README
mellium.im/xmlstream
An API for manipulating XML streams in Go; io
but for XML.
To use it in your project, import it like so:
import "mellium.im/xmlstream"
If you'd like to contribute to the project, see CONTRIBUTING.md.
License
The package may be used under the terms of the BSD 2-Clause License a copy of which may be found in the LICENSE file. Some code in this package has been copied from Go and is used under the terms of Go's modified BSD license, a copy of which can be found in the LICENSE-GO file.
Unless you explicitly state otherwise, any contribution submitted for inclusion in the work by you shall be licensed as above, without any additional terms or conditions.
Documentation
Overview ¶
Package xmlstream provides an API for streaming, transforming, and otherwise manipulating XML data.
BE ADVISED: The API is unstable and subject to change.
Index ¶
- Variables
- func Copy(dst TokenWriter, src xml.TokenReader) (n int, err error)
- func Fmt(d xml.TokenReader, opts ...FmtOption) xml.TokenReader
- func Inner(r xml.TokenReader) xml.TokenReader
- func InnerElement(r xml.TokenReader) xml.TokenReader
- func InnerReader(r io.Reader) io.Reader
- func LimitReader(r xml.TokenReader, n uint) xml.TokenReader
- func MultiReader(readers ...xml.TokenReader) xml.TokenReader
- func Pipe() (*PipeReader, *PipeWriter)
- func ReadAll(r xml.TokenReader) ([]xml.Token, error)
- func Skip(r xml.TokenReader) error
- func TeeReader(r xml.TokenReader, w TokenWriter) xml.TokenReader
- func Token(t xml.Token) xml.TokenReader
- func Unwrap(r xml.TokenReader) (xml.TokenReader, xml.Token, error)
- func Wrap(r xml.TokenReader, start xml.StartElement) xml.TokenReader
- type DecodeCloser
- type DecodeEncoder
- type Decoder
- type EncodeCloser
- type Encoder
- type Flusher
- type FmtOption
- type Iter
- type Marshaler
- type PipeReader
- type PipeWriter
- type ReaderFrom
- type ReaderFunc
- type TokenReadCloser
- type TokenReadEncoder
- type TokenReadWriteCloser
- type TokenReadWriter
- type TokenWriteCloser
- type TokenWriteFlushCloser
- type TokenWriteFlusher
- type TokenWriter
- type Transformer
- func Insert(name xml.Name, m Marshaler) Transformer
- func InsertFunc(f func(start xml.StartElement, level uint64, w TokenWriter) error) Transformer
- func Inspect(f func(t xml.Token)) Transformer
- func Map(mapping func(t xml.Token) xml.Token) Transformer
- func Remove(f func(t xml.Token) bool) Transformer
- func RemoveAttr(f func(start xml.StartElement, attr xml.Attr) bool) Transformer
- func RemoveElement(f func(start xml.StartElement) bool) Transformer
- type WriterTo
- Bugs
Examples ¶
Constants ¶
Variables ¶
var ErrClosedPipe = errors.New("xmlstream: read/write on closed pipe")
ErrClosedPipe is the error used for read or write operations on a closed pipe.
Functions ¶
func Copy ¶
func Copy(dst TokenWriter, src xml.TokenReader) (n int, err error)
Copy consumes a xml.TokenReader and writes its tokens to a TokenWriter until either io.EOF is reached on src or an error occurs. It returns the number of tokens copied and the first error encountered while copying, if any. If an error is returned by the reader or writer, copy returns it immediately. Since Copy is defined as consuming the stream until the end, io.EOF is not returned.
If src implements the WriterTo interface, the copy is implemented by calling src.WriteXML(dst). Otherwise, if dst implements the ReaderFrom interface, the copy is implemented by calling dst.ReadXML(src).
func Fmt ¶
func Fmt(d xml.TokenReader, opts ...FmtOption) xml.TokenReader
Fmt returns a transformer that indents the given XML stream. The default indentation style is to remove non-significant whitespace, start elements on a new line and indent two spaces per level.
