Rework XDR encoding
This commit is contained in:
Jakob Borg
393
xdr/cmd/coder/main.go
Normal file
393
xdr/cmd/coder/main.go
Normal file
@@ -0,0 +1,393 @@
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package main
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import (
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"bytes"
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"flag"
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"fmt"
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"go/ast"
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"go/format"
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"go/parser"
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"go/token"
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"os"
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"regexp"
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"strconv"
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"strings"
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"text/template"
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)
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var output string
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type field struct {
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Name string
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IsBasic bool
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IsSlice bool
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IsMap bool
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FieldType string
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KeyType string
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Encoder string
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Convert string
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Max int
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}
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var headerTpl = template.Must(template.New("header").Parse(`package {{.Package}}
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import (
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"bytes"
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"io"
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"github.com/calmh/syncthing/xdr"
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)
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`))
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var encodeTpl = template.Must(template.New("encoder").Parse(`
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func (o {{.TypeName}}) EncodeXDR(w io.Writer) (int, error) {
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var xw = xdr.NewWriter(w)
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return o.encodeXDR(xw)
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}//+n
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func (o {{.TypeName}}) MarshalXDR() []byte {
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var buf bytes.Buffer
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var xw = xdr.NewWriter(&buf)
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o.encodeXDR(xw)
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return buf.Bytes()
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}//+n
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func (o {{.TypeName}}) encodeXDR(xw *xdr.Writer) (int, error) {
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{{range $field := .Fields}}
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{{if not $field.IsSlice}}
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{{if ne $field.Convert ""}}
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xw.Write{{$field.Encoder}}({{$field.Convert}}(o.{{$field.Name}}))
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{{else if $field.IsBasic}}
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{{if ge $field.Max 1}}
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if len(o.{{$field.Name}}) > {{$field.Max}} {
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return xw.Tot(), xdr.ErrElementSizeExceeded
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}
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{{end}}
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xw.Write{{$field.Encoder}}(o.{{$field.Name}})
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{{else}}
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o.{{$field.Name}}.encodeXDR(xw)
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{{end}}
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{{else}}
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{{if ge $field.Max 1}}
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if len(o.{{$field.Name}}) > {{$field.Max}} {
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return xw.Tot(), xdr.ErrElementSizeExceeded
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}
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{{end}}
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xw.WriteUint32(uint32(len(o.{{$field.Name}})))
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for i := range o.{{$field.Name}} {
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{{if ne $field.Convert ""}}
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xw.Write{{$field.Encoder}}({{$field.Convert}}(o.{{$field.Name}}[i]))
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{{else if $field.IsBasic}}
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xw.Write{{$field.Encoder}}(o.{{$field.Name}}[i])
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{{else}}
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o.{{$field.Name}}[i].encodeXDR(xw)
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{{end}}
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}
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{{end}}
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{{end}}
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return xw.Tot(), xw.Error()
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}//+n
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func (o *{{.TypeName}}) DecodeXDR(r io.Reader) error {
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xr := xdr.NewReader(r)
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return o.decodeXDR(xr)
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}//+n
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func (o *{{.TypeName}}) UnmarshalXDR(bs []byte) error {
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var buf = bytes.NewBuffer(bs)
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var xr = xdr.NewReader(buf)
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return o.decodeXDR(xr)
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}//+n
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func (o *{{.TypeName}}) decodeXDR(xr *xdr.Reader) error {
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{{range $field := .Fields}}
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{{if not $field.IsSlice}}
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{{if ne $field.Convert ""}}
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o.{{$field.Name}} = {{$field.FieldType}}(xr.Read{{$field.Encoder}}())
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{{else if $field.IsBasic}}
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{{if ge $field.Max 1}}
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o.{{$field.Name}} = xr.Read{{$field.Encoder}}Max({{$field.Max}})
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{{else}}
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o.{{$field.Name}} = xr.Read{{$field.Encoder}}()
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{{end}}
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{{else}}
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(&o.{{$field.Name}}).decodeXDR(xr)
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{{end}}
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{{else}}
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_{{$field.Name}}Size := int(xr.ReadUint32())
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{{if ge $field.Max 1}}
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if _{{$field.Name}}Size > {{$field.Max}} {
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return xdr.ErrElementSizeExceeded
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}
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{{end}}
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o.{{$field.Name}} = make([]{{$field.FieldType}}, _{{$field.Name}}Size)
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for i := range o.{{$field.Name}} {
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{{if ne $field.Convert ""}}
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o.{{$field.Name}}[i] = {{$field.FieldType}}(xr.Read{{$field.Encoder}}())
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{{else if $field.IsBasic}}
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o.{{$field.Name}}[i] = xr.Read{{$field.Encoder}}()
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{{else}}
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(&o.{{$field.Name}}[i]).decodeXDR(xr)
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{{end}}
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}
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{{end}}
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{{end}}
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return xr.Error()
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}`))
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var maxRe = regexp.MustCompile(`\Wmax:(\d+)`)
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type typeSet struct {
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Type string
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Encoder string
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}
