summaryrefslogtreecommitdiff
path: root/src/pkg/encoding/xml/read.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/pkg/encoding/xml/read.go')
-rw-r--r--src/pkg/encoding/xml/read.go531
1 files changed, 531 insertions, 0 deletions
diff --git a/src/pkg/encoding/xml/read.go b/src/pkg/encoding/xml/read.go
new file mode 100644
index 000000000..c21682420
--- /dev/null
+++ b/src/pkg/encoding/xml/read.go
@@ -0,0 +1,531 @@
+// Copyright 2009 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 (
+ "bytes"
+ "errors"
+ "reflect"
+ "strconv"
+ "strings"
+ "time"
+)
+
+// BUG(rsc): Mapping between XML elements and data structures is inherently flawed:
+// an XML element is an order-dependent collection of anonymous
+// values, while a data structure is an order-independent collection
+// of named values.
+// See package json for a textual representation more suitable
+// to data structures.
+
+// Unmarshal parses the XML-encoded data and stores the result in
+// the value pointed to by v, which must be an arbitrary struct,
+// slice, or string. Well-formed data that does not fit into v is
+// discarded.
+//
+// Because Unmarshal uses the reflect package, it can only assign
+// to exported (upper case) fields. Unmarshal uses a case-sensitive
+// comparison to match XML element names to tag values and struct
+// field names.
+//
+// Unmarshal maps an XML element to a struct using the following rules.
+// In the rules, the tag of a field refers to the value associated with the
+// key 'xml' in the struct field's tag (see the example above).
+//
+// * If the struct has a field of type []byte or string with tag
+// ",innerxml", Unmarshal accumulates the raw XML nested inside the
+// element in that field. The rest of the rules still apply.
+//
+// * If the struct has a field named XMLName of type xml.Name,
+// Unmarshal records the element name in that field.
+//
+// * If the XMLName field has an associated tag of the form
+// "name" or "namespace-URL name", the XML element must have
+// the given name (and, optionally, name space) or else Unmarshal
+// returns an error.
+//
+// * If the XML element has an attribute whose name matches a
+// struct field name with an associated tag containing ",attr" or
+// the explicit name in a struct field tag of the form "name,attr",
+// Unmarshal records the attribute value in that field.
+//
+// * If the XML element contains character data, that data is
+// accumulated in the first struct field that has tag "chardata".
+// The struct field may have type []byte or string.
+// If there is no such field, the character data is discarded.
+//
+// * If the XML element contains comments, they are accumulated in
+// the first struct field that has tag ",comments". The struct
+// field may have type []byte or string. If there is no such
+// field, the comments are discarded.
+//
+// * If the XML element contains a sub-element whose name matches
+// the prefix of a tag formatted as "a" or "a>b>c", unmarshal
+// will descend into the XML structure looking for elements with the
+// given names, and will map the innermost elements to that struct
+// field. A tag starting with ">" is equivalent to one starting
+// with the field name followed by ">".
+//
+// * If the XML element contains a sub-element whose name matches
+// a struct field's XMLName tag and the struct field has no
+// explicit name tag as per the previous rule, unmarshal maps
+// the sub-element to that struct field.
+//
+// * If the XML element contains a sub-element whose name matches a
+// field without any mode flags (",attr", ",chardata", etc), Unmarshal
+// maps the sub-element to that struct field.
+//
+// * If the XML element contains a sub-element that hasn't matched any
+// of the above rules and the struct has a field with tag ",any",
+// unmarshal maps the sub-element to that struct field.
+//
+// * A non-pointer anonymous struct field is handled as if the
+// fields of its value were part of the outer struct.
+//
+// * A struct field with tag "-" is never unmarshalled into.
+//
+// Unmarshal maps an XML element to a string or []byte by saving the
+// concatenation of that element's character data in the string or
+// []byte. The saved []byte is never nil.
+//
+// Unmarshal maps an attribute value to a string or []byte by saving
+// the value in the string or slice.
+//
+// Unmarshal maps an XML element to a slice by extending the length of
+// the slice and mapping the element to the newly created value.
+//
+// Unmarshal maps an XML element or attribute value to a bool by
+// setting it to the boolean value represented by the string.
