// Copyright 2011 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package xml import ( "bufio" "bytes" "encoding" "errors" "fmt" "io" "reflect" "strconv" "strings" ) const ( // Header is a generic XML header suitable for use with the output of [Marshal]. // This is not automatically added to any output of this package, // it is provided as a convenience. Header = `` + "\n" ) // Marshal returns the XML encoding of v. // // Marshal handles an array or slice by marshaling each of the elements. // Marshal handles a pointer by marshaling the value it points at or, if the // pointer is nil, by writing nothing. Marshal handles an interface value by // marshaling the value it contains or, if the interface value is nil, by // writing nothing. Marshal handles all other data by writing one or more XML // elements containing the data. // // The name for the XML elements is taken from, in order of preference: // - the tag on the XMLName field, if the data is a struct // - the value of the XMLName field of type [Name] // - the tag of the struct field used to obtain the data // - the name of the struct field used to obtain the data // - the name of the marshaled type // // The XML element for a struct contains marshaled elements for each of the // exported fields of the struct, with these exceptions: // - the XMLName field, described above, is omitted. // - a field with tag "-" is omitted. // - a field with tag "name,attr" becomes an attribute with // the given name in the XML element. // - a field with tag ",attr" becomes an attribute with the // field name in the XML element. // - a field with tag ",chardata" is written as character data, // not as an XML element. // - a field with tag ",cdata" is written as character data // wrapped in one or more tags, not as an XML element. // - a field with tag ",innerxml" is written verbatim, not subject // to the usual marshaling procedure. // - a field with tag ",comment" is written as an XML comment, not // subject to the usual marshaling procedure. It must not contain // the "--" string within it. // - a field with a tag including the "omitempty" option is omitted // if the field value is empty. The empty values are false, 0, any // nil pointer or interface value, and any array, slice, map, or // string of length zero. // - an anonymous struct field is handled as if the fields of its // value were part of the outer struct. // - a field implementing [Marshaler] is written by calling its MarshalXML // method. // - a field implementing [encoding.TextMarshaler] is written by encoding the // result of its MarshalText method as text. // // If a field uses a tag "a>b>c", then the element c will be nested inside // parent elements a and b. Fields that appear next to each other that name // the same parent will be enclosed in one XML element. // // If the XML name for a struct field is defined by both the field tag and the // struct's XMLName field, the names must match. // // See [MarshalIndent] for an example. // // Marshal will return an error if asked to marshal a channel, function, or map. func Marshal(v any) ([]byte, error) { var b bytes.Buffer enc := NewEncoder(&b) if err := enc.Encode(v); err != nil { return nil, err } if err := enc.Close(); err != nil { return nil, err } 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. func MarshalIndent(v any, prefix, indent string) ([]byte, error) { var b bytes.Buffer enc := NewEncoder(&b) enc.Indent(prefix, indent) if err := enc.Encode(v); err != nil { return nil, err } if err := enc.Close(); err != nil { return nil, err } return b.Bytes(), nil } // An Encoder writes XML data to an output stream. type Encoder struct { p printer } // NewEncoder returns a new encoder that writes to w. func NewEncoder(w io.Writer) *Encoder { e := &Encoder{printer{w: 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.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. // // Encode calls [Encoder.Flush] before returning. func (enc *Encoder) Encode(v any) error { err := enc.p.marshalValue(reflect.ValueOf(v), nil, nil) if err != nil { return err } return enc.p.w.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. // // EncodeElement calls [Encoder.Flush] before returning. func (enc *Encoder) EncodeElement(v any, start StartElement) error { err := enc.p.marshalValue(reflect.ValueOf(v), nil, &start) if err != nil { return err } return enc.p.w.Flush() } var ( begComment = []byte("") endProcInst = []byte("?