return b.Bytes(), nil
}
+// Marshaler is the interface implemented by objects that can marshal
+// themselves into valid XML elements.
+//
+// MarshalXML encodes the receiver as zero or more XML elements.
+// By convention, arrays or slices are typically encoded as a sequence
+// of elements, one per entry.
+// Using start as the element tag is not required, but doing so
+// will enable Unmarshal to match the XML elements to the correct
+// struct field.
+// One common implementation strategy is to construct a separate
+// value with a layout corresponding to the desired XML and then
+// to encode it using e.EncodeElement.
+// Another common strategy is to use repeated calls to e.EncodeToken
+// to generate the XML output one token at a time.
+// The sequence of encoded tokens must make up zero or more valid
+// XML elements.
+type Marshaler interface {
+ MarshalXML(e *Encoder, start StartElement) error
+}
+
+// MarshalerAttr is the interface implemented by objects that can marshal
+// themselves into valid XML attributes.
+//
+// MarshalXMLAttr returns an XML attribute with the encoded value of the receiver.
+// Using name as the attribute name is not required, but doing so
+// will enable Unmarshal to match the attribute to the correct
+// struct field.
+// If MarshalXMLAttr returns the zero attribute Attr{}, no attribute
+// will be generated in the output.
+// MarshalXMLAttr is used only for struct fields with the
+// "attr" option in the field tag.
+type MarshalerAttr interface {
+ MarshalXMLAttr(name Name) (Attr, error)
+}
+
// MarshalIndent works like Marshal, but each XML element begins on a new
// indented line that starts with prefix and is followed by one or more
// copies of indent according to the nesting depth.
// An Encoder writes XML data to an output stream.
type Encoder struct {
- printer
+ p printer
}
// NewEncoder returns a new encoder that writes to w.
func NewEncoder(w io.Writer) *Encoder {
- return &Encoder{printer{Writer: bufio.NewWriter(w)}}
+ e := &Encoder{printer{Writer: bufio.NewWriter(w)}}
+ e.p.encoder = e
+ return e
}
// Indent sets the encoder to generate XML in which each element
// begins on a new indented line that starts with prefix and is followed by
// one or more copies of indent according to the nesting depth.
func (enc *Encoder) Indent(prefix, indent string) {
- enc.prefix = prefix
- enc.indent = indent
+ enc.p.prefix = prefix
+ enc.p.indent = indent
}
// Encode writes the XML encoding of v to the stream.
// See the documentation for Marshal for details about the conversion
// of Go values to XML.
func (enc *Encoder) Encode(v interface{}) error {
- err := enc.marshalValue(reflect.ValueOf(v), nil)
+ err := enc.p.marshalValue(reflect.ValueOf(v), nil, nil)
+ if err != nil {
+ return err
+ }
+ return enc.p.Flush()
+}
+
+// EncodeElement writes the XML encoding of v to the stream,
+// using start as the outermost tag in the encoding.
+//
+// See the documentation for Marshal for details about the conversion
+// of Go values to XML.
+func (enc *Encoder) EncodeElement(v interface{}, start StartElement) error {
+ err := enc.p.marshalValue(reflect.ValueOf(v), nil, &start)
if err != nil {
return err
}
- return enc.Flush()
+ return enc.p.Flush()
+}
+
+var (
+ endComment = []byte("-->")
+ endProcInst = []byte("?>")
+ endDirective = []byte(">")
+)
+
+// EncodeToken writes the given XML token to the stream.
+// It returns an error if StartElement and EndElement tokens are not properly matched.
+func (enc *Encoder) EncodeToken(t Token) error {
+ p := &enc.p
+ switch t := t.(type) {
+ case StartElement:
+ if err := p.writeStart(&t); err != nil {
+ return err
+ }
+ case EndElement:
+ if err := p.writeEnd(t.Name); err != nil {
+ return err
+ }
+ case CharData:
+ EscapeText(p, t)
+ case Comment:
+ if bytes.Contains(t, endComment) {
+ return fmt.Errorf("xml: EncodeToken of Comment containing --> marker")
+ }
+ p.WriteString("<!--")
+ p.Write(t)
+ p.WriteString("-->")
+ return p.cachedWriteError()
+ case ProcInst:
+ if t.Target == "xml" || !isNameString(t.Target) {
+ return fmt.Errorf("xml: EncodeToken of ProcInst with invalid Target")
+ }
+ if bytes.Contains(t.Inst, endProcInst) {
+ return fmt.Errorf("xml: EncodeToken of ProcInst containing ?> marker")
+ }
+ p.WriteString("<?")