+//
+// Unmarshal maps an XML element or attribute value to an integer or
+// floating-point field by setting the field to the result of
+// interpreting the string value in decimal. There is no check for
+// overflow.
+//
+// Unmarshal maps an XML element to an xml.Name by recording the
+// element name.
+//
+// Unmarshal maps an XML element to a pointer by setting the pointer
+// to a freshly allocated value and then mapping the element to that value.
+//
+func Unmarshal(data []byte, v interface{}) error {
+ return NewDecoder(bytes.NewBuffer(data)).Decode(v)
+}
+
+// Decode works like xml.Unmarshal, except it reads the decoder
+// stream to find the start element.
+func (d *Decoder) Decode(v interface{}) error {
+ return d.DecodeElement(v, nil)
+}
+
+// DecodeElement works like xml.Unmarshal except that it takes
+// a pointer to the start XML element to decode into v.
+// It is useful when a client reads some raw XML tokens itself
+// but also wants to defer to Unmarshal for some elements.
+func (d *Decoder) DecodeElement(v interface{}, start *StartElement) error {
+ val := reflect.ValueOf(v)
+ if val.Kind() != reflect.Ptr {
+ return errors.New("non-pointer passed to Unmarshal")
+ }
+ return d.unmarshal(val.Elem(), start)
+}
+
+// An UnmarshalError represents an error in the unmarshalling process.
+type UnmarshalError string
+
+func (e UnmarshalError) Error() string { return string(e) }
+
+// Unmarshal a single XML element into val.
+func (p *Decoder) unmarshal(val reflect.Value, start *StartElement) error {
+ // Find start element if we need it.
+ if start == nil {
+ for {
+ tok, err := p.Token()
+ if err != nil {
+ return err
+ }
+ if t, ok := tok.(StartElement); ok {
+ start = &t
+ break
+ }
+ }
+ }
+
+ if pv := val; pv.Kind() == reflect.Ptr {
+ if pv.IsNil() {
+ pv.Set(reflect.New(pv.Type().Elem()))
+ }
+ val = pv.Elem()
+ }
+
+ var (
+ data []byte
+ saveData reflect.Value
+ comment []byte
+ saveComment reflect.Value
+ saveXML reflect.Value
+ saveXMLIndex int
+ saveXMLData []byte
+ saveAny reflect.Value
+ sv reflect.Value
+ tinfo *typeInfo
+ err error
+ )
+
+ switch v := val; v.Kind() {
+ default:
+ return errors.New("unknown type " + v.Type().String())
+
+ case reflect.Interface:
+ // TODO: For now, simply ignore the field. In the near
+ // future we may choose to unmarshal the start
+ // element on it, if not nil.
+ return p.Skip()
+
+ case reflect.Slice:
+ typ := v.Type()
+ if typ.Elem().Kind() == reflect.Uint8 {
+ // []byte
+ saveData = v
+ break
+ }
+
+ // Slice of element values.
+ // Grow slice.
+ n := v.Len()
+ if n >= v.Cap() {
+ ncap := 2 * n
+ if ncap < 4 {
+ ncap = 4
+ }
+ new := reflect.MakeSlice(typ, n, ncap)
+ reflect.Copy(new, v)
+ v.Set(new)
+ }
+ v.SetLen(n + 1)
+
+ // Recur to read element into slice.
+ if err := p.unmarshal(v.Index(n), start); err != nil {
+ v.SetLen(n)
+ return err
+ }
+ return nil
+
+ case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr, reflect.String:
+ saveData = v
+
+ case reflect.Struct:
+ typ := v.Type()
+ if typ == nameType {
+ v.Set(reflect.ValueOf(start.Name))
+ break
+ }
+ if typ == timeType {
+ saveData = v
+ break
+ }
+
+ sv = v
+ tinfo, err = getTypeInfo(typ)
+ if err != nil {
+ return err
+ }
+
+ // Validate and assign element name.
