1// Copyright 2011 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package xml 6 7import ( 8 "bufio" 9 "bytes" 10 "encoding" 11 "fmt" 12 "io" 13 "reflect" 14 "strconv" 15 "strings" 16) 17 18const ( 19 // A generic XML header suitable for use with the output of Marshal. 20 // This is not automatically added to any output of this package, 21 // it is provided as a convenience. 22 Header = `<?xml version="1.0" encoding="UTF-8"?>` + "\n" 23) 24 25// Marshal returns the XML encoding of v. 26// 27// Marshal handles an array or slice by marshalling each of the elements. 28// Marshal handles a pointer by marshalling the value it points at or, if the 29// pointer is nil, by writing nothing. Marshal handles an interface value by 30// marshalling the value it contains or, if the interface value is nil, by 31// writing nothing. Marshal handles all other data by writing one or more XML 32// elements containing the data. 33// 34// The name for the XML elements is taken from, in order of preference: 35// - the tag on the XMLName field, if the data is a struct 36// - the value of the XMLName field of type xml.Name 37// - the tag of the struct field used to obtain the data 38// - the name of the struct field used to obtain the data 39// - the name of the marshalled type 40// 41// The XML element for a struct contains marshalled elements for each of the 42// exported fields of the struct, with these exceptions: 43// - the XMLName field, described above, is omitted. 44// - a field with tag "-" is omitted. 45// - a field with tag "name,attr" becomes an attribute with 46// the given name in the XML element. 47// - a field with tag ",attr" becomes an attribute with the 48// field name in the XML element. 49// - a field with tag ",chardata" is written as character data, 50// not as an XML element. 51// - a field with tag ",innerxml" is written verbatim, not subject 52// to the usual marshalling procedure. 53// - a field with tag ",comment" is written as an XML comment, not 54// subject to the usual marshalling procedure. It must not contain 55// the "--" string within it. 56// - a field with a tag including the "omitempty" option is omitted 57// if the field value is empty. The empty values are false, 0, any 58// nil pointer or interface value, and any array, slice, map, or 59// string of length zero. 60// - an anonymous struct field is handled as if the fields of its 61// value were part of the outer struct. 62// 63// If a field uses a tag "a>b>c", then the element c will be nested inside 64// parent elements a and b. Fields that appear next to each other that name 65// the same parent will be enclosed in one XML element. 66// 67// See MarshalIndent for an example. 68// 69// Marshal will return an error if asked to marshal a channel, function, or map. 70func Marshal(v interface{}) ([]byte, error) { 71 var b bytes.Buffer 72 if err := NewEncoder(&b).Encode(v); err != nil { 73 return nil, err 74 } 75 return b.Bytes(), nil 76} 77 78// Marshaler is the interface implemented by objects that can marshal 79// themselves into valid XML elements. 80// 81// MarshalXML encodes the receiver as zero or more XML elements. 82// By convention, arrays or slices are typically encoded as a sequence 83// of elements, one per entry. 84// Using start as the element tag is not required, but doing so 85// will enable Unmarshal to match the XML elements to the correct 86// struct field. 87// One common implementation strategy is to construct a separate 88// value with a layout corresponding to the desired XML and then 89// to encode it using e.EncodeElement. 