+ p.WriteString(t.Target)
+ if len(t.Inst) > 0 {
+ p.WriteByte(' ')
+ p.Write(t.Inst)
+ }
+ p.WriteString("?>")
+ case Directive:
+ if bytes.Contains(t, endDirective) {
+ return fmt.Errorf("xml: EncodeToken of Directive containing > marker")
+ }
+ p.WriteString("<!")
+ p.Write(t)
+ p.WriteString(">")
+ }
+ return p.cachedWriteError()
}
type printer struct {
*bufio.Writer
+ encoder *Encoder
seq int
indent string
prefix string
putNewline bool
attrNS map[string]string // map prefix -> name space
attrPrefix map[string]string // map name space -> prefix
+ prefixes []string
+ tags []Name
}
// createAttrPrefix finds the name space prefix attribute to use for the given name space,
-// defining a new prefix if necessary. It returns the prefix and whether it is new.
-func (p *printer) createAttrPrefix(url string) (prefix string, isNew bool) {
- if prefix = p.attrPrefix[url]; prefix != "" {
- return prefix, false
+// defining a new prefix if necessary. It returns the prefix.
+func (p *printer) createAttrPrefix(url string) string {
+ if prefix := p.attrPrefix[url]; prefix != "" {
+ return prefix
}
// The "http://www.w3.org/XML/1998/namespace" name space is predefined as "xml"
// (The "http://www.w3.org/2000/xmlns/" name space is also predefined as "xmlns",
// but users should not be trying to use that one directly - that's our job.)
if url == xmlURL {
- return "xml", false
+ return "xml"
}
// Need to define a new name space.
// Pick a name. We try to use the final element of the path
// but fall back to _.
- prefix = strings.TrimRight(url, "/")
+ prefix := strings.TrimRight(url, "/")
if i := strings.LastIndex(prefix, "/"); i >= 0 {
prefix = prefix[i+1:]
}
EscapeText(p, []byte(url))
p.WriteString(`" `)
- return prefix, true
+ p.prefixes = append(p.prefixes, prefix)
+
+ return prefix
}
// deleteAttrPrefix removes an attribute name space prefix.
delete(p.attrNS, prefix)
}
+func (p *printer) markPrefix() {
+ p.prefixes = append(p.prefixes, "")
+}
+
+func (p *printer) popPrefix() {
+ for len(p.prefixes) > 0 {
+ prefix := p.prefixes[len(p.prefixes)-1]
+ p.prefixes = p.prefixes[:len(p.prefixes)-1]
+ if prefix == "" {
+ break
+ }
+ p.deleteAttrPrefix(prefix)
+ }
+}
+
+var (
+ marshalerType = reflect.TypeOf((*Marshaler)(nil)).Elem()
+ marshalerAttrType = reflect.TypeOf((*MarshalerAttr)(nil)).Elem()
+)
+
// marshalValue writes one or more XML elements representing val.
// If val was obtained from a struct field, finfo must have its details.
-func (p *printer) marshalValue(val reflect.Value, finfo *fieldInfo) error {
+func (p *printer) marshalValue(val reflect.Value, finfo *fieldInfo, startTemplate *StartElement) error {
+ if startTemplate != nil && startTemplate.Name.Local == "" {
+ return fmt.Errorf("xml: EncodeElement of StartElement with missing name")
+ }
+
if !val.IsValid() {
return nil
}
if val.IsNil() {
return nil
}
- return p.marshalValue(val.Elem(), finfo)
+ val = val.Elem()
+ typ = val.Type()
+ }
+
+ // Check for marshaler.
+ if typ.Name() != "" && val.CanAddr() {
+ pv := val.Addr()
+ if pv.CanInterface() && pv.Type().Implements(marshalerType) {
+ return p.marshalInterface(pv.Interface().(Marshaler), pv.Type(), finfo, startTemplate)
+ }
+ }
+ if val.CanInterface() && typ.Implements(marshalerType) {
+ return p.marshalInterface(val.Interface().(Marshaler), typ, finfo, startTemplate)
}
// Slices and arrays iterate over the elements. They do not have an enclosing tag.
if (kind == reflect.Slice || kind == reflect.Array) && typ.Elem().Kind() != reflect.Uint8 {
for i, n := 0, val.Len(); i < n; i++ {
- if err := p.marshalValue(val.Index(i), finfo); err != nil {
+ if err := p.marshalValue(val.Index(i), finfo, startTemplate); err != nil {
return err
}
}
return err
}
+ // Create start element.