>") ) // EncodeToken writes the given XML token to the stream. // It returns an error if [StartElement] and [EndElement] tokens are not properly matched. // // EncodeToken does not call [Encoder.Flush], because usually it is part of a larger operation // such as [Encoder.Encode] or [Encoder.EncodeElement] (or a custom [Marshaler]'s MarshalXML invoked // during those), and those will call Flush when finished. // Callers that create an Encoder and then invoke EncodeToken directly, without // using Encode or EncodeElement, need to call Flush when finished to ensure // that the XML is written to the underlying writer. // // EncodeToken allows writing a [ProcInst] with Target set to "xml" only as the first token // in the stream. 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, false) case Comment: if bytes.Contains(t, endComment) { return fmt.Errorf("xml: EncodeToken of Comment containing --> marker") } p.WriteString("") return p.cachedWriteError() case ProcInst: // First token to be encoded which is also a ProcInst with target of xml // is the xml declaration. The only ProcInst where target of xml is allowed. if t.Target == "xml" && p.w.Buffered() != 0 { return fmt.Errorf("xml: EncodeToken of ProcInst xml target only valid for xml declaration, first token encoded") } if !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(" 0 { p.WriteByte(' ') p.Write(t.Inst) } p.WriteString("?>") case Directive: if !isValidDirective(t) { return fmt.Errorf("xml: EncodeToken of Directive containing wrong < or > markers") } p.WriteString("") default: return fmt.Errorf("xml: EncodeToken of invalid token type") } return p.cachedWriteError() } // isValidDirective reports whether dir is a valid directive text, // meaning angle brackets are matched, ignoring comments and strings. func isValidDirective(dir Directive) bool { var ( depth int inquote uint8 incomment bool ) for i, c := range dir { switch { case incomment: if c == '>' { if n := 1 + i - len(endComment); n >= 0 && bytes.Equal(dir[n:i+1], endComment) { incomment = false } } // Just ignore anything in comment case inquote != 0: if c == inquote { inquote = 0 } // Just ignore anything within quotes case c == '\'' || c == '"': inquote = c case c == '<': if i+len(begComment) < len(dir) && bytes.Equal(dir[i:i+len(begComment)], begComment) { incomment = true } else { depth++ } case c == '>': if depth == 0 { return false } depth-- } } return depth == 0 && inquote == 0 && !incomment } // Flush flushes any buffered XML to the underlying writer. // See the [Encoder.EncodeToken] documentation for details about when it is necessary. func (enc *Encoder) Flush() error { return enc.p.w.Flush() } // Close the Encoder, indicating that no more data will be written. It flushes // any buffered XML to the underlying writer and returns an error if the // written XML is invalid (e.g. by containing unclosed elements). func (enc *Encoder) Close() error { return enc.p.Close() } type printer struct { w *bufio.Writer encoder *Encoder seq int indent string prefix string depth int indentedIn bool putNewline bool attrNS map[string]string // map prefix -> name space attrPrefix map[string]string // map name space -> prefix prefixes []string tags []Name closed bool err error } // createAttrPrefix finds the name space prefix attribute to use for the given name space, // 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" // and must be referred to that way. // (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 xmlPrefix } // Need to define a new name space. if p.attrPrefix == nil { p.attrPrefix = make(map[string]string) p.attrNS = make(map[string]string) } // Pick a name. We try to use the final element of the path // but fall back to _. prefix := strings.TrimRight(url, "/") if i := strings.LastIndex(prefix, "/"); i >= 0 { prefix = prefix[i+1:] } if prefix == "" || !isName([]byte(prefix)) || strings.Contains(prefix, ":") { prefix = "_" } // xmlanything is reserved and any variant of it regardless of // case should be matched, so: // (('X'|'x') ('M'|'m') ('L'|'l')) // See Section 2.3 of https://www.w3.org/TR/REC-xml/ if len(prefix) >= 3 && strings.EqualFold(prefix[:3], "xml") { prefix = "_" + prefix } if p.attrNS[prefix] != "" { // Name is taken. Find a better one. for p.seq++; ; p.seq++ { if id := prefix + "_" + strconv.Itoa(p.seq); p.attrNS[id] == "" { prefix = id break } } } p.attrPrefix[url] = prefix p.attrNS[prefix] = url p.WriteString(`xmlns:`) p.WriteString(prefix) p.WriteString(`="`) EscapeText(p, []byte(url)) p.WriteString(`" `) p.prefixes = append(p.prefixes, prefix) return prefix } // deleteAttrPrefix removes an attribute name space prefix. func (p *printer) deleteAttrPrefix(prefix string) { delete(p.attrPrefix, p.attrNS[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.TypeFor[Marshaler]() marshalerAttrType = reflect.TypeFor[MarshalerAttr]() textMarshalerType = reflect.TypeFor[encoding.TextMarshaler]() ) // 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, 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 finfo != nil && finfo.flags&fOmitEmpty != 0 && isEmptyValue(val) { return nil } // Drill into interfaces and pointers. // This can turn into an infinite loop given a cyclic chain, // but it matches the Go 1 behavior. for val.Kind() == reflect.Interface || val.Kind() == reflect.Pointer { if val.IsNil() { return nil } val = val.Elem() } kind := val.Kind() typ := val.Type() // Check for marshaler. if val.CanInterface() && typ.Implements(marshalerType) { return p.marshalInterface(val.Interface().(Marshaler), defaultStart(typ, finfo, startTemplate)) } if val.CanAddr() { pv := val.Addr() if pv.CanInterface() && pv.Type().Implements(marshalerType) { return p.marshalInterface(pv.Interface().(Marshaler), defaultStart(pv.Type(), finfo, startTemplate)) } } // Check for text marshaler. if val.CanInterface() && typ.Implements(textMarshalerType) { return p.marshalTextInterface(val.Interface().(encoding.TextMarshaler), defaultStart(typ, finfo, startTemplate)) } if val.CanAddr() { pv := val.Addr() if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { return p.marshalTextInterface(pv.Interface().(encoding.TextMarshaler), defaultStart(pv.Type(), 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, startTemplate); err != nil { return err } } return nil } tinfo, err := getTypeInfo(typ) if err != nil { 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 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 != "" { start.Name.Space, start.Name.Local = xmlname.xmlns, xmlname.name } else { fv := xmlname.value(val, dontInitNilPointers) if v, ok := fv.Interface().(Name); ok && v.Local != "" { start.Name = v } } } if start.Name.Local == "" && finfo != nil { start.Name.Space, start.Name.Local = finfo.xmlns, finfo.name } if start.Name.Local == "" { name := typ.Name() if i := strings.IndexByte(name, '['); i >= 0 { // Truncate generic instantiation name. See issue 48318. name = name[:i] } if name == "" { return &UnsupportedTypeError{typ} } start.Name.Local = name } // Attributes for i := range tinfo.fields { finfo := &tinfo.fields[i] if finfo.flags&fAttr == 0 { continue } fv := finfo.value(val, dontInitNilPointers) if finfo.flags&fOmitEmpty != 0 && (!fv.IsValid() || isEmptyValue(fv)) { continue } if fv.Kind() == reflect.Interface && fv.IsNil() { continue } name := Name{Space: finfo.xmlns, Local: finfo.name} if err := p.marshalAttr(&start, name, fv); err != nil { return err } } // If an empty name was found, namespace is overridden with an empty space if tinfo.xmlname != nil && start.Name.Space == "" && tinfo.xmlname.xmlns == "" && tinfo.xmlname.name == "" && len(p.tags) != 0 && p.tags[len(p.tags)-1].Space != "" { start.Attr = append(start.Attr, Attr{Name{"", xmlnsPrefix}, ""}) } if err := p.writeStart(&start); err != nil { return err } if val.Kind() == reflect.Struct { err = p.marshalStruct(tinfo, val) } else { 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() } // marshalAttr marshals an attribute with the given name and value, adding to start.Attr. func (p *printer) marshalAttr(start *StartElement, name Name, val reflect.Value) error { if val.CanInterface() && val.Type().Implements(marshalerAttrType) { attr, err := val.Interface().(MarshalerAttr).MarshalXMLAttr(name) if err != nil { return err } if attr.Name.Local != "" { start.Attr = append(start.Attr, attr) } return nil } if val.CanAddr() { pv := val.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) } return nil } } if val.CanInterface() && val.Type().Implements(textMarshalerType) { text, err := val.Interface().(encoding.TextMarshaler).MarshalText() if err != nil { return err } start.Attr = append(start.Attr, Attr{name, string(text)}) return nil } if val.CanAddr() { pv := val.Addr() if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { text, err := pv.Interface().