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// 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"
"fmt"
"io"
"reflect"
"strconv"
"strings"
)
const (
// 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 = `<?xml version="1.0" encoding="UTF-8"?>` + "\n"
)
// Marshal returns the XML encoding of v.
//
// Marshal handles an array or slice by marshalling each of the elements.
// Marshal handles a pointer by marshalling the value it points at or, if the
// pointer is nil, by writing nothing. Marshal handles an interface value by
// marshalling 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 xml.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 marshalled type
//
// The XML element for a struct contains marshalled 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 ",innerxml" is written verbatim, not subject
// to the usual marshalling procedure.
// - a field with tag ",comment" is written as an XML comment, not
// subject to the usual marshalling 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.
//
// 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.
//
// See MarshalIndent for an example.
//
// Marshal will return an error if asked to marshal a channel, function, or map.
func Marshal(v interface{}) ([]byte, error) {
var b bytes.Buffer
if err := NewEncoder(&b).Encode(v); 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 interface{}, 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
}
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{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.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 Flush before returning.
func (enc *Encoder) Encode(v interface{}) error {
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.
//
// EncodeElement calls Flush before returning.
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.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.
//
// EncodeToken does not call Flush, because usually it is part of a
// larger operation such as Encode or 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.
//
// When encoding a StartElement holding an XML namespace prefix
// declaration for a prefix that is not already declared, contained
// elements (including the StartElement itself) will use the declared
// prefix when encoding names with matching namespace URIs.
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:
// 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.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("<?")
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()
}
// Flush flushes any buffered XML to the underlying writer.
// See the EncodeToken documentation for details about when it is necessary.
func (enc *Encoder) Flush() error {
return enc.p.Flush()
}
type printer struct {
*bufio.Writer
encoder *Encoder
seq int
indent string
prefix string
depth int
indentedIn bool
putNewline bool
defaultNS string
attrNS map[string]string // map prefix -> name space
attrPrefix map[string]string // map name space -> prefix
prefixes []printerPrefix
tags []Name
}
// printerPrefix holds a namespace undo record.
// When an element is popped, the prefix record
// is set back to the recorded URL. The empty
// prefix records the URL for the default name space.
//
// The start of an element is recorded with an element
// that has mark=true.
type printerPrefix struct {
prefix string
url string
mark bool
}
func (p *printer) prefixForNS(url string, isAttr bool) string {
// 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 "xml"
}
if !isAttr && url == p.defaultNS {
// We can use the default name space.
return ""
}
return p.attrPrefix[url]
}
// defineNS pushes any namespace definition found in the given attribute.
// If ignoreNonEmptyDefault is true, an xmlns="nonempty"
// attribute will be ignored.
func (p *printer) defineNS(attr Attr, ignoreNonEmptyDefault bool) error {
var prefix string
if attr.Name.Local == "xmlns" {
if attr.Name.Space != "" && attr.Name.Space != "xml" && attr.Name.Space != xmlURL {
return fmt.Errorf("xml: cannot redefine xmlns attribute prefix")
}
} else if attr.Name.Space == "xmlns" && attr.Name.Local != "" {
prefix = attr.Name.Local
if attr.Value == "" {
// Technically, an empty XML namespace is allowed for an attribute.
// From http://www.w3.org/TR/xml-names11/#scoping-defaulting:
//
// The attribute value in a namespace declaration for a prefix may be
// empty. This has the effect, within the scope of the declaration, of removing
// any association of the prefix with a namespace name.
//
// However our namespace prefixes here are used only as hints. There's
// no need to respect the removal of a namespace prefix, so we ignore it.
return nil
}
} else {
// Ignore: it's not a namespace definition
return nil
}
if prefix == "" {
if attr.Value == p.defaultNS {
// No need for redefinition.
return nil
}
if attr.Value != "" && ignoreNonEmptyDefault {
// We have an xmlns="..." value but
// it can't define a name space in this context,
// probably because the element has an empty
// name space. In this case, we just ignore
// the name space declaration.
return nil
}
} else if _, ok := p.attrPrefix[attr.Value]; ok {
// There's already a prefix for the given name space,
// so use that. This prevents us from
// having two prefixes for the same name space
// so attrNS and attrPrefix can remain bijective.
return nil
}
p.pushPrefix(prefix, attr.Value)
return nil
}
// createNSPrefix creates a name space prefix attribute
// to use for the given name space, defining a new prefix
// if necessary.
// If isAttr is true, the prefix is to be created for an attribute
// prefix, which means that the default name space cannot
// be used.
func (p *printer) createNSPrefix(url string, isAttr bool) {
if _, ok := p.attrPrefix[url]; ok {
// We already have a prefix for the given URL.
return
}
switch {
case !isAttr && url == p.defaultNS:
// We can use the default name space.
return
case url == "":
// The only way we can encode names in the empty
// name space is by using the default name space,
// so we must use that.
if p.defaultNS != "" {
// The default namespace is non-empty, so we
// need to set it to empty.
p.pushPrefix("", "")
}
return
case url == xmlURL:
return
}
// TODO If the URL is an existing prefix, we could
// use it as is. That would enable the
// marshaling of elements that had been unmarshaled
// and with a name space prefix that was not found.