90// Another common strategy is to use repeated calls to e.EncodeToken 91// to generate the XML output one token at a time. 92// The sequence of encoded tokens must make up zero or more valid 93// XML elements. 94type Marshaler interface { 95 MarshalXML(e *Encoder, start StartElement) error 96} 97 98// MarshalerAttr is the interface implemented by objects that can marshal 99// themselves into valid XML attributes. 100// 101// MarshalXMLAttr returns an XML attribute with the encoded value of the receiver. 102// Using name as the attribute name is not required, but doing so 103// will enable Unmarshal to match the attribute to the correct 104// struct field. 105// If MarshalXMLAttr returns the zero attribute Attr{}, no attribute 106// will be generated in the output. 107// MarshalXMLAttr is used only for struct fields with the 108// "attr" option in the field tag. 109type MarshalerAttr interface { 110 MarshalXMLAttr(name Name) (Attr, error) 111} 112 113// MarshalIndent works like Marshal, but each XML element begins on a new 114// indented line that starts with prefix and is followed by one or more 115// copies of indent according to the nesting depth. 116func MarshalIndent(v interface{}, prefix, indent string) ([]byte, error) { 117 var b bytes.Buffer 118 enc := NewEncoder(&b) 119 enc.Indent(prefix, indent) 120 if err := enc.Encode(v); err != nil { 121 return nil, err 122 } 123 return b.Bytes(), nil 124} 125 126// An Encoder writes XML data to an output stream. 127type Encoder struct { 128 p printer 129} 130 131// NewEncoder returns a new encoder that writes to w. 132func NewEncoder(w io.Writer) *Encoder { 133 e := &Encoder{printer{Writer: bufio.NewWriter(w)}} 134 e.p.encoder = e 135 return e 136} 137 138// Indent sets the encoder to generate XML in which each element 139// begins on a new indented line that starts with prefix and is followed by 140// one or more copies of indent according to the nesting depth. 141func (enc *Encoder) Indent(prefix, indent string) { 142 enc.p.prefix = prefix 143 enc.p.indent = indent 144} 145 146// Encode writes the XML encoding of v to the stream. 147// 148// See the documentation for Marshal for details about the conversion 149// of Go values to XML. 150// 151// Encode calls Flush before returning. 152func (enc *Encoder) Encode(v interface{}) error { 153 err := enc.p.marshalValue(reflect.ValueOf(v), nil, nil) 154 if err != nil { 155 return err 156 } 157 return enc.p.Flush() 158} 159 160// EncodeElement writes the XML encoding of v to the stream, 161// using start as the outermost tag in the encoding. 162// 163// See the documentation for Marshal for details about the conversion 164// of Go values to XML. 165// 166// EncodeElement calls Flush before returning. 167func (enc *Encoder) EncodeElement(v interface{}, start StartElement) error { 168 err := enc.p.marshalValue(reflect.ValueOf(v), nil, &start) 169 if err != nil { 170 return err 171 } 172 return enc.p.Flush() 173} 174 175var ( 176 endComment = []byte("-->") 177 endProcInst = []byte("?>") 178 endDirective = []byte(">") 179) 180 181// EncodeToken writes the given XML token to the stream. 182// It returns an error if StartElement and EndElement tokens are not properly matched. 183// 184// EncodeToken does not call Flush, because usually it is part of a larger operation 185// such as Encode or EncodeElement (or a custom Marshaler's MarshalXML invoked 186// during those), and those will call Flush when finished. 