(v) { |
| t.Fatalf("Union: Could not set Value") |
| } |
| if !p.Equal(msg) { |
| t.Fatalf("%#v !Union Equal %#v", msg, p) |
| } |
| } |
| |
| */ |
| package union |
| |
| import ( |
| "github.com/gogo/protobuf/gogoproto" |
| "github.com/gogo/protobuf/protoc-gen-gogo/generator" |
| ) |
| |
| type union struct { |
| *generator.Generator |
| generator.PluginImports |
| } |
| |
| func NewUnion() *union { |
| return &union{} |
| } |
| |
| func (p *union) Name() string { |
| return "union" |
| } |
| |
| func (p *union) Init(g *generator.Generator) { |
| p.Generator = g |
| } |
| |
| func (p *union) Generate(file *generator.FileDescriptor) { |
| p.PluginImports = generator.NewPluginImports(p.Generator) |
| |
| for _, message := range file.Messages() { |
| if !gogoproto.IsUnion(file.FileDescriptorProto, message.DescriptorProto) { |
| continue |
| } |
| if message.DescriptorProto.HasExtension() { |
| panic("onlyone does not currently support extensions") |
| } |
| if message.DescriptorProto.GetOptions().GetMapEntry() { |
| continue |
| } |
| |
| ccTypeName := generator.CamelCaseSlice(message.TypeName()) |
| p.P(`func (this *`, ccTypeName, `) GetValue() interface{} {`) |
| p.In() |
| for _, field := range message.Field { |
| fieldname := p.GetFieldName(message, field) |
| if fieldname == "Value" { |
| panic("cannot have a onlyone message " + ccTypeName + " with a field named Value") |
| } |
| p.P(`if this.`, fieldname, ` != nil {`) |
| p.In() |
| p.P(`return this.`, fieldname) |
| p.Out() |
| p.P(`}`) |
| } |
| p.P(`return nil`) |
| p.Out() |
| p.P(`}`) |
| p.P(``) |
| p.P(`func (this *`, ccTypeName, `) SetValue(value interface{}) bool {`) |
| p.In() |
| p.P(`switch vt := value.(type) {`) |
| p.In() |
| for _, field := range message.Field { |
| fieldname := p.GetFieldName(message, field) |
| goTyp, _ := p.GoType(message, field) |
| p.P(`case `, goTyp, `:`) |
| p.In() |
| p.P(`this.`, fieldname, ` = vt`) |
| p.Out() |
| } |
| p.P(`default:`) |
| p.In() |
| for _, field := range message.Field { |
| fieldname := p.GetFieldName(message, field) |
| if field.IsMessage() { |
| goTyp, _ := p.GoType(message, field) |
| obj := p.ObjectNamed(field.GetTypeName()).(*generator.Descriptor) |
| |
| if gogoproto.IsUnion(obj.File().FileDescriptorProto, obj.DescriptorProto) { |
| p.P(`this.`, fieldname, ` = new(`, generator.GoTypeToName(goTyp), `)`) |
| p.P(`if set := this.`, fieldname, `.SetValue(value); set {`) |
| p.In() |
| p.P(`return true`) |
| p.Out() |
| p.P(`}`) |
| p.P(`this.`, fieldname, ` = nil`) |
| } |
| } |
| } |
| p.P(`return false`) |
| p.Out() |
| p.P(`}`) |
| p.P(`return true`) |
| p.Out() |
| p.P(`}`) |
| } |
| } |
| |
| func init() { |
| generator.RegisterPlugin(NewUnion()) |
| } |