+ if tinfo.xmlname != nil {
+ finfo := tinfo.xmlname
+ if finfo.name != "" && finfo.name != start.Name.Local {
+ return UnmarshalError("expected element type <" + finfo.name + "> but have <" + start.Name.Local + ">")
+ }
+ if finfo.xmlns != "" && finfo.xmlns != start.Name.Space {
+ e := "expected element <" + finfo.name + "> in name space " + finfo.xmlns + " but have "
+ if start.Name.Space == "" {
+ e += "no name space"
+ } else {
+ e += start.Name.Space
+ }
+ return UnmarshalError(e)
+ }
+ fv := sv.FieldByIndex(finfo.idx)
+ if _, ok := fv.Interface().(Name); ok {
+ fv.Set(reflect.ValueOf(start.Name))
+ }
+ }
+
+ // Assign attributes.
+ // Also, determine whether we need to save character data or comments.
+ for i := range tinfo.fields {
+ finfo := &tinfo.fields[i]
+ switch finfo.flags & fMode {
+ case fAttr:
+ strv := sv.FieldByIndex(finfo.idx)
+ // Look for attribute.
+ for _, a := range start.Attr {
+ if a.Name.Local == finfo.name {
+ copyValue(strv, []byte(a.Value))
+ break
+ }
+ }
+
+ case fCharData:
+ if !saveData.IsValid() {
+ saveData = sv.FieldByIndex(finfo.idx)
+ }
+
+ case fComment:
+ if !saveComment.IsValid() {
+ saveComment = sv.FieldByIndex(finfo.idx)
+ }
+
+ case fAny:
+ if !saveAny.IsValid() {
+ saveAny = sv.FieldByIndex(finfo.idx)
+ }
+
+ case fInnerXml:
+ if !saveXML.IsValid() {
+ saveXML = sv.FieldByIndex(finfo.idx)
+ if p.saved == nil {
+ saveXMLIndex = 0
+ p.saved = new(bytes.Buffer)
+ } else {
+ saveXMLIndex = p.savedOffset()
+ }
+ }
+ }
+ }
+ }
+
+ // Find end element.
+ // Process sub-elements along the way.
+Loop:
+ for {
+ var savedOffset int
+ if saveXML.IsValid() {
+ savedOffset = p.savedOffset()
+ }
+ tok, err := p.Token()
+ if err != nil {
+ return err
+ }
+ switch t := tok.(type) {
+ case StartElement:
+ consumed := false
+ if sv.IsValid() {
+ consumed, err = p.unmarshalPath(tinfo, sv, nil, &t)
+ if err != nil {
+ return err
+ }
+ if !consumed && saveAny.IsValid() {
+ consumed = true
+ if err := p.unmarshal(saveAny, &t); err != nil {
+ return err
+ }
+ }
+ }
+ if !consumed {
+ if err := p.Skip(); err != nil {
+ return err
+ }
+ }
+
+ case EndElement:
+ if saveXML.IsValid() {
+ saveXMLData = p.saved.Bytes()[saveXMLIndex:savedOffset]
+ if saveXMLIndex == 0 {
+ p.saved = nil
+ }
+ }
+ break Loop
+
+ case CharData:
+ if saveData.IsValid() {
+ data = append(data, t...)
+ }
+
+ case Comment:
+ if saveComment.IsValid() {
+ comment = append(comment, t...)
+ }
+ }
+ }
+
+ if err := copyValue(saveData, data); err != nil {
+ return err
+ }
+
+ switch t := saveComment; t.Kind() {
+ case reflect.String:
+ t.SetString(string(comment))
+ case reflect.Slice:
+ t.Set(reflect.ValueOf(comment))
+ }
+
+ switch t := saveXML; t.Kind() {
+ case reflect.String:
+ t.SetString(string(saveXMLData))
+ case reflect.Slice:
+ t.Set(reflect.ValueOf(saveXMLData))
+ }
+
+ return nil
+}
+
+func copyValue(dst reflect.Value, src []byte) (err error) {
+ // Helper functions for integer and unsigned integer conversions
+ var itmp int64
+ getInt64 := func() bool {
+ itmp, err = strconv.ParseInt(string(src), 10, 64)
+ // TODO: should check sizes
+ return err == nil
+ }
+ var utmp uint64
+ getUint64 := func() bool {
+ utmp, err = strconv.ParseUint(string(src), 10, 64)
+ // TODO: check for overflow?
+ return err == nil
+ }
+ var ftmp float64
+ getFloat64 := func() bool {
+ ftmp, err = strconv.ParseFloat(string(src), 64)
+ // TODO: check for overflow?
