Functions
Close
method
#
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
Close
method
#
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
Copy
method
#
Copy creates a new copy of ProcInst.
func (p ProcInst) Copy() ProcInst
Copy
method
#
Copy creates a new copy of CharData.
func (c CharData) Copy() CharData
Copy
method
#
Copy creates a new copy of Comment.
func (c Comment) Copy() Comment
Copy
method
#
Copy creates a new copy of StartElement.
func (e StartElement) Copy() StartElement
Copy
method
#
Copy creates a new copy of Directive.
func (d Directive) Copy() Directive
CopyToken
function
#
CopyToken returns a copy of a Token.
func CopyToken(t Token) Token
Decode
method
#
Decode works like [Unmarshal], except it reads the decoder
stream to find the start element.
func (d *Decoder) Decode(v any) error
DecodeElement
method
#
DecodeElement works like [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 any, start *StartElement) error
Encode
method
#
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
EncodeElement
method
#
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
EncodeToken
method
#
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
End
method
#
End returns the corresponding XML end element.
func (e StartElement) End() EndElement
Error
method
#
func (e *TagPathError) Error() string
Error
method
#
func (e *SyntaxError) Error() string
Error
method
#
func (e UnmarshalError) Error() string
Error
method
#
func (e *UnsupportedTypeError) Error() string
Escape
function
#
Escape is like [EscapeText] but omits the error return value.
It is provided for backwards compatibility with Go 1.0.
Code targeting Go 1.1 or later should use [EscapeText].
func Escape(w io.Writer, s []byte)
EscapeString
method
#
EscapeString writes to p the properly escaped XML equivalent
of the plain text data s.
func (p *printer) EscapeString(s string)
EscapeText
function
#
EscapeText writes to w the properly escaped XML equivalent
of the plain text data s.
func EscapeText(w io.Writer, s []byte) error
Flush
method
#
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
Indent
method
#
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 string, indent string)
InputOffset
method
#
InputOffset returns the input stream byte offset of the current decoder position.
The offset gives the location of the end of the most recently returned token
and the beginning of the next token.
func (d *Decoder) InputOffset() int64
InputPos
method
#
InputPos returns the line of the current decoder position and the 1 based
input position of the line. The position gives the location of the end of the
most recently returned token.
func (d *Decoder) InputPos() (line int, column int)
Marshal
function
#
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.
- an anonymous struct field of interface type is treated the same as having
that type as its name, rather than being anonymous.
- 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)
MarshalIndent
function
#
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 string, indent string) ([]byte, error)
NewDecoder
function
#
NewDecoder creates a new XML parser reading from r.
If r does not implement [io.ByteReader], NewDecoder will
do its own buffering.
func NewDecoder(r io.Reader) *Decoder
NewEncoder
function
#
NewEncoder returns a new encoder that writes to w.
func NewEncoder(w io.Writer) *Encoder
NewTokenDecoder
function
#
NewTokenDecoder creates a new XML parser using an underlying token stream.
func NewTokenDecoder(t TokenReader) *Decoder
RawToken
method
#
RawToken is like [Decoder.Token] but does not verify that
start and end elements match and does not translate
name space prefixes to their corresponding URLs.
func (d *Decoder) RawToken() (Token, error)
Skip
method
#
Skip reads tokens until it has consumed the end element
matching the most recent start element already consumed,
skipping 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
Token
method
#
Token returns the next XML token in the input stream.
At the end of the input stream, Token returns nil, [io.EOF].
Slices of bytes in the returned token data refer to the
parser's internal buffer and remain valid only until the next
call to Token. To acquire a copy of the bytes, call [CopyToken]
or the token's Copy method.
Token expands self-closing elements such as
into separate start and end elements returned by successive calls.
Token guarantees that the [StartElement] and [EndElement]
tokens it returns are properly nested and matched:
if Token encounters an unexpected end element
or EOF before all expected end elements,
it will return an error.
If [Decoder.CharsetReader] is called and returns an error,
the error is wrapped and returned.
Token implements XML name spaces as described by
https://www.w3.org/TR/REC-xml-names/. Each of the
[Name] structures contained in the Token has the Space
set to the URL identifying its name space when known.
If Token encounters an unrecognized name space prefix,
it uses the prefix as the Space rather than report an error.
func (d *Decoder) Token() (Token, error)
Unmarshal
function
#
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 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 has an attribute not handled by the previous
rule and the struct has a field with an associated tag containing
",any,attr", Unmarshal records the attribute value in the first
such 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 ",comment". 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.
- An 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 unmarshaled into.
If Unmarshal encounters a field type that implements the Unmarshaler
interface, Unmarshal calls its UnmarshalXML method to produce the value from
the XML element. Otherwise, if the value implements
[encoding.TextUnmarshaler], Unmarshal calls that value's UnmarshalText method.
