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encode.go
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encode.go
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package xml
import (
"bytes"
"encoding/xml"
"fmt"
"io"
"github.com/aws/aws-sdk-go-v2/private/protocol"
)
// An Encoder provides encoding of the AWS XML protocol. This encoder will will
// write all content to XML. Only supports body and payload targets.
type Encoder struct {
encoder *xml.Encoder
encodedBuf *bytes.Buffer
fieldBuf protocol.FieldBuffer
err error
}
// NewEncoder creates a new encoder for encoding AWS XML protocol. Only encodes
// fields into the XML body, and error is returned if target is anything other
// than Body or Payload.
func NewEncoder() *Encoder {
encodedBuf := bytes.NewBuffer(nil)
return &Encoder{
encodedBuf: encodedBuf,
encoder: xml.NewEncoder(encodedBuf),
}
}
// Encode returns the encoded XMl reader. An error will be returned if one was
// encountered while building the XML body.
func (e *Encoder) Encode() (io.ReadSeeker, error) {
if e.err != nil {
return nil, e.err
}
if err := e.encoder.Flush(); err != nil {
return nil, fmt.Errorf("unable to marshal XML, %v", err)
}
if e.encodedBuf.Len() == 0 {
return nil, nil
}
return bytes.NewReader(e.encodedBuf.Bytes()), e.err
}
// SetValue sets an individual value to the XML body.
func (e *Encoder) SetValue(t protocol.Target, k string, v protocol.ValueMarshaler, meta protocol.Metadata) {
if e.err != nil {
return
}
if t != protocol.BodyTarget && t != protocol.PayloadTarget {
e.err = fmt.Errorf(" invalid target %s for xml encoder SetValue, %s", t, k)
return
}
e.err = addValueToken(e.encoder, &e.fieldBuf, k, v, meta)
}
// SetStream is not supported for XML protocol marshaling.
func (e *Encoder) SetStream(t protocol.Target, k string, v protocol.StreamMarshaler, meta protocol.Metadata) {
e.err = fmt.Errorf("xml encoder SetStream not supported, %s, %s", t, k)
}
// List creates an XML list and calls the passed in fn callback with a list encoder.
func (e *Encoder) List(t protocol.Target, k string, meta protocol.Metadata) protocol.ListEncoder {
if e.err != nil {
return nil
}
if t != protocol.BodyTarget && t != protocol.PayloadTarget {
e.err = fmt.Errorf(" invalid target %s for xml encoder SetValue, %s", t, k)
return nil
}
if v := meta.ListLocationName; len(v) == 0 {
if meta.Flatten {
meta.ListLocationName = k
} else {
meta.ListLocationName = "member"
}
}
return &ListEncoder{
Base: e,
Key: k,
Metadata: meta,
}
}
// Map creates an XML map and calls the passed in fn callback with a map encoder.
func (e *Encoder) Map(t protocol.Target, k string, meta protocol.Metadata) protocol.MapEncoder {
if e.err != nil {
return nil
}
if t != protocol.BodyTarget && t != protocol.PayloadTarget {
e.err = fmt.Errorf(" invalid target %s for xml encoder SetValue, %s", t, k)
return nil
}
me := MapEncoder{Base: e,
// TODO: Get rid of these fields as we need the metadata structure now
Flatten: meta.Flatten,
KeyName: meta.MapLocationNameKey,
ValueName: meta.MapLocationNameValue,
Metadata: meta,
Key: k,
}
return &me
}
// SetFields sets the nested fields to the XML body.
func (e *Encoder) SetFields(t protocol.Target, k string, m protocol.FieldMarshaler, meta protocol.Metadata) {
if e.err != nil {
return
}
if t != protocol.BodyTarget && t != protocol.PayloadTarget {
e.err = fmt.Errorf(" invalid target %s for xml encoder SetFields, %s", t, k)
return
}
tok, err := xmlStartElem(k, meta)
if err != nil {
e.err = err
return
}
e.encoder.EncodeToken(tok)
m.MarshalFields(e)
e.encoder.EncodeToken(xml.EndElement{Name: tok.Name})
}
// A ListEncoder encodes elements within a list for the XML encoder.
