456 lines
12 KiB
Go
456 lines
12 KiB
Go
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// Package text supports marshaling Cap'n Proto messages as text based on a schema.
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package text
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import (
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"bytes"
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"fmt"
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"io"
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"math"
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"strconv"
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"zombiezen.com/go/capnproto2"
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"zombiezen.com/go/capnproto2/internal/nodemap"
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"zombiezen.com/go/capnproto2/internal/schema"
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"zombiezen.com/go/capnproto2/internal/strquote"
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"zombiezen.com/go/capnproto2/schemas"
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)
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// Marker strings.
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const (
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voidMarker = "void"
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interfaceMarker = "<external capability>"
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anyPointerMarker = "<opaque pointer>"
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)
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// Marshal returns the text representation of a struct.
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func Marshal(typeID uint64, s capnp.Struct) (string, error) {
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buf := new(bytes.Buffer)
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if err := NewEncoder(buf).Encode(typeID, s); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// MarshalList returns the text representation of a struct list.
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func MarshalList(typeID uint64, l capnp.List) (string, error) {
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buf := new(bytes.Buffer)
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if err := NewEncoder(buf).EncodeList(typeID, l); err != nil {
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return "", err
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}
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return buf.String(), nil
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}
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// An Encoder writes the text format of Cap'n Proto messages to an output stream.
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type Encoder struct {
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w errWriter
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tmp []byte
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nodes nodemap.Map
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}
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// NewEncoder returns a new encoder that writes to w.
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func NewEncoder(w io.Writer) *Encoder {
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return &Encoder{w: errWriter{w: w}}
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}
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// UseRegistry changes the registry that the encoder consults for
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// schemas from the default registry.
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func (enc *Encoder) UseRegistry(reg *schemas.Registry) {
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enc.nodes.UseRegistry(reg)
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}
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// Encode writes the text representation of s to the stream.
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func (enc *Encoder) Encode(typeID uint64, s capnp.Struct) error {
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if enc.w.err != nil {
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return enc.w.err
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}
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err := enc.marshalStruct(typeID, s)
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if err != nil {
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return err
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}
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return enc.w.err
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}
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// EncodeList writes the text representation of struct list l to the stream.
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func (enc *Encoder) EncodeList(typeID uint64, l capnp.List) error {
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_, seg, _ := capnp.NewMessage(capnp.SingleSegment(nil))
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typ, _ := schema.NewRootType(seg)
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typ.SetStructType()
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typ.StructType().SetTypeId(typeID)
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return enc.marshalList(typ, l)
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}
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func (enc *Encoder) marshalBool(v bool) {
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if v {
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enc.w.WriteString("true")
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} else {
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enc.w.WriteString("false")
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}
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}
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func (enc *Encoder) marshalInt(i int64) {
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enc.tmp = strconv.AppendInt(enc.tmp[:0], i, 10)
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enc.w.Write(enc.tmp)
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}
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func (enc *Encoder) marshalUint(i uint64) {
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enc.tmp = strconv.AppendUint(enc.tmp[:0], i, 10)
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enc.w.Write(enc.tmp)
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}
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func (enc *Encoder) marshalFloat32(f float32) {
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enc.tmp = strconv.AppendFloat(enc.tmp[:0], float64(f), 'g', -1, 32)
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enc.w.Write(enc.tmp)
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}
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func (enc *Encoder) marshalFloat64(f float64) {
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enc.tmp = strconv.AppendFloat(enc.tmp[:0], f, 'g', -1, 64)
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enc.w.Write(enc.tmp)
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}
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func (enc *Encoder) marshalText(t []byte) {