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var xdrEncoders = map[string]typeSet{
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"int16": typeSet{"uint16", "Uint16"},
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"uint16": typeSet{"", "Uint16"},
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"int32": typeSet{"uint32", "Uint32"},
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"uint32": typeSet{"", "Uint32"},
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"int64": typeSet{"uint64", "Uint64"},
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"uint64": typeSet{"", "Uint64"},
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"int": typeSet{"uint64", "Uint64"},
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"string": typeSet{"", "String"},
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"[]byte": typeSet{"", "Bytes"},
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"bool": typeSet{"", "Bool"},
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}
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func handleStruct(name string, t *ast.StructType) {
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var fs []field
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for _, sf := range t.Fields.List {
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if len(sf.Names) == 0 {
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// We don't handle anonymous fields
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continue
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}
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fn := sf.Names[0].Name
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var max = 0
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if sf.Comment != nil {
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c := sf.Comment.List[0].Text
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if m := maxRe.FindStringSubmatch(c); m != nil {
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max, _ = strconv.Atoi(m[1])
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}
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}
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var f field
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switch ft := sf.Type.(type) {
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case *ast.Ident:
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tn := ft.Name
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if enc, ok := xdrEncoders[tn]; ok {
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f = field{
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Name: fn,
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IsBasic: true,
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FieldType: tn,
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Encoder: enc.Encoder,
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Convert: enc.Type,
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Max: max,
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}
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} else {
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f = field{
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Name: fn,
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IsBasic: false,
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FieldType: tn,
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Max: max,
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}
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}
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case *ast.ArrayType:
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if ft.Len != nil {
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// We don't handle arrays
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continue
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}
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tn := ft.Elt.(*ast.Ident).Name
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if enc, ok := xdrEncoders["[]"+tn]; ok {
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f = field{
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Name: fn,
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IsBasic: true,
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FieldType: tn,
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Encoder: enc.Encoder,
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Convert: enc.Type,
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Max: max,
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}
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} else if enc, ok := xdrEncoders[tn]; ok {
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f = field{
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Name: fn,
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IsBasic: true,
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IsSlice: true,
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FieldType: tn,
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Encoder: enc.Encoder,
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Convert: enc.Type,
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Max: max,
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}
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} else {
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f = field{
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Name: fn,
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IsBasic: false,
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IsSlice: true,
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FieldType: tn,
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Max: max,
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}
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}
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}
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fs = append(fs, f)
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}
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switch output {
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case "code":
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generateCode(name, fs)
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case "diagram":
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generateDiagram(name, fs)
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case "xdr":
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generateXdr(name, fs)
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}
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}
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func generateCode(name string, fs []field) {
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var buf bytes.Buffer
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err := encodeTpl.Execute(&buf, map[string]interface{}{"TypeName": name, "Fields": fs})
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if err != nil {
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panic(err)
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}
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bs := regexp.MustCompile(`(\s*\n)+`).ReplaceAll(buf.Bytes(), []byte("\n"))
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bs = bytes.Replace(bs, []byte("//+n"), []byte("\n"), -1)
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bs, err = format.Source(bs)
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if err != nil {
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panic(err)
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}
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fmt.Println(string(bs))
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}
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func generateDiagram(sn string, fs []field) {
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fmt.Println(sn + " Structure:")
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fmt.Println()
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fmt.Println(" 0 1 2 3")
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fmt.Println(" 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1")
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line := "+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+"
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fmt.Println(line)
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for _, f := range fs {
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tn := f.FieldType
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sl := f.IsSlice
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if sl {
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fmt.Printf("| %s |\n", center("Number of "+f.Name, 61))
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fmt.Println(line)
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}
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switch tn {
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case "uint16":
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fmt.Printf("| %s | %s |\n", center(f.Name, 29), center("0x0000", 29))
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fmt.Println(line)
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case "uint32":
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fmt.Printf("| %s |\n", center(f.Name, 61))
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fmt.Println(line)
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case "int64", "uint64":
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fmt.Printf("| %-61s |\n", "")
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fmt.Printf("+ %s +\n", center(f.Name+" (64 bits)", 61))
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fmt.Printf("| %-61s |\n", "")
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fmt.Println(line)
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case "string", "byte": // XXX We assume slice of byte!