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 attribute value to an [Attr] by saving the attribute,
including its name, in the Attr.
Unmarshal maps an XML element or attribute value to a slice by
extending the length of the slice and mapping the element or attribute
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. Whitespace
is trimmed and ignored.
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. Whitespace is trimmed and ignored.
Unmarshal maps an XML element to a 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.
A missing element or empty attribute value will be unmarshaled as a zero value.
If the field is a slice, a zero value will be appended to the field. Otherwise, the
field will be set to its zero value.
func Unmarshal(data []byte, v any) error
Write
method
#
Write implements io.Writer
func (p *printer) Write(b []byte) (n int, err error)
WriteByte
method
#
WriteByte implements io.ByteWriter
func (p *printer) WriteByte(c byte) error
WriteString
method
#
WriteString implements io.StringWriter
func (p *printer) WriteString(s string) (n int, err error)
addFieldInfo
function
#
addFieldInfo adds finfo to tinfo.fields if there are no
conflicts, or if conflicts arise from previous fields that were
obtained from deeper embedded structures than finfo. In the latter
case, the conflicting entries are dropped.
A conflict occurs when the path (parent + name) to a field is
itself a prefix of another path, or when two paths match exactly.
It is okay for field paths to share a common, shorter prefix.
func addFieldInfo(typ reflect.Type, tinfo *typeInfo, newf *fieldInfo) error
attrval
method
#
func (d *Decoder) attrval() []byte
autoClose
method
#
If the top element on the stack is autoclosing and
t is not the end tag, invent the end tag.
func (d *Decoder) autoClose(t Token) (Token, bool)
cachedWriteError
method
#
return the bufio Writer's cached write error
func (p *printer) cachedWriteError() error
copyValue
function
#
func copyValue(dst reflect.Value, src []byte) (err error)
createAttrPrefix
method
#
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
defaultStart
function
#
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
deleteAttrPrefix
method
#
deleteAttrPrefix removes an attribute name space prefix.
func (p *printer) deleteAttrPrefix(prefix string)
emitCDATA
function
#
emitCDATA writes to w the CDATA-wrapped plain text data s.
It escapes CDATA directives nested in s.
func emitCDATA(w io.Writer, s []byte) error
escapeText
function
#
escapeText writes to w the properly escaped XML equivalent
of the plain text data s. If escapeNewline is true, newline
characters will be escaped.
func escapeText(w io.Writer, s []byte, escapeNewline bool) error
getTypeInfo
function
#
getTypeInfo returns the typeInfo structure with details necessary
for marshaling and unmarshaling typ.
func getTypeInfo(typ reflect.Type) (*typeInfo, error)
getc
method
#
Read a single byte.
If there is no byte to read, return ok==false
and leave the error in d.err.
Maintain line number.
func (d *Decoder) getc() (b byte, ok bool)
indirect
function
#
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
isEmptyValue
function
#
func isEmptyValue(v reflect.Value) bool
isInCharacterRange
function
#
Decide whether the given rune is in the XML Character Range, per
the Char production of https://www.xml.com/axml/testaxml.htm,
Section 2.2 Characters.
func isInCharacterRange(r rune) (inrange bool)
isName
function
#
func isName(s []byte) bool
isNameByte
function
#
func isNameByte(c byte) bool
isNameString
function
#
func isNameString(s string) bool
isValidDirective
function
#
isValidDirective reports whether dir is a valid directive text,
meaning angle brackets are matched, ignoring comments and strings.
func isValidDirective(dir Directive) bool
lookupXMLName
function
#
lookupXMLName returns the fieldInfo for typ's XMLName field
in case it exists and has a valid xml field tag, otherwise
it returns nil.
func lookupXMLName(typ reflect.Type) (xmlname *fieldInfo)
markPrefix
method
#
func (p *printer) markPrefix()
marshalAttr
method
#
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
marshalInterface
method
#
marshalInterface marshals a Marshaler interface value.
func (p *printer) marshalInterface(val Marshaler, start StartElement) error
marshalSimple
method
#
func (p *printer) marshalSimple(typ reflect.Type, val reflect.Value) (string, []byte, error)
marshalStruct
method
#
func (p *printer) marshalStruct(tinfo *typeInfo, val reflect.Value) error
marshalTextInterface
method
#
marshalTextInterface marshals a TextMarshaler interface value.
func (p *printer) marshalTextInterface(val encoding.TextMarshaler, start StartElement) error
marshalValue
method
#
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
mustgetc
method
#
Must read a single byte.
If there is no byte to read,
set d.err to SyntaxError("unexpected EOF")
and return ok==false
func (d *Decoder) mustgetc() (b byte, ok bool)
name
method
#
Get name: /first(first|second)
Do not set d.err if the name is missing (unless unexpected EOF is received):
let the caller provide better context.
func (d *Decoder) name() (s string, ok bool)
nsname
method
#
Get name space name: name with a : stuck in the middle.