187// Callers that create an Encoder and then invoke EncodeToken directly, without 188// using Encode or EncodeElement, need to call Flush when finished to ensure 189// that the XML is written to the underlying writer. 190// 191// EncodeToken allows writing a ProcInst with Target set to "xml" only as the first token 192// in the stream. 193func (enc *Encoder) EncodeToken(t Token) error { 194 p := &enc.p 195 switch t := t.(type) { 196 case StartElement: 197 if err := p.writeStart(&t); err != nil { 198 return err 199 } 200 case EndElement: 201 if err := p.writeEnd(t.Name); err != nil { 202 return err 203 } 204 case CharData: 205 EscapeText(p, t) 206 case Comment: 207 if bytes.Contains(t, endComment) { 208 return fmt.Errorf("xml: EncodeToken of Comment containing --> marker") 209 } 210 p.WriteString("<!--") 211 p.Write(t) 212 p.WriteString("-->") 213 return p.cachedWriteError() 214 case ProcInst: 215 // First token to be encoded which is also a ProcInst with target of xml 216 // is the xml declaration. The only ProcInst where target of xml is allowed. 217 if t.Target == "xml" && p.Buffered() != 0 { 218 return fmt.Errorf("xml: EncodeToken of ProcInst xml target only valid for xml declaration, first token encoded") 219 } 220 if !isNameString(t.Target) { 221 return fmt.Errorf("xml: EncodeToken of ProcInst with invalid Target") 222 } 223 if bytes.Contains(t.Inst, endProcInst) { 224 return fmt.Errorf("xml: EncodeToken of ProcInst containing ?> marker") 225 } 226 p.WriteString("<?") 227 p.WriteString(t.Target) 228 if len(t.Inst) > 0 { 229 p.WriteByte(' ') 230 p.Write(t.Inst) 231 } 232 p.WriteString("?>") 233 case Directive: 234 if bytes.Contains(t, endDirective) { 235 return fmt.Errorf("xml: EncodeToken of Directive containing > marker") 236 } 237 p.WriteString("<!") 238 p.Write(t) 239 p.WriteString(">") 240 } 241 return p.cachedWriteError() 242} 243 244// Flush flushes any buffered XML to the underlying writer. 245// See the EncodeToken documentation for details about when it is necessary. 246func (enc *Encoder) Flush() error { 247 return enc.p.Flush() 248} 249 250type printer struct { 251 *bufio.Writer 252 encoder *Encoder 253 seq int 254 indent string 255 prefix string 256 depth int 257 indentedIn bool 258 putNewline bool 259 attrNS map[string]string // map prefix -> name space 260 attrPrefix map[string]string // map name space -> prefix 261 prefixes []string 262 tags []Name 263} 264 265// createAttrPrefix finds the name space prefix attribute to use for the given name space, 266// defining a new prefix if necessary. It returns the prefix. 267func (p *printer) createAttrPrefix(url string) string { 268 if prefix := p.attrPrefix[url]; prefix != "" { 269 return prefix 270 } 271 272 // The "http://www.w3.org/XML/1998/namespace" name space is predefined as "xml" 273 // and must be referred to that way. 274 // (The "http://www.w3.org/2000/xmlns/" name space is also predefined as "xmlns", 275 // but users should not be trying to use that one directly - that's our job.) 276 if url == xmlURL { 277 return "xml" 278 } 279 280 // Need to define a new name space. 281 if p.attrPrefix == nil { 282 p.attrPrefix = make(map[string]string) 283 p.attrNS = make(map[string]string) 284 } 285 286 // Pick a name. We try to use the final element of the path 287 // but fall back to _. 288 prefix := strings.TrimRight(url, "/") 289 if i := strings.LastIndex(prefix, "/"); i >= 0 { 290 prefix = prefix[i+1:] 291 } 292 if prefix == "" || !isName([]byte(prefix)) || strings.Contains(prefix, ":") { 293 prefix = "_" 294 } 295 if strings.HasPrefix(prefix, "xml") { 296 // xmlanything is reserved. 