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fmt.Printf("| %s |\n", center("Length of "+f.Name, 61))
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fmt.Println(line)
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fmt.Printf("/ %61s /\n", "")
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fmt.Printf("\\ %s \\\n", center(f.Name+" (variable length)", 61))
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fmt.Printf("/ %61s /\n", "")
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fmt.Println(line)
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default:
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if sl {
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tn = "Zero or more " + tn + " Structures"
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fmt.Printf("/ %s /\n", center("", 61))
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fmt.Printf("\\ %s \\\n", center(tn, 61))
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fmt.Printf("/ %s /\n", center("", 61))
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} else {
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fmt.Printf("| %s |\n", center(tn, 61))
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}
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fmt.Println(line)
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}
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}
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fmt.Println()
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fmt.Println()
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}
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func generateXdr(sn string, fs []field) {
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fmt.Printf("struct %s {\n", sn)
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for _, f := range fs {
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tn := f.FieldType
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fn := f.Name
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suf := ""
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if f.IsSlice {
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suf = "<>"
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}
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switch tn {
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case "uint16":
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fmt.Printf("\tunsigned short %s%s;\n", fn, suf)
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case "uint32":
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fmt.Printf("\tunsigned int %s%s;\n", fn, suf)
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case "int64":
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fmt.Printf("\thyper %s%s;\n", fn, suf)
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case "uint64":
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fmt.Printf("\tunsigned hyper %s%s;\n", fn, suf)
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case "string":
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fmt.Printf("\tstring %s<>;\n", fn)
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case "byte":
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fmt.Printf("\topaque %s<>;\n", fn)
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default:
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fmt.Printf("\t%s %s%s;\n", tn, fn, suf)
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}
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}
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fmt.Println("}")
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fmt.Println()
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}
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func center(s string, w int) string {
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w -= len(s)
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l := w / 2
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r := l
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if l+r < w {
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r++
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}
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return strings.Repeat(" ", l) + s + strings.Repeat(" ", r)
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}
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func inspector(fset *token.FileSet) func(ast.Node) bool {
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return func(n ast.Node) bool {
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switch n := n.(type) {
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case *ast.TypeSpec:
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switch t := n.Type.(type) {
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case *ast.StructType:
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name := n.Name.Name
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handleStruct(name, t)
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}
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return false
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default:
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return true
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}
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}
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}
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func main() {
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flag.StringVar(&output, "output", "code", "code,xdr,diagram")
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flag.Parse()
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fname := flag.Arg(0)
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// Create the AST by parsing src.
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fset := token.NewFileSet() // positions are relative to fset
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f, err := parser.ParseFile(fset, fname, nil, parser.ParseComments)
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if err != nil {
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panic(err)
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}
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//ast.Print(fset, f)
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if output == "code" {
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headerTpl.Execute(os.Stdout, map[string]string{"Package": f.Name.Name})
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}
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i := inspector(fset)
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ast.Inspect(f, i)
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}
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