Example (Indentation) ¶
Output: <quote> <p> <!-- Chardata is not indented --> How now, my hearts! did you never see the picture of 'we three'? </p> </quote>
func Inner ¶
func Inner(r xml.TokenReader) xml.TokenReader
Inner returns a new TokenReader that returns nil, io.EOF when it consumes the end element matching the most recent start element already consumed.
func InnerElement ¶
func InnerElement(r xml.TokenReader) xml.TokenReader
InnerElement wraps a TokenReader to return nil, io.EOF after returning the end element matching the most recent start element already consumed. It is like Inner except that it returns the end element.
func InnerReader ¶
InnerReader is an io.Reader which attempts to decode an xml.StartElement from the stream on the first call to Read (returning an error if an invalid start token is found) and returns a new reader which only reads the inner XML without parsing it or checking its validity. After the inner XML is read, the end token is parsed and if it does not exist or does not match the original start token an error is returned.
func LimitReader ¶
func LimitReader(r xml.TokenReader, n uint) xml.TokenReader
LimitReader returns a xml.TokenReader that reads from r but stops with EOF after n tokens (regardless of the validity of the XML at that point in the stream).
func MultiReader ¶
func MultiReader(readers ...xml.TokenReader) xml.TokenReader
MultiReader returns an xml.TokenReader that's the logical concatenation of the provided input readers. They're read sequentially. Once all inputs have returned io.EOF, Token will return io.EOF. If any of the readers return a non-nil, non-EOF error, Token will return that error.
Example ¶
Output: <title>Dover Beach</title> <author>Matthew Arnold</author> <incipit>The sea is calm to-night.</incipit>
func Pipe ¶
func Pipe() (*PipeReader, *PipeWriter)
Pipe creates a synchronous in-memory pipe of tokens. It can be used to connect code expecting an TokenReader with code expecting an xmlstream.TokenWriter.
Reads and Writes on the pipe are matched one to one. That is, each Write to the PipeWriter blocks until it has satisfied a Read from the corresponding PipeReader.
It is safe to call Read and Write in parallel with each other or with Close. Parallel calls to Read and parallel calls to Write are also safe: the individual calls will be gated sequentially.
func ReadAll ¶
func ReadAll(r xml.TokenReader) ([]xml.Token, error)
ReadAll reads from r until an error or io.EOF and returns the data it reads. A successful call returns err == nil, not err == io.EOF. Because ReadAll is defined to read from src until io.EOF, it does not treat an io.EOF from Read as an error to be reported.
func Skip ¶
func Skip(r xml.TokenReader) error
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 at the same nesting level as the start element; otherwise it returns an error describing the problem. Skip does not verify that the start and end elements match.
func TeeReader ¶
func TeeReader(r xml.TokenReader, w TokenWriter) xml.TokenReader
TeeReader returns a Reader that writes to w what it reads from r. All reads from r performed through it are matched with corresponding writes to w. There is no internal buffering - the write must complete before the read completes. Any error encountered while writing is reported as a read error.
func Token ¶
func Token(t xml.Token) xml.TokenReader
Token returns a reader that returns the given token and io.EOF, then nil io.EOF thereafter.
func Unwrap ¶
func Unwrap(r xml.TokenReader) (xml.TokenReader, xml.Token, error)
Unwrap reads the next token from the provided TokenReader and, if it is a start element, returns a new TokenReader that skips the corresponding end element. If the token is not a start element the original TokenReader is returned.
Example ¶
Output: message: <body>No mind that ever lived stands firm in evil days, but goes astray.</body>
func Wrap ¶
func Wrap(r xml.TokenReader, start xml.StartElement) xml.TokenReader
Wrap wraps a token stream in a start element and its corresponding end element.