(encoding.TextMarshaler).MarshalText() if err != nil { return err } start.Attr = append(start.Attr, Attr{name, string(text)}) return nil } } // Dereference or skip nil pointer, interface values. switch val.Kind() { case reflect.Pointer, reflect.Interface: if val.IsNil() { return nil } val = val.Elem() } // Walk slices. if val.Kind() == reflect.Slice && val.Type().Elem().Kind() != reflect.Uint8 { n := val.Len() for i := 0; i < n; i++ { if err := p.marshalAttr(start, name, val.Index(i)); err != nil { return err } } return nil } if val.Type() == attrType { start.Attr = append(start.Attr, val.Interface().(Attr)) return nil } s, b, err := p.marshalSimple(val.Type(), val) if err != nil { return err } if b != nil { s = string(b) } start.Attr = append(start.Attr, Attr{name, s}) return nil } // defaultStart returns the default start element to use, // given the reflect type, field info, and start template. func defaultStart(typ reflect.Type, finfo *fieldInfo, startTemplate *StartElement) StartElement { 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() } return start } // marshalInterface marshals a Marshaler interface value. func (p *printer) marshalInterface(val Marshaler, start StartElement) error { // 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 } // marshalTextInterface marshals a TextMarshaler interface value. func (p *printer) marshalTextInterface(val encoding.TextMarshaler, start StartElement) error { if err := p.writeStart(&start); err != nil { return err } text, err := val.MarshalText() if err != nil { return err } EscapeText(p, text) return p.writeEnd(start.Name) } // 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 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 does not match start tag <%s>", name.Local, top.Local) } return fmt.Errorf("xml: end tag 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.Local) p.WriteByte('>') p.popPrefix() return nil } func (p *printer) marshalSimple(typ reflect.Type, val reflect.Value) (string, []byte, error) { switch val.Kind() { case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: return strconv.FormatInt(val.Int(), 10), nil, nil case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: return strconv.FormatUint(val.Uint(), 10), nil, nil case reflect.Float32, reflect.Float64: return strconv.FormatFloat(val.Float(), 'g', -1, val.Type().Bits()), nil, nil case reflect.String: return val.String(), nil, nil case reflect.Bool: return strconv.FormatBool(val.Bool()), nil, nil case reflect.Array: if typ.Elem().Kind() != reflect.Uint8 { break } // [...]byte var bytes []byte if val.CanAddr() { bytes = val.Bytes() } else { bytes = make([]byte, val.Len()) reflect.Copy(reflect.ValueOf(bytes), val) } return "", bytes, nil case reflect.Slice: if typ.Elem().Kind() != reflect.Uint8 { break } // []byte return "", val.Bytes(), nil } return "", nil, &UnsupportedTypeError{typ} } var ddBytes = []byte("--") // indirect drills into interfaces and pointers, returning the pointed-at value. // If it encounters a nil interface or pointer, indirect returns that nil value. // This can turn into an infinite loop given a cyclic chain, // but it matches the Go 1 behavior. func indirect(vf reflect.Value) reflect.Value { for vf.Kind() == reflect.Interface || vf.Kind() == reflect.Pointer { if vf.IsNil() { return vf } vf = vf.Elem() } return vf } func (p *printer) marshalStruct(tinfo *typeInfo, val reflect.Value) error { s := parentStack{p: p} for i := range tinfo.fields { finfo := &tinfo.fields[i] if finfo.flags&fAttr != 0 { continue } vf := finfo.value(val, dontInitNilPointers) if !vf.IsValid() { // The field is behind an anonymous struct field that's // nil. Skip it. continue } switch finfo.flags & fMode { case fCDATA, fCharData: emit := EscapeText if finfo.flags&fMode == fCDATA { emit = emitCDATA } if err := s.trim(finfo.parents); err != nil { return err } if vf.CanInterface() && vf.Type().Implements(textMarshalerType) { data, err := vf.Interface().(encoding.TextMarshaler).MarshalText() if err != nil { return err } if err := emit(p, data); err != nil { return err } continue } if vf.CanAddr() { pv := vf.Addr() if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { data, err := pv.Interface().