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parse.go
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parse.go
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package narcissus
import (
"fmt"
"reflect"
"strconv"
"strings"
)
// Parse parses a structure pointer and feeds its fields with Augeas data
func (n *Narcissus) Parse(val interface{}) error {
ref, err := structRef(val)
if err != nil {
return fmt.Errorf("invalid interface: %v", err)
}
err = n.Autoload(ref)
if err != nil {
return fmt.Errorf("failed to autoload file: %v", err)
}
path, err := getPath(ref)
if err != nil {
return fmt.Errorf("undefined path: %v", err)
}
return n.parseStruct(ref, path)
}
func (n *Narcissus) parseStruct(ref reflect.Value, path string) error {
refType := ref.Type()
for i := 0; i < refType.NumField(); i++ {
if refType.Field(i).Name == "augeasPath" {
// Ignore the special `augeasPath` field
continue
}
value, err := n.getField(ref.Field(i), refType.Field(i), path)
// TODO: implement omitempty
if err == errNodeNotFound {
continue
}
if err != nil {
return fmt.Errorf("failed to retrieve field %s: %v", refType.Field(i).Name, err)
}
if value == "" {
// for now
continue
}
err = setField(ref.Field(i), refType.Field(i), value)
if err != nil {
return err
}
}
return nil
}
func (n *Narcissus) getField(field reflect.Value, fieldType reflect.StructField, path string) (interface{}, error) {
fieldPath := fmt.Sprintf("%s/%s", path, parseTag(fieldType.Tag).path)
if field.Kind() == reflect.Slice {
return n.getSliceField(field, fieldType, path, fieldPath)
} else if field.Kind() == reflect.Map {
return n.getMapField(field, fieldType, fieldPath)
}
return n.getSimpleField(fieldType.Type, fieldPath, fieldType.Tag)
}
func (n *Narcissus) getSimpleField(fieldType reflect.Type, fieldPath string, tag reflect.StructTag) (interface{}, error) {
aug := n.Augeas
var value string
var err error
if parseTag(tag).valueFromLabel {
value, err = aug.Label(fieldPath)
} else {
value, err = aug.Get(fieldPath)
}
if err != nil && strings.Contains(err.Error(), "No matching node") {
return nil, errNodeNotFound
}
switch fieldType.Kind() {
case reflect.String:
return value, nil
case reflect.Bool:
bvalue, err := strconv.ParseBool(value)
if err != nil {
return nil, fmt.Errorf("failed to convert %s to bool: %v", value, err)
}
return bvalue, nil
case reflect.Int:
intValue, err := strconv.ParseInt(value, 10, 32)
if err != nil {
return nil, fmt.Errorf("failed to convert %s to int: %v", value, err)
}
return int(intValue), nil
}
return nil, fmt.Errorf("unsupported type %s", fieldType.Kind())
}
func (n *Narcissus) getSliceField(field reflect.Value, fieldType reflect.StructField, path, fieldPath string) (interface{}, error) {
aug := n.Augeas
if parseTag(fieldType.Tag).seq {
fieldPath = fmt.Sprintf("%s/*[label()=~regexp('[0-9]*')]", path)
}
matches, err := aug.Match(fieldPath)
if err != nil {
return nil, err
}
values := reflect.MakeSlice(field.Type(), len(matches), len(matches))
for i, m := range matches {
value, err := n.getStructOrSimpleField(field, m)
if err != nil {
return nil, fmt.Errorf("Failed to get slice element: %v", err)
}
values.Index(i).Set(value)
}
return values.Interface(), nil
}
func (n *Narcissus) getMapField(field reflect.Value, fieldType reflect.StructField, fieldPath string) (interface{}, error) {
aug := n.Augeas
values := reflect.MakeMap(field.Type())
matches, err := aug.Match(fieldPath)
if err != nil {
return nil, err
}
for _, m := range matches {
var label string
if parseTag(fieldType.Tag).keyFromLabel {
label, err = aug.Label(m)
} else {
label, err = aug.Get(m)
}
if err != nil {
return nil, err
}
value, err := n.getStructOrSimpleField(field, m)
if err != nil {
return nil, fmt.Errorf("Failed to get map element: %v", err)
}
values.SetMapIndex(reflect.ValueOf(label), value)
}
return values.Interface(), nil
}
func (n *Narcissus) getStructOrSimpleField(field reflect.Value, path string) (value reflect.Value, err error) {
vType := field.Type().Elem()
if vType.Kind() == reflect.Struct {
vStruct := reflect.New(vType)
err = n.parseStruct(vStruct.Elem(), path)
if err != nil {
err = fmt.Errorf("failed to get element: %v", err)
return
}
return vStruct.Elem(), nil
}
val, err := n.getSimpleField(vType, path, "")
if err != nil {
err = fmt.Errorf("failed to get element: %v", err)
return
}
return reflect.ValueOf(val), nil
}
func setField(field reflect.Value, fieldType reflect.StructField, value interface{}) error {
if !field.CanSet() {
return fmt.Errorf("cannot set field %s", fieldType.Name)
}
v := reflect.ValueOf(value)
if field.Kind() == v.Kind() {
field.Set(v)
return nil
}
return fmt.Errorf("Wrong value type (%v for %v)", v.Kind(), field.Kind())
}