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enc.tmp = strquote.Append(enc.tmp[:0], t)
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enc.w.Write(enc.tmp)
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}
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func needsEscape(b byte) bool {
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return b < 0x20 || b >= 0x7f
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}
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func hexDigit(b byte) byte {
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const digits = "0123456789abcdef"
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return digits[b]
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}
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func (enc *Encoder) marshalStruct(typeID uint64, s capnp.Struct) error {
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n, err := enc.nodes.Find(typeID)
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if err != nil {
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return err
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}
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if !n.IsValid() || n.Which() != schema.Node_Which_structNode {
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return fmt.Errorf("cannot find struct type %#x", typeID)
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}
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var discriminant uint16
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if n.StructNode().DiscriminantCount() > 0 {
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discriminant = s.Uint16(capnp.DataOffset(n.StructNode().DiscriminantOffset() * 2))
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}
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enc.w.WriteByte('(')
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fields := codeOrderFields(n.StructNode())
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first := true
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for _, f := range fields {
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if !(f.Which() == schema.Field_Which_slot || f.Which() == schema.Field_Which_group) {
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continue
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}
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if dv := f.DiscriminantValue(); !(dv == schema.Field_noDiscriminant || dv == discriminant) {
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continue
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}
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if !first {
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enc.w.WriteString(", ")
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}
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first = false
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name, err := f.NameBytes()
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if err != nil {
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return err
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}
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enc.w.Write(name)
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enc.w.WriteString(" = ")
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switch f.Which() {
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case schema.Field_Which_slot:
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if err := enc.marshalFieldValue(s, f); err != nil {
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return err
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}
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case schema.Field_Which_group:
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if err := enc.marshalStruct(f.Group().TypeId(), s); err != nil {
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return err
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}
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}
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}
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enc.w.WriteByte(')')
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return nil
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}
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func (enc *Encoder) marshalFieldValue(s capnp.Struct, f schema.Field) error {
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typ, err := f.Slot().Type()
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if err != nil {
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return err
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}
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dv, err := f.Slot().DefaultValue()
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if err != nil {
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return err
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}
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if dv.IsValid() && int(typ.Which()) != int(dv.Which()) {
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name, _ := f.Name()
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return fmt.Errorf("marshal field %s: default value is a %v, want %v", name, dv.Which(), typ.Which())
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}
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switch typ.Which() {
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case schema.Type_Which_void:
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enc.w.WriteString(voidMarker)
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case schema.Type_Which_bool:
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v := s.Bit(capnp.BitOffset(f.Slot().Offset()))
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d := dv.Bool()
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enc.marshalBool(!d && v || d && !v)
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case schema.Type_Which_int8:
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v := s.Uint8(capnp.DataOffset(f.Slot().Offset()))
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d := uint8(dv.Int8())
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enc.marshalInt(int64(int8(v ^ d)))
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case schema.Type_Which_int16:
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v := s.Uint16(capnp.DataOffset(f.Slot().Offset() * 2))
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d := uint16(dv.Int16())
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enc.marshalInt(int64(int16(v ^ d)))
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case schema.Type_Which_int32:
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v := s.Uint32(capnp.DataOffset(f.Slot().Offset() * 4))
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d := uint32(dv.Int32())
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enc.marshalInt(int64(int32(v ^ d)))
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case schema.Type_Which_int64:
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v := s.Uint64(capnp.DataOffset(f.Slot().Offset() * 8))
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d := uint64(dv.Int64())
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enc.marshalInt(int64(v ^ d))