297 prefix = "_" + prefix 298 } 299 if p.attrNS[prefix] != "" { 300 // Name is taken. Find a better one. 301 for p.seq++; ; p.seq++ { 302 if id := prefix + "_" + strconv.Itoa(p.seq); p.attrNS[id] == "" { 303 prefix = id 304 break 305 } 306 } 307 } 308 309 p.attrPrefix[url] = prefix 310 p.attrNS[prefix] = url 311 312 p.WriteString(`xmlns:`) 313 p.WriteString(prefix) 314 p.WriteString(`="`) 315 EscapeText(p, []byte(url)) 316 p.WriteString(`" `) 317 318 p.prefixes = append(p.prefixes, prefix) 319 320 return prefix 321} 322 323// deleteAttrPrefix removes an attribute name space prefix. 324func (p *printer) deleteAttrPrefix(prefix string) { 325 delete(p.attrPrefix, p.attrNS[prefix]) 326 delete(p.attrNS, prefix) 327} 328 329func (p *printer) markPrefix() { 330 p.prefixes = append(p.prefixes, "") 331} 332 333func (p *printer) popPrefix() { 334 for len(p.prefixes) > 0 { 335 prefix := p.prefixes[len(p.prefixes)-1] 336 p.prefixes = p.prefixes[:len(p.prefixes)-1] 337 if prefix == "" { 338 break 339 } 340 p.deleteAttrPrefix(prefix) 341 } 342} 343 344var ( 345 marshalerType = reflect.TypeOf((*Marshaler)(nil)).Elem() 346 marshalerAttrType = reflect.TypeOf((*MarshalerAttr)(nil)).Elem() 347 textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem() 348) 349 350// marshalValue writes one or more XML elements representing val. 351// If val was obtained from a struct field, finfo must have its details. 352func (p *printer) marshalValue(val reflect.Value, finfo *fieldInfo, startTemplate *StartElement) error { 353 if startTemplate != nil && startTemplate.Name.Local == "" { 354 return fmt.Errorf("xml: EncodeElement of StartElement with missing name") 355 } 356 357 if !val.IsValid() { 358 return nil 359 } 360 if finfo != nil && finfo.flags&fOmitEmpty != 0 && isEmptyValue(val) { 361 return nil 362 } 363 364 // Drill into interfaces and pointers. 365 // This can turn into an infinite loop given a cyclic chain, 366 // but it matches the Go 1 behavior. 367 for val.Kind() == reflect.Interface || val.Kind() == reflect.Ptr { 368 if val.IsNil() { 369 return nil 370 } 371 val = val.Elem() 372 } 373 374 kind := val.Kind() 375 typ := val.Type() 376 377 // Check for marshaler. 378 if val.CanInterface() && typ.Implements(marshalerType) { 379 return p.marshalInterface(val.Interface().(Marshaler), defaultStart(typ, finfo, startTemplate)) 380 } 381 if val.CanAddr() { 382 pv := val.Addr() 383 if pv.CanInterface() && pv.Type().Implements(marshalerType) { 384 return p.marshalInterface(pv.Interface().(Marshaler), defaultStart(pv.Type(), finfo, startTemplate)) 385 } 386 } 387 388 // Check for text marshaler. 389 if val.CanInterface() && typ.Implements(textMarshalerType) { 390 return p.marshalTextInterface(val.Interface().(encoding.TextMarshaler), defaultStart(typ, finfo, startTemplate)) 391 } 392 if val.CanAddr() { 393 pv := val.Addr() 394 if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { 395 return p.marshalTextInterface(pv.Interface().(encoding.TextMarshaler), defaultStart(pv.Type(), finfo, startTemplate)) 396 } 397 } 398 399 // Slices and arrays iterate over the elements. They do not have an enclosing tag. 400 if (kind == reflect.Slice || kind == reflect.Array) && typ.Elem().Kind() != reflect.Uint8 { 401 for i, n := 0, val.Len(); i < n; i++ { 402 if err := p.marshalValue(val.Index(i), finfo, startTemplate); err != nil { 403 return err 404 } 405 } 406 return nil 407 } 408 409 tinfo, err := getTypeInfo(typ) 410 if err != nil { 411 return err 412 } 413 414 // Create start element. 