// Precedence for the XML element name is:
+ // 0. startTemplate
// 1. XMLName field in underlying struct;
// 2. field name/tag in the struct field; and
// 3. type name
- var xmlns, name string
- if tinfo.xmlname != nil {
+ var start StartElement
+
+ if startTemplate != nil {
+ start.Name = startTemplate.Name
+ start.Attr = append(start.Attr, startTemplate.Attr...)
+ } else if tinfo.xmlname != nil {
xmlname := tinfo.xmlname
if xmlname.name != "" {
- xmlns, name = xmlname.xmlns, xmlname.name
+ start.Name.Space, start.Name.Local = xmlname.xmlns, xmlname.name
} else if v, ok := xmlname.value(val).Interface().(Name); ok && v.Local != "" {
- xmlns, name = v.Space, v.Local
+ start.Name = v
}
}
- if name == "" && finfo != nil {
- xmlns, name = finfo.xmlns, finfo.name
+ if start.Name.Local == "" && finfo != nil {
+ start.Name.Space, start.Name.Local = finfo.xmlns, finfo.name
}
- if name == "" {
- name = typ.Name()
+ if start.Name.Local == "" {
+ name := typ.Name()
if name == "" {
return &UnsupportedTypeError{typ}
}
- }
-
- p.writeIndent(1)
- p.WriteByte('<')
- p.WriteString(name)
-
- if xmlns != "" {
- p.WriteString(` xmlns="`)
- // TODO: EscapeString, to avoid the allocation.
- if err := EscapeText(p, []byte(xmlns)); err != nil {
- return err
- }
- p.WriteByte('"')
+ start.Name.Local = name
}
// Attributes
continue
}
fv := finfo.value(val)
- if (finfo.flags&fOmitEmpty != 0 || fv.Kind() == reflect.Ptr) && isEmptyValue(fv) {
+ name := Name{Space: finfo.xmlns, Local: finfo.name}
+
+ if finfo.flags&fOmitEmpty != 0 && isEmptyValue(fv) {
continue
}
- p.WriteByte(' ')
- if finfo.xmlns != "" {
- prefix, created := p.createAttrPrefix(finfo.xmlns)
- if created {
- defer p.deleteAttrPrefix(prefix)
+
+ if fv.CanAddr() {
+ pv := fv.Addr()
+ if pv.CanInterface() && pv.Type().Implements(marshalerAttrType) {
+ attr, err := pv.Interface().(MarshalerAttr).MarshalXMLAttr(name)
+ if err != nil {
+ return err
+ }
+ if attr.Name.Local != "" {
+ start.Attr = append(start.Attr, attr)
+ }
+ continue
}
- p.WriteString(prefix)
- p.WriteByte(':')
}
- p.WriteString(finfo.name)
- p.WriteString(`="`)
- // Handle pointer values by following the pointer,
- // Pointer is known to be non-nil because we called isEmptyValue above.
- if fv.Kind() == reflect.Ptr {
+
+ if fv.CanInterface() && fv.Type().Implements(marshalerAttrType) {
+ if fv.Kind() == reflect.Interface && fv.IsNil() {
+ continue
+ }
+ attr, err := fv.Interface().(MarshalerAttr).MarshalXMLAttr(name)
+ if err != nil {
+ return err
+ }
+ if attr.Name.Local != "" {
+ start.Attr = append(start.Attr, attr)
+ }
+ continue
+ }
+
+ // Dereference or skip nil pointer, interface values.
+ switch fv.Kind() {
+ case reflect.Ptr, reflect.Interface:
+ if fv.IsNil() {
+ continue
+ }
fv = fv.Elem()
}
- if err := p.marshalSimple(fv.Type(), fv); err != nil {
+
+ s, b, err := p.marshalSimple(fv.Type(), fv)
+ if err != nil {
return err
}
- p.WriteByte('"')
+ if b != nil {
+ s = string(b)
+ }
+ start.Attr = append(start.Attr, Attr{name, s})
+ }
+
+ if err := p.writeStart(&start); err != nil {
+ return err
}
- p.WriteByte('>')
if val.Kind() == reflect.Struct {
err = p.marshalStruct(tinfo, val)
} else {
- err = p.marshalSimple(typ, val)
+ s, b, err1 := p.marshalSimple(typ, val)
+ if err1 != nil {
+ err = err1
+ } else if b != nil {
+ EscapeText(p, b)
+ } else {
+ p.EscapeString(s)
+ }
+ }
+ if err != nil {
+ return err
+ }
+
+ if err := p.writeEnd(start.Name); err != nil {
+ return err
+ }
+
+ return p.cachedWriteError()
+}
+
+// marshalInterface marshals a Marshaler interface value.