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case schema.Type_Which_uint8:
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v := s.Uint8(capnp.DataOffset(f.Slot().Offset()))
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d := dv.Uint8()
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enc.marshalUint(uint64(v ^ d))
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case schema.Type_Which_uint16:
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v := s.Uint16(capnp.DataOffset(f.Slot().Offset() * 2))
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d := dv.Uint16()
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enc.marshalUint(uint64(v ^ d))
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case schema.Type_Which_uint32:
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v := s.Uint32(capnp.DataOffset(f.Slot().Offset() * 4))
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d := dv.Uint32()
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enc.marshalUint(uint64(v ^ d))
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case schema.Type_Which_uint64:
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v := s.Uint64(capnp.DataOffset(f.Slot().Offset() * 8))
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d := dv.Uint64()
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enc.marshalUint(v ^ d)
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case schema.Type_Which_float32:
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v := s.Uint32(capnp.DataOffset(f.Slot().Offset() * 4))
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d := math.Float32bits(dv.Float32())
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enc.marshalFloat32(math.Float32frombits(v ^ d))
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case schema.Type_Which_float64:
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v := s.Uint64(capnp.DataOffset(f.Slot().Offset() * 8))
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d := math.Float64bits(dv.Float64())
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enc.marshalFloat64(math.Float64frombits(v ^ d))
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case schema.Type_Which_structType:
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p, err := s.Ptr(uint16(f.Slot().Offset()))
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if err != nil {
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return err
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}
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if !p.IsValid() {
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p, _ = dv.StructValuePtr()
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}
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return enc.marshalStruct(typ.StructType().TypeId(), p.Struct())
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case schema.Type_Which_data:
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p, err := s.Ptr(uint16(f.Slot().Offset()))
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if err != nil {
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return err
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}
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if !p.IsValid() {
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b, _ := dv.Data()
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enc.marshalText(b)
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return nil
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}
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enc.marshalText(p.Data())
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case schema.Type_Which_text:
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p, err := s.Ptr(uint16(f.Slot().Offset()))
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if err != nil {
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return err
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}
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if !p.IsValid() {
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b, _ := dv.TextBytes()
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enc.marshalText(b)
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return nil
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}
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enc.marshalText(p.TextBytes())
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case schema.Type_Which_list:
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elem, err := typ.List().ElementType()
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if err != nil {
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return err
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}
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p, err := s.Ptr(uint16(f.Slot().Offset()))
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if err != nil {
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return err
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}
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if !p.IsValid() {
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p, _ = dv.ListPtr()
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}
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return enc.marshalList(elem, p.List())
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case schema.Type_Which_enum:
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v := s.Uint16(capnp.DataOffset(f.Slot().Offset() * 2))
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d := dv.Uint16()
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return enc.marshalEnum(typ.Enum().TypeId(), v^d)
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case schema.Type_Which_interface:
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enc.w.WriteString(interfaceMarker)
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case schema.Type_Which_anyPointer:
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enc.w.WriteString(anyPointerMarker)
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default:
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return fmt.Errorf("unknown field type %v", typ.Which())
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}
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return nil
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}
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func codeOrderFields(s schema.Node_structNode) []schema.Field {
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list, _ := s.Fields()
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n := list.Len()
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fields := make([]schema.Field, n)
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for i := 0; i < n; i++ {
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f := list.At(i)
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fields[f.CodeOrder()] = f
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}
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return fields
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}
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func (enc *Encoder) marshalList(elem schema.Type, l capnp.List) error {
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switch elem.Which() {
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case schema.Type_Which_void:
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enc.w.WriteString(capnp.VoidList{List: l}.String())
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case schema.Type_Which_bool:
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enc.w.WriteString(capnp.BitList{List: l}.String())
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case schema.Type_Which_int8:
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enc.w.WriteString(capnp.Int8List{List: l}.String())
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case schema.Type_Which_int16:
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enc.w.WriteString(capnp.Int16List{List: l}.String())
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case schema.Type_Which_int32:
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enc.w.WriteString(capnp.Int32List{List: l}.String())
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case schema.Type_Which_int64:
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enc.w.WriteString(capnp.Int64List{List: l}.String())
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case schema.Type_Which_uint8:
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enc.w.WriteString(capnp.UInt8List{List: l}.String())
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case schema.Type_Which_uint16:
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enc.w.WriteString(capnp.UInt16List{List: l}.String())
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case schema.Type_Which_uint32:
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enc.w.WriteString(capnp.UInt32List{List: l}.String())
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case schema.Type_Which_uint64:
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enc.w.WriteString(capnp.UInt64List{List: l}.String())
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case schema.Type_Which_float32:
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enc.w.WriteString(capnp.Float32List{List: l}.String())
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case schema.Type_Which_float64:
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enc.w.WriteString(capnp.Float64List{List: l}.String())
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case schema.Type_Which_data:
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enc.w.WriteString(capnp.DataList{List: l}.String())
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case schema.Type_Which_text:
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enc.w.WriteString(capnp.TextList{List: l}.String())
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case schema.Type_Which_structType:
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enc.w.WriteByte('[')
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for i := 0; i < l.Len(); i++ {
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if i > 0 {
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enc.w.WriteString(", ")
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}
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err := enc.marshalStruct(elem.StructType().TypeId(), l.Struct(i))
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if err != nil {
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return err
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}
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}
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enc.w.WriteByte(']')
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case schema.Type_Which_list:
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enc.w.WriteByte('[')
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ee, err := elem.List().ElementType()
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if err != nil {
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return err
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}
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for i := 0; i < l.Len(); i++ {
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if i > 0 {
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enc.w.WriteString(", ")
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}
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p, err := capnp.PointerList{List: l}.PtrAt(i)
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if err != nil {
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return err
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}
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err = enc.marshalList(ee, p.List())
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if err != nil {
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return err
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}
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}
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|
|
enc.w.WriteByte(']')
|
||
|
|
case schema.Type_Which_enum:
|
||
|
|
enc.w.WriteByte('[')
|
||
|
|
il := capnp.UInt16List{List: l}
|
||
|
|
typ := elem.Enum().TypeId()
|
||
|
|
// TODO(light): only search for node once
|
||
|
|
for i := 0; i < il.Len(); i++ {
|
||
|
|
if i > 0 {
|
||
|
|
enc.w.WriteString(", ")
|
||
|
|
}
|
||
|
|
enc.marshalEnum(typ, il.At(i))
|
||
|
|
}
|
||
|
|
enc.w.WriteByte(']')
|
||
|
|
case schema.Type_Which_interface:
|
||
|
|
enc.w.WriteByte('[')
|
||
|
|
for i := 0; i < l.Len(); i++ {
|
||
|
|
if i > 0 {
|
||
|
|
enc.w.WriteString(", ")
|
||
|
|
}
|
||
|
|
enc.w.WriteString(interfaceMarker)
|
||
|
|
}
|
||
|
|
enc.w.WriteByte(']')
|
||
|
|
case schema.Type_Which_anyPointer:
|
||
|
|
enc.w.WriteByte('[')
|
||
|
|
for i := 0; i < l.Len(); i++ {
|
||
|
|
if i > 0 {
|
||
|
|
enc.w.WriteString(", ")
|
||
|
|
}
|
||
|
|
enc.w.WriteString(anyPointerMarker)
|
||
|
|
}
|
||
|
|
enc.w.WriteByte(']')
|
||
|
|
default:
|
||
|
|
return fmt.Errorf("unknown list type %v", elem.Which())
|
||
|
|
}
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
func (enc *Encoder) marshalEnum(typ uint64, val uint16) error {
|
||
|
|
n, err := enc.nodes.Find(typ)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if n.Which() != schema.Node_Which_enum {
|
||
|
|
return fmt.Errorf("marshaling enum of type @%#x: type is not an enum", typ)
|
||
|
|
}
|
||
|
|
enums, err := n.Enum().Enumerants()
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if int(val) >= enums.Len() {
|
||
|
|
enc.marshalUint(uint64(val))
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
name, err := enums.At(int(val)).NameBytes()
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
enc.w.Write(name)
|
||
|
|
return nil
|
||
|
|
}
|
||
|
|
|
||
|
|
type errWriter struct {
|
||
|
|
w io.Writer
|
||
|
|
err error
|
||
|
|
}
|
||
|
|
|
||
|
|
func (ew *errWriter) Write(p []byte) (int, error) {
|
||
|
|
if ew.err != nil {
|
||
|
|
return 0, ew.err
|
||
|
|
}
|
||
|
|
var n int
|
||
|
|
n, ew.err = ew.w.Write(p)
|
||
|
|
return n, ew.err
|
||
|
|
}
|
||
|
|
|
||
|
|
func (ew *errWriter) WriteString(s string) (int, error) {
|
||
|
|
if ew.err != nil {
|
||
|
|
return 0, ew.err
|
||
|
|
}
|
||
|
|
var n int
|
||
|
|
n, ew.err = io.WriteString(ew.w, s)
|
||
|
|
return n, ew.err
|
||
|
|
}
|
||
|
|
|
||
|
|
func (ew *errWriter) WriteByte(b byte) error {
|
||
|
|
if ew.err != nil {
|
||
|
|
return ew.err
|
||
|
|
}
|
||
|
|
if bw, ok := ew.w.(io.ByteWriter); ok {
|
||
|
|
ew.err = bw.WriteByte(b)
|
||
|
|
} else {
|
||
|
|
_, ew.err = ew.w.Write([]byte{b})
|
||
|
|
}
|
||
|
|
return ew.err
|
||
|
|
}
|