The part before the : is the name space identifier.
func (d *Decoder) nsname() (name Name, ok bool)
pop
method
#
func (d *Decoder) pop() *stack
popEOF
method
#
Undo a pushEOF.
The element must have been finished, so the EOF should be at the top of the stack.
func (d *Decoder) popEOF() bool
popElement
method
#
Record that we are ending an element with the given name.
The name must match the record at the top of the stack,
which must be a pushElement record.
After popping the element, apply any undo records from
the stack to restore the name translations that existed
before we saw this element.
func (d *Decoder) popElement(t *EndElement) bool
popPrefix
method
#
func (p *printer) popPrefix()
procInst
function
#
procInst parses the `param="..."` or `param='...'`
value out of the provided string, returning "" if not found.
func procInst(param string, s string) string
push
method
#
push adds parent elements to the stack and writes open tags.
func (s *parentStack) push(parents []string) error
push
method
#
func (d *Decoder) push(kind int) *stack
pushEOF
method
#
Record that after the current element is finished
(that element is already pushed on the stack)
Token should return EOF until popEOF is called.
func (d *Decoder) pushEOF()
pushElement
method
#
Record that we are starting an element with the given name.
func (d *Decoder) pushElement(name Name)
pushNs
method
#
Record that we are changing the value of ns[local].
The old value is url, ok.
func (d *Decoder) pushNs(local string, url string, ok bool)
rawToken
method
#
func (d *Decoder) rawToken() (Token, error)
readName
method
#
Read a name and append its bytes to d.buf.
The name is delimited by any single-byte character not valid in names.
All multi-byte characters are accepted; the caller must check their validity.
func (d *Decoder) readName() (ok bool)
receiverType
function
#
receiverType returns the receiver type to use in an expression like "%s.MethodName".
func receiverType(val any) string
savedOffset
method
#
Return saved offset.
If we did ungetc (nextByte >= 0), have to back up one.
func (d *Decoder) savedOffset() int
space
method
#
Skip spaces if any
func (d *Decoder) space()
structFieldInfo
function
#
structFieldInfo builds and returns a fieldInfo for f.
func structFieldInfo(typ reflect.Type, f *reflect.StructField) (*fieldInfo, error)
switchToReader
method
#
func (d *Decoder) switchToReader(r io.Reader)
syntaxError
method
#
Creates a SyntaxError with the current line number.
func (d *Decoder) syntaxError(msg string) error
text
method
#
Read plain text section (XML calls it character data).
If quote >= 0, we are in a quoted string and need to find the matching quote.
If cdata == true, we are in a .
On failure return nil and leave the error in d.err.
func (d *Decoder) text(quote int, cdata bool) []byte
translate
method
#
Apply name space translation to name n.
The default name space (for Space=="")
applies only to element names, not to attribute names.
func (d *Decoder) translate(n *Name, isElementName bool)
trim
method
#
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
ungetc
method
#
Unread a single byte.
func (d *Decoder) ungetc(b byte)
unmarshal
method
#
Unmarshal a single XML element into val.
func (d *Decoder) unmarshal(val reflect.Value, start *StartElement, depth int) error
unmarshalAttr
method
#
unmarshalAttr unmarshals a single XML attribute into val.
func (d *Decoder) unmarshalAttr(val reflect.Value, attr Attr) error
unmarshalInterface
method
#
unmarshalInterface unmarshals a single XML element into val.
start is the opening tag of the element.
func (d *Decoder) unmarshalInterface(val Unmarshaler, start *StartElement) error
unmarshalPath
method
#
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 (d *Decoder) unmarshalPath(tinfo *typeInfo, sv reflect.Value, parents []string, start *StartElement, depth int) (consumed bool, err error)
unmarshalTextInterface
method
#
unmarshalTextInterface unmarshals a single XML element into val.
The chardata contained in the element (but not its children)
is passed to the text unmarshaler.
func (d *Decoder) unmarshalTextInterface(val encoding.TextUnmarshaler) error
value
method
#
value returns v's field value corresponding to finfo.
It's equivalent to v.FieldByIndex(finfo.idx), but when passed
initNilPointers, it initializes and dereferences pointers as necessary.
When passed dontInitNilPointers and a nil pointer is reached, the function
returns a zero reflect.Value.
func (finfo *fieldInfo) value(v reflect.Value, shouldInitNilPointers bool) reflect.Value
writeEnd
method
#
func (p *printer) writeEnd(name Name) error
writeIndent
method
#
func (p *printer) writeIndent(depthDelta int)
writeStart
method
#
writeStart writes the given start element.
func (p *printer) writeStart(start *StartElement) error