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@@ -52,7 +52,7 @@ type ExtensionRange struct {
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// extendableProto is an interface implemented by any protocol buffer that may be extended.
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type extendableProto interface {
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ExtensionRangeArray() []ExtensionRange
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- ExtensionMap() map[int32][]byte
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+ ExtensionMap() map[int32]Extension
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}
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// ExtensionDesc represents an extension specification.
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@@ -65,6 +65,29 @@ type ExtensionDesc struct {
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Tag string // protobuf tag style
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}
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+/*
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+Extension represents an extension in a message.
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+
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+When an extension is stored in a message using SetExtension
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+only desc and value are set. When the message is marshaled
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+enc will be set to the encoded form of the message.
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+
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+When a message is unmarshaled and contains extensions, each
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+extension will have only enc set. When such an extension is
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+accessed using GetExtension (or GetExtensions) desc and value
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+will be set.
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+*/
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+type Extension struct {
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+ desc *ExtensionDesc
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+ value interface{}
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+ enc []byte
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+}
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+
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+// SetRawExtension is for testing only.
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+func SetRawExtension(base extendableProto, id int32, b []byte) {
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+ base.ExtensionMap()[id] = Extension{enc: b}
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+}
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+
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// isExtensionField returns true iff the given field number is in an extension range.
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func isExtensionField(pb extendableProto, field int32) bool {
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for _, er := range pb.ExtensionRangeArray() {
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@@ -88,6 +111,36 @@ func checkExtensionTypes(pb extendableProto, extension *ExtensionDesc) os.Error
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return nil
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}
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+// encodeExtensionMap encodes any unmarshaled (unencoded) extensions in m.
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+func encodeExtensionMap(m map[int32]Extension) os.Error {
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+ for k, e := range m {
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+ if e.value == nil || e.desc == nil {
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+ // Extension is only in its encoded form.
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+ continue
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+ }
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+
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+ // We don't skip extensions that have an encoded form set,
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+ // because the extension value may have been mutated after
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+ // the last time this function was called.
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+
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+ et := reflect.TypeOf(e.desc.ExtensionType)
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+ props := new(Properties)
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+ props.Init(et, "unknown_name", e.desc.Tag, 0)
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+
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+ p := NewBuffer(nil)
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+ // The encoder must be passed a pointer to e.value.
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+ // Allocate a copy of value so that we can use its address.
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+ x := reflect.New(et)
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+ x.Elem().Set(reflect.ValueOf(e.value))
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+ if err := props.enc(p, props, x.Pointer()); err != nil {
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+ return err
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+ }
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+ e.enc = p.buf
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+ m[k] = e
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+ }
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+ return nil
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+}
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+
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// HasExtension returns whether the given extension is present in pb.
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func HasExtension(pb extendableProto, extension *ExtensionDesc) bool {
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// TODO: Check types, field numbers, etc.?
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@@ -98,7 +151,7 @@ func HasExtension(pb extendableProto, extension *ExtensionDesc) bool {
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// ClearExtension removes the given extension from pb.
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func ClearExtension(pb extendableProto, extension *ExtensionDesc) {
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// TODO: Check types, field numbers, etc.?
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- pb.ExtensionMap()[extension.Field] = nil, false
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+ pb.ExtensionMap()[extension.Field] = Extension{}, false
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}
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// GetExtension parses and returns the given extension of pb.
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@@ -108,14 +161,24 @@ func GetExtension(pb extendableProto, extension *ExtensionDesc) (interface{}, os
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return nil, err
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}
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- b, ok := pb.ExtensionMap()[extension.Field]
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+ e, ok := pb.ExtensionMap()[extension.Field]
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if !ok {
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return nil, nil // not an error
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}
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+ if e.value != nil {
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+ // Already decoded. Check the descriptor, though.
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+ if e.desc != extension {
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+ // This shouldn't happen. If it does, it means that
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+ // GetExtension was called twice with two different
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+ // descriptors with the same field number.
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+ return nil, os.NewError("proto: descriptor conflict")
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+ }
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+ return e.value, nil
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+ }
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// Discard wire type and field number varint. It isn't needed.
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- _, n := DecodeVarint(b)
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- o := NewBuffer(b[n:])
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+ _, n := DecodeVarint(e.enc)
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+ o := NewBuffer(e.enc[n:])
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t := reflect.TypeOf(extension.ExtensionType)
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props := &Properties{}
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@@ -132,7 +195,12 @@ func GetExtension(pb extendableProto, extension *ExtensionDesc) (interface{}, os
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if err := props.dec(o, props, uintptr(base), sbase); err != nil {
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return nil, err
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}
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- return unsafe.Unreflect(t, base), nil
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+ // Remember the decoded version and drop the encoded version.
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+ // That way it is safe to mutate what we return.
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+ e.value = unsafe.Unreflect(t, base)
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+ e.desc = extension
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+ e.enc = nil
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+ return e.value, nil
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}
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// GetExtensions returns a slice of the extensions present in pb that are also listed in es.
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@@ -167,18 +235,7 @@ func SetExtension(pb extendableProto, extension *ExtensionDesc, value interface{
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return os.NewError("bad extension value type")
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}
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- props := new(Properties)
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- props.Init(reflect.TypeOf(extension.ExtensionType), "unknown_name", extension.Tag, 0)
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-
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- p := NewBuffer(nil)
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- // The encoder must be passed a pointer to value.
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- // Allocate a copy of value so that we can use its address.
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- x := reflect.New(typ)
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- x.Elem().Set(reflect.ValueOf(value))
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- if err := props.enc(p, props, x.Pointer()); err != nil {
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- return err
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- }
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- pb.ExtensionMap()[extension.Field] = p.buf
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+ pb.ExtensionMap()[extension.Field] = Extension{desc: extension, value: value}
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return nil
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}
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David Symonds