Example ¶
Output: <message from="ismene@example.org/Fo6Eeb2e"> <body>No mind that ever lived stands firm in evil days, but goes astray.</body> </message>
Types ¶
type DecodeCloser ¶
DecodeCloser is the interface that groups Decoder and io.Closer.
type DecodeEncoder ¶
DecodeEncoder is the interface that groups the Encoder and Decoder interfaces.
type Decoder ¶
type Decoder interface { xml.TokenReader Decode(v interface{}) error DecodeElement(v interface{}, start *xml.StartElement) error }
Decoder is the interface that groups the Decode, DecodeElement, and Token methods. Decoder is implemented by xml.Decoder.
type EncodeCloser ¶
EncodeCloser is the interface that groups Encoder and io.Closer.
type Encoder ¶
type Encoder interface { TokenWriter Encode(v interface{}) error EncodeElement(v interface{}, start xml.StartElement) error }
Encoder is the interface that groups the Encode, EncodeElement, and EncodeToken methods. Encoder is implemented by xml.Encoder.
type Flusher ¶
type Flusher interface {
Flush() error
}
The Flusher interface is implemented by TokenWriters that can flush buffered data to an underlying receiver.
type FmtOption ¶
type FmtOption func(*fmter)
FmtOption is used to configure a formatters behavior.
func Indent ¶
Indent is inserted before XML elements zero or more times according to their nesting depth in the stream. The default indentation is " " (two ASCII spaces).
type Iter ¶
type Iter struct {
// contains filtered or unexported fields
}
Iter provides a mechanism for iterating over the children of an XML element. Successive calls to the Next method will step through each child, returning its start element and a reader that is limited to the remainder of the child.
func NewIter ¶
func NewIter(r xml.TokenReader) *Iter
NewIter returns a new iterator that iterates over the children of the most recent start element already consumed from r.
func (*Iter) Close ¶
Close indicates that we are finished with the given iterator. Calling it multiple times has no effect.
If the underlying TokenReader is also an io.Closer, Close calls the readers Close method.
func (*Iter) Current ¶
func (i *Iter) Current() (*xml.StartElement, xml.TokenReader)
Current returns a reader over the most recent child.
type Marshaler ¶
type Marshaler interface {
TokenReader() xml.TokenReader
}
Marshaler is the interface implemented by objects that can marshal themselves into valid XML elements.
type PipeReader ¶
type PipeReader struct {
// contains filtered or unexported fields
}
A PipeReader is the read half of a token pipe.
func (*PipeReader) Close ¶
func (r *PipeReader) Close() error
Close closes the PipeReader; subsequent reads from the read half of the pipe will return a nil token and EOF.
func (*PipeReader) CloseWithError ¶
func (r *PipeReader) CloseWithError(err error)
CloseWithError closes the PipeReader; subsequent reads from the read half of the pipe will return no tokens and the error err, or EOF if err is nil.
func (*PipeReader) Token ¶
func (r *PipeReader) Token() (t xml.Token, err error)
Token implements the TokenReader interface. It reads a token from the pipe, blocking until a writer arrives or the write end is closed. If the write end is closed with an error, that error is returned as err; otherwise err is io.EOF.
type PipeWriter ¶
type PipeWriter struct {
// contains filtered or unexported fields
}
A PipeWriter is the write half of a token pipe.
func (*PipeWriter) Close ¶
func (w *PipeWriter) Close() error
Close closes the PipeWriter; subsequent reads from the read half of the pipe will return a nil token and EOF.
func (*PipeWriter) CloseWithError ¶
func (w *PipeWriter) CloseWithError(err error)
CloseWithError closes the PipeWriter; subsequent reads from the read half of the pipe will return no tokens and the error err, or EOF if err is nil.
func (*PipeWriter) EncodeToken ¶
func (w *PipeWriter) EncodeToken(t xml.Token) error
EncodeToken implements the TokenWriter interface. It writes a token to the pipe, blocking until one or more readers have consumed all the data or the read end is closed. If the read end is closed with an error, that err is returned as err; otherwise err is ErrClosedPipe.
func (*PipeWriter) Flush ¶
func (w *PipeWriter) Flush() error
Flush is currently a noop and always returns nil.
type ReaderFrom ¶
type ReaderFrom interface {
ReadXML(xml.TokenReader) (n int, err error)
}
ReaderFrom reads tokens from r until EOF or error. The return value n is the number of tokens read. Any error except io.EOF encountered during the read is also returned.