type ListEncoder struct {
Base *Encoder
Key string
Metadata protocol.Metadata
Token xml.StartElement
err error
}
// Map will return an error since nested collections are not support by this protocol.
func (e *ListEncoder) Map() protocol.MapEncoder {
e.err = fmt.Errorf("xml list encoder ListSetMap not supported")
return nil
}
// List will return an error since nested collections are not support by this protocol.
func (e *ListEncoder) List() protocol.ListEncoder {
e.err = fmt.Errorf("xml list encoder ListSetList not supported")
return nil
}
// Start will write the start element and set the token for closing
func (e *ListEncoder) Start() {
var tok xml.StartElement
var err error
if !e.Metadata.Flatten {
tok, err = xmlStartElem(e.Key, e.Metadata)
if err != nil {
e.err = err
return
}
e.Base.encoder.EncodeToken(tok)
}
e.Token = tok
}
// End will write the end element if the list is not flat.
func (e *ListEncoder) End() {
if !e.Metadata.Flatten {
e.err = e.Base.encoder.EncodeToken(xml.EndElement{Name: e.Token.Name})
}
}
// ListAddValue will add the value to the list.
func (e *ListEncoder) ListAddValue(v protocol.ValueMarshaler) {
if e.err != nil {
return
}
e.err = addValueToken(e.Base.encoder, &e.Base.fieldBuf, e.Metadata.ListLocationName, v, protocol.Metadata{})
}
// ListAddFields will set the nested type's fields to the list.
func (e *ListEncoder) ListAddFields(m protocol.FieldMarshaler) {
if e.err != nil {
return
}
var tok xml.StartElement
tok, e.err = xmlStartElem(e.Metadata.ListLocationName, protocol.Metadata{})
if e.err != nil {
return
}
e.Base.encoder.EncodeToken(tok)
m.MarshalFields(e.Base)
e.Base.encoder.EncodeToken(xml.EndElement{Name: tok.Name})
}
// A MapEncoder encodes key values pair map values for the XML encoder.
type MapEncoder struct {
Base *Encoder
Flatten bool
Key string
KeyName string
ValueName string
err error
Token xml.StartElement
Metadata protocol.Metadata
}
// Start will open a new scope by creating a new XML start element tag.
func (e *MapEncoder) Start() {
tok, err := xmlStartElem(e.Key, e.Metadata)
if err != nil {
e.err = err
return
}
e.Token = tok
e.Base.encoder.EncodeToken(tok)
}
// End will close the associated tag.
func (e *MapEncoder) End() {
e.Base.encoder.EncodeToken(xml.EndElement{Name: e.Token.Name})
}
// Map will set err as nested collections are not supported in this protocol.
func (e *MapEncoder) Map(k string) protocol.MapEncoder {
e.err = fmt.Errorf("xml map encoder MapSetList not supported, %s", k)
return nil
}
// List will set err as nested collections are not supported in this protocol.
func (e *MapEncoder) List(k string) protocol.ListEncoder {
e.err = fmt.Errorf("xml map encoder ListSetList not supported, %s", k)
return nil
}
// MapSetValue sets a map value.
func (e *MapEncoder) MapSetValue(k string, v protocol.ValueMarshaler) {
if e.err != nil {
return
}
var tok xml.StartElement
if !e.Flatten {
tok, e.err = xmlStartElem("entry", protocol.Metadata{})
if e.err != nil {
return
}
e.Base.encoder.EncodeToken(tok)
}
keyName, valueName := e.KeyName, e.ValueName
if len(keyName) == 0 {
keyName = "key"
}
if len(valueName) == 0 {
valueName = "value"
}
e.err = addValueToken(e.Base.encoder, &e.Base.fieldBuf, keyName, protocol.StringValue(k), protocol.Metadata{})
if e.err != nil {
return
}
e.err = addValueToken(e.Base.encoder, &e.Base.fieldBuf, valueName, v, protocol.Metadata{})
if e.err != nil {
return
}
if !e.Flatten {
e.Base.encoder.EncodeToken(xml.EndElement{Name: tok.Name})
}
}
// MapSetList is not supported.