// although technically it would be incorrect.
// 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 = "_"
}
if strings.HasPrefix(prefix, "xml") {
// xmlanything is reserved.
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.pushPrefix(prefix, url)
}
// writeNamespaces writes xmlns attributes for all the
// namespace prefixes that have been defined in
// the current element.
func (p *printer) writeNamespaces() {
for i := len(p.prefixes) - 1; i >= 0; i-- {
prefix := p.prefixes[i]
if prefix.mark {
return
}
p.WriteString(" ")
if prefix.prefix == "" {
// Default name space.
p.WriteString(`xmlns="`)
} else {
p.WriteString("xmlns:")
p.WriteString(prefix.prefix)
p.WriteString(`="`)
}
EscapeText(p, []byte(p.nsForPrefix(prefix.prefix)))
p.WriteString(`"`)
}
}
// pushPrefix pushes a new prefix on the prefix stack
// without checking to see if it is already defined.
func (p *printer) pushPrefix(prefix, url string) {
p.prefixes = append(p.prefixes, printerPrefix{
prefix: prefix,
url: p.nsForPrefix(prefix),
})
p.setAttrPrefix(prefix, url)
}
// nsForPrefix returns the name space for the given
// prefix. Note that this is not valid for the
// empty attribute prefix, which always has an empty
// name space.
func (p *printer) nsForPrefix(prefix string) string {
if prefix == "" {
return p.defaultNS
}
return p.attrNS[prefix]
}
// markPrefix marks the start of an element on the prefix
// stack.
func (p *printer) markPrefix() {
p.prefixes = append(p.prefixes, printerPrefix{
mark: true,
})
}
// popPrefix pops all defined prefixes for the current
// element.
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.mark {
break
}
p.setAttrPrefix(prefix.prefix, prefix.url)
}
}
// setAttrPrefix sets an attribute name space prefix.
// If url is empty, the attribute is removed.
// If prefix is empty, the default name space is set.
func (p *printer) setAttrPrefix(prefix, url string) {
if prefix == "" {
p.defaultNS = url
return
}
if url == "" {
delete(p.attrPrefix, p.attrNS[prefix])
delete(p.attrNS, prefix)
return
}
if p.attrPrefix == nil {
// Need to define a new name space.
p.attrPrefix = make(map[string]string)
p.attrNS = make(map[string]string)
}
// Remove any old prefix value. This is OK because we maintain a
// strict one-to-one mapping between prefix and URL (see
// defineNS)
delete(p.attrPrefix, p.attrNS[prefix])
p.attrPrefix[url] = prefix
p.attrNS[prefix] = url
}
var (
marshalerType = reflect.TypeOf((*Marshaler)(nil)).Elem()
marshalerAttrType = reflect.TypeOf((*MarshalerAttr)(nil)).Elem()
textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(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, 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.Ptr {
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), p.defaultStart(typ, finfo, startTemplate))
}
if val.CanAddr() {
pv := val.Addr()
if pv.CanInterface() && pv.Type().Implements(marshalerType) {
return p.marshalInterface(pv.Interface().(Marshaler), p.defaultStart(pv.Type(), finfo, startTemplate))
}
}
// Check for text marshaler.
if val.CanInterface() && typ.Implements(textMarshalerType) {
return p.marshalTextInterface(val.Interface().(encoding.TextMarshaler), p.defaultStart(typ, finfo, startTemplate))
}
if val.CanAddr() {
pv := val.Addr()
if pv.CanInterface() && pv.Type().Implements(textMarshalerType) {
return p.marshalTextInterface(pv.Interface().(encoding.TextMarshaler), p.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
// Historic behaviour: elements use the default name space
// they are contained in by default.
start.Name.Space = p.defaultNS
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 if v, ok := xmlname.value(val).Interface().(Name); ok && v.Local != "" {
start.Name = v
}
}
if start.Name.Local == "" && finfo != nil {
start.Name.Local = finfo.name
if finfo.xmlns != "" {
start.Name.Space = finfo.xmlns
}
}
if start.Name.Local == "" {
name := typ.Name()
if name == "" {
return &UnsupportedTypeError{typ}
}
start.Name.Local = name
}
// Historic behaviour: an element that's in a namespace sets
// the default namespace for all elements contained within it.
start.setDefaultNamespace()
// Attributes
for i := range tinfo.fields {
finfo := &tinfo.fields[i]
if finfo.flags&fAttr == 0 {
continue
}
fv := finfo.value(val)
name := Name{Space: finfo.xmlns, Local: finfo.name}
if finfo.flags&fOmitEmpty != 0 && isEmptyValue(fv) {
continue
}
if fv.Kind() == reflect.Interface && fv.IsNil() {
continue
}
if fv.CanInterface() && fv.Type().Implements(marshalerAttrType) {
attr, err := fv.Interface().(MarshalerAttr).MarshalXMLAttr(name)
if err != nil {
return err
}
if attr.Name.Local != "" {
start.Attr = append(start.Attr, attr)
}
continue
}
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
}
}
if fv.CanInterface() && fv.Type().Implements(textMarshalerType) {
text, err := fv.Interface().(encoding.TextMarshaler).MarshalText()
if err != nil {
return err
}
start.Attr = append(start.Attr, Attr{name, string(text)})
continue
}
if fv.CanAddr() {
pv := fv.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)})
continue
}
}
// Dereference or skip nil pointer, interface values.