415 // Precedence for the XML element name is: 416 // 0. startTemplate 417 // 1. XMLName field in underlying struct; 418 // 2. field name/tag in the struct field; and 419 // 3. type name 420 var start StartElement 421 422 if startTemplate != nil { 423 start.Name = startTemplate.Name 424 start.Attr = append(start.Attr, startTemplate.Attr...) 425 } else if tinfo.xmlname != nil { 426 xmlname := tinfo.xmlname 427 if xmlname.name != "" { 428 start.Name.Space, start.Name.Local = xmlname.xmlns, xmlname.name 429 } else if v, ok := xmlname.value(val).Interface().(Name); ok && v.Local != "" { 430 start.Name = v 431 } 432 } 433 if start.Name.Local == "" && finfo != nil { 434 start.Name.Space, start.Name.Local = finfo.xmlns, finfo.name 435 } 436 if start.Name.Local == "" { 437 name := typ.Name() 438 if name == "" { 439 return &UnsupportedTypeError{typ} 440 } 441 start.Name.Local = name 442 } 443 444 // Add type attribute if necessary 445 if finfo != nil && finfo.flags&fTypeAttr != 0 { 446 start.Attr = append(start.Attr, Attr{xmlSchemaInstance, typeToString(typ)}) 447 } 448 449 // Attributes 450 for i := range tinfo.fields { 451 finfo := &tinfo.fields[i] 452 if finfo.flags&fAttr == 0 { 453 continue 454 } 455 fv := finfo.value(val) 456 name := Name{Space: finfo.xmlns, Local: finfo.name} 457 458 if finfo.flags&fOmitEmpty != 0 && isEmptyValue(fv) { 459 continue 460 } 461 462 if fv.Kind() == reflect.Interface && fv.IsNil() { 463 continue 464 } 465 466 if fv.CanInterface() && fv.Type().Implements(marshalerAttrType) { 467 attr, err := fv.Interface().(MarshalerAttr).MarshalXMLAttr(name) 468 if err != nil { 469 return err 470 } 471 if attr.Name.Local != "" { 472 start.Attr = append(start.Attr, attr) 473 } 474 continue 475 } 476 477 if fv.CanAddr() { 478 pv := fv.Addr() 479 if pv.CanInterface() && pv.Type().Implements(marshalerAttrType) { 480 attr, err := pv.Interface().(MarshalerAttr).MarshalXMLAttr(name) 481 if err != nil { 482 return err 483 } 484 if attr.Name.Local != "" { 485 start.Attr = append(start.Attr, attr) 486 } 487 continue 488 } 489 } 490 491 if fv.CanInterface() && fv.Type().Implements(textMarshalerType) { 492 text, err := fv.Interface().(encoding.TextMarshaler).MarshalText() 493 if err != nil { 494 return err 495 } 496 start.Attr = append(start.Attr, Attr{name, string(text)}) 497 continue 498 } 499 500 if fv.CanAddr() { 501 pv := fv.Addr() 502 if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { 503 text, err := pv.Interface().(encoding.TextMarshaler).MarshalText() 504 if err != nil { 505 return err 506 } 507 start.Attr = append(start.Attr, Attr{name, string(text)}) 508 continue 509 } 510 } 511 512 // Dereference or skip nil pointer, interface values. 513 switch fv.Kind() { 514 case reflect.Ptr, reflect.Interface: 515 if fv.IsNil() { 516 continue 517 } 518 fv = fv.Elem() 519 } 520 521 s, b, err := p.marshalSimple(fv.Type(), fv) 522 if err != nil { 523 return err 524 } 525 if b != nil { 526 s = string(b) 527 } 528 start.Attr = append(start.Attr, Attr{name, s}) 529 } 530 531 if err := p.writeStart(&start); err != nil { 532 return err 533 } 534 535 if val.Kind() == reflect.Struct { 536 err = p.marshalStruct(tinfo, val) 537 } else { 538 s, b, err1 := p.marshalSimple(typ, val) 539 if err1 != nil { 540 err = err1 541 } else if b != nil { 542 EscapeText(p, b) 543 } else { 544 p.EscapeString(s) 545 } 546 } 547 if err != nil { 548 return err 549 } 550 551 if err := p.writeEnd(start.Name); err != nil { 552 return err 553 } 554 555 return p.cachedWriteError() 556} 557 558// defaultStart returns the default start element to use, 559// given the reflect type, field info, and start template. 