The Copy function uses ReaderFrom if available.
type ReaderFunc ¶
ReaderFunc type is an adapter to allow the use of ordinary functions as an TokenReader. If f is a function with the appropriate signature, ReaderFunc(f) is an TokenReader that calls f.
type TokenReadCloser ¶
type TokenReadCloser interface { xml.TokenReader io.Closer }
TokenReadCloser is the interface that groups the basic Token and Close methods.
func NopCloser ¶
func NopCloser(r xml.TokenReader) TokenReadCloser
NopCloser returns a TokenReadCloser with a no-op Close method wrapping the provided Reader r.
type TokenReadEncoder ¶
type TokenReadEncoder interface { xml.TokenReader Encoder }
TokenReadEncoder is the interface that groups the Encode, EncodeElement, EncodeToken, and Token methods.
type TokenReadWriteCloser ¶
type TokenReadWriteCloser interface { xml.TokenReader TokenWriter io.Closer }
TokenReadWriteCloser is the interface that groups the basic Token, EncodeToken, Flush, and Close methods.
type TokenReadWriter ¶
type TokenReadWriter interface { xml.TokenReader TokenWriter }
TokenReadWriter is the interface that groups the basic Token, EncodeToken, and Flush methods.
type TokenWriteCloser ¶
type TokenWriteCloser interface { TokenWriter io.Closer }
TokenWriteCloser is the interface that groups the basic EncodeToken, and Close methods.
type TokenWriteFlushCloser ¶
type TokenWriteFlushCloser interface { TokenWriter io.Closer Flusher }
TokenWriteFlushCloser is the interface that groups the basic EncodeToken, Flush, and Close methods.
type TokenWriteFlusher ¶
type TokenWriteFlusher interface { TokenWriter Flusher }
TokenWriteFlusher is the interface that groups the basic EncodeToken, and Flush methods.
type TokenWriter ¶
TokenWriter is anything that can encode tokens to an XML stream, including an xml.Encoder.
func Discard ¶
func Discard() TokenWriter
Discard returns a TokenWriter on which all calls succeed without doing anything.
func MultiWriter ¶
func MultiWriter(writers ...TokenWriter) TokenWriter
MultiWriter creates a writer that duplicates its writes to all the provided writers, similar to the Unix tee(1) command. If any of the writers return an error, the MultiWriter immediately returns the error and stops writing.
type Transformer ¶
type Transformer func(src xml.TokenReader) xml.TokenReader
A Transformer returns a new TokenReader that returns transformed tokens read from src.
func Insert ¶
func Insert(name xml.Name, m Marshaler) Transformer
Insert adds one XML stream to another just before the close token, matching on the token name. If either component of the name is empty it is considered a wildcard.
func InsertFunc ¶
func InsertFunc(f func(start xml.StartElement, level uint64, w TokenWriter) error) Transformer
InsertFunc calls f after writing any start element to the stream. The function can decide based on the passed in StartElement whether to insert any additional tokens into the stream by writing them to w.
func Inspect ¶
func Inspect(f func(t xml.Token)) Transformer
Inspect performs an operation for each token in the stream without transforming the stream in any way.
func Map ¶
func Map(mapping func(t xml.Token) xml.Token) Transformer
Map returns a Transformer that maps the tokens in the input using the given mapping.
func Remove ¶
func Remove(f func(t xml.Token) bool) Transformer
Remove returns a Transformer that removes tokens for which f matches.
func RemoveAttr ¶
func RemoveAttr(f func(start xml.StartElement, attr xml.Attr) bool) Transformer
RemoveAttr returns a Transformer that removes attributes from xml.StartElement's if f matches.
func RemoveElement ¶
func RemoveElement(f func(start xml.StartElement) bool) Transformer
RemoveElement returns a Transformer that removes entire elements (and their children) if f matches the elements start token.
Example ¶
Output: <quote> <p xml:lang="fr">et c’est ainsi que la roue du temps amène les occasions de revanche.</p> </quote>
type WriterTo ¶
type WriterTo interface {
WriteXML(TokenWriter) (n int, err error)
}
WriterTo writes tokens to w until there are no more tokens to write or when an error occurs. The return value n is the number of tokens written. Any error encountered during the write is also returned.
The Copy function uses WriterTo if available.
Notes ¶
Bugs ¶
Multiple uses of RemoveAttr will iterate over the attr list multiple times.