func (e *MapEncoder) MapSetList(k string, fn func(le protocol.ListEncoder)) {
e.err = fmt.Errorf("xml map encoder MapSetList not supported, %s", k)
}
// MapSetMap is not supported.
func (e *MapEncoder) MapSetMap(k string, fn func(me protocol.MapEncoder)) {
e.err = fmt.Errorf("xml map encoder MapSetMap not supported, %s", k)
}
// MapSetFields will set the nested type's fields under the map.
func (e *MapEncoder) MapSetFields(k string, m protocol.FieldMarshaler) {
if e.err != nil {
return
}
var tok xml.StartElement
if !e.Flatten {
tok, e.err = xmlStartElem("entry", protocol.Metadata{})
if e.err != nil {
return
}
e.Base.encoder.EncodeToken(tok)
}
keyName, valueName := e.KeyName, e.ValueName
if len(keyName) == 0 {
keyName = "key"
}
if len(valueName) == 0 {
valueName = "value"
}
e.err = addValueToken(e.Base.encoder, &e.Base.fieldBuf, keyName, protocol.StringValue(k), protocol.Metadata{})
if e.err != nil {
return
}
valTok, err := xmlStartElem(valueName, protocol.Metadata{})
if err != nil {
e.err = err
return
}
e.Base.encoder.EncodeToken(valTok)
m.MarshalFields(e.Base)
e.Base.encoder.EncodeToken(xml.EndElement{Name: valTok.Name})
if !e.Flatten {
e.Base.encoder.EncodeToken(xml.EndElement{Name: tok.Name})
}
}
func addValueToken(e *xml.Encoder, fieldBuf *protocol.FieldBuffer, k string, v protocol.ValueMarshaler, meta protocol.Metadata) error {
b, err := fieldBuf.GetValue(v)
if err != nil {
return err
}
tok, err := xmlStartElem(k, meta)
if err != nil {
return err
}
e.EncodeToken(tok)
e.EncodeToken(xml.CharData(b))
e.EncodeToken(xml.EndElement{Name: tok.Name})
return nil
}
func xmlStartElem(k string, meta protocol.Metadata) (xml.StartElement, error) {
tok := xml.StartElement{Name: xmlName(k, meta)}
attrs, err := buildAttributes(meta)
if err != nil {
return xml.StartElement{}, err
}
tok.Attr = attrs
return tok, nil
}
func xmlName(k string, meta protocol.Metadata) xml.Name {
name := xml.Name{Local: k}
// TODO need to do something with namespace?
// if len(meta.XMLNamespacePrefix) > 0 && len(meta.XMLNamespaceURI) {
// name.Space = prefix
// }
return name
}
func buildAttributes(meta protocol.Metadata) ([]xml.Attr, error) {
n := len(meta.Attributes)
if len(meta.XMLNamespaceURI) > 0 {
n++
}
if n == 0 {
return nil, nil
}
attrs := make([]xml.Attr, n)
for _, a := range meta.Attributes {
str, err := a.Value.MarshalValue()
if err != nil {
return nil, err
}
attrs = append(attrs, xml.Attr{Name: xmlName(a.Name, a.Meta), Value: str})
}
if uri := meta.XMLNamespaceURI; len(uri) > 0 {
attr := xml.Attr{
Name: xml.Name{Local: "xmlns"},
Value: uri,
}
if p := meta.XMLNamespacePrefix; len(p) > 0 {
attr.Name.Local += ":" + p
}
attrs = append(attrs, attr)
}
return attrs, nil
}