560func defaultStart(typ reflect.Type, finfo *fieldInfo, startTemplate *StartElement) StartElement { 561 var start StartElement 562 // Precedence for the XML element name is as above, 563 // except that we do not look inside structs for the first field. 564 if startTemplate != nil { 565 start.Name = startTemplate.Name 566 start.Attr = append(start.Attr, startTemplate.Attr...) 567 } else if finfo != nil && finfo.name != "" { 568 start.Name.Local = finfo.name 569 start.Name.Space = finfo.xmlns 570 } else if typ.Name() != "" { 571 start.Name.Local = typ.Name() 572 } else { 573 // Must be a pointer to a named type, 574 // since it has the Marshaler methods. 575 start.Name.Local = typ.Elem().Name() 576 } 577 578 // Add type attribute if necessary 579 if finfo != nil && finfo.flags&fTypeAttr != 0 { 580 start.Attr = append(start.Attr, Attr{xmlSchemaInstance, typeToString(typ)}) 581 } 582 583 return start 584} 585 586// marshalInterface marshals a Marshaler interface value. 587func (p *printer) marshalInterface(val Marshaler, start StartElement) error { 588 // Push a marker onto the tag stack so that MarshalXML 589 // cannot close the XML tags that it did not open. 590 p.tags = append(p.tags, Name{}) 591 n := len(p.tags) 592 593 err := val.MarshalXML(p.encoder, start) 594 if err != nil { 595 return err 596 } 597 598 // Make sure MarshalXML closed all its tags. p.tags[n-1] is the mark. 599 if len(p.tags) > n { 600 return fmt.Errorf("xml: %s.MarshalXML wrote invalid XML: <%s> not closed", receiverType(val), p.tags[len(p.tags)-1].Local) 601 } 602 p.tags = p.tags[:n-1] 603 return nil 604} 605 606// marshalTextInterface marshals a TextMarshaler interface value. 607func (p *printer) marshalTextInterface(val encoding.TextMarshaler, start StartElement) error { 608 if err := p.writeStart(&start); err != nil { 609 return err 610 } 611 text, err := val.MarshalText() 612 if err != nil { 613 return err 614 } 615 EscapeText(p, text) 616 return p.writeEnd(start.Name) 617} 618 619// writeStart writes the given start element. 620func (p *printer) writeStart(start *StartElement) error { 621 if start.Name.Local == "" { 622 return fmt.Errorf("xml: start tag with no name") 623 } 624 625 p.tags = append(p.tags, start.Name) 626 p.markPrefix() 627 628 p.writeIndent(1) 629 p.WriteByte('<') 630 p.WriteString(start.Name.Local) 631 632 if start.Name.Space != "" { 633 p.WriteString(` xmlns="`) 634 p.EscapeString(start.Name.Space) 635 p.WriteByte('"') 636 } 637 638 // Attributes 639 for _, attr := range start.Attr { 640 name := attr.Name 641 if name.Local == "" { 642 continue 643 } 644 p.WriteByte(' ') 645 if name.Space != "" { 646 p.WriteString(p.createAttrPrefix(name.Space)) 647 p.WriteByte(':') 648 } 649 p.WriteString(name.Local) 650 p.WriteString(`="`) 651 p.EscapeString(attr.Value) 652 p.WriteByte('"') 653 } 654 p.WriteByte('>') 655 return nil 656} 657 658func (p *printer) writeEnd(name Name) error { 659 if name.Local == "" { 660 return fmt.Errorf("xml: end tag with no name") 661 } 662 if len(p.tags) == 0 || p.tags[len(p.tags)-1].Local == "" { 663 return fmt.Errorf("xml: end tag </%s> without start tag", name.Local) 664 } 665 if top := p.tags[len(p.tags)-1]; top != name { 666 if top.Local != name.Local { 667 return fmt.Errorf("xml: end tag </%s> does not match start tag <%s>", name.Local, top.Local) 668 } 669 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) 670 } 671 p.tags = p.tags[:len(p.tags)-1] 672 673 p.writeIndent(-1) 674 p.WriteByte('<') 675 p.WriteByte('/') 676 p.WriteString(name.Local) 677 p.WriteByte('>') 678 p.popPrefix() 679 return nil 680} 681 