xml parser

help.go

package parsing

import (
	"encoding/xml"
	"io"
	"log"
	"reflect"

	"code.google.com/p/go-charset/charset"
	_ "code.google.com/p/go-charset/data" //
)

// StreamXML holds the chan that you will
// need to read your xml from.
type StreamXML struct {
	Stream  chan interface{}
	Element string
}

// NewStreamXML returns a new StreamXML
// struct that will parse on tokens matching
// the passed in element and makes a stream
// of type x. Paincs on wront input types.
func NewStreamXML(element string) *StreamXML {
	return &StreamXML{
		Stream:  make(chan interface{}),
		Element: element,
	}
}

// StreamingDecode takes an io.Reader and marshals the
// value into a given structure
func (s *StreamXML) StreamingDecode(r io.Reader, x interface{}) {
	if reflect.TypeOf(x).Elem().Kind() != reflect.Struct &&
		reflect.TypeOf(x).Kind() == reflect.Ptr {
		panic("StreamingDecode expects a ptr to a struct for the second param")
	}
	decoder := xml.NewDecoder(r)
	decoder.CharsetReader = charset.NewReader

	for {
		t, err := decoder.Token()
		// This code is really just checking if
		// err is signaling to us that we have
		// hit the end of the file with io.EOF
		if err != nil {
			close(s.Stream)
			break
		}

		switch e := t.(type) {
		case xml.StartElement:
			// Look for tokens that are the same as the passed in
			// elem string and decode them into a struct
			if e.Name.Local == s.Element {
				err = decoder.DecodeElement(reflect.ValueOf(x).Interface(), &e)
				if err != nil {
					log.Printf("%s", err.Error())
				}
				// send it down stream
				s.Stream <- x
			}
		}
	}
}