(encoding.TextMarshaler).MarshalText() if err != nil { return err } if err := emit(p, data); err != nil { return err } continue } } var scratch [64]byte vf = indirect(vf) switch vf.Kind() { case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: if err := emit(p, strconv.AppendInt(scratch[:0], vf.Int(), 10)); err != nil { return err } case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: if err := emit(p, strconv.AppendUint(scratch[:0], vf.Uint(), 10)); err != nil { return err } case reflect.Float32, reflect.Float64: if err := emit(p, strconv.AppendFloat(scratch[:0], vf.Float(), 'g', -1, vf.Type().Bits())); err != nil { return err } case reflect.Bool: if err := emit(p, strconv.AppendBool(scratch[:0], vf.Bool())); err != nil { return err } case reflect.String: if err := emit(p, []byte(vf.String())); err != nil { return err } case reflect.Slice: if elem, ok := vf.Interface().([]byte); ok { if err := emit(p, elem); err != nil { return err } } } continue case fComment: if err := s.trim(finfo.parents); err != nil { return err } vf = indirect(vf) k := vf.Kind() if !(k == reflect.String || k == reflect.Slice && vf.Type().Elem().Kind() == reflect.Uint8) { return fmt.Errorf("xml: bad type for comment field of %s", val.Type()) } if vf.Len() == 0 { continue } p.writeIndent(0) p.WriteString("" is invalid grammar. Make it "- -->" p.WriteByte(' ') } p.WriteString("-->") continue case fInnerXML: vf = indirect(vf) iface := vf.Interface() switch raw := iface.(type) { case []byte: p.Write(raw) continue case string: p.WriteString(raw) continue } case fElement, fElement | fAny: if err := s.trim(finfo.parents); err != nil { return err } if len(finfo.parents) > len(s.stack) { if vf.Kind() != reflect.Pointer && vf.Kind() != reflect.Interface || !vf.IsNil() { if err := s.push(finfo.parents[len(s.stack):]); err != nil { return err } } } } if err := p.marshalValue(vf, finfo, nil); err != nil { return err } } s.trim(nil) return p.cachedWriteError() } // Write implements io.Writer func (p *printer) Write(b []byte) (n int, err error) { if p.closed && p.err == nil { p.err = errors.New("use of closed Encoder") } if p.err == nil { n, p.err = p.w.Write(b) } return n, p.err } // WriteString implements io.StringWriter func (p *printer) WriteString(s string) (n int, err error) { if p.closed && p.err == nil { p.err = errors.New("use of closed Encoder") } if p.err == nil { n, p.err = p.w.WriteString(s) } return n, p.err } // WriteByte implements io.ByteWriter func (p *printer) WriteByte(c byte) error { if p.closed && p.err == nil { p.err = errors.New("use of closed Encoder") } if p.err == nil { p.err = p.w.WriteByte(c) } return p.err } // Close the Encoder, indicating that no more data will be written. It flushes // any buffered XML to the underlying writer and returns an error if the // written XML is invalid (e.g. by containing unclosed elements). func (p *printer) Close() error { if p.closed { return nil } p.closed = true if err := p.w.Flush(); err != nil { return err } if len(p.tags) > 0 { return fmt.Errorf("unclosed tag <%s>", p.tags[len(p.tags)-1].Local) } return nil } // return the bufio Writer's cached write error func (p *printer) cachedWriteError() error { _, err := p.Write(nil) return err } func (p *printer) writeIndent(depthDelta int) { if len(p.prefix) == 0 && len(p.indent) == 0 { return } if depthDelta < 0 { p.depth-- if p.indentedIn { p.indentedIn = false return } p.indentedIn = false } if p.putNewline { p.WriteByte('\n') } else { p.putNewline = true } if len(p.prefix) > 0 { p.WriteString(p.prefix) } if len(p.indent) > 0 { for i := 0; i < p.depth; i++ { p.WriteString(p.indent) } } if depthDelta > 0 { p.depth++ p.indentedIn = true } } type parentStack struct { 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) error { split := 0 for ; split < len(parents) && split < len(s.stack); split++ { if parents[split] != s.stack[split] { break } } for i := len(s.stack) - 1; i >= split; i-- { if err := s.p.writeEnd(Name{Local: s.stack[i]}); err != nil { return err } } s.stack = s.stack[:split] return nil } // push adds parent elements to the stack and writes open tags. func (s *parentStack) push(parents []string) error { for i := 0; i < len(parents); i++ { if err := s.p.writeStart(&StartElement{Name: Name{Local: parents[i]}}); err != nil { return err } } s.stack = append(s.stack, parents...) return nil } // UnsupportedTypeError is returned when [Marshal] encounters a type // that cannot be converted into XML. type UnsupportedTypeError struct { Type reflect.Type } func (e *UnsupportedTypeError) Error() string { return "xml: unsupported type: " + e.Type.String() } func isEmptyValue(v reflect.Value) bool { switch v.Kind() { case reflect.Array, reflect.Map, reflect.Slice, reflect.String: return v.Len() == 0 case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.Float32, reflect.Float64, reflect.Interface, reflect.Pointer: return v.IsZero() } return false }