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decode.go
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decode.go
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package hl7x
import (
"errors"
"fmt"
"reflect"
"github.com/kdar/health/hl7"
)
func Unmarshal(src hl7.Data, dst interface{}) error {
v := reflect.ValueOf(dst)
if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
return errors.New("interface must be a pointer to struct")
}
v = v.Elem()
d := newDecoder()
d.decode(src, reflect.ValueOf(dst).Elem())
if d.err.Errors != nil {
return d.err
}
return nil
}
type decoder struct {
err *Error
}
func newDecoder() *decoder {
return &decoder{
err: &Error{},
}
}
func (d *decoder) decode(src hl7.Data, dst reflect.Value) {
dstKind := dst.Kind()
switch dstKind {
case reflect.String:
d.decodeString(src, dst)
case reflect.Struct:
d.decodeStruct(src, dst)
case reflect.Slice:
d.decodeSlice(src, dst)
default:
d.err.append(fmt.Errorf("unsupported type: %s", dstKind))
return
}
}
func (d *decoder) decodeString(src hl7.Data, dst reflect.Value) {
v, ok := src.(hl7.Field)
if !ok {
d.err.append(fmt.Errorf("decodeString: src is not a hl7.Field, it's: %s", reflect.TypeOf(src)))
return
}
dst.SetString(string(v))
}
func (d *decoder) decodeStruct(src hl7.Data, dst reflect.Value) {
typ := dst.Type()
for i := 0; i < typ.NumField(); i++ {
field := typ.Field(i)
fieldName := field.Name
fieldValue := dst.FieldByName(fieldName)
// So just skip it.
if !fieldValue.CanSet() {
d.err.append(fmt.Errorf("%s.%s is not settable", typ.Name(), fieldName))
continue
}
index := i
if _, ok := src.(hl7.Segment); ok {
index += 1
}
newSrc, ok := src.Index(index)
if !ok {
//d.err.append(fmt.Errorf("could not find src index for %s.%s", typ.Name(), fieldName))
continue
}
d.decode(newSrc, fieldValue)
}
}
func (d *decoder) decodeSlice(src hl7.Data, dst reflect.Value) {
dstType := dst.Type()
dstElemType := dstType.Elem()
sliceType := reflect.SliceOf(dstElemType)
srcLen := src.Len()
dstSlice := reflect.MakeSlice(sliceType, srcLen, srcLen)
for i := 0; i < srcLen; i++ {
currentField := dstSlice.Index(i)
if newSrc, ok := src.Index(i); ok {
d.decode(newSrc, currentField)
}
}
dst.Set(dstSlice)
}