+ return err == nil
+ }
+
+ // Save accumulated data.
+ switch t := dst; t.Kind() {
+ case reflect.Invalid:
+ // Probably a comment.
+ default:
+ return errors.New("cannot happen: unknown type " + t.Type().String())
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ if !getInt64() {
+ return err
+ }
+ t.SetInt(itmp)
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+ if !getUint64() {
+ return err
+ }
+ t.SetUint(utmp)
+ case reflect.Float32, reflect.Float64:
+ if !getFloat64() {
+ return err
+ }
+ t.SetFloat(ftmp)
+ case reflect.Bool:
+ value, err := strconv.ParseBool(strings.TrimSpace(string(src)))
+ if err != nil {
+ return err
+ }
+ t.SetBool(value)
+ case reflect.String:
+ t.SetString(string(src))
+ case reflect.Slice:
+ if len(src) == 0 {
+ // non-nil to flag presence
+ src = []byte{}
+ }
+ t.SetBytes(src)
+ case reflect.Struct:
+ if t.Type() == timeType {
+ tv, err := time.Parse(time.RFC3339, string(src))
+ if err != nil {
+ return err
+ }
+ t.Set(reflect.ValueOf(tv))
+ }
+ }
+ return nil
+}
+
+// unmarshalPath walks down an XML structure looking for wanted
+// paths, and calls unmarshal on them.
+// The consumed result tells whether XML elements have been consumed
+// from the Decoder until start's matching end element, or if it's
+// still untouched because start is uninteresting for sv's fields.
+func (p *Decoder) unmarshalPath(tinfo *typeInfo, sv reflect.Value, parents []string, start *StartElement) (consumed bool, err error) {
+ recurse := false
+Loop:
+ for i := range tinfo.fields {
+ finfo := &tinfo.fields[i]
+ if finfo.flags&fElement == 0 || len(finfo.parents) < len(parents) {
+ continue
+ }
+ for j := range parents {
+ if parents[j] != finfo.parents[j] {
+ continue Loop
+ }
+ }
+ if len(finfo.parents) == len(parents) && finfo.name == start.Name.Local {
+ // It's a perfect match, unmarshal the field.
+ return true, p.unmarshal(sv.FieldByIndex(finfo.idx), start)
+ }
+ if len(finfo.parents) > len(parents) && finfo.parents[len(parents)] == start.Name.Local {
+ // It's a prefix for the field. Break and recurse
+ // since it's not ok for one field path to be itself
+ // the prefix for another field path.
+ recurse = true
+
+ // We can reuse the same slice as long as we
+ // don't try to append to it.
+ parents = finfo.parents[:len(parents)+1]
+ break
+ }
+ }
+ if !recurse {
+ // We have no business with this element.
+ return false, nil
+ }
+ // The element is not a perfect match for any field, but one
+ // or more fields have the path to this element as a parent
+ // prefix. Recurse and attempt to match these.
+ for {
+ var tok Token
+ tok, err = p.Token()
+ if err != nil {
+ return true, err
+ }
+ switch t := tok.(type) {
+ case StartElement:
+ consumed2, err := p.unmarshalPath(tinfo, sv, parents, &t)
+ if err != nil {
+ return true, err
+ }
+ if !consumed2 {
+ if err := p.Skip(); err != nil {
+ return true, err
+ }
+ }
+ case EndElement:
+ return true, nil
+ }
+ }
+ panic("unreachable")
+}
+
+// Skip reads tokens until it has consumed the end element
+// matching the most recent start element already consumed.
+// It recurs if it encounters a start element, so it can be used to
+// skip nested structures.
+// It returns nil if it finds an end element matching the start
+// element; otherwise it returns an error describing the problem.
+func (d *Decoder) Skip() error {
+ for {
+ tok, err := d.Token()
+ if err != nil {
+ return err
+ }
+ switch tok.(type) {
+ case StartElement:
+ if err := d.Skip(); err != nil {
+ return err
+ }
+ case EndElement:
+ return nil
+ }
+ }
+ panic("unreachable")
+}
generated by cgit v1.2.3 (git 2.46.0) at 2025-10-12 00:55:53 +0000