+func (p *printer) marshalInterface(val Marshaler, typ reflect.Type, finfo *fieldInfo, startTemplate *StartElement) error {
+ var start StartElement
+
+ // Precedence for the XML element name is as above,
+ // except that we do not look inside structs for the first field.
+ if startTemplate != nil {
+ start.Name = startTemplate.Name
+ start.Attr = append(start.Attr, startTemplate.Attr...)
+ } else if finfo != nil && finfo.name != "" {
+ start.Name.Local = finfo.name
+ start.Name.Space = finfo.xmlns
+ } else if typ.Name() != "" {
+ start.Name.Local = typ.Name()
+ } else {
+ // Must be a pointer to a named type,
+ // since it has the Marshaler methods.
+ start.Name.Local = typ.Elem().Name()
}
+
+ // Push a marker onto the tag stack so that MarshalXML
+ // cannot close the XML tags that it did not open.
+ p.tags = append(p.tags, Name{})
+ n := len(p.tags)
+
+ err := val.MarshalXML(p.encoder, start)
if err != nil {
return err
}
+ // Make sure MarshalXML closed all its tags. p.tags[n-1] is the mark.
+ if len(p.tags) > n {
+ return fmt.Errorf("xml: %s.MarshalXML wrote invalid XML: <%s> not closed", receiverType(val), p.tags[len(p.tags)-1].Local)
+ }
+ p.tags = p.tags[:n-1]
+ return nil
+}
+
+// writeStart writes the given start element.
+func (p *printer) writeStart(start *StartElement) error {
+ if start.Name.Local == "" {
+ return fmt.Errorf("xml: start tag with no name")
+ }
+
+ p.tags = append(p.tags, start.Name)
+ p.markPrefix()
+
+ p.writeIndent(1)
+ p.WriteByte('<')
+ p.WriteString(start.Name.Local)
+
+ if start.Name.Space != "" {
+ p.WriteString(` xmlns="`)
+ p.EscapeString(start.Name.Space)
+ p.WriteByte('"')
+ }
+
+ // Attributes
+ for _, attr := range start.Attr {
+ name := attr.Name
+ if name.Local == "" {
+ continue
+ }
+ p.WriteByte(' ')
+ if name.Space != "" {
+ p.WriteString(p.createAttrPrefix(name.Space))
+ p.WriteByte(':')
+ }
+ p.WriteString(name.Local)
+ p.WriteString(`="`)
+ p.EscapeString(attr.Value)
+ p.WriteByte('"')
+ }
+ p.WriteByte('>')
+ return nil
+}
+
+func (p *printer) writeEnd(name Name) error {
+ if name.Local == "" {
+ return fmt.Errorf("xml: end tag with no name")
+ }
+ if len(p.tags) == 0 || p.tags[len(p.tags)-1].Local == "" {
+ return fmt.Errorf("xml: end tag </%s> without start tag", name.Local)
+ }
+ if top := p.tags[len(p.tags)-1]; top != name {
+ if top.Local != name.Local {
+ return fmt.Errorf("xml: end tag </%s> does not match start tag <%s>", name.Local, top.Local)
+ }
+ return fmt.Errorf("xml: end tag </%s> in namespace %s does not match start tag <%s> in namespace %s", name.Local, name.Space, top.Local, top.Space)
+ }
+ p.tags = p.tags[:len(p.tags)-1]
+
p.writeIndent(-1)
p.WriteByte('<')
p.WriteByte('/')
- p.WriteString(name)
+ p.WriteString(name.Local)
p.WriteByte('>')
-
- return p.cachedWriteError()
+ p.popPrefix()
+ return nil
}
var timeType = reflect.TypeOf(time.Time{})
-func (p *printer) marshalSimple(typ reflect.Type, val reflect.Value) error {
+func (p *printer) marshalSimple(typ reflect.Type, val reflect.Value) (string, []byte, error) {
// Normally we don't see structs, but this can happen for an attribute.