682func (p *printer) marshalSimple(typ reflect.Type, val reflect.Value) (string, []byte, error) { 683 switch val.Kind() { 684 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: 685 return strconv.FormatInt(val.Int(), 10), nil, nil 686 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: 687 return strconv.FormatUint(val.Uint(), 10), nil, nil 688 case reflect.Float32, reflect.Float64: 689 return strconv.FormatFloat(val.Float(), 'g', -1, val.Type().Bits()), nil, nil 690 case reflect.String: 691 return val.String(), nil, nil 692 case reflect.Bool: 693 return strconv.FormatBool(val.Bool()), nil, nil 694 case reflect.Array: 695 if typ.Elem().Kind() != reflect.Uint8 { 696 break 697 } 698 // [...]byte 699 var bytes []byte 700 if val.CanAddr() { 701 bytes = val.Slice(0, val.Len()).Bytes() 702 } else { 703 bytes = make([]byte, val.Len()) 704 reflect.Copy(reflect.ValueOf(bytes), val) 705 } 706 return "", bytes, nil 707 case reflect.Slice: 708 if typ.Elem().Kind() != reflect.Uint8 { 709 break 710 } 711 // []byte 712 return "", val.Bytes(), nil 713 } 714 return "", nil, &UnsupportedTypeError{typ} 715} 716 717var ddBytes = []byte("--") 718 719func (p *printer) marshalStruct(tinfo *typeInfo, val reflect.Value) error { 720 s := parentStack{p: p} 721 for i := range tinfo.fields { 722 finfo := &tinfo.fields[i] 723 if finfo.flags&fAttr != 0 { 724 continue 725 } 726 vf := finfo.value(val) 727 728 // Dereference or skip nil pointer, interface values. 729 switch vf.Kind() { 730 case reflect.Ptr, reflect.Interface: 731 if !vf.IsNil() { 732 vf = vf.Elem() 733 } 734 } 735 736 switch finfo.flags & fMode { 737 case fCharData: 738 if vf.CanInterface() && vf.Type().Implements(textMarshalerType) { 739 data, err := vf.Interface().(encoding.TextMarshaler).MarshalText() 740 if err != nil { 741 return err 742 } 743 Escape(p, data) 744 continue 745 } 746 if vf.CanAddr() { 747 pv := vf.Addr() 748 if pv.CanInterface() && pv.Type().Implements(textMarshalerType) { 749 data, err := pv.Interface().(encoding.TextMarshaler).MarshalText() 750 if err != nil { 751 return err 752 } 753 Escape(p, data) 754 continue 755 } 756 } 757 var scratch [64]byte 758 switch vf.Kind() { 759 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: 760 Escape(p, strconv.AppendInt(scratch[:0], vf.Int(), 10)) 761 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: 762 Escape(p, strconv.AppendUint(scratch[:0], vf.Uint(), 10)) 763 case reflect.Float32, reflect.Float64: 764 Escape(p, strconv.AppendFloat(scratch[:0], vf.Float(), 'g', -1, vf.Type().Bits())) 765 case reflect.Bool: 766 Escape(p, strconv.AppendBool(scratch[:0], vf.Bool())) 767 case reflect.String: 768 if err := EscapeText(p, []byte(vf.String())); err != nil { 769 return err 770 } 771 case reflect.Slice: 772 if elem, ok := vf.Interface().([]byte); ok { 773 if err := EscapeText(p, elem); err != nil { 774 return err 775 } 776 } 777 } 778 continue 779 780 case fComment: 781 k := vf.Kind() 782 if !(k == reflect.String || k == reflect.Slice && vf.Type().Elem().Kind() == reflect.Uint8) { 783 return fmt.Errorf("xml: bad type for comment field of %s", val.Type()) 784 } 785 if vf.Len() == 0 { 786 continue 787 } 788 p.writeIndent(0) 789 p.WriteString("<!--") 790 dashDash := false 791 dashLast := false 792 switch k { 793 case reflect.String: 794 s := vf.String() 795 dashDash = strings.Index(s, "--") >= 0 796 dashLast = s[len(s)-1] == '-' 797 if !dashDash { 798 p.WriteString(s) 799 } 800 case reflect.Slice: 801 b := vf.Bytes() 802 dashDash = bytes.Index(b, ddBytes) >= 0 803 dashLast = b[len(b)-1] == '-' 804 if !dashDash { 805 p.Write(b) 806 } 807 default: 808 panic("can't happen") 809 } 810 if dashDash { 811 return fmt.Errorf(`xml: comments must not contain "--"`) 812 } 813 if dashLast { 814 // "--->" is invalid grammar. Make it "- -->" 815 p.WriteByte(' ') 816 } 817 p.WriteString("-->") 818 continue 819 820 case fInnerXml: 821 iface := vf.Interface() 822 switch raw := iface.