switch fv.Kind() {
case reflect.Ptr, reflect.Interface:
if fv.IsNil() {
continue
}
fv = fv.Elem()
}
s, b, err := p.marshalSimple(fv.Type(), fv)
if err != nil {
return err
}
if b != nil {
s = string(b)
}
start.Attr = append(start.Attr, Attr{name, s})
}
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()
}
// defaultStart returns the default start element to use,
// given the reflect type, field info, and start template.
func (p *printer) 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()
}
// Historic behaviour: elements use the name space of
// the element they are contained in by default.
if start.Name.Space == "" {
start.Name.Space = p.defaultNS
}
start.setDefaultNamespace()
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()
// Define any name spaces explicitly declared in the attributes.
// We do this as a separate pass so that explicitly declared prefixes
// will take precedence over implicitly declared prefixes
// regardless of the order of the attributes.
ignoreNonEmptyDefault := start.Name.Space == ""
for _, attr := range start.Attr {
if err := p.defineNS(attr, ignoreNonEmptyDefault); err != nil {
return err
}
}
// Define any new name spaces implied by the attributes.
for _, attr := range start.Attr {
name := attr.Name
// From http://www.w3.org/TR/xml-names11/#defaulting
// "Default namespace declarations do not apply directly
// to attribute names; the interpretation of unprefixed
// attributes is determined by the element on which they
// appear."
// This means we don't need to create a new namespace
// when an attribute name space is empty.
if name.Space != "" && !name.isNamespace() {
p.createNSPrefix(name.Space, true)
}
}
p.createNSPrefix(start.Name.Space, false)
p.writeIndent(1)
p.WriteByte('<')
p.writeName(start.Name, false)
p.writeNamespaces()
for _, attr := range start.Attr {
name := attr.Name
if name.Local == "" || name.isNamespace() {
// Namespaces have already been written by writeNamespaces above.
continue
}
p.WriteByte(' ')
p.writeName(name, true)
p.WriteString(`="`)
p.EscapeString(attr.Value)
p.WriteByte('"')
}
p.WriteByte('>')
return nil
}
// writeName writes the given name. It assumes
// that p.createNSPrefix(name) has already been called.
func (p *printer) writeName(name Name, isAttr bool) {
if prefix := p.prefixForNS(name.Space, isAttr); prefix != "" {
p.WriteString(prefix)
p.WriteByte(':')
}
p.WriteString(name.Local)
}
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.writeName(name, false)
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.Slice(0, val.Len()).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("--")
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)
// 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:
if vf.CanInterface() && vf.Type().Implements(textMarshalerType) {
data, err := vf.Interface().(encoding.TextMarshaler).MarshalText()
if err != nil {
return err
}
Escape(p, data)
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
}
Escape(p, data)
continue
}
}
var scratch [64]byte
switch vf.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
Escape(p, strconv.AppendInt(scratch[:0], vf.Int(), 10))
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
Escape(p, strconv.AppendUint(scratch[:0], vf.Uint(), 10))
case reflect.Float32, reflect.Float64:
Escape(p, strconv.AppendFloat(scratch[:0], vf.Float(), 'g', -1, vf.Type().Bits()))
case reflect.Bool:
Escape(p, strconv.AppendBool(scratch[:0], vf.Bool()))
case reflect.String:
if err := EscapeText(p, []byte(vf.String())); err != nil {
return err
}
case reflect.Slice:
if elem, ok := vf.Interface().([]byte); ok {
if err := EscapeText(p, elem); err != nil {
return err
}
}
}
continue
case fComment:
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("<!--")
dashDash := false
dashLast := false
switch k {
case reflect.String:
s := vf.String()
dashDash = strings.Index(s, "--") >= 0
dashLast = s[len(s)-1] == '-'
if !dashDash {
p.WriteString(s)
}
case reflect.Slice:
b := vf.Bytes()
dashDash = bytes.Index(b, ddBytes) >= 0
dashLast = b[len(b)-1] == '-'
if !dashDash {
p.Write(b)
}
default:
panic("can't happen")
}
if dashDash {
return fmt.Errorf(`xml: comments must not contain "--"`)
}
if dashLast {
// "--->" is invalid grammar. Make it "- -->"
p.WriteByte(' ')
}
p.WriteString("-->")
continue
case fInnerXml:
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.Ptr && 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()
}
// 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 = parents[: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
}
// A MarshalXMLError 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:
return !v.Bool()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return v.Uint() == 0
case reflect.Float32, reflect.Float64:
return v.Float() == 0
case reflect.Interface, reflect.Ptr:
return v.IsNil()
}
return false
}