if val.Type() == timeType {
- p.WriteString(val.Interface().(time.Time).Format(time.RFC3339Nano))
- return nil
+ return val.Interface().(time.Time).Format(time.RFC3339Nano), nil, nil
}
switch val.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
- p.WriteString(strconv.FormatInt(val.Int(), 10))
+ return strconv.FormatInt(val.Int(), 10), nil, nil
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
- p.WriteString(strconv.FormatUint(val.Uint(), 10))
+ return strconv.FormatUint(val.Uint(), 10), nil, nil
case reflect.Float32, reflect.Float64:
- p.WriteString(strconv.FormatFloat(val.Float(), 'g', -1, val.Type().Bits()))
+ return strconv.FormatFloat(val.Float(), 'g', -1, val.Type().Bits()), nil, nil
case reflect.String:
- // TODO: Add EscapeString.
- EscapeText(p, []byte(val.String()))
+ return val.String(), nil, nil
case reflect.Bool:
- p.WriteString(strconv.FormatBool(val.Bool()))
+ return strconv.FormatBool(val.Bool()), nil, nil
case reflect.Array:
// will be [...]byte
var bytes []byte
bytes = make([]byte, val.Len())
reflect.Copy(reflect.ValueOf(bytes), val)
}
- EscapeText(p, bytes)
+ return "", bytes, nil
case reflect.Slice:
// will be []byte
- EscapeText(p, val.Bytes())
- default:
- return &UnsupportedTypeError{typ}
+ return "", val.Bytes(), nil
}
- return p.cachedWriteError()
+ return "", nil, &UnsupportedTypeError{typ}
}
var ddBytes = []byte("--")
_, err := p.WriteString(val.Interface().(time.Time).Format(time.RFC3339Nano))
return err
}
- s := parentStack{printer: p}
+ s := parentStack{p: p}
for i := range tinfo.fields {
finfo := &tinfo.fields[i]
if finfo.flags&fAttr != 0 {
continue
}
vf := finfo.value(val)
- // Handle pointer values by following the pointer
- if vf.Kind() == reflect.Ptr && !isEmptyValue(vf) {
- vf = vf.Elem()
+
+ // Dereference or skip nil pointer, interface values.
+ switch vf.Kind() {
+ case reflect.Ptr, reflect.Interface:
+ if !vf.IsNil() {
+ vf = vf.Elem()
+ }
}
+
switch finfo.flags & fMode {
case fCharData:
var scratch [64]byte
}
case fElement, fElement | fAny:
- s.trim(finfo.parents)
+ if err := s.trim(finfo.parents); err != nil {
+ return err
+ }
if len(finfo.parents) > len(s.stack) {
if vf.Kind() != reflect.Ptr && vf.Kind() != reflect.Interface || !vf.IsNil() {
- s.push(finfo.parents[len(s.stack):])
+ if err := s.push(finfo.parents[len(s.stack):]); err != nil {
+ return err
+ }
}
}
}
- if err := p.marshalValue(vf, finfo); err != nil {
+ if err := p.marshalValue(vf, finfo, nil); err != nil {
return err
}
}
}
type parentStack struct {
- *printer
+ p *printer
stack []string
}
// trim updates the XML context to match the longest common prefix of the stack
// and the given parents. A closing tag will be written for every parent
// popped. Passing a zero slice or nil will close all the elements.
-func (s *parentStack) trim(parents []string) {
+func (s *parentStack) trim(parents []string) error {
split := 0
for ; split < len(parents) && split < len(s.stack); split++ {
if parents[split] != s.stack[split] {
}
}
for i := len(s.stack) - 1; i >= split; i-- {
- s.writeIndent(-1)
- s.WriteString("</")
- s.WriteString(s.stack[i])
- s.WriteByte('>')
+ if err := s.p.writeEnd(Name{Local: s.stack[i]}); err != nil {
+ return err
+ }
}
s.stack = parents[:split]
+ return nil
}
// push adds parent elements to the stack and writes open tags.
-func (s *parentStack) push(parents []string) {
+func (s *parentStack) push(parents []string) error {
for i := 0; i < len(parents); i++ {
- s.writeIndent(1)
- s.WriteByte('<')
- s.WriteString(parents[i])
- s.WriteByte('>')
+ if err := s.p.writeStart(&StartElement{Name: Name{Local: parents[i]}}); err != nil {
+ return err
+ }
}
s.stack = append(s.stack, parents...)
+ return nil
}
// A MarshalXMLError is returned when Marshal encounters a type