(type) { 823 case []byte: 824 p.Write(raw) 825 continue 826 case string: 827 p.WriteString(raw) 828 continue 829 } 830 831 case fElement, fElement | fAny: 832 if err := s.trim(finfo.parents); err != nil { 833 return err 834 } 835 if len(finfo.parents) > len(s.stack) { 836 if vf.Kind() != reflect.Ptr && vf.Kind() != reflect.Interface || !vf.IsNil() { 837 if err := s.push(finfo.parents[len(s.stack):]); err != nil { 838 return err 839 } 840 } 841 } 842 } 843 if err := p.marshalValue(vf, finfo, nil); err != nil { 844 return err 845 } 846 } 847 s.trim(nil) 848 return p.cachedWriteError() 849} 850 851// return the bufio Writer's cached write error 852func (p *printer) cachedWriteError() error { 853 _, err := p.Write(nil) 854 return err 855} 856 857func (p *printer) writeIndent(depthDelta int) { 858 if len(p.prefix) == 0 && len(p.indent) == 0 { 859 return 860 } 861 if depthDelta < 0 { 862 p.depth-- 863 if p.indentedIn { 864 p.indentedIn = false 865 return 866 } 867 p.indentedIn = false 868 } 869 if p.putNewline { 870 p.WriteByte('\n') 871 } else { 872 p.putNewline = true 873 } 874 if len(p.prefix) > 0 { 875 p.WriteString(p.prefix) 876 } 877 if len(p.indent) > 0 { 878 for i := 0; i < p.depth; i++ { 879 p.WriteString(p.indent) 880 } 881 } 882 if depthDelta > 0 { 883 p.depth++ 884 p.indentedIn = true 885 } 886} 887 888type parentStack struct { 889 p *printer 890 stack []string 891} 892 893// trim updates the XML context to match the longest common prefix of the stack 894// and the given parents. A closing tag will be written for every parent 895// popped. Passing a zero slice or nil will close all the elements. 896func (s *parentStack) trim(parents []string) error { 897 split := 0 898 for ; split < len(parents) && split < len(s.stack); split++ { 899 if parents[split] != s.stack[split] { 900 break 901 } 902 } 903 for i := len(s.stack) - 1; i >= split; i-- { 904 if err := s.p.writeEnd(Name{Local: s.stack[i]}); err != nil { 905 return err 906 } 907 } 908 s.stack = parents[:split] 909 return nil 910} 911 912// push adds parent elements to the stack and writes open tags. 913func (s *parentStack) push(parents []string) error { 914 for i := 0; i < len(parents); i++ { 915 if err := s.p.writeStart(&StartElement{Name: Name{Local: parents[i]}}); err != nil { 916 return err 917 } 918 } 919 s.stack = append(s.stack, parents...) 920 return nil 921} 922 923// A MarshalXMLError is returned when Marshal encounters a type 924// that cannot be converted into XML. 925type UnsupportedTypeError struct { 926 Type reflect.Type 927} 928 929func (e *UnsupportedTypeError) Error() string { 930 return "xml: unsupported type: " + e.Type.String() 931} 932 933func isEmptyValue(v reflect.Value) bool { 934 switch v.Kind() { 935 case reflect.Array, reflect.Map, reflect.Slice, reflect.String: 936 return v.Len() == 0 937 case reflect.Bool: 938 return !v.Bool() 939 case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: 940 return v.Int() == 0 941 case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr: 942 return v.Uint() == 0 943 case reflect.Float32, reflect.Float64: 944 return v.Float() == 0 945 case reflect.Interface, reflect.Ptr: 946 return v.IsNil() 947 } 948 return false 949} 950